WO2013171542A1 - Polymer-metallic nanoparticle hybrid materials - Google Patents

Abstract

The present invention discloses new materials elaborated upon organo-heteroatom (silicon or germanium) polymers (poly(amide-imide)s and poly(amide)s) and a metallic film, such as, but not limited to, copper, silver or gold, having the processability and malleability of a polymer and the structural, thermal, optical, electrical and other characteristics from the metals that it absorbs. The polymers of the invention have the capacity to incorporate, with covalent bonds, in coordinated and arranged form, the metals to its structure, generating a new macromolecular material. The invention is also related to a new method to prepare polymer-metallic nanoparticle hybrid materials, comprising the steps of a) providing a polymer solution dissolving the organo- heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) in an aprotic polar organic solvent; b) providing a metal film from the selected metal; c) dispersing the polymer solution by spin coating on the metal film; and d) simultaneous absorption, nano- encapsulation or incorporation of the metal into the polymer matrix.

Description

POLYMER-METALLIC NANOPARTICLE HYBRID MATERIALS TECHNICAL FIELD

The present invention relates to material sciences field describing polymeric matrices (organo- heteroatom (silicon or germanium) polymers (poly(amide-imide)s or poly(amide)s)) that incorporates different metals, such as, copper, silver or gold, adding structural, thermal, optical, and electrical characteristics from the metals to the polymer. Thus, the synergism or integration of metallic particles into a polymer matrix produces changes or modifications of the initial properties of the systems. Therefore, the new polymer-metallic nanoparticle hybrid materials constitute a kind of advanced composite with interesting properties which can be also used in a broad range of applications such as: electronic and magnetic devices, optoelectronic industry, copper corrosion applications, medical applications, imaging, catalysis, sensors and adhesives. The present invention is also related to a new method to prepare polymer-metallic nanoparticle hybrid materials.

BACKGROUND ART

Polymers have been used in a broad range of applications. In electronic devices, such as, field- effect transistors, sensors, light emitting diodes, LED screens, in the medical field, for tissue regeneration, drugs and active principles controlled release, among others. Nevertheless, the field where these materials can be use as conductors, with embedded metals into the polymeric matrix, has been poorly researched. Only researches describing the use of polymeric matrices with metallic particle groups, forming a composite are currently known.

The polymer-metallic nanoparticle hybrid materials have recently attracted considerable attention owing to their potential application in the catalysis, sensors, memory devices, nonlinear optics and optical filters fields (Raffa P, Evangelisti C, Vitelli G, Salvatori P. (2008). First examples of gold nanoparticles catalyzed sihne alcoholysis and silylative pinacol coupling of carbonyl compounds. Tetrahed. Letter., 49: 3221-3224; Arcadi A. (2008). Alternative Synthetic Methods through New Developments in Catalysis by Gold. Chem. Rev., 108: 3266-3325₅ Lin P, Yan F, Yu J, Chan HLW, Yang M. (2010). The Application of Organic Electrochemical Transistors in Cell-Based Biosensors. Adv. Mater., 22: 3655-3660; Lin P, Yan F, Chan HLW. (2010). Ion Sensitive Properties of Organic Electrochemical Transistors. ACS Appl. Mater. Interfaces, 2: 1637-1641 ; Chen Q, Zhao L, Li C, Shi G. (2007). Electrochemical Fabrication of a Memory Device Based on Conducting Polymer Nanocomposites. J. Phys. Chem. C, 111 : 18392-18396; Innocenzi P, Lebeau B. (2005). Organic-inorganic hybrid materials for nonlinear optics. J. Mater. Chem., 15: 3821 -3831 ; De Leon AG, Dirix Y, Staedler Y, Feldman K, Hahner, G., Caseri, W. R., Smith, P. (2000). Method for fabricating pixelated, multicolor Polarizing Films. Appl. Optics, 39: 4847-4851)

Well-dispersed metal nanoparticles in dry polymer films (polymer-metallic nano composites) show the same optical behavior as that in solution, if there is no aggregation of metal particles in the polymer films. The optical properties of the film can be tuned by adjusting the particle size and spacing. Interestingly, such dispersion of nanoparticles in the polymer matrix alters the properties of the host polymer matrix such as tensile strength, glass transition temperature, thermal degradation and viscoelastic properties (Mbhele ZH, Salemane MG, E van Sittert CGC, Nedeljkovic JM, Djokovic V, Luyt AS. (2003). Fabrication and Characterization of Silver-Polyvinyl Alcohol Nano composites. Chem. Mater., 15: 5019-5024; Takele H, Schiirmann U, Greve H, Paretkar D, Zaporojtchenko V, Faupel F. (2006). Controlled growth of Au nanoparticles in co-evaporated metal/polymer composite films and their optical and electrical properties. Eur. Phys. J. Appl. Phys., 33: 83-89; Giesfeldt KS, Connatser RM, De Jesus MA, Lavrik NV, Dutta P, Sepaniak MJ. (2003). Studies of the Optical Properties of Metal-Pliable Polymer Composite Materials. Appl. Spectroscopy, 57(11): 1346-1352).

Previous studies on the successful preparation of polymer/metal hybrids were based on three different techniques. The first method consists in the "in-situ" preparation of nanoparticles in the matrix, either by the reduction of metal salts dissolved in the polymer matrix (Mayer A. B. R. (1998). Formation of noble metal nanoparticles within a polymeric matrix: nanoparticle features and overall morphologies. Mater. Sci. Eng. C, 6: 155-166; Selvan ST, Spatz JP, Klok HA, Moller M. (1998). Gold-Polypyrrole Core-Shell Particles in Diblock Copolymer Micelles. Adv. Mater., 10(2): 132-134; Watkins JJ, McCarthy TJ. (1995). Polymer/Metal Nanocomposite Synthesis in Supercritical CO₂. Chem. Mater., 7: 1991-1994) or by the evaporation of metals on the heated polymer surface (Sayo K, Deki S, Hayashi S. (1999). A novel method of preparing nano-sized gold and palladium particles dispersed in composites that uses the thermal rehxation technique. Eur. Phys. J.D., 9(1-4): 429-432). Another method is the polymerization of the matrix around the nanoparticles (Lee J, Sundar VC, Heine JR, Bawendi MG, Jensen KF. (2000). Full Color Emission from II— VI Semiconductor Quantum Dot— Polymer Composites. Adv. Mater., 12(15): 1102-1105). The third technique is the blending of pre-made metallic nanoparticles with pre-made polymer since this method provides full synthetic control over both the nanoparticles and the polymer matrix (Mallick K, Witcomb MJ, Erasmus R, Strydom A. (2009). Low- temperature magnetic property of polymer encapsulated gold nanop articles. J. Appl. Phys., 106: 074303-074308). Moreover, using an appropriate stabilizer the metallic nanoparticles can be blended with a variety of polymers. However, the dispersion of the nanoparticles in the system is incompatible nature due to the hydrophobic characteristics of the polymer.

STATE OF THE ART

Document US7750076B2 describes a polymer layer comprising silicone contains oxide particles of S1O₂, T1O₂, Sb₂0₃, SnC>₂, AI₂O₃, ZnO, Fe₂0₃, Fe₃0₄, talc, hydro xyapatite or mixtures thereof and one or more metal traces embedded in the polymer layer, where the metal trace is bonded to the polymer silicon metal bond. The polymer can be other than silicone and the metal traces can include titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver or gold, or an alloy of two or more metals, or a combination of two or more alloys or metal layers thereof.

Document WO2006131616A1 relates to a new type of molecular junction in which molecules belonging to the families of 7-dialkylamino phenothiazines, 7-dialkylamino phenoxazines and of 5-alkyl or 5-aryl, 7-dialkylamino phenazines are grafted to a semiconductor by establishing a covalent bond between their carbon 3 and a surface atom of a semiconductor that can be a silicon atom, arsenic atom or germanium atom, and in which a metal is then electrolytically deposited onto the grafted surface of the semiconductor. The document also relates to a new type of molecular junction in which the grafting of preceding organic molecules to a semiconductor is followed by the polymerization of acrylonitrile or N-vinyl-imidazole forming a polymer connected by a covalent bond to the grafted molecules and in which a metal, preferably copper, is then electrolytically deposited onto the grafted surface of the semiconductor. The inventive devices are particularly used for producing new types of electronic components and for realizing copper deposits in the submicronic semiconductor structures.

There is not disclosure in the state of the art related to polymeric matrices that contain silicon or germanium in the main chain that incorporate metals, such as, copper, silver or gold, and acquire the structural, thermal, optical, and electrical characteristics from the metals, keeping its processability and malleability characteristics. Most of the documents in the state of the art describe silicon polymers based on siloxane, they are not related to the present invention, because it is based on organo-heteroatom (silicon or germanium) polymers (poly(amide-imide)s or poly(amide)s). There are several disclosures related to films and deposits of metals in the surface of polymers, but the present invention discloses a polymer that absorbs the metal into its structure, generating polymer-metallic nanoparticle hybrid materials.

SUMMARY OF THE INVENTION

The present invention discloses new materials having the processability and malleability of a polymer and the structural, thermal, optical, and electrical characteristics from the metals that it absorbs (such as copper, silver or gold). The present invention uses an organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) and a metal film as substrates for a process at room temperature, humidity and pressure generating polymer-metallic nanoparticle hybrid materials. The new materials are conductors that can be used in electronic and magnetic devices, optoelectronic industry, copper corrosion applications, medical applications, imaging, catalysis and adhesives. The present invention is also related to a new method to prepare polymer-metallic nanoparticle hybrid materials.

DETAILED DESCRIPTION OF THE INVENTION

The present invention discloses new materials elaborated upon organo-heteroatom (silicon or germanium) polymers (poly(amide-imide)s or poly(amide)s) and a metallic film, such as, but not limited to copper, silver or gold, having the processability and malleability of a polymer and the structural, thermal, optical, electrical and other characteristics from the metals that it absorbs.

The polymers of the invention have the capacity to incorporate, with covalent bonds, in coordinated and arranged form, the metals to its structure, generating a new macromolecular material, keeping or improving the original properties of the polymers, adding the properties of the coordinated metal.

The organo-heteroatom (silicon or germanium) polymer for the new macromolecular material is selected among poly(amide-imide) or poly(amide) and the metal is selected among, but not limited to copper, gold, or silver.

The new materials are poly(amide-imide)-metallic nanoparticle hybrids and poly(amide)- metallic nanoparticle hybrids, using different kinds of pure metals, such as, but not limited to copper, silver, or gold. The characterization experimental techniques involve the use of solid UV-vis and Raman spectroscopy, X-ray diffraction and Scanning Electronic Microscopy (SEM). All these techniques contribute to discover a possible mechanism of interaction between the metal cluster and the capping polymer and shed light on the relationship between polymer adsorption and the cluster size and distribution.

The present invention is also related to a new method at room temperature, humidity and pressure to prepare polymer-metallic nanoparticle hybrid materials. The method for preparing the polymer-metallic nanoparticle hybrid materials comprises the steps of a) providing a polymer solution dissolving the organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) in an aprotic polar organic solvent; b) providing a metal film from the selected metal; c) dispersing the polymer solution by spin coating on the metal film; and d) simultaneous absorption, nano-encapsulation or incorporation of the metal into the polymer matrix.

The preparation of the new materials, starts with a polymeric solution, which is dispersed by spin coating on a metallic substrate (such as Cu, Ag or Au), previously deposited by physical vapor deposition (PVD). Additionally, metal film can be realized with other methods such as: Chemical vapor deposition (CVD) or sputtering. Immediately, when the polymer gets in contact with the metal, the nano-encapsulation, absorption or incorporation of the metal into the polymer matrix is produced. In addition, the objective of this invention enhances the understanding of the polymer-metal interaction.

The polymerization of the polymer matrix of the present invention is carried out by standard methods, known by a person having ordinary skill in the art (Figure 1 and Figure 2) (Faghihi K, Shabanian M, Hajibeygi M. (2009). Optically Active and Organosoluble Poly(amide-imide)s Derived from N,N'-(Pyromellitoyl)bis-L-histidine and Various Diamines: Synthesis and Characterization. Macromolecular Research, 17 (11): 912-918; Yamazaki N., Matsumoto M., Higashi F. (1975). Studies on Reactions of the N-Phosphonium Salts of Pyridines. XW. Wholly Aromatic Polyamides by the Direct Polycondensation Reaction by Using Phosphites in the Presence of Metal Salts. J. Polym. Sci., Polym. Chem. Ed., 13: 1373-1380; Gonzalez CM, Tagle LH, Terraza CA., Barriga A, Volkmann UG, Cabrera AL, Ramos-Moore E, Pavez-Moreno M. (2011). Structural symmetry breaking of silicon-containing poly(amide-imide) oligomers and their relation with electrical conductivity and Raman active vibrations. Polym. Int., 61(2): 197- 204; CM. Gonzalez-Henriquez, L.H. Tagle, C.A. Terraza, A. Barriga Gonzalez, U.G. Volkmann, A.L. Cabrera, E. Ramos-Moore, M. Pavez-Moreno (2012). In a preferred embodiment, the organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) is preparing upon a mixture of dicarboxylic acid, diamine, anhydrous calcium dichloride (CaC^), triphenylphosphite (TPP), pyridine (Py) and N-methyl-2-pirrolydone (ΝΜΡ) that is heated at 100-130 °C during 2-5 hours under stirring. In a preferred embodiment, the stirring is performed at 110 °C. In another preferred embodiment, the stirring is performed during three hours. Normal yields for this procedures are between 78-90 % and 70-73 % yields by poly(amide-imide)s and poly(amide)s; respectively. The poly(amide-imide)s used in the present invention are shown in Figure 1, where R= -CH₃ (PALA); (CH₃)₂CHCH₂- (PALL); (CH₃)₂CH- (PALV) and PhCH₂- (P ALPHA). The poly(amide)s used in the present invention are shown in Figure 2, (PAtX), where X= Si (PAtSi) and X= Ge (PAtGe).

In a preferred embodiment the preparation of the metal films is realized by the following procedure: evaporation of metal grains with a purity of 99.90-99.95 % by Physical Vapor Deposition (PVD) in high vacuum onto a glass substrate at room temperature (20-30 °C) is performed. The metal for the film is selected among, but not limited to copper, silver, or gold. In a preferred embodiment, the metal is copper, silver or gold. In another preferred embodiment, the metal has a purity of at least 99.90 %. In a preferred embodiment the glass substrate temperature is 25 °C. Metal film thicknesses are between 30-70 nm. In a preferred embodiment, the thicknesses of the films are 50 nm. On top of the metal films, the polymer dissolved in an aprotic polar organic solvent at concentration between 0.05-2.00 mgl\L is deposited by spin coating using rotation velocity ramps: 300-700 rpm for 5-25 s and 1000-2000 rpm for 5-25 s. In a preferred embodiment, the polymers are dissolved in dimethylsulfoxide (DMSO) at 0.09 mgl\L and the spin coating process is developed using 500 rpm during 10 s and 1600 rpm for 10 s.

The incorporation of the metal into the polymer is produced immediately when the polymer gets in contact with the metal film. The complete process can take from a few minutes to several hours. This incorporation kinetic can be controlled, by modifying kinetic parameters (reaction conditions), and the specific structure of the polymer.

The new method is a promising alternative to existing conventional methods which need of a mixing device for a physical mixture of the solutions made at room temperature and thus producing the nano-encapsulation of the metals into the polymer. In the new proposed methodology, the metallic nanoparticles are dispersed in the poly(amide-imide)s matrices due to the coordinate covalent bonds between the metal and the silicon or germanium atoms. Moreover, poly(amide)s with a thiophene moiety in the main chain produce the incorporation of the metal in their structure changing the crystalline pattern of the system.

The new materials severely increase their electric and thermal transport capacity.

There are semi-conductive polymers having a low conductivity (10^~6 S/cm), that are more like insulators, and must be oxidized to increase their conductivity. This property is related to the polymer structure. Nevertheless, the new materials of the present invention has the special characteristic of having charge carriers inside of their structure, which movement of electrons is performed by percolation, similar to a heavy metal. This fact implies that the incorporation of the metal into the polymeric structure is highly arranged, because of the covalent bonds that originate the incorporation. The metals itself are conductors, but since they have extremely poor processability and malleability properties, they can not be used in devices that need these properties. The present invention combines all these properties, generating a new material with the processability and malleability of the polymers and conductivity and other electrical properties of the metals.

The adhesive industry has not found an optimal way to produce the adhesion between polymer and metal, due to lack of strong interactions, such as covalent or ionic bonds. The present invention provides a complete, stable and arranged inclusion of the metal into the polymer, a property that could be used in this industry.

The inclusion of a metal, such as copper and silver, with bactericide properties, into a polymer is very important for the medical industry. The new material of the invention, with their high processability and malleability that also include bactericide properties from metal can certainly be used in medical applications. On the other hand, the inclusion of gold into polymer can be used in biological sensors. Thus, the low toxicity shown by this metal is an advantage in biological and medical application. Therefore, the modification of some initial optical properties such as fluorescence is widely used in biomarkers that allow the detection and quantification of biological systems, such as proteins.

The new polymer-metallic nanoparticle hybrid materials can be used in electronic and magnetic devices due to that the new materials are conductors of electricity, optoelectronic industry, copper corrosion applications, due to the protection that confers the polymeric matrix, medical applications due to that the new materials have bactericide and optical (absorption, transmittance and fluorescence) properties and adhesives due to that the covalent bonds between the polymer and the metal allow the interaction for a strong adhesion. Other possible applications would be related to the imaging and the catalysis fields.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 : Schematic representation of synthesis of poly(amide-imide)s, where R= -CH₃ (PALA); (CH₃)₂CHCH₂- (PALL); (CH₃)₂CH- (PALV) and PhCH₂- (P ALPHA).

Figure 2: Schematic representation of synthesis of poly(amide)s (PAtX), where X= Si (PAtSi) and X= Ge (PAtGe).

Figure 3: Four point measurements of conductivity in polymers.

Figure 4: Raman spectroscopy of poly(amide-imide)s with the incorporation of copper (Cu), silver (Ag) and gold (Au): a) PALA; b) PALL; c) PALV and d) P ALPHA.

Figure 5 : Raman spectroscopy of poly(amide)s with incorporation of copper (Cu), silver (Ag) and gold (Au): a) PAtSi and b) PAtGe.

Figure 6: XRD patterns of poly(amides-imide)s with incorporation of copper (Cu), silver (Ag) and gold (Au): a) PALA; b) PALL; c) PALV and d) PALPHA

Figure 7: X-Ray diffraction of poly(amide)s with incorporation of copper (Cu), silver (Ag) and gold (Au): a) PAtSi and b) PAtGe.

Figure 8: SEM micrographs of poly(amide-imide)-metal hybrids.

Figure 9: Poly(amides-imide)-metal hybrids: a) Nanoparticle areas and b) Elemental analysis results.

Figure 10: SEM micrographs of poly(amide) -metal hybrids.

Figure 11 : Elemental analysis of poly(amide)-metallic nanoparticle hybrids.

Figure 12: Possible mechanism for generation of polymer-metallic nanoparticle hybrids: a) poly(amide-imide)s and b) poly(amide)s.

EXPERIMENTAL SECTION In this section illustrative examples are given as guidance, therefore, these examples are in no way to be construed as limiting.

EXAMPLES

Example 1: Preparation of the metal films of silver, gold or copper

Evaporation of gold or silver grains with a purity of 99.95 % from ESPI (Electronic Space Products International) by Physical Vapor Deposition (PVD) in high vacuum onto a glass substrate at room temperature was performed. Gold and silver film thicknesses were 50 nm. In the same way small copper pieces with purity of 99.90 % (ESPI copper sheet material of 0.01 " thickness) were evaporated by PVD. Copper film thickness on the glass substrate was also 50 nm.

Example 2: Preparation of polymer- metallic nano particle hybrid materials

On top of the metal films preparing in Example 1, the polymer solution was deposited by spin coating using rotation velocity ramps: 500 rpm about 10 s and 1600 rpm for 10 s.

Example 3: Characterization of polymer-metallic nano particle hybrid films

Polymer-metallic nanoparticle hybrid films prepared according to the present invention were characterized by UV-visible spectroscopy. These optical measurements were carried out by using UV-visible spectrophotometer (UV-2450 Shimadzu) and scanning the spectra between 200-800 nm at a resolution of 1 nm using barium sulfate as standard compound. To determine the resistance and conductivity in the hybrid films a four point probe system, connected to a multimeter (Keithley, Model 2000-200) was utilized (Figure 3).

The structural and vibration properties of the hybrid films were characterized by Raman spectroscopy with a Lab Ram 010 instrument from ISA equipped with a 5.5 mW HeNe laser beam (633 nm). The Raman microscope uses a back- scattering geometry, where the incident beam is linearly polarized at 500:1 ratio. The objective lens of the microscope was an Olympus Mplan lOOx (numerical aperture 0.9), which provide sufficient distance between the objective and the samples. The integration time was 25 s for all the samples with an accumulation of 5 s. X-ray diffraction patterns of the hybrid materials were taken at room temperature with a Bruker D-8 Advanced Diffractometer, using a tube with a copper anode (λ(ΟιΚα) = 0.154 nm). The diffraction patterns were obtained in the usual Θ-2Θ geometry. The X-ray tube was operated at 40 kV and 40 mA. The goniometer was swept between 5 ° and 140 ° at 0.02 7s over the whole 2Θ interval. The diffracted X-rays were detected with a scintillation detector.

The morphology of the hybrid films was examined with a scanning electron microscope (SEM), model LEO 1420VP, 100 μΑ beam current and a working distance of 12-14 mm. The microscope was operated at high vacuum (~10^~5 mbar).

Example 4: Optical and electrical properties

The optical properties of the poly(amide-imide)-metallic nanoparticles and poly(amide)-metallic nanoparticle hybrids were studied by solid UV-vis spectra, whose results are showed in Table 1 and Table 2. These analyses describe the electronic transitions and the possible formation of the surface plasmon resonance (SRS) (Storhoff AJJ, Elghanian R, Mirkin CA, Letsinger RL. (2002). Sequence-Dependent Stability of DNA-Modified Gold Nanoparticles. Langmuir, 18: 6666-6670; Kottmann AJP, Martin OJF, Smith DR, Schultz S. (2000). Spectral response of plasmon resonant nanoparticles with a non-regular shape. Opt. Express, 6: 213-219; Evanoff Jr DD, Chumanov G. (2004). Size-Controlled Synthesis of Nanoparticles. 1. "Silver-Only" Aqueous Suspensions via Hydrogen Reduction. J. Phys. Chem., B 108: 13948-13956), related to the nanoparticles embedded into the polymeric matrix.

Table 1. Maximum wavelength k^), resistance and conductivity of poly(amide-imide)- metallic nanoparticle hybrids.

System l_ms (nm) Resistance Conductivity

1 2 3 4 (ΚΩ) (Scm ¹)

PALA 350 - - - > ΜΩ

PALA-Cu 359 405 501 684 4.6 8.70x1ο^-4

PALA-Ag 374 454 - - 3.4 1.18xl0^"3 System ^max (nm) Resistance Conductivity

1 2 3 4 (ΚΩ) (Scm^"1)

PALA-Au 357 453 - - 14.0 2.86X10^"4

PALL 330 - - - > ΜΩ -

PALL-Cu 359 404 483 680 0.0042 9.52xl0

PALL-Ag 387 459 - - 0.02 2.00xl0^_1

PALL-Au 363 449 - - 0.005 8.00X10^"1

PALV 331 - - - > ΜΩ -

PALV-Cu 350 397 501 692 0.026 1.54xl0

PALV-Ag 396 478 - - 0.01 4.00xl0

PALV-Au 363 445 - - 0.0056 7.14xl0^_1

PALPHA 342 363 - - > ΜΩ -

PALPHA-Cu 366 414 539 - 2500 1.6xl0^"6

PALPHA-Ag 394 486 5000 8.0xl0^"7

PALPHA-Au 364 454 0.006 6.67X10^"1

Maximum wavelengths of metals: copper (671 nm), silver (492 and 539 nm) and gold (428 nm). Distances between the two points are 2.5 mm. For comparison: The resistances (conductivities) of the pure metals are: Copper: 0.115 ΚΩ (3.48xl0 ² Scm^"1), silver: 0.014 ΚΩ (2.86xl0^_1 Scm^"1) and gold: 0.0033 ΚΩ (1.21 Scm^"1).

The solid state UV-vis spectrum of PALA showed one absorption maxima at 330 nm, corresponding to the π- π* transition. This band shifted to the longer wavelength side in PALA- Cu along showed three absorption maxima at 359, 405 and 501 nm, assigned to π- π*, η-π* and charge transfer transitions; respectively, with a relatively weak band appearing at 684 nm due to the d-d transition in the visible region (Gotoh Y, Igarashi R, Ohkoshi Y, Nagura M, Akamatsu K, Deki S. (2000). Preparation and structure of copper Nanoparticle/poly(acrylic acid) composite films. J. Mater. Chem., 10: 2548-2552). These results indicate that the copper (II) has been successfully anchored on the polymer. Nevertheless, these results do not indicate that only exist copper (II), without the presence of elemental copper (Cu°) in the new system.

On the other hand, the results showed in Table 1 also reveal, that PALA-Ag has a wide absorbance throughout the visible region, presenting two absorption maxima at 374 and 454 nm, corresponding to π- π* transition and that the second absorption band is related to a SRS (Filippo E, Serra A, Manno D. (2009). Polyvinyl alcohol) capped silver nanoparticles as localized surface plasmon resonance-based hydrogen peroxide sensor. Sens. Actuators B, 138(2): 625- 630). This last band shifted to a higher wavelength can be attributed to the difference in the size and distribution of the particles in the system.

Finally, the absorption spectrum of PALA-Au showed two absorption maxima at 357 nm corresponding to the π- π* transition. In this same spectrum, the typical surface absorption band appears with a shoulder at 453 nm (SRS) (Ghosh SK, Pal T. (2007). Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles: From Theory to Applications. Chem. Rev., 107(11): 4797-4862). This last transition, denominated surface plasmon resonance band, appears as a broad absorption that is related to a decreasing particle size (Kreibig U, Vollmer M. (1995). Optical Properties of Metal Clusters. Spinger, Berlin, Germany, 25: 1-532).

The main absorption band observed at 330 nm in the UV-vis spectrum of PALL is attributed to the π-π* transition. In the studies of copper nanoparticles embedded in the polymeric matrix (PALL-Cu) was possible to observe a copper surface plasmon peak at around 680 nm and three absorption maxima at 359, 404 and 483 nm assigned to π- π*, η-π* and charge transfer transitions; respectively. In addition, PALA-Ag presented one broad absorption spectra in the UV and visible region that contribute the absorption bands at 387 and 459 nm, corresponding to the π- π* transition and the silver surface plasmon; respectively. The absorption spectrum of PALL-Au showed two absorption maxima, one at 363 nm corresponding to the π- π* transition and a second at 449 nm, related to the surface plasmon resonance band.

PALV showed one maximum band at similar wavenumber than PALL (331 nm), corresponding to the π-π* transition. Moreover, PALV-Cu showed three absorption maxima at 350, 397 and 501 nm assigned to π- π*, η-π* and charge transfer transitions; respectively, and a lower band at 692 nm, corresponding to the copper surface plasmon. In addition, when silver nanoparticles are embedded in the polymeric matrices (PALV-Ag), appears one broad absorption spectra in the UV and visible region that contribute the absorption bands at 387 and 459 nm, corresponding to π- π* transition and the silver surface plasmon. The absorption spectrum of PALV-Au showed two absorption maxima, at 363 nm, corresponding to the π- π* transition and at 449 nm, related to the surface plasmon resonance band.

The incorporation of the phenyl units into polymeric chains (Figure 1) changes the optical properties of the system. Thus, the PALPHA showed two absorption bands at 342 and 363 nm, that possibly are related to the π- π* transition and the charge transfer transitions; respectively. This result demonstrates that the introduction of this group affects the mobility of the electron in the system. In addition, when copper nanoparticles are incorporated into the polymer, only three absorption bands at 366, 414 and 539 nm are observed, assigned to π- π*, η-π* and charge transfer transitions; respectively. However the copper surface plasmon resonance is not observed, or simply the amount of copper nanoparticles found in the surface of the film is too small. PALPHA-Ag showed also one broad absorption spectra in the UV and visible region that contributes to the absorption bands at 394 and 454 nm, corresponding to π- π* transition and the silver surface plasmon. Finally, the spectrum of PALPHA-Au showed two absorption maxima at 364 nm, corresponding to the π- π* transition and at 454 nm, related to the surface plasmon resonance band.

A four-point electrical resistance measurement (Figure 3) was applied to these films, composed of polymer and polymer-metallic nanoparticle hybrids with the finality to obtain the conductivity of the systems (Table 1 and Table 2).

The conductivities of PALL and PALV were changed from insulator to semiconductor behavior when the incorporation of metals into of the polymeric matrices takes place (Table 1). This behavior is related to the homogeneous distribution of the nanoparticles in the polymeric matrix and to the extension of electrical percolations between metallic islands embedded in the polymer. A similar behavior is showed by PALPHA-Au. These characteristics are not observed for PALA and PALPHA, whose conductivities decrease due to the heterogeneity and breaks in the film caused by the evaporation of the solvent that implies a lower aggregation of the metals into the polymeric matrix. The results shown in Table 2 correspond to poly(amide)s with a thiophene moiety (Figure 2) and the incorporation of the metal into the polymeric matrices. Thus, the polymeric structure PAtSi showed a strong absorption band at 349 nm, corresponding to the π- π* transition. On the other hand, PAtSi-Cu showed three absorption maxima at 353, 413 nm and 558 nm, assigned to π- π*, η-π* and charge transfer transitions; respectively, without the presence of the copper surface plasmon.

Table 2. Maximum wavelength (k^), resistance and conductivity of poly(amide)-metallic nanoparticle hybrids.

System (nm) Resistance Conductivity

1 2 3 4 (ΜΩ) (Scm^"1)

PAtSi 349 - - - > ΜΩ -

PAtSi -Cu 353 413 558 - 0.6 6.67xl0^"3

PAtSi -Ag 356 414 - - 0.0042 9.52X10^"1

PAtSi -Au 362 463 - - 0.0032 1.25

PAtGe 352 - - - 100000 4xl0^"9

PAtGe-Cu 356 404 - 681 1000 4.0x10^"6

PAtGe-Ag 372 405 491 538 6000 6.67xl0^"7

PAtGe-Au 369 452 - - 6000 6.67xl0^"7

Maximum wavelengths of metals: copper (671 nm), silver (492 and 539 nm) and gold (428 nm). Distances between the two points are 2.5 mm. For comparison: The resistances (conductivities) of the pure metals are: Copper: 0.1 15 ΚΩ (3.48xl0 ² Scm^"1), silver: 0.014 ΚΩ (2.86xl0^_1 Scm^"1) and gold: 0.0033 ΚΩ (1.21 Scm^"1).

With the technique showed in the Figure 3, the resistance of the material is obtained. Moreover, using Ohm's law (V= IR), where R is the resistance, I the current through the resistor and V the voltage across the resistor, the current of the material (Ii and I₂) can be obtained, when a voltage between two surface points (Vi and V₂) with a constant distance between each points is applied. This method is convenient to eliminate lead resistance or contact resistance.

The presence of an absorption peak at around 690 nm in the solid state electronic spectrum represents a d-d transition of the Cu (II) centers with a square pyramidal geometry, which is not observed by PAtSi-Cu. The extinction of this band suggests that the hybrids do not present a totally delocalized conjugated π system and the copper nanoparticles are randomly distributed in the polymeric matrix that disfavors the movement of the electrons. These characteristics are related to the conductivity of the hybrid (Table 2). In addition, when the incorporation of silver atoms into the polymeric matrix PAtSi-Ag takes place, two bands are observed, at 356 and 414 nm, related to the π-π* transition and the silver surface plasmon; respectively. Finally, the spectrum of PAtSi-Au showed two absorption maxima at 362 nm corresponding to the π-π* transition and 463 nm, related to the surface plasmon resonance band.

On the other hand, when the silicon atom is changed for germanium into polymeric matrix, it is produced a displacement of the absorption band at 352 nm, which also is related to the π-π* transition. However, PAtGe-Cu presented one weak band at 681 nm that involves the surface plasmon resonance band, characteristic of the copper nanoparticles. In addition, the PAtGe-Ag presented one broad absorption spectra in the UV and visible region where contribute the absorption bands at 371, 405, 491 and 538 nm corresponding to π-π*, η-π*, charge transfer transitions and the silver surface plasmon; respectively. Finally, the absorption spectrum of PAtGe-Au showed two absorption maxima, at 369 nm corresponding to the π-π* transition, and 452 nm related to the surface plasmon resonance band.

In general, if the two absorption bands of the polymer and the metallic nanoparticles in the same system are compared, the band related to the surface plasmon resonance is higher than the band of the polymer, with the exception of the hybrid polymer-copper nanoparticle systems.

The electrical conductivities of the polymers and the hybrid systems are shown in Table 2. For both polymeric systems, the conductivity increases with the incorporation of the metals. Thus, PAtSi-Au hybrid showed conductivities one and three orders of magnitude higher than PAtSi-Ag and PAtSi-Cu; respectively. These behaviors are related to the optical properties of the systems, thus when the wavelength moves to higher values, the electrical conductivity also increases. On the other hand, the PAtGe presented an insulator behavior, similar to their hybrid systems.

Example 5: Structural and vibration properties The Raman spectra obtained from thin pure metal films showed two vibrations for copper and silver; respectively. Thus, at 628 cm^"1 appears theoretically a band related to Cu-0 (Kazuo N, Infrared and Raman spectra of Inorganic and Coordination Compounds: Part A: Theory and Applications in Inorganic Chemistry. (1997). 5^th edition. John Wiley & Sons, Inc. New York, USA, p. 155), which is experimentally shown at 523 and 607 cm^"1. On the other hand, the vibrations of the silver metal show two bands at 1356 and 1591 cm^"1. These vibrations are related to the process of thermal evaporation of the metal in high vacuum (PVD) and the deposition of amorphous carbon on the silver film (Itoh K, Kudryashov I, Yamagata J, Nishizawa T, Fujii M, Osaka N. (2005). Raman Microspectroscopic Study on Polymerization and Degradation Processes of a Diacetylene Derivative at Surface Enhanced Raman Scattering Active Substrates. 2. Confocal Raman Microscopic Observation of Polydiacetylene Adsorbed on Active Sites. J. Phys. Chem. B, 109(1): 271-276). Finally, gold does not exhibit a vibration mode in the Raman spectrum, due to the intrinsic characteristics of the material; a noble metal.

Raman spectra of the PALA (Figure 4a) exhibited a medium band at 3050 cm^"1 corresponding to C-H stretching vibration of substituted benzene. The bands at 1027 cm^"1 and 997 cm^"1 involve in- plane (ip) and out-of plane {pop) C-H bending vibrations that interact with various C-C vibrations. These bands showed weak and strong intensities; respectively. On the other hand, the C=0 group absorbs usually at 1740-1670 cm^_1((a) Uno T, Machida K. (1961). Infrared Spectra of Acyclic Imides. I. Two Modifications of Diacetamide in the Crystalline State. Bull. Chem. Soc. Jpn. 34(4): 545-550. (b) Uno T, Machida K. (1961). Infrared Spectra of Acyclic Imides. II. The Characteristic Absorption Bands of Saturated Acyclic Imides in the Crystalline State. Bull. Chem. Soc. Jpn. 34(4):551-556; Abromovitch RA. (1957). The Infrared Spectra of Some Diacylamines in the 6μ Region. J. Chem. Soc. London, 1413-1417). Thus, the cyclic imides in five member rings generally have two bands in the carbonyl region (in-phase and out-phase). Moreover, it is only observed the in-phase C=0 band which appears at 1769 cm^"1 with a medium intensity. The intensity of C=0 bands tend to depend mainly on the resonance effects and are little affected by inductive effects (Freeman SK. (1974). Applications of Laser Raman Spectroscopy. John Wiley & Sons, New York, USA). Finally, a Raman band at 1590 cm^"1 with a strong intensity is associated at C=C stretching mode. When the incorporation of Cu, Ag or Au into of the crystalline network takes place, changes their Raman vibrations and their crystallinity. In fact, the band that appears at 1588 cm^"1 in PALA-Cu, shows two possible coupled vibrational modes, with their respective areas: 1566 cm^"1 (111233.91 ± 2014.28) and 1594 cm^"1 (33511.10 ± 1300.41) corresponding to Si-C arom. and C=C stretching; respectively. This behavior can be related to the interaction of the silyl group and the copper atom, which change the area of the Raman vibrations. In addition, vibrations at 520 and 610 cm^"1 are related to the remainder part produced by CuO.

The band at 1189 cm^"1 is assigned to C-H ip bending, together with the 1027 cm^"1 vibration. On the other hand, the band at 1588 cm^"1 in PALA-Ag presents the same behavior than PALA-Cu. Thus, this vibration corresponds to three bands, proportional to their total areas at 1476 cm^"1 (31255.79+1715.57); 1531cm^"1 (60936.28+6007.12) and 1594 cm^"1 (205415.88+5594.78), that are in accordance with C-NH stretch-bending, Si-C arom. and C=C ring stretching; respectively. So, the interaction between the silver metal and the silyl group affect the special configuration of other vibrations, due to the large atomic radio of the silver atom. Finally, PALA-Au showed one wide band at 1586 cm^"1, which is related to two vibration modes at 1566 cm^"1 (1939.06+517.54) and 1594 cm^"1 (45389.98+1040.65), corresponding to Si-C arom. and C=C stretching; respectively. In this case, the areas of the vibrational modes decrease with respect to modes observed for PALA-Cu, due to the steric impediment produced by gold nanoparticles.

Raman spectra of the polymer designated as PALL (Figure 4b) represent a broad band assigned at 3050 cm^"1, corresponding to the aromatic C-H stretching vibration. In addition, the C-H ip and oop bending are observed at 1028 cm^"1 and 997 cm^"1, with a weak and strong intensity; respectively. In addition, the C=0 ip band absorbs at 1773 cm^"1 with a medium intensity. Moreover, one Raman band at 1593 cm^"1, with a strong intensity is associated to the C=C stretching mode. One C-H oop bending vibration band is assigned to 619 cm^"1, which is related to the movement of the hydrogen in the aromatic ring. The incorporation of the metals in the polymer changes the movement of the specific vibrations and therefore the area and intensity of the bands. Thus, the inclusion of the copper affects the degree of crystallinity producing amorphous systems that cause the loss of the vibration at 3050 cm^"1 corresponding to C-H stretching. This fact decreases the resonance effect due to the possible twisted geometry assumed by the aromatic rings. PALL-Cu showed a band at 1593 cm^"1 with an area of 6309.36+616.7. In addition, the bands at 519 and 609 cm^"1 are related to the remainder part of CuO. On the other hand, a broad band at 1593 cm^"1 in PALL-Ag shows two vibrations modes at 1551 cm^"1 (10027.26+2368.70) and 1598 cm^"1 (171616.76+3913.84) attributed to the Si-Ar and C=C stretching; respectively. The detection of a weak, broad band at 1356 cm^"1 is assigned to the silver residues in the film. Finally, PALL-Au exhibits one strong band at 1593 cm^"1 (35522.58+898.31) coupled at one weak band at 1566 cm^"1 (2118.33+473.85), corresponding to C=C and Si-C arom. stretching; respectively. In this case, the inclusion of silver and gold into the crystalline network of the polymer affects the vibration of C=C stretching and interrupted the movement of C-H oop bending, which shows a decrease in the intensity of the signal obtained by Raman spectra.

Raman spectra of PALV (Figure 4c) represent one strong band at 3054 cm^"1, corresponding to the aromatic C-H stretching vibration. In addition, C-H ip and oop bending bands are assigned to three signs; 1194 cm^"1, 1030 cm^"1 and 993 cm^"1, with weak and strong intensities; respectively. The C=0 ip band absorb at 1771 cm^"1 with a medium intensity. Moreover, a Raman band at 1590 cm^"1, with a strong intensity is associated to a C=C stretching mode. On the other hand, the inclusion of the copper into the polymer (PALV-Cu) showed a crystalline behavior, very different to the amorphous patterns of PALV. Thus, the bands that appear at 1590 cm^"1 represent two coupled vibrational modes at 1563 cm^"1 (2307.46+436.7) and 1592 cm^"1 (28744.49+666.88), related to Si-C arom. and C=C stretching; respectively. The high intensity of the vibrational modes assigned to 520 and 611 cm^"1 are related to the remainder CuO. On the other hand, the bands at 3047 cm^"1, corresponding to the aromatic CH stretching vibration, change its intensity in relation to the polymer (PALV) showing the loss of planarity and the resonance effect in the aromatic rings. One broad band at 1590 cm^"1 in PALL-Ag showed two coupled vibrations modes at 1519 cm^"1 (103602+3316.52) and 1593 cm^"1 (144692.70+3133.95) attributed to the Si-C arom. and C=C stretching; respectively. The detection of a weak broad band at 1356 cm^"1 is assigned to the silver residues in the film. Finally, PALV-Au exhibits one strong band at 1593 cm^"1 (37343.76+896.60) coupled at one weak band at 1566 cm^"1 (1520.65+440.73), corresponding to C=C and Si-Ar stretching; respectively.

The existence of one or more aromatic rings in the structure is normally determined from the C- H and C=C stretching vibrations. So, the Raman spectra of PALPHA (Figure 4d) exhibited a band at 3050 cm^"1 with a wide range and medium intensity. In addition, the C-H ip and oop bending are assigned to four bands at 1194 cm^"1, 1030 cm^"1 and 995 cm^"1, 617 cm^"1 with weak and strong intensities; respectively. C=0 ip mode absorb at 1778 cm^"1 with a medium intensity. A Raman band at 1587 cm^"1 with a strong intensity is associated to the C=C stretching vibration. When the incorporation of the metals into the polymer takes place, change the vibration of C=C and Si-C arom. stretching in the region near 1600 cm^"1. Thus, the sign of PALPHA-Cu at 1590 cm^"1 include two coupled vibrations modes, the first at 1566 cm^"1 (1408+272.61) and the second at 1594 cm^"1 (31627+539.91) with medium and strong intensities, corresponding to the Si-C arom. and C=C stretching. On the other hand, the band observed for PALPHA-Ag near at 1590 cm^"1 in the aromatic region, contains four absorption bands: 1385 cm^"1 (86046.47+3742.98), 1424 cm^"1 (7235.85+1402.56), 1552 cm^"1 (315744.47+9229.44) and 1596 cm^"1 (152480.07+9507.06). These vibrations are related to the inclusion of the silver nanoparticles, C- N in the stretch-bend mode, Si-C arom. and C=C stretching; respectively. Sign observed for PALPHA-Au at 1589 cm^"1 with a strong intensity is associated to three bands and two common types of vibration: the first band at 1567 cm^"1 (4046.826+357.45), corresponding to Si-C arom., the second vibrations at 1591 cm^"1 (38456.86+9256.34) and 1604 cm^"1 (26482.47+9307.08), both modes are related to C=C stretching.

Raman spectra of PAtSi (Figure 5a) exhibit a weak band at 3050 cm^"1, due to the aromatic C-H stretching vibration and strong band related to C-H ip bending vibration at 995 cm^"1. In this last mode, the carbon atoms present a radial ip movement, which is the in-phase ring stretching (or "breathing") mode. One band at 1593 cm^"1, with a strong intensity, is associated to the C=C ring stretching mode. With respect to the thiophene moiety, the most intense bands at 1454 cm^"1 and 1413 cm^"1 are assigned to the symmetric stretching vibration of the aromatic C=C ring bond. Another interesting band at 1527 cm^"1 corresponds to the Si-C arom. stretching, while the band at 708 cm^"1 is related to C-S-C ip deformation. On the other hand, the bands that are assigned for PAtSi-Cu can be related to the distorted conformation around the silyl group. Thus, this compound does not show the band of the C-H stretching around 3050 cm^"1, presenting a loss of planarity in the system. However, the band that appears close to 1588 cm^"1 (11641.8+15833.5), associated to C=C ring stretching, is strongly coupled to multi-band systems, such as the case of the Si-C arom., absorptions, at 1530 cm^"1 (15970.54+18455.76), 1415 cm^"1 (4633.74+477.62) and 1449 cm^"1 (16822.89+1617.82), corresponding to symmetric stretching vibrations of the aromatic C=C of thiophene ring. Besides, the vibrations produced by the remainder CuO are assigned to 519 and 619 cm^"1 with a strong intensity, in comparison to the other vibrations. On the other hand, the inclusion of silver into the amorphous network of the polymer (PAtSi-Ag) produces a crystalline behavior in the new structure formed. Thus, the band at 3050 cm^"1 is related to the aromatic C-H stretching vibrations. In addition, the bands that appear at 1415 cm^"1 (9286.56+326.98) and 1448 cm^"1 (19697.12+563.16) are associated to symmetric stretching vibration of the C=C thiophene ring, 1518 cm^"1 (6307.01+739.05) and 1591 cm^"1 (14339.91+895.76) correspond to the Si-C arom., and C-H stretching vibrations; respectively. PAtSi-Au, showed a band at 3050 cm^"1 associated to an increase of the crystalline degree. On the other hand, the bands that appear at 1415 cm^"1 (14573.41+286.34) and 1449 cm^"1 (16765.24+514.58) are related to symmetric stretching vibrations of the C=C thiophene ring, while the signs at 1532 cm^"1 (39965.98+1575.61) and at 1591 cm^"1 (15980.14+1343.79) correspond to the Si-C arom., and C=C stretching vibrations; respectively. In comparison to PAtSi-Cu, the PAtSi-Au showed a displacement of Si-C arom. vibration, produced by the disturbance from the electronic distribution of the gold atom.

PAtGe (Figure 5b) presented three vibrational modes with strong, medium and weak intensities at 1583 cm^"1, 1334 cm^"1 and 1086 cm^"1; respectively. The first band corresponds to C=C stretching vibration of the aromatic ring. The band at 1334 cm^"1 possibly can be attributed to two vibrational modes, Ge-C arom. stretching and C-C intra-ring symmetric stretching vibration of the thiophene moiety. Another interesting band, observed at 1086 cm^"1 in the thiophene ring zone, corresponds to the antisymmetric stretching vibration C-C bonds. On the other hand, PAtGe-Cu showed two coupled vibrational mode corresponding to aromatic C=C stretching at 1538 cm^"1 (161908.38+27704.34) and at 1593 cm^"1 (58147.03+16131.24). Moreover, the bands with weak intensities at 1740 cm^"1 (17514.26 +3218.53), 1372 cm^"1 (16237.12+1680.96) and 1172 cm^"1 (30697.43+809.82) are related C=0 ip of the amide group, Ge-C arom. stretching or C-C intra-ring symmetric stretching vibration of thiophene and C-0 stretching vibrations; respectively. In the Raman spectra of PAtGe-Ag it is possible to see a superposition of bands in the interval of 1516 to 1640 cm^"1, which contains the following bands: 1575 cm^"1 (20360.33+3116.5) and 1611 cm^"1 (14784.21+1488.87), corresponding to the C=C stretching vibration of the aromatic ring. In addition, the vibrations at 1372 cm^"1 (75489.43+2745.39) and 1266 cm^"1 (276347.03+5145.22) are associated to Ge-C arom. stretching, silver metal and C-C intra-ring symmetric stretching vibration of thiophene ring; respectively. Other interesting bands observed at 1149 cm^"1 (6034.86+298.97) and 1107 cm^"1 (47865.18+767.83) are related to C-0 stretching vibrations and antisymmetric stretching vibration C-C bonds of the thiophene ring. Finally, PAtGe-Au presents an amorphous behavior, showing two bands with a medium intensities at 1597 cm^"1 (14355.57+410.33) and 1610 cm^"1 (3048.42+262.38) which correspond to the aromatic C=C stretching. In addition, the band at 1385 cm^"1 (3442.05+298.83) with a weak intensity is related to the Ge-C arom. absorption.

Example 6: X-ray diffraction

The X-ray patterns studied from poly(amide-imide)s and poly(amide)s, showed different behavior with the incorporation of the metal into the polymeric matrix (Figure 6 and Figure 7). The presence of Ag and Au nanoparticles (Kishore PS, Viswanathan B, Varadarajan TK. (2008). Synthesis and Characterization of Metal Nanoparticle Embedded Conducting Polymer— Polyoxometalate Composites. Nanoscale Res. Lett., 3(1): 14-20; Jiang X, Zeng Q, Yu A. (2006). A self-seeding coreduction method for shape control of silver nanoplates. Nanotechnology 17: 4929-4935) in the poly(amide-imide)s was further confirmed by X-ray diffraction (XRD) measurements, as it is shown in Figure 6 and Table 3. The XRD pattern of Ag nanoparticles showed a strong peak with a maximum intensity at 38.09 °, representing Bragg 's reflection (111) planes of the standard cubic phase of Ag (Hu J, Cai W, Li C, Gan Y, Chen L. (2005). In situ x- ray diffraction study of the thermal expansion of silver nanoparticles in ambient air and vacuum. Appl. Phys. Lett., 86: 151915- 151915-3). In addition, the polymer-gold hybrid also exhibited the presence of a strong peak with a maximum intensity at 38.20 °, representing (111) planes of the standard cubic phase of Au.

Data of Figure 6 correspond to polymer-copper nanoparticle hybrids, with the presence of a significant diffuse X-ray amorphous component. The best fit for both, the residual and the original measured data, suggested a single halo X-ray amorphous contribution centered at 2Θ -24 °. This spectrum confirms the presence of a disordered nanocrystalline phase, when the copper is incorporated to polymer. Thus, this phase suggest that the amorphous state is relatively homogenous and restricted. The phenyl rings around the silicon atom and the inclusion of the copper showed slower mobility than the chain carbons of the chiral groups which is consistent with the proposed packing model.

Table 3. X-Ray diffraction data for hybrid systems.

System β _a b c

(deg) (A) (A) (A)

PALA-Cu

PALA-Ag 90 4.08 4.08 4.08

PALA-Au 90 4.07 4.07 4.07

PALL-Cu -

PALL-Ag 90 4.08 4.08 4.08 System β a b c

(deg) (A) (A) (A)

PALL-Au 90 4.07 4.07 4.07

PALV-Cu - - - -

PALV-Ag 90 4.08 4.08 4.08

PALV-Au 90 4.07 4.07 4.07

PALPHA-Cu - - - -

PALPHA-Ag 90 4.08 4.08 4.08

PALPHA-Au 90 4.07 4.07 4.07

Poly(amide-imide) hybrids with Ag and Au produced sharp diffraction peaks, indicating the crystalline nature of the nanoparticles, which are associated to a face-centered cubic systems. Interestingly, X-ray diffraction pattern show that the nanoparticles present a high symmetry (ot= β= γ= 90 °) with the appearance of reflections at 38.09 ° and 38.20 ° for Ag and Au; respectively. Additionally, the silver nanoparticle lattices decreased 0.24 % in a, b and c directions in comparison with the gold nanoparticles incorporated into the polymeric matrix (Table 3).

On the other hand, the incorporation of the metal (Cu, Ag or Au) into silicon/germanium- containing poly(amide)s was studied by X-ray diffraction measurements, as it is shown in Figure 7 and Table 4.

X-ray diffraction pattern of PAtSi-Ag (Figure 7a) presented low intensity peaks at 23.04 °, 27.30 ° and a strong diffraction peak at 38.21 ° with the parameters: OJ= = 90 ⁰ and β= 72 °; a= 4.60 A; b= 4.60 A and c= 10.95 A, corresponding to a monoclinic lattice. On the other hand, when the polymer was segregated on gold (PAtSi-Au), it was possible to see a crystalline structure with strong diffraction peaks at 8.49 °, 17.10 °, 25.76 ° and 38.21 °. The same parameters were obtained by silver metal hybrid: OF= = 90 ⁰ and β= 72 °; a= 4.60 A; b= 4.60 A and c= 10.95 A, showing also one monoclinic lattice. Both polymer-metallic hybrids did not show diffraction peaks associated to a crystalline phase of the nanoparticles incorporated into the system (Figure 6). In addition, PAtSi-Cu presented an amorphous behavior, indicating that the atoms bonding to the metal present a random or disordered arranged.

When the silicon atoms are changed by germanium atoms, the embedded nanoparticles are observed in the polymeric matrix. Thus, the X-ray diffraction pattern of PAtGe-Ag presented low intensity peaks at 8.44 °, 25.29 ° and a strong diffraction peak at 38.12 ° with the parameters: OF= β= = 90 °; a= 4.08 A; b= 4.08 A and c= 4.08 A. The presence of Ag nanoparticles in the polymeric matrix was further confirmed by the XRD measurements (Figure 7b). On the other hand, when the polymer was segregated on gold (PAtGe-Au), it was observed a crystalline structure with one low diffraction peak at 8.44 ° and a strong diffraction peak at 38.21 ° with the parameters: OF= β= = 90 °; a= 4.07 A; b= 4.07 A and c= 4.07 A. In this case, the presence of Au nanoparticles in the polymeric matrix was observed by XRD, thus the strong peak with a maximum intensity is related to gold. Finally, PAtGe-Cu presents an amorphous behavior similar to PAtSi-Cu.

In particular, in the formation of poly(amide-imide)-Ag or poly(amide-imide)-Au hybrids it was confirmed the presence of the nanoparticles embedded in the polymeric matrix by a strong peak of maximum intensity. On the other hand, the poly(amide)s with a thiophene moiety in the main chain showed coordinate bonds between the metal and the sulfur atom, which is related to change in the crystalline network of the system. Finally, all polymer-Cu hybrids presented an amorphous behavior.

Table 4. X-Ray powder diffraction data for hybrid systems.

System β a b c

(deg) (A) (A)

( )

PAtSi -Cu

PAtSi -Ag 72 4.6 4.6 10.95

(weak PAtSi no Ag)

PAtSi -Au 72 4.6 4.6 10.95

(PAtSi lattice no Au) System β _a b c

(deg) _(A) (A) (A)

PAtGe -Cu ^'- ^'- ^'- ^~

PAtGe -Ag (Weak Ag) 90 4.08 4.08 4.08

PAtGe -Au (Only Au) 90 4.07 4.07 4.07

Example 7: Scanning electronic microscopy (SEM)

The preparation of polymer-metallic nanoparticles was carried out using 5,4 mg of polymer dissolved in 60

of DMSO. This solution was spin coated on a metallic substrate (Cu, Ag or Au), and afterwards the solvent was removed by a soft baking at 60 °C in vacuum.

Figure 8 shows the scanning electron microscopy SEM images of the surface of the polymer film-metallic nanoparticles at 5 kV magnification voltage. In this figure it is possible to see that the nanoparticles are uniformly dispersed in the polymeric matrix despite some agglomerated particles. MacroscopicaUy, the nanoparticles appear as a long chain of interacting particles, but at a higher magnification these chains appear to be composed of small nanoparticles with a calculated area of 92 to 45 nm² (Figure 9a). The relative standard deviation obtained from this analysis ranged from 68 to 18 %. Clearly, when the evaporation of the solvent takes place, a break in the film is produced, thus the nanoparticles are mostly exposed to the surface.

On the other hand, SEM micrographs showed that the metal is embedded into the polymeric matrix, forming nanocapsules, which had a nearly spherical shape. In this study, the size effect of the microspheres towards the polymer was also studied. The area shows a dependence of the metal atomic radius with the steric effect of the functional group of the poly(amide-imide)s. Thus, PALA and PALL showed an increase in the area of nanocapsules with respect to the atomic radius of the metal (Figure 9a). In addition, when the polymer present steric hindrances, decreases the formation of ionic or covalent bonds and therefore disfavor the interaction with the metal. So, the areas of the nanocapsules PALV and PALPHA are smaller in relation to their atomic radius.

The amount of metal obtained from SEM microanalysis and elemental analysis is shown in Figure 9b. These studies were realized on the nanospheres marked with a circle (Figure 8). Clearly it is observed that the metal is encapsulated by the polymer, thus the atomic percentage of carbon is larger in comparison with the other elements. In addition, the high concentrations of silicon and oxygen atoms are mainly related to the glass substrate and the polymeric structure.

Poly(amide)s with thiophene moiety (Figure 10), in difference to the poly(amide-imide)s, did not show nano-encapsulation of the metal. Thus, the shape of the nanoparticles changes from near to spherical particles to irregular particles with several large polymer-metal aggregates. This fact demonstrates that the polymer can stabilize the metallic nanoparticles through coordination between the metal and the sulphur atom of the repetitive unit. In addition, it is evident that increases the superficial agglomeration in the polymer with copper due to its atomic radius as consequence of smallest inter-separation of metal-polymer system.

Figure 11 shows the atomic percentage of some elements in the poly(amide)-metal hybrid. The significant amount of oxygen and silicon atoms is related to the glass (S1O₂) used as substrate. Carbon signal is generally weaker than the oxygen signal due to its polymeric structure. However, the significant metal atomic percentage within the polymer indicates its inclusion in the polymeric matrix.

Poly(amide-imide)s show the formation of spherical metallic nanoparticles, which are well distributed and stabilized by the polymer. The particles are aggregated into dendrite-structures, that contain silicon atoms, where probably the coordinated covalent bonds are produced (Figure 12a).

Figure 12b presents a different behavior for the poly(amide-imide)s. In this case, the formation of nanoencapsulation of the metal is not observed. Thus, the thiophenes stabilize the metallic nanoparticles by the interaction between the lone pairs of electrons on the central atom (-S-) and the metal, changing the crystalline network of the new system formed.

Example 8: Summary of characterization of polymer- metal hybrids

A simple method has been introduced to prepare metallic nanoparticles embedded or absorbed in a polymer matrix or incorporated into polymer structures. Thus, these behaviors are related to the functional groups that form the repetitive unit of the polymeric chains. Therefore, the poly(amide-imide)s that contain silyl groups in the main chain, produce "in-situ" metallic nanoparticles, due to the coordinate covalent bonds between the metal and the silicon atom. In this case, spherical metallic nanoparticles are obtained, which are well distributed and stabilized by the polymer. On the other hand, the poly(amide)s with a thiophene moiety in the main chain produce the incorporation of the metal in their structure, changing the crystalline network of the system. In this last case, the formation of nanoencapsulation of the metal is not observed. However, the thiophene moieties stabilize the metallic nanoparticles produced by the interaction between the lone pairs of electrons on the central atom (-S-) and the metal.

The formation of the hybrids was demonstrated by optical properties, Raman spectroscopy and X-ray diffraction. In some cases, the surface plasmon resonance bands related to metallic nanoparticles were observed. However, these bands are coupled to the π-π* transition observed for the polymers with the exception of the polymer-copper nanoparticle hybrids. In addition, the metals embedded in the polymeric matrices produce a distortion around the silyl group and the aromatic rings, changing the vibration and intensities of these bands. Moreover, in certain polymers X-ray reflection planes of the metals were observed, showing the presence of one strong peak at 38.09 ° (Ag) and 38.20 ° (Au), with the exception of polymer-copper nanoparticle hybrids, which presented an amorphous behavior.

Finally, the incorporation of metal into the polymeric matrices increases the conductivity, based on the homogeneity of the films or possibly by percolation effects.

Claims

1. A polymer-metallic nanoparticle hybrid material having the processability and malleability of a polymer and the structural, thermal, optical and electrical characteristics from the metal, wherein an organo-heteroatom (silicon or germanium) polymer incorporates a metal to its structure through covalent bonds in coordinated and arranged form, generating a new macromolecular material.

2. The material of claim 1, wherein the polymer is selected among poly(amide-imide) and poly( amide) and the metal is selected among copper, gold, or silver.

3. A method for preparing the material of claim 2, wherein the method comprises the steps of a) providing a polymer solution dissolving the organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) in an aprotic polar organic solvent; b) providing a metal film from the selected metal; c) dispersing the polymer solution by spin coating on the metal film; and d) simultaneous incorporation, nano -encapsulation or incorporation of the metal into the polymer matrix.

4. The method of claim 3, wherein the organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) is dissolved at a concentration between 0.05 to 2.00 mg/μΐ.

5. The method of claim 4, wherein the organo-heteroatom (silicon or germanium) polymer (poly(amide-imide)s or poly(amide)s) is dissolved in dimethylsulfoxide (DMSO).

6. The method of claim 3, wherein the selected metal has a purity between 99.90 and 99.95 %.

7. The method of claim 6, wherein the thickness of the film is between 30 to 70 nm.

8. The method of claim 3, wherein the spin coating is performed using rotation velocity ramps between 300 to 700 rpm for 5 to 25 s and 1000 to 2000 rpm for 5 to 25 s.

9. Use of material of claim 2 for the manufacture of an adhesive, wherein the covalent bonds between the polymer and the selected metal allow the interaction for a strong adhesion.

10. Use of material of claim 2 for the manufacture of medical devices, wherein the selected metal is copper or silver with intrinsic bactericide properties and the material is highly processable and malleable.

11. Use of material of claim 2 for the manufacture of biological sensors, wherein the selected metal is gold and the material has optical properties such as fluorescence.

12. Use of material of claim 2 for the manufacture of electronic devices, wherein the material is an electrical conductor.

13. Use of material of claim 2 for the manufacture of magnetic devices, wherein the material is an electrical conductor.

14. Use of material of claim 2 for the manufacture of optoelectronic devices, wherein the material showed change in their optical properties such as absorption, transmittance and fluorescence.

15. Use of material of claim 2 for the manufacture of anticorrosion products, wherein the polymeric matrix confers protection to the metal.