CN103146146B - Epoxy nanocomposite with controllable phase structure and based on polyhedral oligomeric silsesquioxanes (POSS) - Google Patents

Abstract

The invention discloses an epoxy nanocomposite based on polyhedral oligomeric silsesquioxanes (POSS) and a preparation method of the epoxy nanocomposite based on the POSS and relates to the epoxy nanocomposite with a controllable phase structure capable of improving effect and based on the POSS. The preparation method includes the following steps of allocating a POSS monomer, a chain transfer agent and an initiating agent in a solution according to the measuring amount through a reversible addition-fragmentation chain transfer (RAFT) method, conducting freeze thaw and degassing through liquid nitrogen, charging argon shield to enable the mixture to react, and obtaining PMAiBuPOSS; further allocating PMAiBuPOSS, Methl Methacrylate monomer (MMA) and an initiating agent in a solution, and obtaining POSS base block copolymer , namely, PMAiBuPOSS-b-PMMA, through the RAFT; conducting melt blending on the POSS monomer, epoxy resin, the prepared POSS base block copolymer to obtain blend precursor of the POSS and the epoxy, adding in a curing agent, fully stirring, dissolving the mixture the curing agent, pouring the blend into a die, conducting temperature programming and curing, and obtaining the nanocomposite with the controllable phase structure and based on the POSS.

Description

A POSS-based epoxy nanocomposite with controllable phase structure

technical field

The invention relates to a POSS-based epoxy nano-composite material and a preparation method thereof, in particular to a POSS-based epoxy nano-composite material with a controllable phase structure with a strengthening effect, belonging to the field of organic polymer materials.

Background technique

With the rapid development and progress of society, functional new materials with various excellent properties have become an important direction of scientific and technological development. Driven by this demand, more and more researchers have expressed great research interest in organic-inorganic nanocomposites. Organic-inorganic nanocomposites are favored by researchers because they combine the advantages of polymers (such as low density, ease of processing, toughness) with the advantages of inorganic materials (such as high modulus, high hardness, non-flammability) .

In recent years, the emergence of inorganic nanoparticle clusters with controllable structures, such as polyhedraloligomeric silsesquioxanes (POSS), provides an effective way for the preparation of organic-inorganic nanocomposites. The typical molecular formula of polyhedral oligomerized silsesquioxane (POSS) is (RSiO _1·5 ) _n (n≥4, R=H, alkyl, aryl or organic functional group), silicon and oxygen constitute its inorganic structure center, the structure center is surrounded by organic substituents. The siloxane cage skeleton endows it with excellent performance as an inorganic material, and the peripheral organic groups provide opportunities for it to participate in the construction of composite materials. Polymer-based nanocomposites based on POSS can be obtained by directly blending POSS with polymers or reactive copolymerization blending systems, and can also be grafted and copolymerized to polymer chains through reactive organic groups of POSS.

As we all know, epoxy resin has become one of the most widely used commercial resins, and it plays an extremely important role in the fields of electronics, aerospace and automation. However, epoxy resin has fatal weaknesses such as high brittleness and low fracture toughness due to its own rigid cross-linked network structure. In recent years, the use of monomers or polymers of POSS and epoxy resins to construct organic-inorganic nanocomposites to improve the performance of epoxy has received more and more attention. The use of multiple components to construct nanostructures in epoxy systems can effectively realize the "nanostructure strengthening" of epoxy resins.

Maria J.Abad et al. (Abad, M.J., et al., Macromolecules, 2003.36 (9): p.3128-3135.) successfully introduced high-content POSS into epoxy resin by two-step method, POSS and diamine with 1 : The molar ratio of 1 is completely reacted. Zeng et al. (Zeng, K., et al., Polymer, 2009.50 (2): p.685-695.) synthesized seven (trifluoropropyl) POSS end-capped PCL, PEO polybisphenol A ether and used them Used as epoxy resin modifier to construct nanocomposites in situ. Ni et al. (Ni C, et al., Colloid & Polymer Science, 2009, 288(4): 469-477.) obtained POSS with reactive hydroxyl and amine groups by reacting butyl glycidyl ether with aminopropyl POSS , which can be added to epoxy resin to improve the mechanical and thermal properties of epoxy resin. Zhang Zengping (Zhang Zengping, Liang Guozheng, Liu Jisan, Xie Jianqiang, Guan Xinghua, Research on curing reaction kinetics and performance of cage-type silsesquioxane POSS-epoxy hybrid resin system, China Adhesives, 2007, 16 (9): 1-4) Bisphenol A epoxy resin E51 was modified by cage oligomerization silsesquioxane (POSS) to obtain an organic-inorganic hybrid resin with improved heat resistance. Li Qifang et al. (Li Qifang, Lu Peng, Chinese patent, CN102815071A) used a unique monoisocyanate-based cage silsesquioxane (POSS) to graft and modify epoxy molecules to obtain high heat resistance and low dielectric epoxy resin. Zhang Chunling et al. (Zhang Chunling, Liu Bo, Sun Guoen, Bai Xuetao, Chinese patent, CN102492116A) introduced the octaepoxy POSS monomer into the epoxy resin structure system to form a network crosslinked structure without phase separation. At present, the use of POSS monomers or polymers and epoxy resins to construct organic-inorganic nanocomposites has made great progress, but none of the above research reports involves a POSS-based block copolymer compatibilized POSS monomer Epoxy nanocomposites with epoxy direct physical blending system.

Contents of the invention

The invention aims to provide a POSS-based epoxy nanocomposite material with a controllable phase structure and a preparation method thereof.

A POSS-based epoxy nano-composite material with a controllable phase structure involved in the present invention uses a POSS-based block copolymer to expand the direct blending system of POSS monomers and epoxy resins, effectively improving POSS monomers and epoxy resins. Compatibility of the resin, prepared POSS-based epoxy nanocomposites with nanoscale controllable phase structure. In the above-mentioned epoxy nanocomposite material, the POSS component is uniformly dispersed in the epoxy system in the form of nanoparticles to realize the construction of nanoscale controllable phase structure of the epoxy system, which can effectively strengthen the epoxy resin. The preparation method of the epoxy nanocomposite material is simple, has strong operability and is easy to realize industrialization.

The present invention adopts the following technical solutions: Step 1, the preparation of POSS-based block copolymers, using the reversible addition-fragmentation transfer radical polymerization (RAFT) method to prepare POSS-based block copolymers; Step 2, epoxy nanocomposite based on POSS Preparation of materials: Melt and blend POSS-based block copolymers, POSS monomers and epoxy resins, stir to form a homogeneous phase, add curing agent, pour into molds and program curing, and prepare POSS-based epoxy nanocomposites.

The POSS monomer described in the present invention is methacryloxypropyl isobutyl POSS (MAiBuPOSS), and its structural formula is as follows:

Wherein, R is -iBu, isobutyl.

The POSS-based block copolymer described in the present invention is a diblock copolymer with polymethacryloxypropyl isobutyl polyhedral oligomeric silsesquioxane (PMAiBuPOSS) and polymethyl methacrylate (PMMA) as blocks. Segment copolymer, namely polymethacryloxypropyl isobutyl polyhedral oligomeric silsesquioxane-b-polymethyl methacrylate (PMAiBuPOSS-b-PMMA), the molecular weight M _n of the copolymer is 20000～100000 , the dispersion index PDI=M _n /M _w =1.1～1.5, wherein M _w represents the weight average molecular weight, and M _n represents the number average molecular weight.

In the above-mentioned technical scheme, step one: the preparation method of POSS base block copolymer is described in detail as follows:

Step 1) Configure POSS monomer, chain transfer agent and initiator in tetrahydrofuran solution according to the metering, put the solution in the reactor and degas it with liquid nitrogen for three to five times, then fill it with argon to protect the reaction, and the reaction is over Afterwards, the reaction was stopped by freezing with liquid nitrogen, diluted with tetrahydrofuran, and precipitated with methanol. The precipitation was repeated until no POSS monomer existed, and the pink PMAiBuPOSS was obtained by drying.

Step 2) PMAiBuPOSS, methyl methacrylate monomer (MMA) and initiator are configured in tetrahydrofuran solution according to the metering, and the solution is placed in the reactor and degassed with liquid nitrogen for three to five times, and then filled with argon Protect the reaction, stop the reaction with liquid nitrogen freezing after the reaction, add tetrahydrofuran to dilute and precipitate with methanol, repeat the precipitation until no PMAiBuPOSS and monomers exist, and dry to obtain a light pink POSS-based block copolymer, namely PMAiBuPOSS-b-PMMA.

In step 1), the reaction temperature is 65°C, the reaction time is 24-48h, preferably 48h; the molar ratio of POSS monomer to chain transfer agent is 10-50, preferably 20; the molar ratio of chain transfer agent to initiator The ratio is 1-20, preferably 5.

In step 2), the reaction temperature is 65°C, the reaction time is 12-24h, preferably 24h; the molar ratio of MMA and PMAiBuPOSS is 200-2000, preferably 800; the molar ratio of chain transfer agent and initiator is 5- 20, preferably 20.

The above-mentioned initiator is azobisisobutyronitrile (AIBN) or benzoyl peroxide BPO; the chain transfer agent adopts cumyl dithiobenzoate (CDB) or benzyl dithiobenzoate BDB, preferably CDB, Its structural formula is as follows:

In the technical scheme of the present invention, step 2: the preparation method of the epoxy nanocomposite material based on POSS is described in detail as follows:

1) Put the POSS monomer, epoxy resin and the POSS-based block copolymer prepared above in the reactor according to the metering ratio, melt blend, and continue to stir for 2 to 4 hours after forming a homogeneous phase to obtain the blend of POSS and epoxy Precursor;

2) Add a curing agent to the POSS and epoxy blend precursor, continue to stir for 10-20 minutes, after the curing agent is fully dissolved, pour the blend into a mold, and after programmed temperature rise and curing, a yellow and transparent POSS-based resin with Epoxy nanocomposites with controlled phase structure.

The above-mentioned epoxy resin can be a bisphenol A type epoxy resin, preferably commercially available epoxy E-51; the curing agent can be an amine curing agent for epoxy, preferably 4,4'-methylene-bis-(3- Chloro-2,6-diethylaniline) (MCDEA), the amount of curing agent is calculated according to the quality of epoxy resin and epoxy equivalent.

The above-mentioned POSS monomer, epoxy resin and POSS-based block copolymer are in a mass ratio of 1-100:100:1-100.

The curing temperature of the above programmed temperature rise is set as follows: 135° C. for 14 hours; heat up to 190° C. for 4 hours.

The epoxy nanocomposite material with controllable phase structure based on POSS of the present invention has the following advantages:

1) The POSS-based epoxy nanocomposite prepared by the present invention has a uniformly dispersed nanoscale inorganic phase, and the "nano-reinforcement" effect provides better mechanical properties for the POSS polymer-based epoxy nanocomposite prepared by the present invention . POSS-based block copolymers use PMAiBuPOSS and PMMA as blocks; according to the principle of "likes are compatible", PMAiBuPOSS blocks have good compatibility with POSS monomers, and at the same time, since PMMA and epoxy resin have similar solubility parameters , PMMA blocks can be miscible with epoxy resin, therefore, the POSS base prepared by the present invention is easy to self-assemble in situ in epoxy resin system to form micelles, and the in situ formation takes POSS monomer and POSS block as the core, and PMMA as the core. The inorganic phase-rich nanoparticles of the crown play a "nano-reinforced" effect on the epoxy resin. Its schematic diagram is shown in Figure 1.

2) The present invention uses POSS-based block copolymers and POSS monomers to blend with epoxy systems to prepare epoxy nanocomposites based on POSS polymers. POSS-based block copolymers form micelles while self-assembling in situ , it plays a compatibilizing effect on the blending of POSS monomer and epoxy resin, and effectively improves the problem of poor compatibility that occurs when POSS monomer is used alone to modify epoxy resin. At the same time, POSS-based block copolymers and POSS monomers are blended together with the epoxy system, which provides a new way for the preparation of organic-inorganic epoxy nanocomposites with a large content of inorganic components.

3) The epoxy nanocomposite material based on POSS prepared by the present invention is prepared by direct melt blending method, the preparation method is simple and easy to industrialize, and has great prospects.

Description of drawings

Figure 1 is a schematic diagram of the principle model of the POSS-based block copolymer in situ self-assembly and compatibilization of the POSS monomer and epoxy resin blend system, in which, A) is the model and molecular structure of the POSS-based block copolymer; B) It is the model and molecular structure formula of POSS monomer; C) is the microscopic dispersion morphology model of POSS-based epoxy nanocomposite with controllable phase structure.

Fig. 2 is a scanning electron microscope (SEM) microstructure photo of the POSS-based epoxy nanocomposite material sample with a controllable phase structure obtained in Example 1. After the sample was etched with dichloromethane, it was sprayed with gold and used for SEM observation; the concave hole in the photo is the inorganic phase area etched by dichloromethane.

In Figure 3, a is the DMTA test result of the sample after the pure epoxy resin E-51 is completely cured; b is the POSS-based epoxy nanocomposite sample with a controllable phase structure obtained in Example 1, and the DMTA test result is . The abscissa is the temperature, the ordinate is the mechanical loss tangent, and its peak value reflects the glass transition temperature Tg.

Detailed ways

The specific embodiment of the epoxy nanocomposite material with controllable phase structure based on POSS of the present invention is given below

Example 1

Prepare POSS monomer (MAiBuPOSS): chain transfer agent (CDB): initiator (AIBN) = 20:1:0.2 tetrahydrofuran solution system, the monomer concentration is 0.7mol/L, put the solution in the reactor and freeze it with liquid nitrogen After melting and degassing for three to five times, fill it with argon to protect the reaction for 48 hours. After the reaction, freeze it with liquid nitrogen to stop the reaction, add a small amount of tetrahydrofuran to dilute, drop it into methanol for precipitation, dry the precipitate and take a sample for NMR test. Repeat this step for repeated precipitation Until there is no POSS monomer, dry to obtain pink PMAiBuPOSS. The molar ratio of methyl methacrylate monomer (MMA): PMAiBuPOSS: initiator (AIBN) = 16000: 20: 1 prepares a tetrahydrofuran solution system with a monomer concentration of 4 mol/L, and puts the solution in the reactor with liquid After three to five times of nitrogen freeze-thaw degassing, fill with argon to protect the reaction for 20 hours. After the reaction, stop the reaction by freezing with liquid nitrogen, add a small amount of tetrahydrofuran to dilute, drop into methanol to precipitate, dry the precipitate and take a sample for NMR test, repeat this step Precipitate repeatedly until no PMAiBuPOSS and monomers exist, and dry to obtain a light pink POSS-based block copolymer, that is, PMAiBuPOSS-b-PMMA.

POSS monomer, epoxy resin and the POSS-based block copolymer prepared above are placed in the reactor according to the mass ratio POSS monomer: epoxy resin: POSS-based block copolymer=5:100:1, and melt blended After forming a homogeneous phase, continue to stir for 2-4 hours to obtain a POSS and epoxy blended precursor. Add an appropriate amount of curing agent to the blended precursor (such as: 100g of epoxy E-51, add 48.45g of MCDEA curing agent), continue to stir for 10-30min, after the curing agent is fully dissolved, pour the blend into the mold, Programmed curing: heat preservation at 135°C for 14 hours; heat up to 190°C and heat preservation for 4 hours. A yellow and transparent POSS-based epoxy nanocomposite with a controllable phase structure was obtained and used for DMTA testing. The performance test results are shown in Table 1.

Example 2

Prepare POSS monomer (MAiBuPOSS): chain transfer agent (CDB): initiator (AIBN) = 20:1:0.2 tetrahydrofuran solution system, the monomer concentration is 0.7mol/L, put the solution in the reactor and freeze it with liquid nitrogen After melting and degassing for three to five times, fill it with argon to protect the reaction for 48 hours. After the reaction, freeze it with liquid nitrogen to stop the reaction, add a small amount of tetrahydrofuran to dilute, drop it into methanol for precipitation, dry the precipitate and take a sample for NMR test. Repeat this step for repeated precipitation Until there is no POSS monomer, dry to obtain pink PMAiBuPOSS. The molar ratio of methyl methacrylate monomer (MMA): PMAiBuPOSS: initiator (AIBN) = 16000: 20: 1 prepares a tetrahydrofuran solution system with a monomer concentration of 4 mol/L, and puts the solution in the reactor with liquid Nitrogen freeze-thaw degassing three to five times, then filled with argon to protect the reaction for 40 hours, after the reaction was completed, freeze with liquid nitrogen to stop the reaction, add a small amount of tetrahydrofuran to dilute, drop into methanol for precipitation, dry the precipitate and take a sample for NMR test, repeat this step Precipitate repeatedly until no PMAiBuPOSS and monomers exist, and dry to obtain a light pink POSS-based block copolymer, that is, PMAiBuPOSS-b-PMMA. All the other steps are the same as in Example 1, and the performance test results are shown in Table 1.

Example 3

Prepare POSS monomer (MAiBuPOSS): chain transfer agent (CDB): initiator (AIBN) = 30:1:0.2 tetrahydrofuran solution system, the monomer concentration is 0.7mol/L, put the solution in the reactor and freeze it with liquid nitrogen After melting and degassing for three to five times, fill it with argon to protect the reaction for 48 hours. After the reaction, freeze it with liquid nitrogen to stop the reaction, add a small amount of tetrahydrofuran to dilute, drop it into methanol for precipitation, dry the precipitate and take a sample for NMR test. Repeat this step for repeated precipitation Until there is no POSS monomer, dry to obtain pink PMAiBuPOSS. The molar ratio of methyl methacrylate monomer (MMA): PMAiBuPOSS: initiator (AIBN) = 16000: 20: 1 prepares a tetrahydrofuran solution system with a monomer concentration of 4 mol/L, and puts the solution in the reactor with liquid After three to five times of nitrogen freeze-thaw degassing, fill with argon to protect the reaction for 20 hours. After the reaction, stop the reaction by freezing with liquid nitrogen, add a small amount of tetrahydrofuran to dilute, drop into methanol to precipitate, dry the precipitate and take a sample for NMR test, repeat this step Precipitate repeatedly until no PMAiBuPOSS and monomers exist, and dry to obtain a light pink POSS-based block copolymer, that is, PMAiBuPOSS-b-PMMA. All the other steps are the same as in Example 1, and the performance test results are shown in Table 1.

Example 4

Similar to Example 1, the difference is that the POSS monomer, epoxy resin and the resulting POSS-based block copolymer are placed in a mass ratio POSS monomer: epoxy resin: POSS-based block copolymer=10:100:1 In the reactor, melt blending. All the other steps are the same as in Example 1, and the performance test results are shown in Table 1.

Example 5

Similar to Example 1, the difference is that POSS monomer, epoxy resin and the resulting POSS-based block copolymer are prepared according to the mass ratio POSS monomer: epoxy resin: POSS-based block copolymer=20:100:1 In the reactor, melt blending. All the other steps are the same as in Example 1, and the performance test results are shown in Table 1.

Example 6

Similar to Example 1, the difference is that POSS monomer, epoxy resin and the resulting POSS-based block copolymer are prepared in a mass ratio POSS monomer: epoxy resin: POSS-based block copolymer=10:100:5 In the reactor, melt blending. All the other steps are the same as in Example 1, and the performance test results are shown in Table 1.

Table 1 Performance test results of POSS-based epoxy nanocomposites with controllable phase structure

sample Inorganic domain size (nm) Glass transition temperature (°C) Storage modulus (dyn/cm ² , 25°C) Example 1 50～100 193.4 2.43×10 ¹⁰ Example 2 50～100 192.6 2.40×10 ¹⁰ Example 3 100～200 189.7 2.55×10 ¹⁰ Example 4 700～1000 188.1 2.64×10 ¹⁰ Example 5 1000～1500 182.5 2.68×10 ¹⁰ Example 6 100～200 193.1 2.70×10 ¹⁰ Pure epoxy resin E-51 -------------- 187.6 2.02×10 ¹⁰

Claims (8)

1. A preparation method based on POSS-based epoxy nanocomposites, characterized in that step 1, the preparation of POSS-based block copolymers, adopts reversible addition-fragmentation-transfer radical polymerization (RAFT) method to prepare POSS-based block copolymers Thing; Step 2, the preparation of the epoxy nanocomposite material based on POSS, with POSS base block copolymer, POSS monomer and epoxy resin melt blending, after stirring into homogeneous phase, add curing agent, pour into mold procedure solidification, Prepare the epoxy nanocomposite material based on POSS, and described POSS monomer is methacryloxypropyl isobutyl POSS (MAiBuPOSS), and its structural formula is as follows: Wherein, R is -iBu, isobutyl; The POSS-based block copolymer is a two-block copolymer with polymethacryloxypropyl isobutyl polyhedral oligomerized silsesquioxane (PMAiBuPOSS) and polymethyl methacrylate (PMMA) as blocks. The product is polymethacryloxypropyl isobutyl polyhedral oligomeric silsesquioxane-b-polymethyl methacrylate (PMAiBuPOSS-b-PMMA), the molecular weight M _n of the copolymer is 20000-100000, and the dispersion Index PDI=M _n /M _w =1.1-1.5, wherein M _w represents the weight average molecular weight, and M _n represents the number average molecular weight. 2. the preparation method of a kind of epoxy nanocomposite based on POSS according to claim 1, is characterized in that described step one: the preparation method of POSS base block copolymer is described in detail as follows: Step 1) Dispose the POSS monomer, chain transfer agent and initiator in the tetrahydrofuran solution according to the metering, put the solution in the reactor and degas it with liquid nitrogen for three to five times, then fill it with argon to protect the reaction, and the reaction is over Afterwards, stop the reaction by freezing with liquid nitrogen, add tetrahydrofuran to dilute and precipitate with methanol, repeatedly precipitate until no POSS monomer exists, and dry to obtain pink PMAiBuPOSS; Step 2) PMAiBuPOSS, methyl methacrylate monomer (MMA) and initiator are configured in tetrahydrofuran solution according to metering, and the solution is placed in the reactor and degassed with liquid nitrogen for three to five times, and then filled with argon Protect the reaction, stop the reaction with liquid nitrogen freezing after the reaction, add tetrahydrofuran to dilute and precipitate with methanol, repeat the precipitation until no PMAiBuPOSS and monomers exist, and dry to obtain a light pink POSS-based block copolymer, namely PMAiBuPOSS-b-PMMA. 3. the preparation method of a kind of epoxy nanocomposite based on POSS according to claim 2, is characterized in that in step 1), described temperature of reaction is 65 ℃, and the reaction times is 24～48h, POSS monomer The molar ratio of the chain transfer agent to the chain transfer agent is 10-50; the molar ratio of the chain transfer agent to the initiator is 1-20. 4. the preparation method of a kind of epoxy nanocomposite based on POSS according to claim 2, is characterized in that in step 2) in, described temperature of reaction is 65 ℃, and the reaction times is 12～24h; MMA and PMAiBuPOSS The molar ratio of the chain transfer agent and the initiator is 5-20. 5. the preparation method of a kind of epoxy nanocomposite based on POSS according to claim 2, is characterized in that described initiator is azobisisobutyronitrile (AIBN) or benzoyl peroxide BPO; Chain transfer The agent adopts cumyl dithiobenzoate (CDB) or benzyl dithiobenzoate BDB, and the structural formula of CDB is as follows: 6. a kind of preparation method based on the epoxy nanocomposite material of POSS according to claim 2, is characterized in that described step 2: the preparation method based on the epoxy nanocomposite material of POSS is described in detail as follows: 1) Put the POSS monomer, epoxy resin and the obtained POSS-based block copolymer in the reactor according to the metering ratio, melt blend, and continue to stir for 2 to 4 hours after forming a homogeneous phase to obtain the POSS and epoxy blended precursor ; 2) Add a curing agent to the POSS and epoxy blend precursor, continue to stir for 10-20 minutes, after the curing agent is fully dissolved, pour the blend into a mold, and after curing by programming temperature, a yellow and transparent POSS-based resin with Epoxy nanocomposites with controlled phase structure. 7. the preparation method of a kind of epoxy nanocomposite material based on POSS according to claim 6, is characterized in that described epoxy resin is bisphenol A type epoxy resin; Curing agent is epoxy amine curing agent . 8. the preparation method of a kind of epoxy nanocomposite based on POSS according to claim 6, is characterized in that described POSS monomer, epoxy resin and POSS base block copolymer, by mass ratio are, 1～ 100: 100: 1～100; the heating and curing temperature is set as follows: 135°C for 14 hours; heat up to 190°C for 4 hours.