ABSTRACT Steady state fluorescence (SSF) and photon transmission (PT) techniques were used for st... more ABSTRACT Steady state fluorescence (SSF) and photon transmission (PT) techniques were used for studying film formation from TiO2 and Al2O3 covered polystyrene (PS) latex particles. These films were annealed at elevated temperatures in 10 min time intervals above glass transition (Tg) temperature of polystyrene. Fluorescence emission, Ip and transmitted photon, Itr intensities were measured after each annealing step to monitor the stages of film formation. Films present dramatic increase in both Itr and Ip above the certain onset temperature called minimum film forming temperature, T0. Dissolution of annealed PS film, with high TiO2 content presented a nice, ordered nano-sized ceramic structure, which may predict the construction of nano-layer photonic crystals. It was observed that latex particles are encapsulated above a critical Al2O3 content of 33 wt% which corresponds to the critical occupation probability of pc=0.33 at which the film obey the site-percolation model with a critical exponent of 0.45.
ABSTRACT Small molecule sorption and slow release in and out of polyacrylamide (PAAm) gels were s... more ABSTRACT Small molecule sorption and slow release in and out of polyacrylamide (PAAm) gels were studied by using steady state fluorescence (SSF) technique. Pyranine (Py) dissolved in water used as a probe. Fluorescence emission intensity, Ip from Py was used to monitor for studying sorption and slow release processes at various temperatures. Sorption and slow release processes were analyzed by using Fickian diffusion model and coefficients were obtained. Related activation energies were also calculated for the corresponding physical processes.
Polyacrylamide (PAAm) hydrogels have been proposed for use as promising biomaterials in biomedica... more Polyacrylamide (PAAm) hydrogels have been proposed for use as promising biomaterials in biomedical and tissue engineering but their poor mechanical and water-retention properties have hindered their development. Graphene oxide (GO), an excellent nanofiller, was added to PAAm to produce mechanically strong GO–PAAm composites. The free radical crosslinking copolymerization method was used with GO content varying in the range between 5 and 50 µl of GO. The mechanical properties of the GO–PAAm composites are measured by compressive test, revealing a decrease in the shear modulus and toughness of the composites above 8 µl of GO by increasing GO content.
Antifouling paints are used to protect the surface against these organisms such as algae, sea squ... more Antifouling paints are used to protect the surface against these organisms such as algae, sea squirts, and barnacles. According to previous research, fish and seaweeds do not adhere to submerged surfaces using wet and soft hydrogels. The aim of this study is to investigate the temperature effect on the performance of antifouling composites to develop new useful antifouling composites for shipping sector. In this swelling experiment, the behavior of hydrogels produced from polyacrylamide (PAAm) and graphene oxide (GO) was investigated at different temperatures. Free‐radical cross‐linking copolymerization formed composite, using acrylamide, ammonium persulfate, N, N′‐methylenebisacrylamide (BIS, Merck), and graphene oxide with various contents. The steady‐state fluorescence technique was used for studying the swelling of PAAm‐GO composites at various temperatures in pure water. When pyranine fluorescence intensity, I was measured, it decreased until swelling equilibrium was achieved. After the swelling experiment was started, the fluorescence emission (Iem) and scattering light intensities, Isc from different GO content hydrogels were observed by real‐time monitoring at various temperatures. Li‐Tanaka and Fickian models were used to determine the diffusion coefficients for the swelling experiments in distilled and Marmara Sea Water for 8 and 50 μl of GO content hydrogels, respectively. According to literature, PAAm is utilized as a surface coating material to reduce biofouling, for this reason, this research will show a way to be able to use PAAm inside antifouling paints material for the marine industry.
Carrageenans are widely used in the food industry to produce milk gels and to stabilize products;... more Carrageenans are widely used in the food industry to produce milk gels and to stabilize products; on the other hand alginate is useful in sauces, in syrups, and toppings for ice cream. First, in this chapter, the effect of contents and temperature on gelation, drying, swelling, and elasticity behaviors of kappa carragenan (κC) doped polyacrylamide gels are reported. Second, the work on steady state fluorescence technique, which was used to study pyranine release from the alginate beads, crosslinked with calcium, barium, and aluminum ions, are reported, respectively. The release of pyranine from the alginate beads of different cationic beads exhibits that the encapsulation efficiencies and the initial amount of pyranine follow of the order Ba2+< Ca2+< Al3+. Last, the work on alginate beads, prepared by nonionic and anionic surfactants with calcium, and barium ions are reported, where compression measurements were performed to investigate the effect of the surfactant and cation types and their contents on Young’s modulus of alginate beads.
New generation nano-filler polymer composites have many applications including biomedical, electr... more New generation nano-filler polymer composites have many applications including biomedical, electronic and maritime related applications because of their mechanical, electronic and optical properties. The properties of composites were investigated as a function of nano-filler content. Among these, tungsten disulfide (WS2) has the potential to be used as a component in electronic devices owing to its high electron mobility and easily tunable optical band gap energy. Tungsten disulfide (WS2)- Polyacrylamide (PAAm) composite was prepared using free radical co-polymerization and wet laboratory methods with WS2 content. Composites were characterized for mechanical and optical properties using an Elasticity Instrument and UV-vis Spectrophotometer, respectively. Elastic modulus was modeled by a statistical thermodynamics model. Tauc’s and Urbach’s Tail model for direct transition were used to model for the optical band gap. In this study, the swelling and WS2 effect on the optical band gap and elasticity of WS2 - PAAm composites were investigated. It was observed that the elasticity presented a reversed behavior of optical band gap energies with respect to WS2 content. For the applications of nano-filler doped polymer composites in flexible electronic devices, WS2 content strongly influences the mechanical and optical properties.
ABSTRACT Steady state fluorescence (SSF) and photon transmission (PT) techniques were used for st... more ABSTRACT Steady state fluorescence (SSF) and photon transmission (PT) techniques were used for studying film formation from TiO2 and Al2O3 covered polystyrene (PS) latex particles. These films were annealed at elevated temperatures in 10 min time intervals above glass transition (Tg) temperature of polystyrene. Fluorescence emission, Ip and transmitted photon, Itr intensities were measured after each annealing step to monitor the stages of film formation. Films present dramatic increase in both Itr and Ip above the certain onset temperature called minimum film forming temperature, T0. Dissolution of annealed PS film, with high TiO2 content presented a nice, ordered nano-sized ceramic structure, which may predict the construction of nano-layer photonic crystals. It was observed that latex particles are encapsulated above a critical Al2O3 content of 33 wt% which corresponds to the critical occupation probability of pc=0.33 at which the film obey the site-percolation model with a critical exponent of 0.45.
ABSTRACT Small molecule sorption and slow release in and out of polyacrylamide (PAAm) gels were s... more ABSTRACT Small molecule sorption and slow release in and out of polyacrylamide (PAAm) gels were studied by using steady state fluorescence (SSF) technique. Pyranine (Py) dissolved in water used as a probe. Fluorescence emission intensity, Ip from Py was used to monitor for studying sorption and slow release processes at various temperatures. Sorption and slow release processes were analyzed by using Fickian diffusion model and coefficients were obtained. Related activation energies were also calculated for the corresponding physical processes.
Polyacrylamide (PAAm) hydrogels have been proposed for use as promising biomaterials in biomedica... more Polyacrylamide (PAAm) hydrogels have been proposed for use as promising biomaterials in biomedical and tissue engineering but their poor mechanical and water-retention properties have hindered their development. Graphene oxide (GO), an excellent nanofiller, was added to PAAm to produce mechanically strong GO–PAAm composites. The free radical crosslinking copolymerization method was used with GO content varying in the range between 5 and 50 µl of GO. The mechanical properties of the GO–PAAm composites are measured by compressive test, revealing a decrease in the shear modulus and toughness of the composites above 8 µl of GO by increasing GO content.
Antifouling paints are used to protect the surface against these organisms such as algae, sea squ... more Antifouling paints are used to protect the surface against these organisms such as algae, sea squirts, and barnacles. According to previous research, fish and seaweeds do not adhere to submerged surfaces using wet and soft hydrogels. The aim of this study is to investigate the temperature effect on the performance of antifouling composites to develop new useful antifouling composites for shipping sector. In this swelling experiment, the behavior of hydrogels produced from polyacrylamide (PAAm) and graphene oxide (GO) was investigated at different temperatures. Free‐radical cross‐linking copolymerization formed composite, using acrylamide, ammonium persulfate, N, N′‐methylenebisacrylamide (BIS, Merck), and graphene oxide with various contents. The steady‐state fluorescence technique was used for studying the swelling of PAAm‐GO composites at various temperatures in pure water. When pyranine fluorescence intensity, I was measured, it decreased until swelling equilibrium was achieved. After the swelling experiment was started, the fluorescence emission (Iem) and scattering light intensities, Isc from different GO content hydrogels were observed by real‐time monitoring at various temperatures. Li‐Tanaka and Fickian models were used to determine the diffusion coefficients for the swelling experiments in distilled and Marmara Sea Water for 8 and 50 μl of GO content hydrogels, respectively. According to literature, PAAm is utilized as a surface coating material to reduce biofouling, for this reason, this research will show a way to be able to use PAAm inside antifouling paints material for the marine industry.
Carrageenans are widely used in the food industry to produce milk gels and to stabilize products;... more Carrageenans are widely used in the food industry to produce milk gels and to stabilize products; on the other hand alginate is useful in sauces, in syrups, and toppings for ice cream. First, in this chapter, the effect of contents and temperature on gelation, drying, swelling, and elasticity behaviors of kappa carragenan (κC) doped polyacrylamide gels are reported. Second, the work on steady state fluorescence technique, which was used to study pyranine release from the alginate beads, crosslinked with calcium, barium, and aluminum ions, are reported, respectively. The release of pyranine from the alginate beads of different cationic beads exhibits that the encapsulation efficiencies and the initial amount of pyranine follow of the order Ba2+< Ca2+< Al3+. Last, the work on alginate beads, prepared by nonionic and anionic surfactants with calcium, and barium ions are reported, where compression measurements were performed to investigate the effect of the surfactant and cation types and their contents on Young’s modulus of alginate beads.
New generation nano-filler polymer composites have many applications including biomedical, electr... more New generation nano-filler polymer composites have many applications including biomedical, electronic and maritime related applications because of their mechanical, electronic and optical properties. The properties of composites were investigated as a function of nano-filler content. Among these, tungsten disulfide (WS2) has the potential to be used as a component in electronic devices owing to its high electron mobility and easily tunable optical band gap energy. Tungsten disulfide (WS2)- Polyacrylamide (PAAm) composite was prepared using free radical co-polymerization and wet laboratory methods with WS2 content. Composites were characterized for mechanical and optical properties using an Elasticity Instrument and UV-vis Spectrophotometer, respectively. Elastic modulus was modeled by a statistical thermodynamics model. Tauc’s and Urbach’s Tail model for direct transition were used to model for the optical band gap. In this study, the swelling and WS2 effect on the optical band gap and elasticity of WS2 - PAAm composites were investigated. It was observed that the elasticity presented a reversed behavior of optical band gap energies with respect to WS2 content. For the applications of nano-filler doped polymer composites in flexible electronic devices, WS2 content strongly influences the mechanical and optical properties.
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