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2009 Volume 27 Issue 6
2009, 27(6): 761-770
doi: 10.1007/s10118-010-8191-1
Abstract:
Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups. The structure of the polymer was confirmed by spectral techniques. GPC analysis reveals that the polymers have moderate molecular weight with narrow distribution. Hot stage optical polarizing microscopic investigation confirms the liquid crystalline nature of the polymers with lengthy flexible spacers, while the short chain containing polymers does not show the mesomorphic properties. Differential scanning calorimetric analysis confirms the formation of mesophase in some of the polymers, and it is in accordance with the microscopic results. Thermal stabilities of the polymers were analyzed by thermogravimetric analysis.
Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups. The structure of the polymer was confirmed by spectral techniques. GPC analysis reveals that the polymers have moderate molecular weight with narrow distribution. Hot stage optical polarizing microscopic investigation confirms the liquid crystalline nature of the polymers with lengthy flexible spacers, while the short chain containing polymers does not show the mesomorphic properties. Differential scanning calorimetric analysis confirms the formation of mesophase in some of the polymers, and it is in accordance with the microscopic results. Thermal stabilities of the polymers were analyzed by thermogravimetric analysis.
2009, 27(6): 771-780
Abstract:
Thin-film zeolite-filled silicone/PVDF composite membranes were fabricated by incorporating zeolite particles into PDMS (poly(dimethylsiloxane)) membranes. The morphology of zeolite particles and zeolite filled silicone composite membranes were characterized by SEM. The zeolite-filled PDMS/PVDF composite membranes were applied for the pervaporation of ethanol/water mixtures and showed higher flux compared with that reported in literatures. The effect of zeolite loading and Si/Al ratio of zeolite particles on pervaporation performance of ethanol/water mixtures was investigated. With the increase of zeolite loading from 10% to 30%, the total flux increased significantly from 265.0 g/(m2h) to 820.7 g/(m2h) with 5 wt% ethanol feed concentration at 50oC, and the separation factor increased from 11.3 to 13.7. The effects of operation temperature and ethanol feed concentration on pervaporation performance were also studied. As the temperature increased from 40oC to 80oC, the separation factor varied from 12.1 to 13.7 which maintained the maximum value at 50oC, and the total flux increased exponentially from 435.5 g/(m2h) to 2993.8 g/(m2h) with 30% zeolite loading. Besides, the zeolite filled PDMS/PVDF composite membrane with 30% zeolite loading was ethanol perm-selective over a wide range of ethanol feed concentration (5 wt%-90 wt%), and especially showed excellent pervaporation performance in the low concentration range.
Thin-film zeolite-filled silicone/PVDF composite membranes were fabricated by incorporating zeolite particles into PDMS (poly(dimethylsiloxane)) membranes. The morphology of zeolite particles and zeolite filled silicone composite membranes were characterized by SEM. The zeolite-filled PDMS/PVDF composite membranes were applied for the pervaporation of ethanol/water mixtures and showed higher flux compared with that reported in literatures. The effect of zeolite loading and Si/Al ratio of zeolite particles on pervaporation performance of ethanol/water mixtures was investigated. With the increase of zeolite loading from 10% to 30%, the total flux increased significantly from 265.0 g/(m2h) to 820.7 g/(m2h) with 5 wt% ethanol feed concentration at 50oC, and the separation factor increased from 11.3 to 13.7. The effects of operation temperature and ethanol feed concentration on pervaporation performance were also studied. As the temperature increased from 40oC to 80oC, the separation factor varied from 12.1 to 13.7 which maintained the maximum value at 50oC, and the total flux increased exponentially from 435.5 g/(m2h) to 2993.8 g/(m2h) with 30% zeolite loading. Besides, the zeolite filled PDMS/PVDF composite membrane with 30% zeolite loading was ethanol perm-selective over a wide range of ethanol feed concentration (5 wt%-90 wt%), and especially showed excellent pervaporation performance in the low concentration range.
2009, 27(6): 781-787
Abstract:
A new diamine containing sulfone, sulfide and amide groups was synthesized via a three-step reaction process. The nucleophilic substitution reaction of 4-aminothiophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide (PO) afforded N-(4-mercaptophenyl)-4-nitrobenzamide (MPNB). The catalytic reduction of the nitro group in MPNB to amino group was accomplished by using Pd/C and hydrazine monohydrate to produce 4-amino-N-(4-mercapto phenyl)benzamide (AMPB). Reaction of two moles of AMPB with bis(4-chlorophenyl)sulfone in the presence of K2CO3 resulted in preparation of a sulfone sulfide amide diamine (SSAD). The precursors and final monomer were characterized by FTIR, 1H-NMR and elemental analysis. Polycondensation reactions of the prepared diamine with different commercially available diacid chlorides resulted in the preparation of novel polyamides that were characterized by FTIR, HNMR and elemental analysis. The physical and thermal properties of them such as inherent viscosity, solubility, thermal behavior and thermal stability were studied.
A new diamine containing sulfone, sulfide and amide groups was synthesized via a three-step reaction process. The nucleophilic substitution reaction of 4-aminothiophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide (PO) afforded N-(4-mercaptophenyl)-4-nitrobenzamide (MPNB). The catalytic reduction of the nitro group in MPNB to amino group was accomplished by using Pd/C and hydrazine monohydrate to produce 4-amino-N-(4-mercapto phenyl)benzamide (AMPB). Reaction of two moles of AMPB with bis(4-chlorophenyl)sulfone in the presence of K2CO3 resulted in preparation of a sulfone sulfide amide diamine (SSAD). The precursors and final monomer were characterized by FTIR, 1H-NMR and elemental analysis. Polycondensation reactions of the prepared diamine with different commercially available diacid chlorides resulted in the preparation of novel polyamides that were characterized by FTIR, HNMR and elemental analysis. The physical and thermal properties of them such as inherent viscosity, solubility, thermal behavior and thermal stability were studied.
2009, 27(6): 789-796
Abstract:
Novel 9-proparylcarbazole monomers containing amino acid moieties, 2-N-(tert-butoxycarbonyl)-L-alanine-9-proparylcarbazole ester (1), 2-N-(tert-butoxycarbonyl)-L-O-cyclohexyl-L-glutamic acid-9-proparylcarbazole ester (2) and 2-N-(tert-butoxycarbonyl)-L-phenylalanine-9-proparylcarbazole ester (3) were synthesized and polymerized with (nbd)Rh+[η6-C6H5B–(C6H5)3] to give the corresponding polymers with number-average molecular weights ranging from 7050 to 10500 in 70%-86% yields. The polymers were completely soluble in toluene, CHCl3, CH2Cl2, THF and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation studies revealed that poly(1)-(3) do not took predominantly one-handed helical structures in the solvents although they possess chiral groups. The polymers emitted fluorescence in 0.40%–2.35% quantum yields. The cyclic voltammograms of the polymers indicated that the polymers exhibited electrochemical properties.
Novel 9-proparylcarbazole monomers containing amino acid moieties, 2-N-(tert-butoxycarbonyl)-L-alanine-9-proparylcarbazole ester (1), 2-N-(tert-butoxycarbonyl)-L-O-cyclohexyl-L-glutamic acid-9-proparylcarbazole ester (2) and 2-N-(tert-butoxycarbonyl)-L-phenylalanine-9-proparylcarbazole ester (3) were synthesized and polymerized with (nbd)Rh+[η6-C6H5B–(C6H5)3] to give the corresponding polymers with number-average molecular weights ranging from 7050 to 10500 in 70%-86% yields. The polymers were completely soluble in toluene, CHCl3, CH2Cl2, THF and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation studies revealed that poly(1)-(3) do not took predominantly one-handed helical structures in the solvents although they possess chiral groups. The polymers emitted fluorescence in 0.40%–2.35% quantum yields. The cyclic voltammograms of the polymers indicated that the polymers exhibited electrochemical properties.
2009, 27(6): 797-805
Abstract:
Dendritic poly(amidoamine)-b-poly(L-glutamate) (PAMAM-b-PLG) biohybrids were synthesized by the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride monomer, followed by the deprotection of benzyl groups on poly(benzyl-L-glutamate), and were characterized by 1H-NMR, FT-IR and gel permeation chromatography. The self-assembly behavior of the PAMAM-b-PLG biohybrid was investigated by means of UV-Vis, dynamic light scattering (DLS), transmission electronic microscopy (TEM) and 1H-NMR. UV-Vis analysis demonstrated that the critical aggregation concentration of PAMAM-b-PLG was dependent on the pH value of aqueous solutios. DLS results further evidenced that the PAMAM-b-PLG biohybrid exhibited a pH-sensitive self-assembly behavior, and the average size of the self-assembled nanoparticles decreased gradually with the increasing pH value of the PAMAM-b-PLG solution. The self-assembled nanoparticles gave a nearly spherical morphology, and the pH-induced self-assembly had no obvious effect on the morphology of nanoparticles.
Dendritic poly(amidoamine)-b-poly(L-glutamate) (PAMAM-b-PLG) biohybrids were synthesized by the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride monomer, followed by the deprotection of benzyl groups on poly(benzyl-L-glutamate), and were characterized by 1H-NMR, FT-IR and gel permeation chromatography. The self-assembly behavior of the PAMAM-b-PLG biohybrid was investigated by means of UV-Vis, dynamic light scattering (DLS), transmission electronic microscopy (TEM) and 1H-NMR. UV-Vis analysis demonstrated that the critical aggregation concentration of PAMAM-b-PLG was dependent on the pH value of aqueous solutios. DLS results further evidenced that the PAMAM-b-PLG biohybrid exhibited a pH-sensitive self-assembly behavior, and the average size of the self-assembled nanoparticles decreased gradually with the increasing pH value of the PAMAM-b-PLG solution. The self-assembled nanoparticles gave a nearly spherical morphology, and the pH-induced self-assembly had no obvious effect on the morphology of nanoparticles.
2009, 27(6): 807-812
Abstract:
Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride. The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry (TG), X-ray diffraction (XRD), limiting oxygen index (LOI) and cone calorimeter (CONE). The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34, and the heat release rate (HRR), total heat release (THR), CO and CO2 concentrations during combustion are much lower compared with those of viscose fibers. Calcium carbonate and calcium oxide were formed during thermal degradation of calcium alginate fibers at different temperatures. The shape of calcium alginate fibers is well kept after LOI test. The rigid combustion residue char acts as an effective barrier to the outward diffusion of flame and heat. The combustion process and flame retardant mechanism of calcium alginate fibers are also discussed.
Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride. The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry (TG), X-ray diffraction (XRD), limiting oxygen index (LOI) and cone calorimeter (CONE). The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34, and the heat release rate (HRR), total heat release (THR), CO and CO2 concentrations during combustion are much lower compared with those of viscose fibers. Calcium carbonate and calcium oxide were formed during thermal degradation of calcium alginate fibers at different temperatures. The shape of calcium alginate fibers is well kept after LOI test. The rigid combustion residue char acts as an effective barrier to the outward diffusion of flame and heat. The combustion process and flame retardant mechanism of calcium alginate fibers are also discussed.
2009, 27(6): 813-820
Abstract:
Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone) (PPESK) as main chains was carried out by atom transfer radical polymerization (ATRP). The precursor, chloromethylated PPESK (CMPPESK), was prepared by using chloromethylether as chloromethylation agent. Then, poly(ethylene glycol) methyl ether methacrylate (PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system. PPESK/PPESK-g-P(PEGMA) blend membranes were prepared and characterized. Chemical structures of the products were confirmed by FT-IR spectroscopy and 1H-NMR analysis. The thermal properties of PPESK-g-P(PEGMA) were analyzed by thermal gravity analysis (TGA). XPS method was used to analyze the composition of the blend membrane. FESEM was employed to investigate the morphology of the membranes. The hydrophilicity of blend membranes was measured by water contact angle test. It turns out that the hydrophilicity and surface wettability were enhanced after modification. However, the thermal properties were negatively affected.
Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone) (PPESK) as main chains was carried out by atom transfer radical polymerization (ATRP). The precursor, chloromethylated PPESK (CMPPESK), was prepared by using chloromethylether as chloromethylation agent. Then, poly(ethylene glycol) methyl ether methacrylate (PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system. PPESK/PPESK-g-P(PEGMA) blend membranes were prepared and characterized. Chemical structures of the products were confirmed by FT-IR spectroscopy and 1H-NMR analysis. The thermal properties of PPESK-g-P(PEGMA) were analyzed by thermal gravity analysis (TGA). XPS method was used to analyze the composition of the blend membrane. FESEM was employed to investigate the morphology of the membranes. The hydrophilicity of blend membranes was measured by water contact angle test. It turns out that the hydrophilicity and surface wettability were enhanced after modification. However, the thermal properties were negatively affected.
2009, 27(6): 821-831
Abstract:
The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by 1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H2O and methanol, while lower solubility in CHCl3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.
The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by 1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H2O and methanol, while lower solubility in CHCl3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.
2009, 27(6): 833-842
Abstract:
Low density polyethylene (LDPE)/lignin blends were prepared using melt blending. Two kinds of compatibilizers, ethylene-vinylacetate (EVA) which is softer than LDPE and polyethylene grafted with maleic anhydride (PE-g-MA) which is harder than LDPE were used to improve the interfacial adhesion. Scanning electron microscope (SEM) was used to investigate the dispersion of lignin in LDPE matrix. The results showed that both of the compatibilizers could improve the interaction between the low density polyethylene and lignin. However, the effects of the two compatibilizers on the mechanical properties of LDPE/lignin blends were different. The elongation at break of the blends was obviously increased by adding EVA, while significant improvement of tensile strength was observed by adding PE-g-MA. Several theoretical models have been used to further analyze the experimental data, combined with the morphological observation of tensile fractured surfaces by SEM.
Low density polyethylene (LDPE)/lignin blends were prepared using melt blending. Two kinds of compatibilizers, ethylene-vinylacetate (EVA) which is softer than LDPE and polyethylene grafted with maleic anhydride (PE-g-MA) which is harder than LDPE were used to improve the interfacial adhesion. Scanning electron microscope (SEM) was used to investigate the dispersion of lignin in LDPE matrix. The results showed that both of the compatibilizers could improve the interaction between the low density polyethylene and lignin. However, the effects of the two compatibilizers on the mechanical properties of LDPE/lignin blends were different. The elongation at break of the blends was obviously increased by adding EVA, while significant improvement of tensile strength was observed by adding PE-g-MA. Several theoretical models have been used to further analyze the experimental data, combined with the morphological observation of tensile fractured surfaces by SEM.
2009, 27(6): 843-849
Abstract:
The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.
The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.
2009, 27(6): 851-856
Abstract:
1,4-Bis-(4-bromobenzoyl)benzene and proflavine, 3,6-diaminoacridine free base were synthesized first. Using 1,4-bis-(4-bromobenzoyl)benzene and proflavine, 3,6-diaminoacridine free base as the monomers, poly(aryl imino) containing acridine units (PAIA) was synthesized via palladium-catalyzed amination. The structure of PAIA was characterized by means of FTIR, 1H-NMR spectroscopy and elemental analysis, the results show an agreement with the proposed structure. The UV absorption and photoluminescence spectra were tested. The absorption spectrum of the PAIA was dependent on the acidity of the media. The emission and excitation spectra of the two different forms of PAIA were investigated by photoluminescence, the addition of the trifluoroacetic acid (TFA) to the solution of PAIA does not lead to a quenching effect in the photoluminescent spectra. Additionally, DSC and TG measurements show that PAIA possess high glass transition temperature (Tg 230°C) and good thermal stability with high decomposition temperatures in nitrogen atmosphere (TD 500°C).
1,4-Bis-(4-bromobenzoyl)benzene and proflavine, 3,6-diaminoacridine free base were synthesized first. Using 1,4-bis-(4-bromobenzoyl)benzene and proflavine, 3,6-diaminoacridine free base as the monomers, poly(aryl imino) containing acridine units (PAIA) was synthesized via palladium-catalyzed amination. The structure of PAIA was characterized by means of FTIR, 1H-NMR spectroscopy and elemental analysis, the results show an agreement with the proposed structure. The UV absorption and photoluminescence spectra were tested. The absorption spectrum of the PAIA was dependent on the acidity of the media. The emission and excitation spectra of the two different forms of PAIA were investigated by photoluminescence, the addition of the trifluoroacetic acid (TFA) to the solution of PAIA does not lead to a quenching effect in the photoluminescent spectra. Additionally, DSC and TG measurements show that PAIA possess high glass transition temperature (Tg 230°C) and good thermal stability with high decomposition temperatures in nitrogen atmosphere (TD 500°C).
2009, 27(6): 857-864
Abstract:
A natural nanotubular material, halloysite nanotubes (HNTs), was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube (SBR/m-HNT) nanocomposites. Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier. The structure, morphology and mechanical properties of SBR/m-HNT nanocomposites, especially the interfacial interactions, were investigated. SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at nanometer scale, but also enhance the interfacial combination between HNTs and rubber matrix. FTIR and XPS investigations confirmed that a number of hydrogen bonds were formed between the phenol hydroxyl groups in resorcinol-formaldehyde resin derived from RH and the oxygen atoms in Si―O bonds or hydroxyl groups on HNTs surfaces. The m-HNTs modified with RH have significant reinforcing effect on SBR vulcanizates. RH as a good interfacial modifier can remarkably improve mechanical properties of SBR/HNT composites. The substantial improvement of comprehensive properties for SBR/m-HNT nanocomposites can be attributed to good dispersion and orientation of HNTs in SBR matrix at nanometer scale and the enhanced interfacial interaction between HNTs and rubber matrix.
A natural nanotubular material, halloysite nanotubes (HNTs), was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube (SBR/m-HNT) nanocomposites. Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier. The structure, morphology and mechanical properties of SBR/m-HNT nanocomposites, especially the interfacial interactions, were investigated. SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at nanometer scale, but also enhance the interfacial combination between HNTs and rubber matrix. FTIR and XPS investigations confirmed that a number of hydrogen bonds were formed between the phenol hydroxyl groups in resorcinol-formaldehyde resin derived from RH and the oxygen atoms in Si―O bonds or hydroxyl groups on HNTs surfaces. The m-HNTs modified with RH have significant reinforcing effect on SBR vulcanizates. RH as a good interfacial modifier can remarkably improve mechanical properties of SBR/HNT composites. The substantial improvement of comprehensive properties for SBR/m-HNT nanocomposites can be attributed to good dispersion and orientation of HNTs in SBR matrix at nanometer scale and the enhanced interfacial interaction between HNTs and rubber matrix.
2009, 27(6): 865-871
Abstract:
A dermal equivalent having a trilayered structure was designed by combining a silver nanoparticles incorporated chitosan film with a bilayer collagen-chitosan/silicon membrane dermal equivalent (BDE). The silver nanoparticles prepared at different conditions were characterized by UV-Vis and transmission electron microscopy (TEM). The macroscopic sharp and the microstructure of the trilayer dermal equivalent (TDE) were also studied. Then, the in vitro antibacterial property of TDE was evaluated by the antibacterial zone test. The effect of the incorporated silver nanoparticles on the resistance of wound infection was further studied by the in vivo animal test. The results prove that the silver nanoparticles incorporated TDE has a better antibacterial property, thus may be potentially applied to a broader field in skin repair such as full thickness defect and burn.
A dermal equivalent having a trilayered structure was designed by combining a silver nanoparticles incorporated chitosan film with a bilayer collagen-chitosan/silicon membrane dermal equivalent (BDE). The silver nanoparticles prepared at different conditions were characterized by UV-Vis and transmission electron microscopy (TEM). The macroscopic sharp and the microstructure of the trilayer dermal equivalent (TDE) were also studied. Then, the in vitro antibacterial property of TDE was evaluated by the antibacterial zone test. The effect of the incorporated silver nanoparticles on the resistance of wound infection was further studied by the in vivo animal test. The results prove that the silver nanoparticles incorporated TDE has a better antibacterial property, thus may be potentially applied to a broader field in skin repair such as full thickness defect and burn.
2009, 27(6): 873-877
Abstract:
A series of novel hybrid photoinitiators (YPhCOPhXPhI+PhPF6-, Y = 4-NO2, 4-MeO or 3-Cl, X = O, OCH2, or nothing), which contain multiple aromatic rings (PhCOPhXPh), were prepared by reaction of easily available aryl ketones (YPhCOPhXPh) with iodosobenzene diacetate [PhI+OCOCH3(CH3CO2)-]. The inset of an aromatic ring into p-benzoyldiphenyliodonium hexafluorophophate (PhCOPhI+PhPF6-) (BDPIH, He-type photoinitiator) between diphenyliodonium and benzoyl is propitious both to the preparation and the photoinitiating activity of ketonic diphenyliodonium photoinitiators. The yield and performance of the novel hybrid photoinitiators are much better than those of the He-type initiator.
A series of novel hybrid photoinitiators (YPhCOPhXPhI+PhPF6-, Y = 4-NO2, 4-MeO or 3-Cl, X = O, OCH2, or nothing), which contain multiple aromatic rings (PhCOPhXPh), were prepared by reaction of easily available aryl ketones (YPhCOPhXPh) with iodosobenzene diacetate [PhI+OCOCH3(CH3CO2)-]. The inset of an aromatic ring into p-benzoyldiphenyliodonium hexafluorophophate (PhCOPhI+PhPF6-) (BDPIH, He-type photoinitiator) between diphenyliodonium and benzoyl is propitious both to the preparation and the photoinitiating activity of ketonic diphenyliodonium photoinitiators. The yield and performance of the novel hybrid photoinitiators are much better than those of the He-type initiator.
2009, 27(6): 879-888
Abstract:
A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene (PP)/organically modified montmorillonite (OMMT) nanocomposites. The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation. The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis (TGA). The structural evolution and composition change in the surface region of PP/OMMT nanocomposites during heating were monitored by means of X-ray photoelectron spectroscopy (XPS), ATR-FTIR and field emission scanning electron microscopy (FESEM). The results showed that the formation of the carbonaceous silicate barrier in the surface region of PP/OMMT nanocomposites resulted from the following three processes: (1) The formation of strong acid sites on the MMT sheets, which could promote the degradation of PP and the carbonization of its degradation products; (2) The gases and gas bubbles formed by decomposition of the surfactant and degradation of PP, which pushed the molten sample to the surface; (3) The degradation of PP and the carbonization of the degradation products, which led to accumulation of MMT sheets tightly linked by the char in the surface region.
A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene (PP)/organically modified montmorillonite (OMMT) nanocomposites. The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation. The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis (TGA). The structural evolution and composition change in the surface region of PP/OMMT nanocomposites during heating were monitored by means of X-ray photoelectron spectroscopy (XPS), ATR-FTIR and field emission scanning electron microscopy (FESEM). The results showed that the formation of the carbonaceous silicate barrier in the surface region of PP/OMMT nanocomposites resulted from the following three processes: (1) The formation of strong acid sites on the MMT sheets, which could promote the degradation of PP and the carbonization of its degradation products; (2) The gases and gas bubbles formed by decomposition of the surfactant and degradation of PP, which pushed the molten sample to the surface; (3) The degradation of PP and the carbonization of the degradation products, which led to accumulation of MMT sheets tightly linked by the char in the surface region.
2009, 27(6): 889-894
Abstract:
A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction. The molecular structure and optical properties were highly investigated through 1H-NMR, UV and PL spectroscopy. The quenching behavior was also investigated, and the results demonstrate that incomplete quenching exists, which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents, probably correlated with the conformation of conjugated backbone and intermolecular aggregation.
A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction. The molecular structure and optical properties were highly investigated through 1H-NMR, UV and PL spectroscopy. The quenching behavior was also investigated, and the results demonstrate that incomplete quenching exists, which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents, probably correlated with the conformation of conjugated backbone and intermolecular aggregation.
2009, 27(6): 895-902
Abstract:
Sulfonated poly(arylene ether sulfone) (SPAES) copolymer with degree of sulfonation of 1.0 was synthesized and characterized. A series of SPAES-TiO2 hybrid membranes with various contents of nano-sized TiO2 particles were prepared and characterized through sol-gel reactions. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These composite membranes were evaluated for proton exchange membranes (PEMs) in direct methanol fuel cell (DMFC). These membranes showed good thermal stability and mechanical properties. It was found that the water uptake of these membranes increased with the increase of the TiO2 contents in the hybrid membranes. Meanwhile, the introduction of inorganic particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities (0.118-0.162 S/cm) of SPAES-TiO2 hybrid membranes with 8% TiO2 particles are much higher than those of Nafion 117 membrane (0.095-0.117 S/cm) and pure SPAES membrane (0.100-0.124 S/cm) with degree of sulfonation of 1.0 at all temperatures (25-100°C). Especially, the methanol diffusion coefficient (8.4× 10-7 cm2/s) of SPAES-TiO2 hybrid membranes with 8% TiO2 is much lower than that of Nafion 117 membrane (2.1 ×10-6 cm2/s). SPAES-TiO2 hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.
Sulfonated poly(arylene ether sulfone) (SPAES) copolymer with degree of sulfonation of 1.0 was synthesized and characterized. A series of SPAES-TiO2 hybrid membranes with various contents of nano-sized TiO2 particles were prepared and characterized through sol-gel reactions. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These composite membranes were evaluated for proton exchange membranes (PEMs) in direct methanol fuel cell (DMFC). These membranes showed good thermal stability and mechanical properties. It was found that the water uptake of these membranes increased with the increase of the TiO2 contents in the hybrid membranes. Meanwhile, the introduction of inorganic particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities (0.118-0.162 S/cm) of SPAES-TiO2 hybrid membranes with 8% TiO2 particles are much higher than those of Nafion 117 membrane (0.095-0.117 S/cm) and pure SPAES membrane (0.100-0.124 S/cm) with degree of sulfonation of 1.0 at all temperatures (25-100°C). Especially, the methanol diffusion coefficient (8.4× 10-7 cm2/s) of SPAES-TiO2 hybrid membranes with 8% TiO2 is much lower than that of Nafion 117 membrane (2.1 ×10-6 cm2/s). SPAES-TiO2 hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.
2009, 27(6): 903-908
Abstract:
A novel, facile method to prepare copolymers by virtue of the reinitiation of precursor containing isopropylthioxanthone (ITX) residues (ITXH) was reported. Using poly(maleic anhydride-co-vinyl acetate) (P(MAH-co-VAc)) with incorporated ITX residues as a macroinitiator, polymerization of styrene was performed, and poly(maleic anhydride-co-vinyl acetate)-b-polystyrene (P(MAH-co-VAc)-b-PSt) was produced. Applying the resultant copolymer in a breath figure procedure, honeycomb structure films having pore size around 250 nm were prepared under low temperature and relative humidity.
A novel, facile method to prepare copolymers by virtue of the reinitiation of precursor containing isopropylthioxanthone (ITX) residues (ITXH) was reported. Using poly(maleic anhydride-co-vinyl acetate) (P(MAH-co-VAc)) with incorporated ITX residues as a macroinitiator, polymerization of styrene was performed, and poly(maleic anhydride-co-vinyl acetate)-b-polystyrene (P(MAH-co-VAc)-b-PSt) was produced. Applying the resultant copolymer in a breath figure procedure, honeycomb structure films having pore size around 250 nm were prepared under low temperature and relative humidity.
