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2012 Volume 30 Issue 3
2012, 30(3): 337-342
doi: 10.1007/s10118-012-1158-7
Abstract:
Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D). It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.
Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D). It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.
2012, 30(3): 343-349
doi: 10.1007/s10118-012-1144-0
Abstract:
The master curves of a series of aliphatic polycarbonates (APCs) with different lengths of methylene segments in the repeat unit were obtained by dynamic rheological measurements. The plateau modulus and entanglement molecular weight were determined and cross-checked by different methods. Though having distinct difference in chemical structure of repeat units, both APCs and bisphenol-A polycarbonates have the similar entanglement weight and entanglement spacing. On the other side, the plateau modulus decreases with increasing the length of the side group of aliphatic polycarbonates with different side-chain lengths in the literature. The packing length model can explain the relationship between chain structure and entanglements.
The master curves of a series of aliphatic polycarbonates (APCs) with different lengths of methylene segments in the repeat unit were obtained by dynamic rheological measurements. The plateau modulus and entanglement molecular weight were determined and cross-checked by different methods. Though having distinct difference in chemical structure of repeat units, both APCs and bisphenol-A polycarbonates have the similar entanglement weight and entanglement spacing. On the other side, the plateau modulus decreases with increasing the length of the side group of aliphatic polycarbonates with different side-chain lengths in the literature. The packing length model can explain the relationship between chain structure and entanglements.
2012, 30(3): 350-358
doi: 10.1007/s10118-012-1123-5
Abstract:
This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain. The theoretical framework is the same as in the recent works by Steinhauser et al., where a Rouse approach is adopted. Our model differs in that our chains have a finite average bending angle. As in the works by Steinhauser et al., Langevin dynamic simulations were performed without hydrodynamic interactions. Whereas this doesn't impact the static properties we obtain, it also allows us to compare our results on dynamic properties to those predicted by Rouse theory, where hydrodynamic interactions are also neglected. Our results show that the structural properties are very sensitive to the chain stiffness, whereas the dynamic scaling laws remain the same as those by Rouse theory, with the prefactor depending on the persistence length.
This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain. The theoretical framework is the same as in the recent works by Steinhauser et al., where a Rouse approach is adopted. Our model differs in that our chains have a finite average bending angle. As in the works by Steinhauser et al., Langevin dynamic simulations were performed without hydrodynamic interactions. Whereas this doesn't impact the static properties we obtain, it also allows us to compare our results on dynamic properties to those predicted by Rouse theory, where hydrodynamic interactions are also neglected. Our results show that the structural properties are very sensitive to the chain stiffness, whereas the dynamic scaling laws remain the same as those by Rouse theory, with the prefactor depending on the persistence length.
2012, 30(3): 359-369
doi: 10.1007/s10118-012-1134-2
Abstract:
Tri-layer CdS/SiO2/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate (EGDMA) or EGDMA together with comonomers having different functional groups, such as methacrylic acid, 4-vinylpyridine and 2-hydroxyethylmethacrylate, in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified CdS/SiO2 nanoparticles as seeds in acetonitrile with 2,2?-azobisisobutyronitrile (AIBN) as initiator. In this approach, MPS-modified inorganic seeds were prepared by the modification of CdS/SiO2 nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols, in which the CdS/SiO2 nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer. The polymer shell-layers encapsulated over the MPS-modified CdS/SiO2 inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification, in which the polymer shell-thickness and functional groups including carboxyl, pyridyl and hydroxyl, were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization. These nanospheres were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), fluorescence spectroscopy and zeta potential.
Tri-layer CdS/SiO2/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate (EGDMA) or EGDMA together with comonomers having different functional groups, such as methacrylic acid, 4-vinylpyridine and 2-hydroxyethylmethacrylate, in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified CdS/SiO2 nanoparticles as seeds in acetonitrile with 2,2?-azobisisobutyronitrile (AIBN) as initiator. In this approach, MPS-modified inorganic seeds were prepared by the modification of CdS/SiO2 nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols, in which the CdS/SiO2 nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer. The polymer shell-layers encapsulated over the MPS-modified CdS/SiO2 inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification, in which the polymer shell-thickness and functional groups including carboxyl, pyridyl and hydroxyl, were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization. These nanospheres were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), fluorescence spectroscopy and zeta potential.
2012, 30(3): 370-377
doi: 10.1007/s10118-012-1124-4
Abstract:
Poly(p-arylene sulfide ketone/Schiff base) copolymers (PASK/SB) were prepared by solution polycondensation of 4,4'-diflurobenzophenone (DFBP) and N-phenyl(4,4'-diflurodiphenyl) ketimine (DFBI) with sodium sulfide in the presence of sodium hydroxide under normal pressure. Elemental analyses, FT-IR, NMR, DSC, TGA and XRD were used to characterize the resultant copolymers. It was found that the copolymers had good thermal properties with glass transition temperature (Tg) of 155.0-172.0℃, melting temperature (Tm) of 298-344℃, 5% weight loss temperatures (Td) of 471.0-501.5℃. These copolymers were almost amorphous with the content of DFBI beyond 30%. The polymer with 100% DFBI had excellent solubility, and it could dissolve in some solvents such as tetrahydrofuran (THF) and N-methyl-2-pyrrolidone (NMP). The processability of polymers was improved. Meantime the viscosity of PASK made from hydrolysis of PASK/SB (H-PASK/SB) was greatly improved from 0.135 dL/g to 0.605 dL/g.
Poly(p-arylene sulfide ketone/Schiff base) copolymers (PASK/SB) were prepared by solution polycondensation of 4,4'-diflurobenzophenone (DFBP) and N-phenyl(4,4'-diflurodiphenyl) ketimine (DFBI) with sodium sulfide in the presence of sodium hydroxide under normal pressure. Elemental analyses, FT-IR, NMR, DSC, TGA and XRD were used to characterize the resultant copolymers. It was found that the copolymers had good thermal properties with glass transition temperature (Tg) of 155.0-172.0℃, melting temperature (Tm) of 298-344℃, 5% weight loss temperatures (Td) of 471.0-501.5℃. These copolymers were almost amorphous with the content of DFBI beyond 30%. The polymer with 100% DFBI had excellent solubility, and it could dissolve in some solvents such as tetrahydrofuran (THF) and N-methyl-2-pyrrolidone (NMP). The processability of polymers was improved. Meantime the viscosity of PASK made from hydrolysis of PASK/SB (H-PASK/SB) was greatly improved from 0.135 dL/g to 0.605 dL/g.
2012, 30(3): 378-386
doi: 10.1007/s10118-012-1137-z
Abstract:
Crosslinking reaction of LDPE resin in the presence of dicumyl peroxide (DCP) was studied by isothermal rheological measurements at different temperatures and non-isothermal differential scanning calorimetry (DSC) technique with different heating rates. The kinetic parameters of crosslinking reaction were calculated by both rheological and DSC measurements. The results reveal that with the increase of DCP contents, the apparent activation energy, Ea, ranges from about 140 kJ/mol to 170 kJ/mol and the order of crosslinking reaction, n, approaches unity. The influence of measurement frequency, , on crosslinking reaction was also investigated. It can be found that n does not change with the increase of , and Ea decreases slightly with the increase of .
Crosslinking reaction of LDPE resin in the presence of dicumyl peroxide (DCP) was studied by isothermal rheological measurements at different temperatures and non-isothermal differential scanning calorimetry (DSC) technique with different heating rates. The kinetic parameters of crosslinking reaction were calculated by both rheological and DSC measurements. The results reveal that with the increase of DCP contents, the apparent activation energy, Ea, ranges from about 140 kJ/mol to 170 kJ/mol and the order of crosslinking reaction, n, approaches unity. The influence of measurement frequency, , on crosslinking reaction was also investigated. It can be found that n does not change with the increase of , and Ea decreases slightly with the increase of .
2012, 30(3): 387-396
doi: 10.1007/s10118-012-1138-y
Abstract:
An anti-tumor drug doxorubicin was encapsulated in micelles of poly(ethylene glycol)-b-poly(2,2-dihydroxyl- methyl propylene carbonate) (PEG-b-PDHPC) diblock copolymers. The morphology of both blank micelles and drug loaded micelles was characterized by TEM. The in vitro drug release profiles of micelles were investigated. The cytotoxicity of the micelles was evaluated by incubating with Hela tumor cells and 3T3 fibroblasts. The drug loaded micelles were co-cultured with HepG2 cells to evaluate the in vitro anti-tumor efficacies. The results showed that the mean sizes of both micelles with different copolymer compositions increased after being loaded with drugs. The drug release rate of PEG45-b-PDHPC34 micelles was faster than that of mPEG114-b-PDHPC26 micelles. Both of the two block copolymers were non-toxic. The confocal laser scanning microscopy and flow cytometry results showed that both the drug loaded micelles could be internalized efficiently in HepG2 cells. The PEG45-b-PDHPC34 micelles exhibited higher anti-tumor activity comparing to mPEG114-b-PDHPC26 micelles.
An anti-tumor drug doxorubicin was encapsulated in micelles of poly(ethylene glycol)-b-poly(2,2-dihydroxyl- methyl propylene carbonate) (PEG-b-PDHPC) diblock copolymers. The morphology of both blank micelles and drug loaded micelles was characterized by TEM. The in vitro drug release profiles of micelles were investigated. The cytotoxicity of the micelles was evaluated by incubating with Hela tumor cells and 3T3 fibroblasts. The drug loaded micelles were co-cultured with HepG2 cells to evaluate the in vitro anti-tumor efficacies. The results showed that the mean sizes of both micelles with different copolymer compositions increased after being loaded with drugs. The drug release rate of PEG45-b-PDHPC34 micelles was faster than that of mPEG114-b-PDHPC26 micelles. Both of the two block copolymers were non-toxic. The confocal laser scanning microscopy and flow cytometry results showed that both the drug loaded micelles could be internalized efficiently in HepG2 cells. The PEG45-b-PDHPC34 micelles exhibited higher anti-tumor activity comparing to mPEG114-b-PDHPC26 micelles.
2012, 30(3): 397-404
doi: 10.1007/s10118-012-1148-9
Abstract:
Poly(methyl methacrylate)/soy protein (PMMA/SP) composites were prepared by emulsion polymerization method using potassium persulphate (KPS) as the radical initiator. The interaction of soy protein with PMMA was evidenced by Fourier transformed infrared (FTIR) spectroscopy. The structure of PMMA/SP composites was investigated by X-ray diffraction (XRD) study and scanning electron microscopy (SEM). The thermal properties of soy protein and PMMA/SP composites were compared with soy protein and virgin PMMA sample. PMMA/SP composites were found to be flame retardant materials from the measurement of limiting oxygen index (LOI) of samples. The oxygen permeability of PMMA/SP composites was substantially decreased as compared to virgin PMMA.
Poly(methyl methacrylate)/soy protein (PMMA/SP) composites were prepared by emulsion polymerization method using potassium persulphate (KPS) as the radical initiator. The interaction of soy protein with PMMA was evidenced by Fourier transformed infrared (FTIR) spectroscopy. The structure of PMMA/SP composites was investigated by X-ray diffraction (XRD) study and scanning electron microscopy (SEM). The thermal properties of soy protein and PMMA/SP composites were compared with soy protein and virgin PMMA sample. PMMA/SP composites were found to be flame retardant materials from the measurement of limiting oxygen index (LOI) of samples. The oxygen permeability of PMMA/SP composites was substantially decreased as compared to virgin PMMA.
2012, 30(3): 405-414
doi: 10.1007/s10118-012-1131-5
Abstract:
Two kinds of polyfluorenes bearing two lateral pyrene terminated alkyl chains and two alkyl chains per repeating unit were synthesized by Suzuki polycondensation and used to disperse single-walled carbon nanotubes (SWCNT) in organic solvents. Stable polymer-SWCNT complex can be formed via the multivalent - stacking interaction of the lateral pyrene functional groups and the polyfluorene backbone with the outer surface of carbon nanotubes; meanwhile the lateral alkyl chains can impart good solubility to the complex. As expected, polyfluorenes bearing lateral pyrene functional groups and octyl chains exhibited much higher carbon nanotube solubility in common organic solvents than the corresponding polyfluorenes bearing only octyl chains. Photophysical studies indicated that the formation of polymer-SWCNT complex can effectively quench the fluorescence of polyfluorenes.
Two kinds of polyfluorenes bearing two lateral pyrene terminated alkyl chains and two alkyl chains per repeating unit were synthesized by Suzuki polycondensation and used to disperse single-walled carbon nanotubes (SWCNT) in organic solvents. Stable polymer-SWCNT complex can be formed via the multivalent - stacking interaction of the lateral pyrene functional groups and the polyfluorene backbone with the outer surface of carbon nanotubes; meanwhile the lateral alkyl chains can impart good solubility to the complex. As expected, polyfluorenes bearing lateral pyrene functional groups and octyl chains exhibited much higher carbon nanotube solubility in common organic solvents than the corresponding polyfluorenes bearing only octyl chains. Photophysical studies indicated that the formation of polymer-SWCNT complex can effectively quench the fluorescence of polyfluorenes.
2012, 30(3): 415-422
doi: 10.1007/s10118-012-1139-x
Abstract:
Three epoxy-based azo polymers (PEP-AZ-Cl, PEP-AZ-CN and PEP-AZ-NT) with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer (PEP-AN) and diazonium salts of 4-chloroaniline, 4-aminobenzonitrile and 4-nitroaniline, respectively. The structures and properties of the azo polymers were characterized by using 1H-NMR, FT-IR, UV-Vis and thermal analyses. The photoinduced birefringence of the azo polymers was studied by irradiating spin-coated films of the polymers with laser beam at three different wavelengths (488, 532, and 589 nm). The results indicate that the photoinduced birefringence of the azo polymers is related with the electron-withdrawing group on azo chromophores and the excitation wavelength. The excitation wavelength that can cause the efficient responses is determined by the absorption band positions of the azo chromophores, which are mainly affected by the electron-withdrawing group on the chromophores. Therefore, the azo polymers containing chromophores with different electron-withdrawing groups show different responsive behavior to the irradiation light at different wavelengths. When irradiated with 488 nm light, PEP-AZ-Cl shows the shortest time to reach the saturated birefringence but with the lowest saturation birefringence level compared with the other two azo polymers. When irradiated with 532 nm light, PEP-AZ-CN shows the shortest time to reach the saturated birefringence. When irradiated with 532 and 589 nm light, PEP-AZ-NT shows the highest saturation birefringence level.
Three epoxy-based azo polymers (PEP-AZ-Cl, PEP-AZ-CN and PEP-AZ-NT) with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer (PEP-AN) and diazonium salts of 4-chloroaniline, 4-aminobenzonitrile and 4-nitroaniline, respectively. The structures and properties of the azo polymers were characterized by using 1H-NMR, FT-IR, UV-Vis and thermal analyses. The photoinduced birefringence of the azo polymers was studied by irradiating spin-coated films of the polymers with laser beam at three different wavelengths (488, 532, and 589 nm). The results indicate that the photoinduced birefringence of the azo polymers is related with the electron-withdrawing group on azo chromophores and the excitation wavelength. The excitation wavelength that can cause the efficient responses is determined by the absorption band positions of the azo chromophores, which are mainly affected by the electron-withdrawing group on the chromophores. Therefore, the azo polymers containing chromophores with different electron-withdrawing groups show different responsive behavior to the irradiation light at different wavelengths. When irradiated with 488 nm light, PEP-AZ-Cl shows the shortest time to reach the saturated birefringence but with the lowest saturation birefringence level compared with the other two azo polymers. When irradiated with 532 nm light, PEP-AZ-CN shows the shortest time to reach the saturated birefringence. When irradiated with 532 and 589 nm light, PEP-AZ-NT shows the highest saturation birefringence level.
2012, 30(3): 423-435
doi: 10.1007/s10118-012-1130-6
Abstract:
The surface of polypropylene (iPP) is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy (SEM) show the surface etching pattern of iPP films. The chemical structures of iPP films are confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The wetting properties of modified surfaces of iPP films are characterized by contact angle, and the free energy of surfaces is calculated. The free radical of modification surfaces of iPP is measured by chemical method. The surfaces of iPP are achieved with Ar plasma treatment followed by grafting copolymerization with styrene (St) in St. The grafting polymer of St onto iPP is characterized by FTIR. The grafting rate is dependent on plasma exposure time and discharge voltage. The studies show that homopolymerization of St is undergone at the same time during the grafting-copolymerization of St onto iPP.
The surface of polypropylene (iPP) is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy (SEM) show the surface etching pattern of iPP films. The chemical structures of iPP films are confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The wetting properties of modified surfaces of iPP films are characterized by contact angle, and the free energy of surfaces is calculated. The free radical of modification surfaces of iPP is measured by chemical method. The surfaces of iPP are achieved with Ar plasma treatment followed by grafting copolymerization with styrene (St) in St. The grafting polymer of St onto iPP is characterized by FTIR. The grafting rate is dependent on plasma exposure time and discharge voltage. The studies show that homopolymerization of St is undergone at the same time during the grafting-copolymerization of St onto iPP.
2012, 30(3): 436-442
doi: 10.1007/s10118-012-1133-3
Abstract:
A facile approach to construct ferroferric oxide/chitosan composite scaffolds with three-dimensional oriented structure has been explored in this research. Chitosan and ferroferric oxide are co-precipitated by using an in situ precipitation method, and then lyophilized to get the composite scaffolds. XRD indicated that Fe3O4 was generated during the gel formation process, and increasing the content of magnetic particles could destruct the crystal structure of chitosan. When the content of magnetic particles is lower than 10%, the layer-by-layer structure and wheel spoke structure are coexisting in the scaffolds. Increasing the content of magnetic particles, just layer-by-layer structure could be observed in the scaffolds. Ferroferric oxide particles were uniformly distributed in the matrix, the size of which was about 0.48 m in diameter, 2 m in length. Porosity of magnetic chitosan composite scaffolds is about 90%. When the ratio of ferroferric oxide to chitosan is 5/100, the compressive strength of the material is 0.4367 MPa, which is much higher than that of pure chitosan scaffolds, indicating that the layer-by-layer and wheel spokes complex structure is beneficial for the improvement of the mechanical properties of chitosan scaffolds. However, increasing the content of ferroferric oxide, the compressive strength of scaffolds decreased, because of the decreasing of chitosan crystallization and aggregation of magnetic particles as stress centralized body. Another reason is that the layer-by-layer and wheel spokes complex structure makes bigger contributions for the compressive strength than the layer-by-layer structure does. Three-dimensional ferroferric oxide/chitosan scaffolds could be used as hyperthermia generator system, improving the local circulation of blood, promoting the aggradation of calcium salt and stimulating bone tissue regeneration.
A facile approach to construct ferroferric oxide/chitosan composite scaffolds with three-dimensional oriented structure has been explored in this research. Chitosan and ferroferric oxide are co-precipitated by using an in situ precipitation method, and then lyophilized to get the composite scaffolds. XRD indicated that Fe3O4 was generated during the gel formation process, and increasing the content of magnetic particles could destruct the crystal structure of chitosan. When the content of magnetic particles is lower than 10%, the layer-by-layer structure and wheel spoke structure are coexisting in the scaffolds. Increasing the content of magnetic particles, just layer-by-layer structure could be observed in the scaffolds. Ferroferric oxide particles were uniformly distributed in the matrix, the size of which was about 0.48 m in diameter, 2 m in length. Porosity of magnetic chitosan composite scaffolds is about 90%. When the ratio of ferroferric oxide to chitosan is 5/100, the compressive strength of the material is 0.4367 MPa, which is much higher than that of pure chitosan scaffolds, indicating that the layer-by-layer and wheel spokes complex structure is beneficial for the improvement of the mechanical properties of chitosan scaffolds. However, increasing the content of ferroferric oxide, the compressive strength of scaffolds decreased, because of the decreasing of chitosan crystallization and aggregation of magnetic particles as stress centralized body. Another reason is that the layer-by-layer and wheel spokes complex structure makes bigger contributions for the compressive strength than the layer-by-layer structure does. Three-dimensional ferroferric oxide/chitosan scaffolds could be used as hyperthermia generator system, improving the local circulation of blood, promoting the aggradation of calcium salt and stimulating bone tissue regeneration.
2012, 30(3): 443-450
doi: 10.1007/s10118-012-1135-1
Abstract:
Poly(phenylene ethynylene)s (P1) with 4-vinylaniline pendant groups were successfully prepared by the Sonogashira coupling polymerization between 1,4-diethynyl-2,5-bis(pentyloxy)benzene and 4-[2-(2,5-dibromophenyl)vinyl]-aniline. In comparison with its analogue P2 without amino group, the emission of P1 is only enhanced by aggregation when adding n-hexane into its THF solution, exhibiting an aggregation-induced emission enhancement (AIEE) effect. When methanol or water instead of hexane was added into THF solution, P1, however, didnt show AIEE. The results indicated that amino groups strengthen the inter-chain and intra-chain interactions in P1 and restrict the non-radiative energy transition. This strategy can provide a platform for developing highly sensitive and efficient bio- and chemosensors.
Poly(phenylene ethynylene)s (P1) with 4-vinylaniline pendant groups were successfully prepared by the Sonogashira coupling polymerization between 1,4-diethynyl-2,5-bis(pentyloxy)benzene and 4-[2-(2,5-dibromophenyl)vinyl]-aniline. In comparison with its analogue P2 without amino group, the emission of P1 is only enhanced by aggregation when adding n-hexane into its THF solution, exhibiting an aggregation-induced emission enhancement (AIEE) effect. When methanol or water instead of hexane was added into THF solution, P1, however, didnt show AIEE. The results indicated that amino groups strengthen the inter-chain and intra-chain interactions in P1 and restrict the non-radiative energy transition. This strategy can provide a platform for developing highly sensitive and efficient bio- and chemosensors.
2012, 30(3): 451-459
doi: 10.1007/s10118-012-1136-0
Abstract:
Polystyrene (PS) microspheres were functionalized with poly(styrene-b-tert-butyl acrylate) (P(S-b-tBA)) by adsorption from supercritical mixture of CO2 and hexane. Supercritical deposition formed a shell-core structure that contained a shell of poly(tert-butyl acrylate) (PtBA) blocks and a core of the PS blocks entangling with the PS microspheres. The thickness of the PtBA layer and thereby the areal density of tert-butyl ester groups increased with the deposition pressure until plateau values attained at 20 MPa and higher. The tert-butyl ester groups were hydrolyzed to carboxyl groups for conjugation with tert-butylamine molecules via amide bonds that were further chlorinated into biocidal N-halamine moieties. The functionalization layer and its bonded N-halamine moieties were stable in flowing water and the chlorine could be regenerated upon eventual loss. This functionalization concept is applicable to polymers of any external and internal surfaces to achieve diverse surface properties by varying block copolymer and conjugated moieties.
Polystyrene (PS) microspheres were functionalized with poly(styrene-b-tert-butyl acrylate) (P(S-b-tBA)) by adsorption from supercritical mixture of CO2 and hexane. Supercritical deposition formed a shell-core structure that contained a shell of poly(tert-butyl acrylate) (PtBA) blocks and a core of the PS blocks entangling with the PS microspheres. The thickness of the PtBA layer and thereby the areal density of tert-butyl ester groups increased with the deposition pressure until plateau values attained at 20 MPa and higher. The tert-butyl ester groups were hydrolyzed to carboxyl groups for conjugation with tert-butylamine molecules via amide bonds that were further chlorinated into biocidal N-halamine moieties. The functionalization layer and its bonded N-halamine moieties were stable in flowing water and the chlorine could be regenerated upon eventual loss. This functionalization concept is applicable to polymers of any external and internal surfaces to achieve diverse surface properties by varying block copolymer and conjugated moieties.
2012, 30(3): 460-469
doi: 10.1007/s10118-012-1140-4
Abstract:
Vitamin C (VC) content in commercial juices was voltammetrically determined using a highly selective and sensitive poly(3,4-ethylenedioxythiophene methanol)/ascorbate oxidase/Nafion-single-walled carbon nanotubes (PEDOTM/AO/Nafion-SWCNT) biosensor. The biocompatible PEDOTM matrix was prepared facilely by the one-step electrochemical deposition technique in lithium perchlorate aqueous solutions. AO was dip-coated on the surface of the biocompatible PEDOTM matrix. The mixture of Nafion-SWCNT was dip-cast onto the surface of AO layer when it was obtained by blending Nafion solution and SWCNT dispersion together in a volume ratio of 1:1. The prepared PEDOTM/AO/Nafion-SWCNT biosensor was used for the voltammetric determination of VC, which exhibited the good linear range (4.0 ? 10-5-3 ? 10-3 mol/L), low detection limit (13 祄ol/L), pronounced sensitivity (1.4072 mA (mmol/L)-1 cm-2), high bioaffinity (low apparent Michaelis-Menten constant), good stability (good repeatability), high specificity (good anti-interference ability) coupled with the good reliability and feasibility (the determination of VC in commercial juices). Meanwhile, the good aqueous solubility and the low onset oxidation potential of EDOTM will be more beneficial to the application in biosensor field compared to 3,4-ethylenedioxythiophene. Moreover, the good biocompatibility of PEDOTM matrix and high selectivity of Nafion-SWCNT films also provide a promising platform for the development of biosensing devices.
Vitamin C (VC) content in commercial juices was voltammetrically determined using a highly selective and sensitive poly(3,4-ethylenedioxythiophene methanol)/ascorbate oxidase/Nafion-single-walled carbon nanotubes (PEDOTM/AO/Nafion-SWCNT) biosensor. The biocompatible PEDOTM matrix was prepared facilely by the one-step electrochemical deposition technique in lithium perchlorate aqueous solutions. AO was dip-coated on the surface of the biocompatible PEDOTM matrix. The mixture of Nafion-SWCNT was dip-cast onto the surface of AO layer when it was obtained by blending Nafion solution and SWCNT dispersion together in a volume ratio of 1:1. The prepared PEDOTM/AO/Nafion-SWCNT biosensor was used for the voltammetric determination of VC, which exhibited the good linear range (4.0 ? 10-5-3 ? 10-3 mol/L), low detection limit (13 祄ol/L), pronounced sensitivity (1.4072 mA (mmol/L)-1 cm-2), high bioaffinity (low apparent Michaelis-Menten constant), good stability (good repeatability), high specificity (good anti-interference ability) coupled with the good reliability and feasibility (the determination of VC in commercial juices). Meanwhile, the good aqueous solubility and the low onset oxidation potential of EDOTM will be more beneficial to the application in biosensor field compared to 3,4-ethylenedioxythiophene. Moreover, the good biocompatibility of PEDOTM matrix and high selectivity of Nafion-SWCNT films also provide a promising platform for the development of biosensing devices.
2012, 30(3): 470-477
doi: 10.1007/s10118-012-1145-z
Abstract:
The influences of shearing conducted by a Brabender rheometer on phase morphology, thermal and rheological behavior of a commercial impact polypropylene copolymer (IPC) were studied. The crystallization and melting traces show that short-time annealing at 210℃ is unable to completely erase the influence of shearing on the samples. When the samples which were treated at a rotation speed of 80 r/min crystallize at a cooling rate of 10 K/min, their Tcs and corresponding Tms obviously rise with the increase of shearing time. Furthermore, the POM results reveal that the shearing can lead to the formation of shish-kebab and the shish-kebab amount is proportional to shearing time. The rheological measurement results show that the treated samples exhibit different G~ dependences. The second plateau appears when the sample is treated at a rotation speed of 60 r/min or 80 r/min for 10 min, and linear G~ dependence is observed at other rotation speeds. In addition, it is found that the appearance of the second plateau depends on the shearing time when the rotation speed is fixed. According to SEM observations, it is proposed that the second plateau of IPC samples should be ascribed to the aggregation of dispersion particles.
The influences of shearing conducted by a Brabender rheometer on phase morphology, thermal and rheological behavior of a commercial impact polypropylene copolymer (IPC) were studied. The crystallization and melting traces show that short-time annealing at 210℃ is unable to completely erase the influence of shearing on the samples. When the samples which were treated at a rotation speed of 80 r/min crystallize at a cooling rate of 10 K/min, their Tcs and corresponding Tms obviously rise with the increase of shearing time. Furthermore, the POM results reveal that the shearing can lead to the formation of shish-kebab and the shish-kebab amount is proportional to shearing time. The rheological measurement results show that the treated samples exhibit different G~ dependences. The second plateau appears when the sample is treated at a rotation speed of 60 r/min or 80 r/min for 10 min, and linear G~ dependence is observed at other rotation speeds. In addition, it is found that the appearance of the second plateau depends on the shearing time when the rotation speed is fixed. According to SEM observations, it is proposed that the second plateau of IPC samples should be ascribed to the aggregation of dispersion particles.
2012, 30(3): 478-486
doi: 10.1007/s10118-012-1142-2
Abstract:
In this work, surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers. The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched structure were synthesized by step-growth polycondensation of AB2 type monomers. The AB2 monomer, 4-(4'-(bis(2-chloroethyl)amino)-phenylazo)benzoic acid (BAA), was prepared through azo-coupling reaction between N,N'-bis(2-chloroethyl)aniline and 4-aminobenzenic acid. The another AB2 monomer, 4-(4'-(bis(2-chloroethyl)amino)phenylazo)-3-nitro-benzoic acid (BANA), was prepared through azo-coupling reaction between N,N-bis(2-chloroethyl)aniline and 3-nitro-4-aminobenzenic acid. The hyperbranched polymers (PBAA and PBANA) were prepared through nucleophilic substitution reaction of BAA and BANA, respectively. The polymers synthesized were characterized by using spectroscopic methods and thermal analysis. The photoinduced dichroism and photo-induced surface-relief-grating (SRG) formation of the hyperbranched polymers were investigated upon irradiation with Ar+ laser at 488 nm. PBAA shows typical photoinduced dichroism SRG formation behavior. On the contrary, PBANA does not show the photoresponsive properties. The results indicate that the nitro at the ortho position of azo group of PBANA shows the effect of inhibiting the photoinduced variations. The effect can be attributed to the blockage of the trans-cis isomerization of the azobenzene moieties by the steric hindrance.
In this work, surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers. The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched structure were synthesized by step-growth polycondensation of AB2 type monomers. The AB2 monomer, 4-(4'-(bis(2-chloroethyl)amino)-phenylazo)benzoic acid (BAA), was prepared through azo-coupling reaction between N,N'-bis(2-chloroethyl)aniline and 4-aminobenzenic acid. The another AB2 monomer, 4-(4'-(bis(2-chloroethyl)amino)phenylazo)-3-nitro-benzoic acid (BANA), was prepared through azo-coupling reaction between N,N-bis(2-chloroethyl)aniline and 3-nitro-4-aminobenzenic acid. The hyperbranched polymers (PBAA and PBANA) were prepared through nucleophilic substitution reaction of BAA and BANA, respectively. The polymers synthesized were characterized by using spectroscopic methods and thermal analysis. The photoinduced dichroism and photo-induced surface-relief-grating (SRG) formation of the hyperbranched polymers were investigated upon irradiation with Ar+ laser at 488 nm. PBAA shows typical photoinduced dichroism SRG formation behavior. On the contrary, PBANA does not show the photoresponsive properties. The results indicate that the nitro at the ortho position of azo group of PBANA shows the effect of inhibiting the photoinduced variations. The effect can be attributed to the blockage of the trans-cis isomerization of the azobenzene moieties by the steric hindrance.
