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2011 Volume 29 Issue 6
2011, 29(6): 639-649
doi: 10.1007/s10118-011-1077-z
Abstract:
Novel aromatic-aliphatic poly(amide-imide)s containing chiral units in the main chain and hydroxyl benzamide units in the side chain have been obtained from the step-growth polymerization of 3,5-diamino-N-(4-hydroxyphenyl) benzamide (2) with different chiral diacid chlorides (1a-1e). Theoretical calculations were done by means of computational chemistry methods to narrate the stable conformation and orientation of each diacid chloride monomers under reaction conditions. These polymers were characterized by conventional techniques. The resulting polymers show good thermal stability. Other physical properties of polymers including crystallinity, inherent viscosity and morphological characteristics were also studied.
Novel aromatic-aliphatic poly(amide-imide)s containing chiral units in the main chain and hydroxyl benzamide units in the side chain have been obtained from the step-growth polymerization of 3,5-diamino-N-(4-hydroxyphenyl) benzamide (2) with different chiral diacid chlorides (1a-1e). Theoretical calculations were done by means of computational chemistry methods to narrate the stable conformation and orientation of each diacid chloride monomers under reaction conditions. These polymers were characterized by conventional techniques. The resulting polymers show good thermal stability. Other physical properties of polymers including crystallinity, inherent viscosity and morphological characteristics were also studied.
2011, 29(6): 650-657
doi: 10.1007/s10118-011-1079-x
Abstract:
The acoustical damping property of electrospun polyacrylonitrile (PAN) nanofibrous membranes with different thicknesses and porosities was investigated. The sound absorption coefficients were measured using the impedance tube instrument based on ISO10534-2:1998(E). Results indicate that the first resonance absorption frequency of nanofibrous membranes shifts to the lower frequency with the increase of the back cavity or the thickness of membranes. Moreover, the sound absorption performance of the perforated panel can be greatly improved by combination with a thin layer of PAN nanofibrous membrane. Traditional acoustical damping materials (foam, fiber) coated with nanofibrous membranes have better acoustical performance in the low and medium frequency range than that of acoustical materials alone. All of the results demonstrate the PAN nanofibrous membrane is a suitable candidate for noise reduction.
The acoustical damping property of electrospun polyacrylonitrile (PAN) nanofibrous membranes with different thicknesses and porosities was investigated. The sound absorption coefficients were measured using the impedance tube instrument based on ISO10534-2:1998(E). Results indicate that the first resonance absorption frequency of nanofibrous membranes shifts to the lower frequency with the increase of the back cavity or the thickness of membranes. Moreover, the sound absorption performance of the perforated panel can be greatly improved by combination with a thin layer of PAN nanofibrous membrane. Traditional acoustical damping materials (foam, fiber) coated with nanofibrous membranes have better acoustical performance in the low and medium frequency range than that of acoustical materials alone. All of the results demonstrate the PAN nanofibrous membrane is a suitable candidate for noise reduction.
2011, 29(6): 658-669
doi: 10.1007/s10118-011-1082-2
Abstract:
A new ion-imprinted polymer (IIP) was synthesized by copolymerization of 4-vinylpyridine (monomer), ethyleneglycoldimethacrylate (cross-linker) and 2,2-azobis-isobutyronitrile (initiator) in the presence of Cd2+ and quinaldic acid (complexing agent). It was found that the adsorption capacity of IIP and blank polymer were 45.0 and 6.2 mg g-1, respectively. The relative selectivity coefficients of the imprinted polymer for different binary mixture were also calculated. Compared to non-imprinted polymer (NIP), the IIP had higher selectivity for Cd(II). The IIP was used as a sorbent for cadmium extraction from water samples by using a simple batch extraction procedure. The effect of different parameters on Cd2+ extraction and its recovery from the IIP were evaluated and optimized by using experimental design methodology. The optimized adsorption/desorption procedure was applied for cadmium removal from the real water samples. The obtained recoveries proved that this IIP could be used for removal of trace cadmium ions from water samples.
A new ion-imprinted polymer (IIP) was synthesized by copolymerization of 4-vinylpyridine (monomer), ethyleneglycoldimethacrylate (cross-linker) and 2,2-azobis-isobutyronitrile (initiator) in the presence of Cd2+ and quinaldic acid (complexing agent). It was found that the adsorption capacity of IIP and blank polymer were 45.0 and 6.2 mg g-1, respectively. The relative selectivity coefficients of the imprinted polymer for different binary mixture were also calculated. Compared to non-imprinted polymer (NIP), the IIP had higher selectivity for Cd(II). The IIP was used as a sorbent for cadmium extraction from water samples by using a simple batch extraction procedure. The effect of different parameters on Cd2+ extraction and its recovery from the IIP were evaluated and optimized by using experimental design methodology. The optimized adsorption/desorption procedure was applied for cadmium removal from the real water samples. The obtained recoveries proved that this IIP could be used for removal of trace cadmium ions from water samples.
2011, 29(6): 670-683
doi: 10.1007/s10118-011-1080-4
Abstract:
A series of hyperbranched polyurethane-benzyltetrazoles (H-PBTZs) with different linkage structures were synthesized via the polycondensation of hexamethylenediisocyanate as an A2 type monomer with (4-(1H-tetrazol-5- yl)benzyl)-diethanolamine (TBDEA) as a BB2' type monomer in the absence of catalyst at different temperatures. The FTIR, and 13C and 1H-NMR spectroscopy were used to characterize the molecular structures of TBDEA and H-PBTZs as well as the counterpart linear polyurethane-benzyltetrazole (L-PBTZ). The molecular composition was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring. Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring. The degrees of branching (DB) for H-PBTZs obtained from the 1H-NMR spectra increased with raising reaction temperature. The wider molecular weight distribution of 1.7-2.9 for H-PBTZs was obtained via GPC analysis. TGA results showed that H-PBTZs had high thermal stability compared with L-PBTZ.
A series of hyperbranched polyurethane-benzyltetrazoles (H-PBTZs) with different linkage structures were synthesized via the polycondensation of hexamethylenediisocyanate as an A2 type monomer with (4-(1H-tetrazol-5- yl)benzyl)-diethanolamine (TBDEA) as a BB2' type monomer in the absence of catalyst at different temperatures. The FTIR, and 13C and 1H-NMR spectroscopy were used to characterize the molecular structures of TBDEA and H-PBTZs as well as the counterpart linear polyurethane-benzyltetrazole (L-PBTZ). The molecular composition was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring. Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring. The degrees of branching (DB) for H-PBTZs obtained from the 1H-NMR spectra increased with raising reaction temperature. The wider molecular weight distribution of 1.7-2.9 for H-PBTZs was obtained via GPC analysis. TGA results showed that H-PBTZs had high thermal stability compared with L-PBTZ.
2011, 29(6): 684-691
doi: 10.1007/s10118-011-1072-4
Abstract:
The topic of self-assembly of cylinder-forming diblock copolymers (DBCPs) under spherical shell confinement in different surface fields is explored using real-space self-consistent field theory calculations (SCFT). Using this approach we observed various microstructures of cylinder-forming DBCPs at different confinement dimensions and surface fields. From detailed searching for the microdomain morphologies, an obvious conclusion is that the interactions between the confinement surface and the polymers have a great effect on the self-assembly. Most of the microstructures are unique and not reported in bulk or under planar and cylindrical confinements.
The topic of self-assembly of cylinder-forming diblock copolymers (DBCPs) under spherical shell confinement in different surface fields is explored using real-space self-consistent field theory calculations (SCFT). Using this approach we observed various microstructures of cylinder-forming DBCPs at different confinement dimensions and surface fields. From detailed searching for the microdomain morphologies, an obvious conclusion is that the interactions between the confinement surface and the polymers have a great effect on the self-assembly. Most of the microstructures are unique and not reported in bulk or under planar and cylindrical confinements.
2011, 29(6): 692-698
doi: 10.1007/s10118-011-1081-3
Abstract:
Novel copolymerization of ethylene with substituted allenes (CH2＝C＝CH―R, 1: R = n-butyl, 2: R = n-octyl) using bis(-enaminoketonato)titanium catalysts [PhN＝C(R2)CHC(R1)O]2TiCl2 (1a: R1 = CF3, R2 = CH3; 1b: R1 = Ph, R2 = CF2) has been investigated. In the presence of modified methylaluminoxane, these catalysts can copolymerize ethylene with substituted allenes, affording copolymers with unimodal molecular weight distributions and homogeneous compositions. By varying the reaction conditions, the comonomer incorporation can be tuned in the range of 0-3.6 mol%. 1H-NMR spectra reveal that the copolymerization proceeds through 1,2-insertion fashion of allene comonomer exclusively, and the regioselective nature maintains under various reaction conditions. The retained intra-chain double bond can be converted into the epoxy group under mild conditions.
Novel copolymerization of ethylene with substituted allenes (CH2＝C＝CH―R, 1: R = n-butyl, 2: R = n-octyl) using bis(-enaminoketonato)titanium catalysts [PhN＝C(R2)CHC(R1)O]2TiCl2 (1a: R1 = CF3, R2 = CH3; 1b: R1 = Ph, R2 = CF2) has been investigated. In the presence of modified methylaluminoxane, these catalysts can copolymerize ethylene with substituted allenes, affording copolymers with unimodal molecular weight distributions and homogeneous compositions. By varying the reaction conditions, the comonomer incorporation can be tuned in the range of 0-3.6 mol%. 1H-NMR spectra reveal that the copolymerization proceeds through 1,2-insertion fashion of allene comonomer exclusively, and the regioselective nature maintains under various reaction conditions. The retained intra-chain double bond can be converted into the epoxy group under mild conditions.
2011, 29(6): 699-711
doi: 10.1007/s10118-011-1083-1
Abstract:
In this work, the syntheses of new thermally stable poly(amide-imide)s with pendant 2-pyridyl-1,3,4-oxadiazole units in n-butyl methyl imidazolium bromide as reaction media have been reported. A new dicarboxylic acid has been derived from the reaction of diamine, 2-(5-(3,5-diaminophenyl)-1,3,4-oxadiazole-2-yl)pyridine (POBD), and trimellitic acid anhydride. Polymers were prepared from the reaction of the diimide-diacid (DIDA) and different aromatic diamines in butyl methyl imidazolium bromide, [bmim][Br], in the presence of triphenyl phosphite (TPP) as condensing agent without needing any extra components. The prepared poly(amide-imide)s were characterized by FTIR, elemental analysis, and through the synthesis of a model compound. The prepared polymers were soluble in polar and aprotic solvents, such as DMF, DMSO, NMP and DMAc. The inherent viscosity of the polymer solutions was in the range of 0.52-1.33 dL/g measured in concentrated H2SO4 at a concentration of 0.125 g/dL at (25 0.5)C. The results are compared with the results obtained from common direct polycondensation with NMP as solvent. Polymers obtained in ionic liquid showed higher inherent viscosity than that of polymers obtained via classical method in NMP. Thermal properties of the polymers were studied with DSC and TGA methods.
In this work, the syntheses of new thermally stable poly(amide-imide)s with pendant 2-pyridyl-1,3,4-oxadiazole units in n-butyl methyl imidazolium bromide as reaction media have been reported. A new dicarboxylic acid has been derived from the reaction of diamine, 2-(5-(3,5-diaminophenyl)-1,3,4-oxadiazole-2-yl)pyridine (POBD), and trimellitic acid anhydride. Polymers were prepared from the reaction of the diimide-diacid (DIDA) and different aromatic diamines in butyl methyl imidazolium bromide, [bmim][Br], in the presence of triphenyl phosphite (TPP) as condensing agent without needing any extra components. The prepared poly(amide-imide)s were characterized by FTIR, elemental analysis, and through the synthesis of a model compound. The prepared polymers were soluble in polar and aprotic solvents, such as DMF, DMSO, NMP and DMAc. The inherent viscosity of the polymer solutions was in the range of 0.52-1.33 dL/g measured in concentrated H2SO4 at a concentration of 0.125 g/dL at (25 0.5)C. The results are compared with the results obtained from common direct polycondensation with NMP as solvent. Polymers obtained in ionic liquid showed higher inherent viscosity than that of polymers obtained via classical method in NMP. Thermal properties of the polymers were studied with DSC and TGA methods.
2011, 29(6): 712-718
doi: 10.1007/s10118-011-1084-0
Abstract:
Technical properties of two naphthalimide based disperse dyes on nylon 6 and polyester fibers were investigated in the presence of urea. The two naphthalimide based disperse dyes were synthesized. The dyes were purified and then fully characterized using 1H-NMR, FTIR and melting point analysis. Dispersion of the dyes was prepared in water and applied on nylon 6 and PET fibers. The dyes offered good build-up properties on the substrates. In order to increase dye adsorption of the substrates, urea was added into the dyebath. By adding urea, the dye adsorption of polyester was increased significantly, while the increase of that of nylon 6 was not marked. The dyes showed good fastness properties on the substrates.
Technical properties of two naphthalimide based disperse dyes on nylon 6 and polyester fibers were investigated in the presence of urea. The two naphthalimide based disperse dyes were synthesized. The dyes were purified and then fully characterized using 1H-NMR, FTIR and melting point analysis. Dispersion of the dyes was prepared in water and applied on nylon 6 and PET fibers. The dyes offered good build-up properties on the substrates. In order to increase dye adsorption of the substrates, urea was added into the dyebath. By adding urea, the dye adsorption of polyester was increased significantly, while the increase of that of nylon 6 was not marked. The dyes showed good fastness properties on the substrates.
2011, 29(6): 719-725
doi: 10.1007/s10118-011-1085-z
Abstract:
A series of poly(aryl ether sulfone ketone)s containing phthalazinone and biphenyl moieties were synthesized by aromatic nucleophilic displacement polycondensation of 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ), 4,4'-dichlorobenzophenone (DCB), 4,4'-dichlorodiphenyl sulfone (DCS) and 4,4'-biphenol (BP) in different molar ratios. The obtained copolymers were characterized by different instrumental techniques (FTIR, TGA, DSC, WAXD, etc.). The inherent viscosities of these polymers were in the range of 0.43-0.56 dL g-1. They were amorphous and had good solubility in polar aprotic organic solvents. The copolymers exhibited high glass transition temperatures (Tgs) between 225C and 256C and excellent thermal stability up to 517-526C (thermal decomposition temperatures for 5% weight loss, Td, 5%) in nitrogen. The tensile strength and elongation at break of the polymers ranged from 63 MPa to 71 MPa and from 18% to 21%, respectively. The processability of the material was effectively improved by the introduction of biphenyl group into polymer backbone.
A series of poly(aryl ether sulfone ketone)s containing phthalazinone and biphenyl moieties were synthesized by aromatic nucleophilic displacement polycondensation of 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ), 4,4'-dichlorobenzophenone (DCB), 4,4'-dichlorodiphenyl sulfone (DCS) and 4,4'-biphenol (BP) in different molar ratios. The obtained copolymers were characterized by different instrumental techniques (FTIR, TGA, DSC, WAXD, etc.). The inherent viscosities of these polymers were in the range of 0.43-0.56 dL g-1. They were amorphous and had good solubility in polar aprotic organic solvents. The copolymers exhibited high glass transition temperatures (Tgs) between 225C and 256C and excellent thermal stability up to 517-526C (thermal decomposition temperatures for 5% weight loss, Td, 5%) in nitrogen. The tensile strength and elongation at break of the polymers ranged from 63 MPa to 71 MPa and from 18% to 21%, respectively. The processability of the material was effectively improved by the introduction of biphenyl group into polymer backbone.
2011, 29(6): 726-731
doi: 10.1007/s10118-011-1086-y
Abstract:
A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). Scanning electron microscope (SEM) was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.
A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). Scanning electron microscope (SEM) was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.
2011, 29(6): 732-740
doi: 10.1007/s10118-011-1087-x
Abstract:
The effect of clay on the nucleating behavior of 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS) in cryatallization of isotactic polypropylene (iPP) was investigated by means of differential scanning calorimetry (DSC), dynamic rheology and polarized light microscopy (PLM). It is interesting to note that the incorporation of layered clay nanoparticles into DMDBS-nucleated iPP may induce a synergetic nucleation effect while the DMDBS content is below 0.1 wt%, otherwise it restricts the crystallization rate prominently as the DMDBS content increases up to 0.3 wt%, which has exceeded the content threshold to yield a nucleating agent (NA) network. As shown by dynamic rheological investigations, the clay nanoparticles demonstrate an obstructive effect of disturbing the consistency of DMDBS fibrils network. Moreover, to further demonstrate the importance of NA network formation in the crystallization of iPP, we used another NA named HPN-20e, which can not form network structure at all over the concentration studied, for comparison. In this case, the nucleated-crystallization rate is independent on the addition of clay nanoparticles, as the nucleating mechanism is an individual nuclei manner without NA network forming.
The effect of clay on the nucleating behavior of 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol (DMDBS) in cryatallization of isotactic polypropylene (iPP) was investigated by means of differential scanning calorimetry (DSC), dynamic rheology and polarized light microscopy (PLM). It is interesting to note that the incorporation of layered clay nanoparticles into DMDBS-nucleated iPP may induce a synergetic nucleation effect while the DMDBS content is below 0.1 wt%, otherwise it restricts the crystallization rate prominently as the DMDBS content increases up to 0.3 wt%, which has exceeded the content threshold to yield a nucleating agent (NA) network. As shown by dynamic rheological investigations, the clay nanoparticles demonstrate an obstructive effect of disturbing the consistency of DMDBS fibrils network. Moreover, to further demonstrate the importance of NA network formation in the crystallization of iPP, we used another NA named HPN-20e, which can not form network structure at all over the concentration studied, for comparison. In this case, the nucleated-crystallization rate is independent on the addition of clay nanoparticles, as the nucleating mechanism is an individual nuclei manner without NA network forming.
2011, 29(6): 741-749
doi: 10.1007/s10118-011-1089-8
Abstract:
An anhydride monomer containing ether oxide bridge, 7-oxa-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (ONA), was successfully synthesized by Diels-Alder reaction of furan and maleic anhydride. The ONA was also studied as an end-cap for the polymerization of monomer reactant (PMR) type polyimides. Three molecular weight levels of the ONA end-capped PMR resins were evaluated. The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated. It was demonstrated that the imidized prepolymers using the end-cap have good processability, and the cured polyimide specimens exhibited good thermal stability. The initial decomposition temperature, Td (ca. 580℃) and glass transition temperature, Tg (330℃) of the novel resin (PI-20), prepared under optimum process conditions, compare favorably with the Td (ca. 620℃) and Tg (ca. 348℃) of the state-of-the-art resin (PI'-20), respectively.
An anhydride monomer containing ether oxide bridge, 7-oxa-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic anhydride (ONA), was successfully synthesized by Diels-Alder reaction of furan and maleic anhydride. The ONA was also studied as an end-cap for the polymerization of monomer reactant (PMR) type polyimides. Three molecular weight levels of the ONA end-capped PMR resins were evaluated. The effects of process conditions of these novel PMR resins on thermal and mechanical properties were investigated. It was demonstrated that the imidized prepolymers using the end-cap have good processability, and the cured polyimide specimens exhibited good thermal stability. The initial decomposition temperature, Td (ca. 580℃) and glass transition temperature, Tg (330℃) of the novel resin (PI-20), prepared under optimum process conditions, compare favorably with the Td (ca. 620℃) and Tg (ca. 348℃) of the state-of-the-art resin (PI'-20), respectively.
2011, 29(6): 750-756
doi: 10.1007/s10118-011-1088-9
Abstract:
It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect. According to this theory, we have reviewed the previous viscosity data of derivatives of poly-2-vinylpyridine reported by Maclay and Fuoss first. Then, the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further. The solute adsorption behaviors and structural information of polymers have been discussed carefully.
It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly, and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect. According to this theory, we have reviewed the previous viscosity data of derivatives of poly-2-vinylpyridine reported by Maclay and Fuoss first. Then, the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further. The solute adsorption behaviors and structural information of polymers have been discussed carefully.
2011, 29(6): 757-761
doi: 10.1007/s10118-011-1090-2
Abstract:
Hard poly(vinyl chloride) (PVC)/acrylonitrile-butadiene-styrene (ABS) blends were prepared using injectionmolding and influence of crosshead speed on mechanical properties was examined. Based on morphology parameters obtained from transmission electron microscopy photography and the material parameters from true stress-strain curves of neat PVC and ABS, yield stresses of the blends at different crosshead speeds were simulated employing a two-dimensional nine-particle model based on the finite element analysis (FEA). The FEA results were compared with the experimental yielding stress and the good agreement validated the simulation approach. The FEA approach allowed establishing a yielding criterion related to local yielding of the interstitial matrix between ABS particles.
Hard poly(vinyl chloride) (PVC)/acrylonitrile-butadiene-styrene (ABS) blends were prepared using injectionmolding and influence of crosshead speed on mechanical properties was examined. Based on morphology parameters obtained from transmission electron microscopy photography and the material parameters from true stress-strain curves of neat PVC and ABS, yield stresses of the blends at different crosshead speeds were simulated employing a two-dimensional nine-particle model based on the finite element analysis (FEA). The FEA results were compared with the experimental yielding stress and the good agreement validated the simulation approach. The FEA approach allowed establishing a yielding criterion related to local yielding of the interstitial matrix between ABS particles.
2011, 29(6): 762-771
doi: 10.1007/s10118-011-1068-0
Abstract:
Functional amphiphilic block copolymer poly(ethylene glycol)-block-poly[(3-(triethoxysilyl)propyl methacrylate)-co-(1-pyrene-methyl) methacrylate], PEG113-b-P(TEPM26-co-PyMMA4), was synthesized via atom transfer radical polymerization (ATRP) initiated by monomethoxy capped poly(ethylene glycol) bromoisobutyrate. This polymer exhibited strong ability to disperse and exfoliate single-walled carbon nanotubes (SWNTs) in different solvents due to the adhesion of pyrene units to surface of SWNTs. In aqueous solution, the PTEPM segments that were located on the nanotube surfaces with the pyrene units could be gelated and, as a result, the silica oxide networks with PEG coronas were formed on the surface of nanotubes, which ensured the composites with a good dispersibility and stability. Furthermore, functional silane coupling agents, 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, were introduced during dispersion of SWNTs using the block copolymers. They were co-gelated with PTEPM segments, and the ―SH and ―NH2 functionalities were introduced into the silica oxide coats respectively.
Functional amphiphilic block copolymer poly(ethylene glycol)-block-poly[(3-(triethoxysilyl)propyl methacrylate)-co-(1-pyrene-methyl) methacrylate], PEG113-b-P(TEPM26-co-PyMMA4), was synthesized via atom transfer radical polymerization (ATRP) initiated by monomethoxy capped poly(ethylene glycol) bromoisobutyrate. This polymer exhibited strong ability to disperse and exfoliate single-walled carbon nanotubes (SWNTs) in different solvents due to the adhesion of pyrene units to surface of SWNTs. In aqueous solution, the PTEPM segments that were located on the nanotube surfaces with the pyrene units could be gelated and, as a result, the silica oxide networks with PEG coronas were formed on the surface of nanotubes, which ensured the composites with a good dispersibility and stability. Furthermore, functional silane coupling agents, 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, were introduced during dispersion of SWNTs using the block copolymers. They were co-gelated with PTEPM segments, and the ―SH and ―NH2 functionalities were introduced into the silica oxide coats respectively.
