Summary: Coupling reactions between terminal functionalized polymer chains were chosen for the synthesis of star‐like polymers consisting of polystyrene and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] arms. For the preparation of terminal functionalized polymer chains a side reaction of the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) mediated free radical polymerization of methacrylates could be used successfully to convert TEMPO terminated polymers into end functionalized polymers. The number of functionalized monomer units attached to the polymer chain is directly related to the TEMPO concentration during this reaction. Different polystyrenes and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] block copolymers were functionalized with a variable number of epoxide and alcohol groups at the chain end. For the determination of the optimal reaction parameters for the coupling reactions between these polymer chains, epoxy functionalized polystyrenes were converted with hydroxy functionalized polystyrenes under basic and acidic conditions. By activation with sodium hydride or boron trifluoride star‐like polymers were synthesized under mild conditions. The transfer of the reaction conditions to coupling reactions between end functionalized polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] copolymers showed that star‐like polymers with more than 12 arms were formed using boron trifluoride as activating agent.
Carbon nanotubes were functionalized with poly(vinyl alcohol) (PVA). The water-soluble PVA-functionalized carbon nanotubes were then embedded into PVA matrix via a wet-casting method, resulting in polymer-carbon nanocomposite films with homogeneous nanotube dispersion. Composites with pristine and functionalized nanotubes were tested in tension. It was found that the mechanical properties of these nanocomposite films were significantly improved compared to the neat polymer film. Functionalization allowed good distribution of the nanotubes in the matrix, leading to higher film strength. Scanning electron microscopy shows an apparent good wetting of the nanotubes by the PVA matrix. These results are supportive of good interfacial bonding between the functionalized carbon nanotubes and the hosting polymer matrix. 相似文献
A rapid and efficient post-polymerization functionalization of poly(urea-co-urethane) (PUU) onto the graphene oxide (GO) nanosheets has been developed to produce super-acidic polymer/GO hybrid nanosheets. Thus, the surface of GO nanosheets were functionalized with 3-(triethoxysilyl)propyl isocyanate (TESPIC) from hydroxyl groups to yield isocyanate functionalized graphene oxide nanosheets. Then, sulfonated polymer/GO hybrid nanosheets were prepared by condensation polymerization of isocyanate-terminated pre-polyurea onto isocyanate functionalized graphene oxide nanosheets through the formation of carbamate bonds. FTIR and TGA results indicated that TESPIC modifier agent and poly(urea-co-urethane) were successfully grafted onto the GO nanosheets. The grafting efficiency of poly(urea-co-urethane) polymer onto the GO nanosheets was estimated from TGA thermograms to be 205.9%. Also, sulfonated polymer/GO hybrid nanosheets showed a proton conductivity as high as 3.7 mS cm?1. Modification and morphology of GO nanosheets before and after modification processes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). 相似文献
The synthesis of a new functionalized terthiophene monomer with an unsaturated side chain, 3-((2′:2″,5″:2?-terthiophene)-3″-yl) acrylic acid, is described. A conducting polymer was obtained by electropolymerization of the functionalized monomer. The properties of the polymer were investigated using FT-IR, Raman and UV-vis spectroscopy. The application of the polymer as an active substrate for a genosensor is demonstrated by the covalent attachment of amino-end modified oligonucleotide probes to the carboxylic acid group of the polymer. The hybridization of the complementary ODNs can be clearly detected by an increase in the admittance without the need for an indicator or any sample modifications. 相似文献
The polysilaether polymers bearing Si-H bonds (PSEHs) were synthesized using Wurtz coupling reaction of dichlorosilanes, mediated by alkali metals, after alcoholysis, the reactant was further hydrolyzed and polycondensation. The Si-H bonds in the macromolecular side chains provide tremendous potentials to prepare a variety of functionalized polysilaethers via hydrosilylation. In this work, the functionalization of PSEHs was carried out via hydrosilylation with acrylic acid and the functionalized derivative was characterized by means of nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography and thermal analysis. It is noted that both PSEHs and the functionalized derivative polymer displayed the characteristics of ultraviolet (UV) absorption and photoluminescence. The functionalized polymers show a considerable blue shift (∼325 nm) and red shift (∼390 nm) in comparison with the starting polymer, which provides the potential to obtain some tunable optoelectronic properties via the structural modifications of PSEHs. 相似文献