In this study, we observed significant differences in the electrical and optical properties of polymer films electrochemically synthesized from two 3-alkylthiophene monomers on platinum wires in 0.100 mol L?1 LiClO4/acetonitrile (ACN) or Et4NBF4/ACN, when compared to the following homopolymer films: poly(3-methylthiophene) (P3MT), poly(3-hexylthiophene) (P3HT) and poly(3-octylthiophene) (P3OT), prepared under the same conditions. Electrical impedance spectroscopy was used to assess the resistive and capacitive properties of the polymer films [P3MT and P3HT—CP3(MT-HT); P3MT and P3OT—CP3(MT-OT); P3HT and P3OT—CP3(HT-OT)] at overpotentials determined beforehand by Cyclic Voltammetry. The films synthesized in LiClO4/ACN with the lowest charge transfer resistance values were CP3(MT-HT) and CP3(MT-OT), and synthesized in Et4NBF4/ACN, CP3(HT-OT). In terms of their optical properties, the films synthesized in LiClO4/ACN exhibited hypsochromic shift of Eg values and a drop in electron affinity values by comparison with homopolymer films and those synthesized in Et4NBF4/ACN. Based on Photoluminescence (PL) Spectroscopy it was possible to identify the contributions of the quinone and aromatic segments characteristic of homopolymers in the films synthesized in Et4NBF4/ACN. For the films synthesized in LiClO4/ACN, it was not possible to perform the same comparison because there was a discrepancy between the bands observed in the PL images of these materials and those of the homopolymers, suggesting the formation of not only blend structures but also copolymer films. Using Raman Spectroscopy it was possible to identify aromatic, radical cation and dication segments and verify the higher stabilization of radical cation and dication segments in resistive films. It was also possible to observe changes in the morphological structures of the films by comparison with the homopolymers, in addition to alterations due to changes in electrolyte during synthesis using scanning electron microscopy. 相似文献
In this work, acrylic acid (AAc) monomer was grafted onto low-density polyethylene (LDPE) films by the direct method to obtain acid (LDPE-grafted poly(acrylic acid) (LDPE-g-PAAc)) graft copolymers. The presence of the grafted PAAc with COOH groups allows coupling with Fe2+/3+ ions. The stabilization of Fe3O4 particles onto the graft copolymers was done by in situ reduction of LDPE-g-PAAc/Fe2+/3+ with sodium borohydride (NaBH4) in aqueous solution. The LDPE-g-PAAc graft copolymer and LDPE-g-PAAc/Fe3O4 composite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and electron spin resonance (ESR). The synthesized composites exhibit excellent magnetic properties. The results indicated that the magnetic oxide (Fe3O4) was embedded and homogenously dispersed into the surfaces of the graft copolymer films as indicated by SEM. The FT-IR analysis clearly suggests that an AAc monomer was effectively grafted onto LDPE. The XRD studies elucidate the change in the crystallinity of the graft copolymers.
Porous TiO2 thin films have been prepared using an amphiphilic graft copolymer, i.e. poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(oxyethylene methacrylate) (P(VDF-co-CTFE)-g-POEM) as a structure-directing agent via the sol-gel process. The graft copolymer was synthesized via atom transfer radical polymerization using CTFE units as an initiating site and designed to have a hydrophobic P(VDF-co-CTFE) domain and a hydrophilic POEM domain. Fourier transform-infra red spectroscopy indicated that a hydrophilic titania precursor was selectively incorporated into hydrophilic POEM domains. In-situ formation and morphologies of porous TiO2 thin films were confirmed by ultraviolet-visible spectroscopy, X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The resultant porous TiO2 films with 10-25 nm in size were used as a photoelectrode for solid-state dye-sensitized solar cells, exhibiting energy conversion efficiency of 2.8% at 100 mW/cm2. 相似文献
Using copolymerization functionalization, a Novel solution-processable π-conjugated 3-alkylthiophene copolymer (molar ratio
of monomer 3-octylthiophene (3OT) and 3-(2-ethyl-1-hexyl) thiophene (3EHT) was 1:1) combining electrochemical properties of
poly (3-octylthiophene) (P3OT) and poly (3-isooctylthiophene) (P3EHT) was synthesized by FeCl3-oxidative approach. Characterization of the polymers included FT-IR, NMR, gel permeation chromatography (GPC), thermo-gravimetric
analysis (TGA), UV-Vis spectroscopy photoluminescence (PL) and electroluminescence (EL). P3OTEHT depicted excellent solubility
in common organic solvents. The optical properties investigations showed that the band-gap energy of P3OTEHT was similar to
P3OT (2.43 eV) at 2.45 eV and 6% lower than that of P3EHT in CHCl3 solution. The emission maxima of P3OTEHT was 50 nm blue-shifted with respect to that of P3OT. However, the PL intensity of
P3OTEHT was seven times higher than that of P3OT in film. The turn-on voltage of LED (ITO/P3OTEHT/Ag) devices was approaching
to P3OT (5.5 V) at 5.6 V and 1.9 V lower than that of P3EHT. The EL color of P3OTEHT was bright pure orange-red (emission
λmaxEL of 600 nm), meanwhile, the half-wave bandwidth was 70 nm. TGA studies showed that P3OTEHT exhibited very good thermal stabilities,
losing 5% of its weight on heating to 300 °C. The results indicate that the P3OTEHT with low band-gap energy, low turn-on
voltage, high photoluminescence quantum yield pure EL color and processability, and might be promising polymer materials for
applications in polymer light-emitting diodes, light-emitting electrochemical cells and polymer solar cells, etc. 相似文献
Organic semiconducting polymer thin-films of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene, containing highly oriented crystal were fabricated by gas-phase polymerization using the CVD technique. These poly(3-alkylthiophene) films had a crystallinity up to 80%, and possessed a Hall mobility up to 10 cm2/Vs. The degree of crystalinity and the mobility values increased as the alkyl chain length increased. The crystal structure of the polymers was composed of stacked layers constructed by a side-by-side arrangement of alkyl chains and in-plane pi-pi stacking. These thin films are capable of being applied to organic electronics as the active materials used in thin-film transistors and organic photovoltaic cells. 相似文献
In this study, we prepared nanocomposites of multi-walled carbon nanotubes (MWCNTs) and low-energy-bandgap conjugated polymers incorporating 3,4-alkoxythiophene monomers. Poly(3,4-dihexyloxythiophene) (PDHOT) and poly(3,4-dimethoxythiophene-co-3,4-dihexyloxythiophene) [P(DMOT-co-DHOT)] have relatively low-energy-bandgaps (ca. 1.38 and 1.34 eV, respectively), determined from the onsets of absorbances in their UV–Vis spectra, because of the electron-donating effects of their alkoxy groups. MWCNTs have poor solubility in common organic solvents; after surface modification with alkyl side chains using the Tour reaction, however, the p-hexylaniline modified MWCNT derivative (MWCNT-HA) was readily dispersed in CHCl3 and could be mixed with the low bandgap polymers. Scanning electron microscopy images revealed that MWCNT-HA was dispersed well in each polythiophene derivative; only a few MWCNT-HA bundles could be observed at a high MWCNT-HA content (≧20 wt.%). The electrical conductivities of the MWCNTs/PDHOT composites were dependent on their MWCNT content, reaching 16 S/cm at 30 wt.% MWCNT-HA. We suspect that the two hexyloxy chains of PDHOT enhanced its solubility and allowed it to wrap around the surfaces of the MWCNTs more readily. 相似文献
The research developed on functionalized model or prosthetic surfaces with bioactive polymers has raised the possibility to modulate and/or control the biological in vitro and in vivo responses to synthetic biomaterials. The mechanisms underlying the bioactivity exhibited by sulfonated groups on surfaces involves both selective adsorption and conformational changes of adsorbed proteins. Indeed, surfaces functionalized by grafting poly(sodium styrene sulfonate) [poly(NaSS)] modulate the cellular and bacterial response by inducing specific interactions with fibronectin (Fn). Once implanted, a biomaterial surface is exposed to a milieu of many proteins that compete for the surface which dictates the subsequent biological response. Once understood, this can be controlled by dictating exposure of active binding sites. In this in vitro study, we report the influence of binary mixtures of proteins [albumin (BSA), Fn and collagen type I (Col I)] adsorbed on poly(NaSS) grafted Ti6Al4V on the adhesion and differentiation of MC3T3-E1 osteoblast-like cells and the adhesion and proliferation of Staphylococcus aureus (S. aureus). Outcomes showed that poly(NaSS) stimulated cell spreading, attachment strength, differentiation and mineralization, whatever the nature of protein provided at the interface compared with ungrafted Ti6Al4V (control). While in competition, Fn and Col I were capable of prevailing over BSA. Fn played an important role in the early interactions of the cells with the surface, while Col I was responsible for increased alkaline phosphatase, calcium and phosphate productions associated with differentiation. Poly(NaSS) grafted surfaces decreased the adhesion of S. aureus and the presence of Fn on these chemically altered surfaces increased bacterial resistance ≈70 % compared to the ungrafted Ti6Al4V. Overall, our study showed that poly(NaSS) grafted Ti6Al4V selectively adsorbed proteins (particularly Fn) promoting the adhesion and differentiation of osteoblast-like cells while reducing bacterial adhesion to create a bioactive surface with potential for orthopaedic applications. 相似文献
The orientation and alignment of regioregular poly(3-hexylthiophene) (P3HT) molecules on Au (111) surface and on poly(4-vinylphenol) (PVP) thin film were investigated. The P3HT molecules on the smooth Au (111) are oriented with both the backbones and the side chains parallel to the substrate (plane-on orientation) as revealed by the scanning tunneling microscope (STM) images. However, the P3HT molecules on the PVP thin films are preferably oriented with side chains perpendicular to the surface (edge-on orientation). Surface modification of the PVP by hexamethyldisilazane (HMDS) can increase the crystalline size in the P3HT semicrystalline films. The performance of an all-polymer organic field-effect transistor (OFET) with the drop-cast P3HT semiconductor layer and the crosslinked PVP gate insulator on poly(ethylene naphthalate) (PEN) substrate was evaluated. 相似文献
Hydrophilic poly (vinyl alcohol-co-ethylene) (PVA-co-PE) copolymers with 27 mol %, 32 mol % and 44 mol % ethylene were functionalized by melt radical graft copolymerization with 2,4-diamino-6-diallylamino-1,3,5-triazine (NDAM) using reactive extrusion. This functionalization imparts antibacterial properties. The covalent attachments of the NDAM as side chains onto the PVA-co-PE polymer backbones were confirmed. The effects of initiator concentrations and ethylene contents in PVA-co-PE polymers on grafting of NDAM were studied. The chain scissions of PVA-co-PE polymers during reactive extrusion were investigated by monitoring changes in the melt torque and FTIR spectra. The NDAM grafted PVA-co-PE polymers were successfully fabricated into hydrophilic nanofibers and nanofibrous membranes with sufficient surface exposure of the grafted NDAM. The hydrophilicity of the PVA-co-PE polymers and the large specific surface area offered by the nanofiber membranes significantly facilitated the chlorine activation process, enhanced the active chlorine contents of the grafted PVA-co-PE nanofiber membranes, and therefore led to their superior antibacterial properties. 相似文献
Siloxane-containing transparent hybrid hydrogels, coupled with high oxygen permeability and moderate equilibrium water content (EWC), were successfully obtained through free radical bulk copolymerization of hydrophobic and hydrophilic monomers. Due to obvious incompatibility of hydrophobic tris(trimethylsiloxy)-3-methacrryloxypropylsilane (TRIS) and hydrophilic 2-hydroxyehtyl methacrylate (HEMA) or N-vinyl pyrrolidone (NVP) monomers, alpha,omega-methacrylate terminated poly(dimethyl siloxane) (PDMS) macromer was employed as a compatibilizer in the formulations, resulting in high optical transmittance (> 90% at 400 nm) of the hybrid hydrogels. Although properties such as EWC and oxygen permeability of the hybrid hydrogels could be tailored over a wide range, the formulations with the PDMS macromer could not increase both EWC and oxygen permeability of the hybrid hydrogels without sacrificing one of them. For controlling these two properties simultaneously, an amphiphilic alpha,omega-methacrylate terminated PEO-PDMS-PEO triblock copolymer was synthesized as a surface-active macromer, and showed its usefulness in controlling phase separation and improving oxygen permeability and EWC, at the same time, of the hybrid hydrogels. 相似文献
Plasma-initiated graft polymerization of water-soluble vinyl monomers such as acrylic acid, 2-hydroxyethyl methacrylate and acrylamide was carried out onto polyethylene, polypropylene and poly(ethylene terephthalate) films. It was found that these monomers could be graft polymerized quite easily to 0.5%–670% of the mass of the dry films by exposing the films to a plasma for 90s, with subsequent post-polymerization at room temperature. Thus, polyethylene films capable of adsorbing and desorbing metal ions reversibly could be prepared by grafting the monomers described. 相似文献
This work aimed to produce poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) nanocomposites with poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-methoxythiophene) (PMOT). An anionic surfactant sodium dodecyl benzene sulphonate was used in emulsion polymerization for nanocomposite production. Incorporations of PEDOT and PMOT on the nanoparticles were characterized by scanning electron microscopy (SEM), atomic force microscopy, Fourier transform infrared-attenuated total reflectance spectroscopy and ultra-violet spectroscopy. These nanoparticles were blended with PAN and the blends were electrospun to produce P(AN-co-IA)–polythiophene-derivative-based nanofibres, and the obtained nanofibres were characterized by SEM and energy dispersive spectroscopy. In addition, electrochemical impedance studies conducted on nanofibres showed that PEDOT and PMOT in matrix polymer P(AN-co-IA) exhibited capacitive behaviour comparable to that of ITO–PET. Their capacitive behaviour changed with the amount of electroactive polymer. 相似文献
A solid polymer electrolyte chemically bonded to a π-conjugated polymer was prepared for the use as a designed ladder-type structure by the graft copolymerization of poly (aminobenzyl alcohol) (PABA) with poly (ethylene glycol) (PEG). PABA was used as the frame for the ladder and the PEG as the rungs. The expected synergic effect afforded by the introduction of the ionic salts into the crosslinked conjugated polymer and PEG network was investigated as a function of its structure, morphology, and ionic conductivity. The insertion of the ionic salts into the PABA-PEG-PABA network led to the enhancement of the ionic conductivity compared to that of PEG/LiClO4. The synergic effect may be explained by the more efficient segmental motion of the polymer chains or better ion mobility in the network due to the interrupted crystallization of the PEG chains. The fine tuning of the crosslinked conjugated polymer gel might enable it to show a faster response to electrochemical stimuli. 相似文献
The novel graphene oxide (GO)/silica (SiO2)/polyacrylonitrile (PAN) mixed matrix membranes (MMMs) with high filtration flux and excellent antifouling performance were designed and fabricated in situ by the method of non-solvent induced phase separation (NIPS) from the precursor of PAN hybridized with GO, tetraethoxysilane and 3-aminopropyltriethoxysilane. The influences of GO sheets on the pore and chemical structure, hydrophilic nature and filtration performance of derived GO/SiO2/PAN MMMs were investigated by the scanning electron microscopy, field emission scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray, Fourier transform infrared spectrometer, pure water contact angles and filtration performance. Results indicated that in situ incorporation of GO sheets and SiO2 molecules into PAN matrix via NIPS reconstructs the porous structure of derived GO/SiO2/PAN MMMs with the upright finger-like holes, porous bottom, thinner top layer and high porosity. The spontaneous surface migration or segregation of hydrophilic GO sheets and SiO2 molecules as well as their synergistic interaction occurred during NIPS greatly ameliorate the top surface structure and property of derived membranes with smoother surface, uniform pore structure and good hydrophilicity. The derived GO/SiO2/PAN MMMs exhibit a high water filtration flux of 387 L m?2 h?1 with the bull serum albumin rejection rate up to 99% and significant enhancement of antifouling performance. 相似文献
Raw, dewaxed and oxidized jute fibres and those chemically modified with phenol and formaldehyde (treatment done for 3 h at 95° C and pH 8) before or subsequent to oxidation, were subjected to graft copolymerization with methyl methacrylate (MMA) in the presence or absence of some other monomers such as maleic anhydride (MA) or methacrylic acid (MAA) in limited aqueous system using K2S2O8 as the initiator under photoconditions with the objective of inducing improved rot resistance and dyeability without loss in tensile strength of the fibre. For preparing oxy-jute, dewaxed and preswollen (dewaxed jute fibre swollen with 10% aqueous urea at 90° C for 2h) jute fibre were separately subjected to mild oxidation or bleaching using aqueous H2O2 and NalO4 and non-aqueous chlorine (Cl2 in CCl4) under specified conditions. Optimum conditions for graft copolymerization have been established by examination of the effect of such variables as monomer concentration, time of polymerization and nature of chemical modification of jute fibre prior to vinyl grafting. Percentage grafting, tenacity (g denier–1), dye fixation (%) and rot resistance (expressed as percentage retention of tensile strength of the fibre after a standard soil burial test) were evaluated and analysed. High rot resistance (80–90% retention of tensile strength after soil burial test) and dye fixation (%) of as high as 86% were readily obtained for grafted jute fibres. Washing fastness and light fastness properties of the dyed fibres (grafted and ungrafted) were also examined and compared. 相似文献