Poly(3-alkylthiophene)s represent a family of conjugated polymers that are soluble and processable, but still retaining the good electrical conductivity of the insoluble parent polymer thiophene ring backbone. Poly(3-hexylthiophene) (P3HT) is reported to be a best candidate in the family for solar cell applications. In situ polymerization of 3-hexylthiophene monomer with double-walled carbon nanotubes (DWCNTs) has been attempted with the aim of addressing two main issues, namely, the interfacial bonding and proper dispersion of the carbon nanotubes in the polymer matrix to get a high-performing polymer/ nanocomposite. Fourier transform infrared spectroscopy, Raman, and X-ray diffraction studies indicate the physical wrapping of the polymer on the nanotubes in the absence of any ground-state interaction between them. The ultraviolet-visible measurements also support this view. The photoluminescence quenching indicates the effectiveness of the interface in the formation of the donor-acceptor-type composite. The impressive conductivity values encourage the utility of the composites as photovoltaic material.
Novel linear and crosslinked polyampholytes of betaine structure based on acrylic acid and ethyl 3-aminocrotonate (ethyl ester of 3-amino-2-butenoic acid) have been synthesized by Michael addition reaction followed by radical copolymerization. The mechanism of formation of monomer and polymer betaines is discussed. The linear polyampholyte has been characterized by potentiometric titration, IR, NMR and GPC. Crosslinked polymeric betaines were synthesized in the presence of N,Nmethylenebisacrylamide. The stimuli-sensitive properties of amphoteric gels have been studied as a function of pH, ionic strength, water-organic mixture composition, electric, and combined electric and magnetic fields. The isoelectric points of linear and crosslinked polymeric betaines correspond to pH 2.0-2.1. The effect of ionic strength on the solution and gel properties of polybetaine has been interpreted on the basis of destruction of inter-chain, intra-chain and intra-group salt bonds. Water-acetone, water-ethanol or water-DMF mixtures cause the shrinking of amphoteric gel due to change of the dielectric constant of the medium and decrease of the osmotic pressure. Electrocollapse is observed under the action of DC electric field. Simultaneously cross action of electric and magnetic fields enhances the collapsing rate. Appearance of pH gradient within the volume of polyampholyte gel under the externally imposed DC electric field has been observed.
A novel hydrophobic monomer was synthesized from the acetoacetic ester and dodecylamine by condensation reaction in mild conditions. The modification by the dodecyl groups monomer was involved in the Michael addition reaction with acrylic (or methacrylic) acid followed by radical polymerization. Both linear and crosslinked novel betaine-type polyampholytes bearing hydrophobic "tail" and hydrophilic "head" were obtained. The linear polymer was characterized by viscometry, FTIR, and Raman spectroscopy. Swelling-shrinking behavior of linear and crosslinked samples was studied in water-DMF and water-DMSO mixtures. The applicability of hydrophobically modified polybetaines as pour point depressants (fluidity improvers) was also demonstrated.
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