Effects of thermal oxidative ageing on dynamic viscosity, TG/DTG, DTA and FTIR of SBS- and SBS/sulfur-modified asphalts

π-Conjugated block copolymers have been prepared from terminal azide functionalized polystyrenes (PS) and alkyne functionalized poly(3-hexylthiophene)s (P3HT) via a copper(I) catalyzed Huisgen [3 + 2] dipolar cycloaddition reaction. The functionalized α-azido-PS homopolymer was prepared by atom transfer radical polymerization from a specifically designed initiator bearing the azide function, whereas ω-ethynyl-P3HT and α,ω-pentynyl-P3HT were synthesized by a modified Grignard metathesis polymerization using alkynyl Grignard derivatives. The electronic environment of the alkynyl end groups was shown to be decisive in determining triazole ring formation.

Poly(3-hexylthiophene) based block copolymers prepared by "click" chemistry

Although recently considerable attention has been paid to the impact of polymer alkyl side chains on conjugated-polymer:fullerene solar cell performance, and especially the Voc and Jsc, a clear and comprehensive picture of the effect of side-chain positioning, length, and branching has yet to evolve. In order to address some of these questions, we designed a simple and modular model system of random copolymers based on rr-P3HT. The influence of increasing amounts of branched 2-ethylhexyl side chains (10, 25, and 50%) in rr-poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) copolymers on properties such as UV–vis absorption, polymer crystallinity, HOMO energy levels, polymer:PC61BM solar cell performance, and especially the Voc was studied and compared to the corresponding homopolymers P3HT and poly(3-(2-ethylhexyl)thiophene) (P3EHT). Polymers with 50% or less 2-ethylhexyl side chains (P3HT90-co-EHT10, P3HT75-co-EHT25, P3HT50-co-EHT50) have the same band gap and similar absorption properties and also reta...

Influence of the Ethylhexyl Side-Chain Content on the Open-Circuit Voltage in rr-Poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) Copolymers

The synthesis and characterization of a series of poly(3-alkyltellurophene)s are described. Polymers are prepared by both electrochemical and Kumada catalyst transfer polymerization methods. These polymers have reasonably high molecular weights (Mn = 5.4–11.3 kDa) and can be processed in a manner analogous to that of their lighter atom analogues. All examples exhibit red-shifted optical absorption, as well as solid-state organization, as evidenced by absorption spectroscopy and atomic force microscopy. Overall, the synthesis and characterization of these materials open up a wide range of future studies involving tellurium-based polyheterocycles.

Poly(3-alkyltellurophene)s Are Solution-Processable Polyheterocycles

A simplified route to regio-regular poly(3-alkylthiophene)s (P3AT) with predetermined molecular weights and low molecular weight distributions based on the chain-growth GRIM polymerisation of 2,5-dibromo-3-alkylthiophenes is detailed. It is proposed by way of in-depth 13 C-, 1 H- and two-dimensional NMR characterisations that the resulting P3ATs are quasi-100% regio-regular except for one regio-irregular pair at one chain-end. It is probable that chain-end groups exhibit reduced conjugation with the rest of the polymer. A comparison of the preparation of poly(3-hexylthiophene) and poly(3-butylthiophene) (P3BT) is presented. New methods required for the hydrogenation, formylation and bromomethylation of the chain-ends of P3BT, necessary to overcome its poor solubility and low reactivity, are described.

Extremely regio‐regular poly (3‐alkylthiophene)s from simplified chain‐growth Grignard metathesis polymerisations and the modification of their chain‐ends

Series of thiophenes containing mesogenic side chains at the 3 rd position are synthesized. The thermal transitions and thermal stability of the synthesized monomers and polymers are studied. The polarizing microscopic studies of synthesized monomers showed nematic liquid crystalline phase and these mesophases further confirmed by differential scanning calorimetric study. The obtained melting and the isotropic temperatures decrease linearly with the increase of aliphatic chain length. The transition temperatures determined from DSC analysis, overlap well with the temperatures obtained from optical microscopy studies. Thermal stability of the compounds is analysed using thermogravimetric studies. Thermal stability of monomers and polymers has been determined by calculating IPDT values. Structural influence on thermal degradation patterns of monomers and polymers are also discussed.

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Thermal studies on polythiophene containing mesogenic side chains

The regio-regularity and properties of the poly[3-(2-ethylhexyl)thiophene] were studied, and compared with the poly[3′-(2-ethylhexyl)-2,2′,5′,2′′-terthiophene]. The thermal stability of the polymers was improved due to the addition of thiophene rings with (2-ethylhexyl)thiophene. Due to the additional thiophenes at the 2,5 position of ethylhexylthiophene, even though the absorption wavelength was red-shifted, there is no characteristic change in photoemission for the latter polymer. Addition of thiophene rings to the 3-(2-ethylhexyl)thiophene improves the thermal properties without loosing the 3-(2-ethylhexyl)thiophene characteristics.

Studies on 3-(2-ethylhexyl)thiophene polymers

Thiophene monomer structures containing different hetero aromatic rings (containing five-member/six-member, varying electronegativity, functional groups) were designed and synthesized. The influence of structural components of the side chain on the thermal stability of the polymers of the above monomers was analyzed using thermogravimetric analysis. The results show that thiophene-containing hetero aromatic side chains linked through six-member ring show high thermal stability.

Thermal Degradation Studies of Polythiophenes Containing Hetero Aromatic Side Chains

The present investigation focuses the influence of polythiophene i) containing hetero aromatic structures and ii) containing mesogenic groups towards the photoluminescence properties of substituted polyperylene (PPE). The structural contribution towards the optical properties was individually discussed. The photoluminescence of PPE was quenched to the maximum level (30%) when it was blended with polythiophene with mesogenic groups containing longer alkyl spacer. Results of the same blend in solid-state shows 85% of PL quenching.

Narayamasastri Somanathan

Papers

Thermal studies on polythiophene containing mesogenic side chains

Studies on 3-(2-ethylhexyl)thiophene polymers

Thermal Degradation Studies of Polythiophenes Containing Hetero Aromatic Side Chains

Fluorescence quenching of substituted polyperylene with functionalized polythiophenes.