Synthesis and properties of cationic polyelectrolyte with regioregular polyalkylthiophene backbone and ionic‐liquid like side groups

Abstract

High-regioregular poly{3-[6-(1-methylimidazolium-3yl)hexyl]thiophene-2,5-diyl bromide}, PMHT-Br, has been prepared by reaction of high-regioregular (above 92%) poly[3-(6bromohexyl)thiophene-2,5-diyl] with 1-methylimidazole. PMHT-Br is soluble in water and water miscible solvents such as methanol, DMSO and shows solvatochromism; k max (nm): 423 (H 2 O); 435 (MeOH); 452 (DMSO). Increased absorption band broadening observed for aqueous solution as well as NMR spectra in D 2 O suggests a micelle-like structure of PMHT-Br molecules in these solutions: poly(3-hexylthiophene) core and 1-methylimidazolium bromide shell. Despite the disturbing effect of ionic groups, the solid-state PMHT-Br shows absorption maximum at 520 nm, the band edge at 660 nm (ca. 1.9 eV), and fluorescence emission with maximum at 635 nm, in a good agreement with the polymer regioregularity. Fluorescence emission maxima: k em (nm): 598 (H 2 O); 562 (MeOH); 574 (DMSO), occur in a vicinity of corresponding adsorption band edges. Plot of electrical conductivity of PMHT-Br (measured under the dynamic vacuum conditions, 5 Â 10 À5 Pa) versus 1/T shows a break at about 70 C same as the temperature dependence of k max of the solid PMHT-Br. These breaks indicate an increase in the mobility of polymer segments and ions within PMHT-Br; however, a thermal analysis did not provide solid evidence for it. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3073-3081, 2010 INTRODUCTION Conjugated polyelectrolytes (CPEs) show unique optical and electrical properties together with good solubility in water making possible processing of these polymers from aqueous solutions. As CPEs exhibit both electronic and ionic conductivity, they can be used as layers reducing electron injection barrier from metal electrodes, such as aluminum and gold electrodes into polymer in various optoelectronic applications 1 and also as new solid polyelectrolytes with increased room-temperature electrical conductivity. 2,3 Solubility in aqueous environment and water-miscible solvents also substantially simplifies preparation of the composites of CPEs with noble-metal nanoparticles, which exhibit the effect of local enhancement of electromagnetic field. 4 Another possible application field of CPEs is their use as water-soluble sensing agents for the detection of ions, nucleic acids, and some proteins on the basis of changes in UV/vis and photoluminescence spectra induced by conformational changes of CPE macromolecules caused by their complexation with oppositely charged analyte species. 5-10

Colloidal systems of silver nanoparticles and high-regioregular cationic polythiophene with ionic-liquid-like pendant groups: Optical properties and SERS

“…1 , 133.8 C, 130.7 C, 128.7 C, 33.8, 32.8, 30.3, 29.3 28.6, 28.0 C. The isolated precursor polymer was allowed to react with 1-methylimidazole to give PMHT-Br isolated as a dark-red powder. Characterization of PMHT-Br: 1 [22].…”

“…DMSO was used to suppress the formation of large polymer aggregates that appear in concentrated (higher than 10 À3 M) aqueous solutions [22]. Molar concentrations of PMHT-Br monomeric units in resulting sols, c pol , were set to be: 5 Â 10 À8 M, 5 Â 10 À7 M, 1 Â 10 À6 M, 2.5 Â 10 À6 M, 5 Â 10 À6 M, 1 Â 10 À5 M and 1 Â 10 À4 M. The content of DMSO in the resulting colloidal systems was from 10 À4 to 1% by volume.…”

“…In the present paper we deal with the formation, structure and properties of the composite systems composed of Ag NPs and recently prepared [22] new cationic conjugated polyelectrolyte with polythiophene main chain and ionic-liquid like side groups. This polymer is easily soluble in water and water-miscible solvents such as methanol and dimethylsulfoxide (DMSO).…”

Conjugated Polyelectrolyte (CPE) Poly{3-[6-(N-methylimidazolium)hexyl]-2,5-thiophene} Complexed with DNA: Relation between Colloidal Level Solution Structure and Chromic Effects

“…The synthesis of P3ImiHT (P3) via post-polymerization functionalization has been described earlier. 51,50 The number-and weight-average molecular weights of the precursor polymer P3BrHT were 11.5 kg/mol and 13 kg/mol (the degree of polymerization is about 47). Double stranded DNA lot # BCBK2089V with about 2000 base pairs (average 660 Daltons) was obtained from SigmaAldrich.…”

SERS active systems of water-soluble polythiophene and plasmonic nanoparticles: preparation and optical properties

“…Regioregular poly{3- [6-(1-methylimidazolium-3-yl)hexyl]thiophene-2,5-diyl bromide}, PMHT-Br, was synthesized using recently developed two step procedure [13]: first the regioregular poly[3-(6-bromohexyl)thiophene-2,5-diyl] was prepared from 3-(6-bromohexyl)thiophene by Kumada coupling reaction catalyzed with Ni based catalyst, which was subsequently modified using reaction with 1-methylimidazole. The resulting cationic polythiophene polyelectrolyte is soluble in water, common polar solvents like dimethyl sulfoxide (DMSO) or dimethylformamide and some alcohols.…”