Langmuir and Langmuir–Blodgett films from the N-hexyl-pyrrole-thiophene (AB) semi-amphiphilic copolymer

A report is made of Langmuir film of a new semi-amphiphilic alternating N-hexylpyrrole-thiophene AB copolymer (PHPT) that is amenable to transfer as Langmuir–Blodgett (LB) films. PHPT was synthesized by condensation copolymerization via Stille coupling between N-hexyl-2,5-bis(trimethylstannyl)pyrrole and 2,5-dibromothiophene in the presence of Pd(PPh3)2Cl2 as a catalyst in dry DMF and characterized with various analytical techniques. In contrast to homopolymers (e.g. poly(N-alkylpyrrole)s and poly(3-alkylthiophene)s), PHPT formed a reasonably stable monolayer, as inferred through surface pressure and surface potential isotherms, and Brewster angle microscopy (BAM). The dependence of monolayer characteristics on the spreading volume, subphase temperature and compression speeds was also investigated. Electrical characterization revealed the possibility of using PHPT LB films as gas sensors.