pH-controlled assembly and properties of LbL membranes from branched conjugated poly(alkoxythiophene sulfonate) and various polycations

Langmuir. 2010 May 18;26(10):7138-47. doi: 10.1021/la9042099.

Abstract

We report on multilayer layer-by-layer (LbL) films of the conjugated polymer sodium poly[2-(3-thienyl)ethyloxy-4-butylsulfonate] (PTH) assembled with polycations: poly(diallyldimethylammonium chloride) (PDDA), 20% quaternized poly(N-ethyl-4-vinylpyridinium bromide) (Q20), poly(ethylene imine) (PEI), and poly(allylamine hydrochloride) (PAH). These films were prepared through spin-assisted LbL assembly under various pH conditions. We demonstrated a crucial role of the deposition pH in formation of PTH/polycation films and showed that decrease in the deposition pH from 7.5 to 2.5 limits the PTH multilayer formation to Q20/PTH and PDDA/PTH films due to reduced charge density in the poly(thiophene) chains. We show that optical and surface properties of the resulting PTH/polycation films can be tuned by varying a polycation component and/or by varying the deposition pH. The fluorescence properties of the Q20/PTH, PEI/PTH, and PDDA/PTH films are pH-dependent, and the films exhibit the drastic changes in photoluminescent intensity when transferred into solutions with different pH values, which may find useful in optical sensing applications.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cations / chemistry
  • Hydrogen-Ion Concentration
  • Imines / chemistry*
  • Membranes, Artificial*
  • Molecular Structure
  • Particle Size
  • Polyamines / chemistry*
  • Polyethylenes / chemistry*
  • Polyvinyls / chemistry*
  • Quaternary Ammonium Compounds / chemistry*
  • Surface Properties
  • Thiophenes / chemistry*

Substances

  • Cations
  • Imines
  • Membranes, Artificial
  • Polyamines
  • Polyethylenes
  • Polyvinyls
  • Quaternary Ammonium Compounds
  • Thiophenes
  • poly(2-(3-thienyl)ethyloxy-4-butylsulfonate)
  • poly(ethylene imine)
  • poly-4-vinyl-N-ethylpyridine
  • poly-N,N-dimethyl-N,N-diallylammonium chloride
  • polyallylamine