NUSNNI Seminar Series 2003 No.1

Time: July 15, 2003, 11:00-12:00pm
Venue: Physics Conference Rm (S13-M01-15)
Speaker: Dr Paul Pigram (Centre for Materials and Surface Science, and Department of
Physics La Trobe University, Melbourne Victoria 3086 Australia)
Title: Micro-patterning of fluoropolymer surfaces for electronic and biomaterials applications
Abstract:
A brief introduction of the activities and resources of the Centre for Materials and Surface Science at La Trobe University will be presented focussing on electron spectroscopy and secondary ion mass spectrometry. A three year project investigating micro-patterning of fluoropolymers via the micro-contact printing (¦ÌCP) pathway, in collaboration with Professor E.T. Kang, National University of Singapore, commenced in 2002. The principal aim of this program is to achieve convergence between controlled fluoropolymer surface modification technologies and micro-patterning of polymer surfaces using ¦ÌCP. Ultimately, flexible device structures with sensor and other electronic applications will be produced.

Work to date has focussed on optimising the multilayer films required to produce a polypyrrole-based ¦ÌCP sensor. Polypyrrole (PPy) films doped with dodecylbezenesulfonic acid (DBSA) on copper substrates have been prepared using electrochemical pre-treatment of the copper surface. Formation of a passivating oxide at the Cu surface impedes substrate dissolution without preventing pyrrole electropolymerisation; there have been only two previous reports of PPy deposition on Cu using alternative pathways. Film formation and interfacial phenomena have been explored using XPS, TOF-SIMS and cyclic voltammetry.

Multilayer films have been created for sensor construction comprising PPy deposited on PTFE via an electroless Cu interlayer. Fluoropolymer substrates were Ar plasma-treated, modified by silanisation and activated by PdCl2 for electroless Cu deposition. The commonly used SnCl2 sensitisation stage in electroless deposition was eliminated to create a tin-free process. Attention has recently shifted to introducing ¦ÌCP patterning at key stages of the multilayer deposition pathway. Initial XPS, TOF-SIMS and contact angle results will be presented arising from the optimisation of surface chemistries and micro-contact printing methodologies. Factors determining minimum feature dimensions and adhesion characteristics are currently under investigation.