Surface-Enhanced Photopolymerization of a Diacetylene Derivative in Langmuir−Blodgett Films on a Silver Island Film

Abstract

Surface-enhanced resonance Raman scattering (SERRS) spectroscopy was applied to monitor the photopolymerization process of one monolayer (L = 1) of a Langmuir−Blodgett (LB) film of the cadmium salt of a diacetylene monocarboxylic acid derivative, 10,12-pentacosadiynoic acid (DA), prepared on an evaporated silver island film with a mass thickness of 60 A. The result indicated that the polymerization proceeds in a way that is similar to that of the multilayer LB films (L ≥ 3) of DA prepared on a smooth silver substrate with a mass thickness of 1000 A, exhibiting a transition from a blue phase (λmax ≈ 635 nm) to a red phase (λmax ≈ 540 nm). In addition, the photopolymerization on the SERS-active substrate with d = 60 A was found to proceed much faster than that on the smooth (SERS-inactive) substrate (d = 1000 A). The rate of the photopolymerization of the monolayer on the island film was compared with the rates of a series of LB films of DA prepared on evaporated silver films with d = 60−1000 A, including t...