A chemiluminescence and fluorescence spectroscopy study: An investigation of photocrosslinking processes in polymer systems

摘要

Chemiluminescence emission is shown to be a valuable method for the analysis and monitoring of the photochemical transformation process in BZMA-co-S copolymers. BZMA-co-S copolymer films are synthesized and irradiated at λ > 400 nm, in order to induce the phototransformation of benzyl (BZ) to benzoyl peroxide (BP) pendant groups, resulting in thermal decomposition and crosslinking. The chemiluminescence emission increases with irradiation time, and is shown to be related to the benzoyl peroxide moieties generated during irradiation. The increase in chemiluminescence intensity is interrupted at longer periods of irradiation, when the concentration of these species tends to a nearly constant value. In this case, others factors are considered to influence the chemiluminescence emission, for example the increasing crosslinking on irradiated samples, which would restrict the mobility of radicals to recombine due to crosslinking of the network. A good correlation between fluorescence, FTIR and CL measurements during photochemical formation and thermal decomposition of peroxides is found. In this work, an intramolecular excimer forming fluorescent probe, DiPyM, is also used to analyse the crosslinking process. The results obtained contribute significantly to the development of chemiluminescence as a highly sensitive methodology for assessing the photocrosslinking of a polymeric material in the early stages of the process and is due to its sensitivity in comparison to that of fluorescence analysis. © 2008 Elsevier B.V. All rights reserved.