FURTHER EVIDENCE FOR THE EFFECTS OF CRITICAL CONCENTRATION FLUCTUATIONS ON THE DIFFUSION-CONTROLLED REACTION-KINETICS IN BINARY POLYMER MIXTURES

Kinetics of the intramolecular photodimerization reaction of a molecular probe, 9-(hydroxymethyl)-10-[(Naphthylmethoxy)methyl] anthracene (HNMA) was studied in the miscible region of binary polymer mixtures. Poly(ethylene oxide)/poly(methyl methacrylate)(PEO/PMMA), polystyrene/poly(vinyl methyl ether) (PSH/PVME) and deuterated polystyrene/poly(vinyl methyl ether) (PSD/PVME) mixtures were used as binary polymer blends. It was found that the reaction kinetics is strongly affected by the concentration fluctuations in the vicinity of the coexistence curve. These behavior are consistent with the magnitude of the binary interaction parameters-chi estimated from the small-angle neutron-scattering and the melting point depression data. These experimental results confirm the fact that the reaction kinetics of HNMA reflects the concentration fluctuations with the wavelength comparable to the dimension of the probe.