MALEIMIDO-FLUOROPROBE - A DUAL-PURPOSE FLUOROGENIC PROBE OF POLYMERIZATION DYNAMICS

Maleimido-fluoroprobe (MFP) is a derivative of ''fluoroprobe'' (FP), t he most sensitive known fluorescent polarity probe. MFP differs from F P in that it is completely nonfluorescent. The characteristic strong F P-type fluorescence is however switched on when the C=C bond of the ma leimide group becomes saturated forming the succinimide derivative, SF P. This fluorogenic behavior is shown to be induced by copolymerizatio n of MFP into growing polyacrylate chains. The increase in the intensi ty of the fluorescence, which is observable even in the early, low-vis cosity stage of polymerization, provides therefore a measure of the de gree of polymerization. The strong blue shift of the fluorescence of c hain-incorporated SFP moieties fulfills the usual polarity probe funct ion of monitoring changes in the microscopic dielectric environment of the polymer as vitrification takes place. This duality in the probe c haracteristics of MFP is illustrated by results on the radiation-induc ed bulk polymerization of methyl methacrylate.