Photoinitiation Mechanisms And Photogelation Kinetics Of Blue Light Induced Polymerization Of Acrylamide With Bicomponent Photoinitiators

Blue light induced free radical photopolymerization of acrylamide (AM) was studied using five bicomponent photoinitiators, camphorquinon, riboflavin-5 '-phosphate sodium, curcumin, eosin Y, and Ru(bpy)(3)Cl-2 (Ru(II)) as photosensitizer, and diphenyliodonium hexafluorophosphate or potassium persulfate as electron acceptor. Fluorescence and UV-vis spectroscopies were used in combination with molecular orbital computations to characterize the photochemical behaviors of the five bicomponent photoinitiators, explore the possible electron transfer pathways of the photoinitiation processes, and quantify photopolymerization efficiencies. Real-time photogelation behavior of poly(AM) was monitored by Photo-differential scanning calorimetry and photo-rheometry. Photogelation kinetic parameters, including dG ' (storage modulus)/dt, dG '' (loss modulus)/dt, time delay of gelation (t(d)), and duration of gelation (Delta t(gel)), were derived from photorheological data analyses and used to identify the best bicomponent photoinitiator candidate for rapid fabrication of blue light induced photopolymerizable hydrogels for biomedical applications.