UV-CURING OF HYPERBRANCHED POLYSILAZANES-THIOL COMPOUND SYSTEM

A hyperbranched polysilazanes (HBP) with multifunctionaility of allyl end groups was prepared by polymerization reaction via hydrosilylation of AB(2) type monomer (N-diallyamine) dimethlsilane, which was synthesized by aminolysis of Me2HSiCl. The molecular structure of HBP was characterized and determined by FT-IR, H-1-NMR spectra analysis and GPC. Further more, the photo-initiated curing kinetics of HBP with thiol compound was studied by differential photo-scanning calorimetry (DPC) technology. The comparing analysis among HBP, HBP-thiol compound and low-functionality monomer of B2M-thiol compound indicated that thiol functional group reacts with allyl functional group quickly under lower amount of photoinitiator (0.1 wt%) and lower light intensity (about 5 mW/cm(2)) in ambient condition. The curing rate and ultimate conversion of allyl group in HBP-thiol compound is higher than that in HBP, however, the ultimate conversion of allyl group in HBP-thiol compound is lower than that in B2M-thiol compound due to the unique hyperbranched structure and high multifunctionality. The effects of photoinitiator concentration [A], UV light intensity (I-0) and reaction temperature on the UV curing rate and the final allyl bond conversion of HBP-thiol compound system were also investigated by DPC. The results indicate that the effects of photoinitiator concentration ([A]), UV light intensity (I-0) and temperature on kinetics of HBP-thiol compound reveal that the curing rate (R-p) is directly proportion to square root of [A] and I-0 respectively, which is found to fit with theoretical predictions very well at [A] no more than 0.50 wt% and I-0 lower than 19.40 mW/cm(2). Kinetics parameters were determined for HBP-thiol compound according to an autocatalytic model with a diffusion coefficient attached. The total apparent reaction exponent and apparent activation energy are 8.76 and 13.49 kJ/mol, respectively.