Objective: The objective of this work is to investigate and compare a number of chemical and mixed cationic initiation (MI) systems for a silorane resin, with respect to a light initiation (LC) system.
Methods: The general procedure for the initiation system was as follows. The silorane monomers (~1.5 g) and the mixed initiation system were combined in a speed mixer and mixed. The material was then placed on a microscope slide and irradiated with one of eight different light sources for time ranging from 30 seconds to 10 minutes. The samples were then tested for hardness after various time intervals using a Gillmore needle (one pound for pass/fail). Degree of cure (DC) studies using FTIR were performed along with pH tests of the resulting polymer.
Results: A total of 32 chemical cure and 7 MI systems were tested. One mixed initiation (MI1) system as composed of acetic acid (3 wt%), camphorquinone (1 wt%), and a phenyliodonium salt (3 wt%) and resulted in the polymerization the silorane resin using a halogen light source. Another system MI2 system composed of phosphoric acid did polymerize, however, the pH change of the resulting polymer was 3 units and too extreme for further studies. When silorane (MI1) was filled to 50% wt, it was polymerized using a flashlight between 5–10 minutes. Preliminary FTIR data showed no significant difference between MI1 (69±5%) and LC (72±8%) in the DC at 24hr.
Conclusion: A mixed initiation system was found to be a viable option in the polymerization of the silorane.
This work was supported in part by NIH/NIDCR Grant R21 DE018336, NIH/NIDCR T32 (DE07294), DOD Grant W81XWH, and Missouri Life Science Research Board Grant (#13234-2007).