Structural features of functional polysiloxanes radical and ionic photo-curing for laser printing applications

The laser induced curing of acryloxy terminated ethyleneoxide dimethylsiloxane-ethyleneoxide ABA block copolymer (PDMS-AO) and (3-glycidoxypropyl)trimethoxysilane (GPTMS) was carried out with 2-hydroxy-2-methylpropiophenone as radical photoinitiator and p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate as cationic photoinitiator, respectively. The cross-linking mechanisms for both mixtures were determined through monitoring of photocuring by SSNMR, FTIR and Raman spectroscopies. The obtained silicone rubbers were tested by swelling measurements and thermogravimetric analysis. In comparison with PDMS-AO, cross-linked GPTMS had slightly more cross-linking density (by approximately 20% more). The cross-linked GPTMS was more thermally stable in air than cured PDMS-AO (by c.a. 190° C) due to both mechanisms: epoxy polymerization and Si–O–Si formation. The possibility of laser printing with defined framework for PDMS-AO was successfully demonstrated that allows obtaining laser printed polymer objects.