Photocatalytic Kinetics Of Hydrosilylation By Platinum Catalysts And Application

Silicone polymers such as silicone rubber and silicone resin are widely used in electronic transportation,construction,automobile,aerospace and other fields due to their excellent properties.At present,the common method to prepare silicone polymers in industry is by hydrosilylation with Pt complexes at room temperature or high temperature.But this method is time-consuming and energy-consuming.In recent years,photopolymerization and UV-curing technology has attracted attention widely by its advantages of fast,efficient,energy-saving and environmental protection under the trend of sustainable development.The UV-curing kinetics and application of hydrosilylation catalyzed by Pt complexes were studied.The results show that hydrosilylation can be catalyzed by（Me?Cp）PtMe₃ and Pt（acac）₂ in a short time under UV light.（Me?Cp）PtMe₃ has better photocatalytic activity than Pt（acac）₂.The system of（Me?Cp）PtMe₃ can obtain higher conversion and reaction rate.Cured silicone rubbers have higher thermal stability,mechanical properties,higher glass transition temperature and storage modulus.Post-curing of two Pt complexes systems was studied.It was found that post-curing process can effectively improve the conversion of hydrosilylation reaction without UV light,and the final conversion is twice as the initial.In addition,the sensitization of（Me?Cp）PtMe₃ by various polycyclic aromatic hydrocarbon photosensitizers were investigated.The results show that na p h t h a l e n e is found to be the most applicable photosensitizer,which leads to an increment of 24.8%in the quantum yield of（M e?C p）P t M e₃.The enhancement of photopolymerization conversion from about 70%to 100%,decreseing the activation energy from 35.6 kJ/mol to 30.9 kJ/mol.The mechanical strengths,storage modulus,glass transition temperature and thermostability of the UV-cured silicone rubbers are also enhanced by the incorporation of na p h t h a l e n e.Moreover,this UV-activated hydrosilylation of silicone rubber reveals an enormous potential to quickly prepare complicated geometry shapes by photolithography.The effects of PDMS?Vi（viscosity,vinyl distribution of PDMS?Vi）,PMHS（H content,different additions）on reaction kinetics and properties of silicone rubber were systematically discussed by studying the formulation of photocatalytic hydrosilylation substrates.