Synthesis And Photopolymerization Of Polymeric Photoinitiators

During the last decades, the fields of photopolymerisation and photoimaging science and technology have grown from subjects of esoteric research specialities into major industrial developments. They are now fields of central importance in polymer science and technology. These technologies is the use of a photoactivator system which is capable of absorbing the UV and/or visible radiation wavelengths used for converting a monomer or prepolymer system into a linear polymer or crosslinked network. In recent years, there have been many new developments in the synthesis and photochemical studies of novel photoinitiator molecules, which have desirable properties such as higher activity or greater curing speed coupled with lower migration rates and/or water solubility. The important area in this regard is the development of polymeric photoinitiators with reactive functionalities. Polymeric photoinitiators can be defined as macro-molecular systems that contain pendant or in-chain chromophores which through a light absorption process can generate active species able to initiate the polymerisation and crosslinking of monomers and oligomers. In this paper , A benzophenone derivative photoinitiator, HBP-TDI-HQ-TDI-HBP (HTCTH), was synthesized basing on 4-hydroxy benzophenone (HBP), toluene-2, 4-diisocyanate (TDI) and Hydroquinone (HQ). The influence of the concentration of photoinitiator system, the light intensity and different monomers on photocuring was investigated by Realtime FTIR. The UV absorption spectra of HTCTH and benzophenone (BP) was measured by UV-vis spectrophotometer. It showed that both rate of polymerization and final conversion increased with increase of amine and HTCTH concentration in photopolymerization. HTCTH was a more effective photoinitiator which had longer wavelength absorption (283 nm) in the UV-vis absorption spectra than the low molecular counterpart BP(250nm).Polysiloxane production had some outstanding features, such as high temperature resistance, high resistance to weathering, excellent electrical insulation, dielectric properties and excellent release due to low surface energy. Some new desirable property was obtained when the polysiloxane backbone contained photoinitiator chromophores.In this paper, two polysiloxysilane-based polymeric photoinitiators, HBSiBH and HCSICH, were synthesized basing on photoinitiatorsα-hydroxy ketone (HCPK), 4-hydroxy benzophenone (HBP) and polysiloxane (CSi 2342). The influence of the concentration of photoinitiator system, the light intensity, different stand time and different monomers on photocuring was investigated. The concentration of photoinitiator in different elevation of solid pillar was investigated by XPS. The results indicated that two polysiloxysilane-based polymeric photoinitiators both can spontaneously floated to the surface of the formulations to improve surface performance. The improvement of mechanical properties of the formulations via polysilxane was investigated by DMA.