Synthesis, Photopolymerization Behavior And Properties Of Sulfur-containing Monomers

UV-curable monomers with heteroatom have a special function in thecoatings after curing. The excellent chemical and physical properties of theUV-cured film make monomers with heteroatom highly attractive forapplications as coatings, adhesives, inks and composites. Sulfur-containingmonomers possess lots of unique characteristics including: hydrophobicity,high refractive index, low moisture absorption, low solvent swelling, etc.Sulfur-containing monomers are least sensitive to oxygen inhibition as well asgive the best results when free radical polymerized in Air. It’s important tonote that there have been few studies on cationic polymerization of theepisulfide. UV-curable monomers with sulfur heteroatom could be used indifferent areas, such as lenses,display devices,coatings and adhesives.Sulfur-containing monomers could be synthetized and photopolymerizein the presence of free or cationic initiator. Dimethacrylates based onbisphenol-S were synthesized. The DBSMA resin was modified with vasiousamount of3-isocyanatepropyltriethoxysilane (KBE9007) coupling agent. Thephotocuring kinetics, primary physical and mechanical properties of polymerswas investigated by Real Time Infrared, DMA and TGA. Difunctional episulfide (BPT) was synthesized. Then Episulfide based systems wereinvestigated in cationic photopolymerization process. Some properties such asrefractive index and adhesion strength of BPT polymer were studied.1．A dimethacrylate based on bisphenol-S (DBSMA) was prepared andcharacterized by FTIR, ESI/MS,1HNMR and13CNMR. DBSMA wasinvestigated by a real-time infrared spectroscopy (RT-IR), under differentconditions such as varying photoinitiator type and concentration, with andwithout oxygen, mixing with different amount of a reactive diluents(1,6-hexanediol dimethacrylate). The mechanical and thermal properties ofthese curing films were also investigated by DMA and TGA. The resultsshowed homopolymer of DBSMA has better thermal stability than copolymersof DBSMA/HDDMA systems. Also, the cured DBSMA polymer exhibitedhigher glass transition temperature (Tg) and better thermal stability and higherrefractive index compared with commercial available resin Bis-GMA(CN151).2．Novel hybrid oligomers based on a UV-curable bisphenol-S epoxydimethacrylate (DBSMA) were synthetized. DBSMA was modifed withvarious amount of (3-Isocyanatopropyl) triethoxysilane (IPTES) couplingagent. The modifcation degree of the hybrid oligomer was varied from0to70wt%. The photopolymerization kinetics was monitored by a real-time infraredspectroscopy (RT-IR). The conversion and rate of hybrid coatings increasedwith the increase in modifcation degree. UV-curable, hard and transparent organic–inorganic hybrid coatings were prepared. They were performed by theanalyses of various properties such as surface property and mechanicalproperty. Results from the mechanical measurements showed that theproperties of hybrid coatings improved with the increase in modifcationdegree. The thermal behavior of coatings was also investigated.3．A low-viscosity dimethacrylate based on bisphenol-S (DMAPPS) wasprepared and characterized by FTIR,1HNMR and elemental analysis.DMAPPS had low viscosity and no crystallization. DMAPPS was investigatedby a real-time infrared spectroscopy (RT-IR), under different conditions suchas varying photoinitiator type and concentration. The mechanical and thermalproperties of these curing films were also investigated by DMA and TGA. Theresults showed the cured DMAPPS polymer exhibited higher glass transitiontemperature (Tg), better thermal stability and higher refractive index comparedwith DBSMA.4．Sulfur-containing compounds have attracted widely interest in the UV area.A episulfide monomer,1,4-Butanediol episulfide (BDDGE-PSTC (BPT)),was synthesized via replacement of the oxygen atoms in1,4-Butanedioldiglycidyl ether (BDDGE) with sulfur atoms. Its structure was confrmed byFT-IR,1H-NMR and ESI/MS. The photopolymerization kinetics of the BPTwas studied by real-time Infrared spectroscopy (FT-IR), under differentcondition such as photoinitiator concentration and type, atmosphere and so on.Some properties such as refractive index and adhesion strength of the cured BPT polymer were studied. It was found that the cured BPT polymer showedhigher refractive index in comparison with BDDGE. The cured BPT polymerhad better adhesive strength in polyethylene terephthalate (PET) and iron. Thethermal and mechanical properties of UV-curing BPT films were alsoinvestigated by TGA and DMA.5．Episulfide based systems were investigated in cationicphotopolymerization process. The effect on the rate and conversion of BPTpolymerization enhanced in the presence of monofunctional epoxy monomer,but suppressed by vinyl ether monomers. The rate and conversion ofmonofunctional epoxy monomer and vinyl ether monomers were suppressedby episulfide. It was found that the rate and conversion of comonomersdrastically increased when temperature risen, which breaked comonomerscomplexing. DSC showed that comonomers had a single glass transitiontemperature. Acrylate and BPT could occur hybrid polymerization. It wasfound that they could form IPN crosslinked network.