Synthesis And Photopolymerization Of Mutifunctional Monomers

UV-curable resins are now being increasingly used in various industrial applications, such as protective coatings, varnishes, printing inks, adhesives and the high-definition images, due to their distinct advantages, mainly great speed of cure, low-energy consumption, solvent-free formulations, room temperature operations, high-quality end-products and the production of polymer materials having tailor-made properties. The UV-curable resins usually consist of photoinitiator, functionalized oligomer and mono or multifunctional monomer. The monomer acts as reactive diluent and plays a key role, because it affects the polymerization rate and the cure extent, as well as the physical and chemical properties of the final polymer. Multifunctional monomers, being of higher molecular weight than many monofunctional materials, are generally much less volatile than many monofunctional monomers. And their odour is generally lower and their flammability hazard is significantly reduced. Multifunctional monomers can be crosslinked by itself, unlike a monofunctional monomer which needs a multifunctional material to be present for crosslinking. In this thesis, a series of multifunctional monomers were synthesized by the reaction of ethylene carbonate with amine and the Michael Addition reaction. The photocuring kinetics, primary photochemistry and mechanical properties of polymers initiated by different photointiator were investigated by Real Time Infrared and DMA.1. The urethane diacrylates of AEAEC could be prepared via a non-isocyanate route. The photopolymerization kinetic results indicated that the relationship between the rate of polymerization and the incident light intensity was R_p∝I₀^0.7 instead of the 0.5 power that the classical rate equation suggested when bimolecular termination occurs. So it was suggested that a combination of bimolecular and unimolecular termination was happening in the polymerization. An increase of the initiator content strongly accelerated the photopolymerization of the urethane diacrylate and the maximum of the polymerization rate was achieved earlier. The R_p was proportional to [A]^0.5. Photoinitiator type and concentration influenced the curing of urethane diacrylate. The DMA results indicated T_g and the storage modulus of AEAEC was better than that of TPGDA.2. The urethane triacrylate (2-(Acryloyloxy) ethyl bis(2-(Acryloyloxy)ethyl)carbamate) (AEBAC) was synthesize from ethylene carbonate via non-isocyanate route. The characterization of the synthesized monomer was carried by IR and ¹HNMR spectroscopies. The results were in agreement with the expected structures. The viscosity of AEBAC was 31.5 mpa·s (15℃) and lower than the conventional triacrylate monomer TMPTA. The radical polymerization behaviors of this monomer were investigated by real-time FTIR. It could be seen that the polymerization rate R_p was proportional to the square root of light intensity and initiator concentration. Type I photoinitiator had higher activate than Type II initiator. DMA results showed T_g of AEBAC was about 80℃which was lower than that of TMPTA.3. A novel urethane hexaacrylates was prepared via a two steps route. The characterization of the synthesized hexaacrylate was carried by IR and ¹HNMR spectroscopies. The spectral data were in agreement with the expected structures. The photopolymerizations of this monomer were studied by real time FTIR. The results indicated that both the R_p and the DC_F of MABAPP was very high and the R_p was proportional to the square root of light intensity and initiator concentration. The kinetic constants k_p and k_t were investigated to conclude the polymerization process. MABAPP could act as the reactive monomer and the coinitiator when BP system without amine was used as the coinitiator.4. Three multifunctional methylacrylates (PMDETA, HMTETA and HMTEPA) were synthesized by Michael Addition reaction. The photopolymerizations of these monomers were studied by real time FTIR. The results showed the initial polymerization rate R_p of HMTEPA was higher than that of PMDETA and HMTETA, and the final double bond conversion of HMTEPA was highest in three monomers. The polymerization rates R_p of three monomers were all proportional to the square root of light intensity and initiator concentration. DMA results showed the T_g and the storage modulus of PMDETA were both highest among three monomers.