Research Of Optical Transparent Polymer Materials Based On Norbornene

Cyclic Olefin Copolymer (COC) is widely used in many fields, such as photo logy, electronic components and biology medicine, due to their high transparency, low birefringence, the excellent heat/chemical resistance, melt fluidity, dimensional stability, the very low dielectric constant and good moisture resistance et.al.In this thesis, the addition polymerizations of norbornene (NB) were conducted by using (t-BuNSiMe2Flu)TiMe2(1) complex to realize the random and block copolymerization with ethylene, propylene, and higher a-olefin.First, we condocted random copolymerization of NB/octene to optimize the polymerization condition by using different cocatalysts of dry methylaluminoxane (dMAO), modified methylaluminoxane (MMAO) and organoboron compound Ph3CB(C6H5)4respectively. The polymerization activity by1-(Ph3CB(C6H5)4of which value is5940kg-mol-1-h-1was5times higher than that of1-MMAO system. The produced copolymers had the relatively high molecular weight, controllable glass transition temperature with large range of80℃～250℃and good transmittance (92%)Based on the above research, the random copolymerization of norbornene with ethylene, propene, and higher a-olefin were proceeded by using1-Ph3CB(C6H5)4system. The polymerization activity was closely related to the structure and concentration of comonomer. The copolymerization activity increased with raising the chain length and the concentration of the a-olefin and reached～63000kg-mol-1-h-1for NB/octadencene copolymerization. The catalytic systems produced random copolymers with the high molecular weight(Mn=10×104～20×104)and narrow molecular weight distribution (Mw/Mn=1.0-1.5), and the glass transition temperature of copolymers obtained is controllable by changing comonomer feed ratio (100～300℃). The copolymers show high transmittance value of approximately90%, of which value slightly increased with the length of a-olefin. Compared with the alternating copolymer, the random copolymer films have the better tensile strength and elasticity modulus. And the tensile strength increased with chain length of comonomers. When decene used as the comonomer, the tensile strength will get the maximum value of26.7Mpa.Moreover, we also synthesized the new block copolymers formed by chain segments of random copolymer and homopolymer of the corresponding comonomer. All the block copolymers showed the high Tg, which can be controlled in a large range. And there existed the crystal in the block copolymer of NB/ethylene. The optical transparency of the new bolock copolymer films were not so excellent as the random copolymers and can also enhance by increase of the chain length of a-olefin. Compared with the random copolymer, the new block copolymer films had the advantages in elastic modulus. When octene was used as comonomer, its elastic modulus reached the peak, which is1.51GPa.