Preparation And Living Ring-Opening Metathesis Polymerization Reaction Of Norbornene-Based Derivatives

Living ring-opening metathesis polymetization (ROMP) which can control chain length and sequential structure is one of the most optimal methods to synthesize functional polymers. Especially with the development of stable and efficient catalysts with definite structure, the synthesis of polymers with complex functional groups become easier, which further promotes the rapid development of ROMP.Norbornene and its derivatives are commonly used monomers for ROMP reaction. The configuration, steric exclusion and polarity of the norbornene-based monomers are important factors to affect the ROMP reaction. Water-soluble polymers are of great interest in drug delivery, biomaterials, flocculants and other material applications. Poly(ethylene oxide)(PEO) and carbohydrate compounds are widely used in the synthesis of functionalized polymers because of the water-soluble nature. Recent studies have found that nitrogen-containing compounds could coordinate with metal ions of optical activity, thermal activity or magnetic properties, and the assembled metal organic compounds showed good physical properties. This paper mainly aimed at the preparation and living ROMP reaction of norbornene-based derivatives.Firstly, norbornene-based monomers with different side groups were synthesized. Monomers M1-M5could be prepared from the corresponding norbornenecarbonyl chlorides (endo isomers in M1-M3, endo and exo isomers in M4-M5) and the acetal-protected sugars, poly(ethylene oxide) and isopropyl alcohol. Monomer M6was synthesized by the reduction reaction of5-norbornene-2,3-dicarboxylic anhydride, and M7was synthesized by the esterification reaction of the dimethanol (M6) with tosyl chloride. Functionalized nitrogen-containing monomer M8was synthesized by M7and tert-butyl amine. The structures of the monomers were confirmed by1H NMR and FT-IR.Then, norbornene-based monomers with different side groups were polymerized via ROMP initiated by Grubbs second generation initiator. The effect of monomer configuration, steric exclusion and polarity of side groups on living ROMP was researched in detail. The molecular weight was characterized by GPC and1H NMR, and the monomer conversion was calculated by1H NMR using the area ratio between the signals for double bonds in homopolymers to the sum of those for the unreacted double bonds in monomers.Finally, on the basis of homopolymers, block copolymers with different block microstructure were prepared by the suitable monomers. The sequence and the length of the polymer chain segments were controlled by adjusting the feeding order and the amount of monomers. The block copolymers containing both water-soluble units and nitrogen-containing units were obtained finally.