Preparation Of Structurally Controlled Polyolefin-graft-Poly (Ethylene Glycol) And Its Properties

This thesis describes the synthesis and application of a new series of amphiphilic graft copolymers with a hydrophobic polyolefin backbone and pendent hydrophilic poly(ethylene glycol)(PEG) grafts. These copolymers are synthesized by ruthenium benzylidene-catalyzed ring-opening metathesis polymerization (ROMP) of PEG-functionalized cyclic olefin macromonomers to afford polycyclooctene-graft-PEG (PCOE-g-PEG) copolymers with a number of tunable features, such as PEG graft density and length, crystallinity, and amphiphilicity. In order to gain better control over graft density, graft copolymers can be prepared by direct polymerization of macromonomers, pendent grafts are incorporated directly through polymerization or copolymerization of the macromonomer itself.In this work, both the effects of PEG side chain lengths (350to1000g/mol) at a fixed PEG content (50wt.%) and the neat PEG content (30wt.%to70wt.%) at a fixed PEG molecular weight (750g/mol) on the anti-protein and anti-platelet adsorption properties are studied. It is shown that when the neat PEG content is fixed at50wt%, the copolymer with750g/mol PEG side chain is optimal to reduce the adsorption of bovine serum albumin (BSA) and platelet. This result is the co-effect of the two competitive factors (graft chain length and graft chain density) on the protein and platelet resistance properties of the graft copolymer film. Furthermore, the study of the neat PEG contents of the copolymer varied from30to70wt%at a fixed PEG side chain length (750g/mol) showed that lowest adsorption of BSA and platelet is obtained when the PEG content is60wt%,at this time, phase inversion happens. When the PEG content further increases to70wt%, the BSA and platelet adsorption will slightly increase because of the increasing of surface roughness.Both the micro-phase separation in PCOE-g-PEG copolymer film and its self-assembly in polar solvent have been studied. In PCOE-g-PEG copolymer film, ordered pillar of PEG phase is regularly located in PE matrix, while spherical micelles formed in ethanol and methanol solvent.In addition, ion conductivity properties of the PCOE-g-PEG copolymer film has also been studied. In order to balance the ion conductivity and mechanical property, a comb like copolymers with high content (>50wt%) free PEG side chains and cross-linked polyolefin main chains are synthesized via ROMP. The cross-linking degree will determine the mechanical properties but will not affect the mobility of PEG side chains and also ion conductivity of the solid polymer electrolyte (SPE).We have solved the problems of the preparation of copolymer and membrane forming property. And we have investigated the effect of the molecular weight of PEG and PEG percentage on the ion conductivity and membrane-forming property. The copolymer membrane containing71wt%PEG of750g/mol obtain the ion conductivity of1.4x10-4S/cm.