Synthesis, Characterization, Application Of Polyethylene-Hyperbranched Grafted Copolymers

Linear-hyperbranched hybrid polymer, with the unique structure different from convenient linear polymers or conventional hyperbranched polymers, has been a focal point of research due to its unusual relationship between structure and properties. And untilnow a variety of linear-hyperbranched polymer architectures has been pubilished mostly with one long linear block of one amorphous type and several shorter homonomous segements of different structure. However, the amphiphilic linear polyethylene-hyperbranched copolymers have never been reported, which could exhibit special characteristics propertities as a result of combination the crystallization properties of polyethylene with unique properties of hyperbranched polymer including their globular shape, a large number of end-groups and lack of entanglement. Therefore, we synthesized a series of linear polyethylene-hyperbranched polyglycidol grafted copolymers by using olefin coordination polymerization, acyclic diene metathesis polymerization and ring-opening multibranching polymerization, and discussed the tight relationships between structure and properties of this novel lybrid polymer. In this paper, the distance of hyperbranched side chains of linear polyethylene-hyperbranched polyglycidol grafted copolymers was controlled by applying acyclic diene methathesis polymerizaiton technology. The main research contents are as follows:1. The linear polyethylene with terminated hydroxyls, prepared by copolymerization of ethylene and 10-undecen-1-ol, was used as macroinitiator for ring-opening multibranching polymerization of glycidol by a typical slow monomer addition approach. Successful attachment of the hyperbranched grafts to the linear polyethylene backbone was confirmed by 1H/13 C NMR, GPC. The degree of polymerization and Mw/Mn of hyperbranched copolymers were efficiently controlled by temperature, deprotonation ratio as well as the molar ratio of glycidol/ hydroxyl(Nglycidol/NOH). The complicated microstructures caused by unsymmetric glycidol structure were analyzed by DEPT and 2D HSQC spectra, the degree of branching of 0.63–0.66 were calculated, indicating the extent of branch is close to theoretical values. The thermal, crystallization and hydrophlilic analyses of linear-hyperbranched copolymers via TGA, DSC, XRD and contact angle is also presented.2. The linear polyethylene with hydroxyl side chain was prepared by acyclic diene metathesis(ADMET) polymerization. Then, the polyethylene-hyperbranched grafted copolymers, with equidistant hyperbranched side chains, were synthesized via ring-opening multibranching polymerization of glycidol using the aboved linear polyethylene as macroinitiator. A series of hyperbranched copolymers were obtained by altering reaction conditions and characterized through FIT-IR, 1H and 13 C NMR spectra, XRD, TGA, DSC and contact angle.3. A large amount of chemical and physicall analyses were conducted by on the functionalization of the resultant linear-hyperbranched grafted copolymers through acylation with different fucntional groups. DSC, XRD and contact angle testing results show that the crystallization and hydrophile properties can be changed significantly with the non-polar end-groups. The application of amphiphilic hyperbranched copolymers to the compatibilizing of LLDPE/PCL blends was also studied in details by SEM observation of fracture surface.