Synthesis, Modification, And Application Of Hyperbranched Polymers

Due to the unique molecular structures as well as the special physical andchemical properties, in the resent decade, hyperbranched polymers have receivedconsiderable attention. Compared with the traditional linear polymers, hyperbranchedpolymers possess some traits such as a large amount of terminal groups, goodsolubility, low solution and melt viscosity, and so on. In addition, hyperbranchedpolymers can be easily synthesized through a simply one-step polymerizationprocedure. These advantages make hyperbranched polymers promising in the fields ofpolymer processing, coating, biomedicine, and surface modification etc. At present,the researches on hyperbranched polymers have been focusing on two importantdirections. One is to look for more simple and practical synthetic methods ofpreparing hyperbranched polymers, and the other is to explore functionalization ofhyperbranched polymers and finally industrialize the synthesis of hyperbranchedpolymers. In this dissertation, we mainly focus on the researches of the synthesis,modification and application of hyperbranched polymers. The dissertation includes:1. Hydroxyl-terminated hyperbranched polyether polyols were synthesized bypolymerization of glycidol and propylene oxide (PO) catalyzed by double metalcyanide (DMC) catalyst for the first time. Tri-(2-hydroxyethyl) isocyanurate (THEIC)was used as initiator for the polymerization. Effects of reaction conditions such aspretreatment of monomer, polymerization temperature, catalyst concentration, themolar ratio of monomers et al on the polymerization were investigated.Hyperbranched polyether polyols with different degree of branching (DB) wereprepared by controlling the ratio of PO to diglycidyl. It was found that highly activecatalyst resulted in ring-opening polymerization of monomers with high yield (90%).In addition, the branching degree of hyperbranched polyether polyols was found to beabout72%, indicating that the polymers are highly branched.2. Unsaturated hyperbranched polyether polyols were prepared by the modification of hydroxyl-terminated hyperbranched polyether polyols. In theexperiments, many factors such as content of AGE and hyperbranched polyether,catalyst concentration et al on the polymerization were investigated. They wereimportant indicators for evaluating of catalytic activity. The molecular structure andDB were measured by IR spectra,1H NMR spectra and13C NMR spectra.3. Unsaturated hyperbranched polyetherester polyols were synthesized by theintroduction of maleic anhydride (MA) and phthalic anhydride (PhA). The resultsdemonstrated that the introduction of MA and PhA could improve the catalyticactivity of the catalyst and shorten the polymerization time. But the ratio of PO toPhA was mostly no more than45:1.4. Hydroxyl-terminated polyether polyols were synthesized by ring-openingpolymerization of PO, using glycidol as initiator. Samples with different molecularweight were prepared by controlling the ratio of initiator to monomer (RI/M).Moreover, with the increasing of RI/M, the capacity of polymerization was enhanced.5. Rigid polyurethane foams were prepared by using hydroxyl-terminatedhyperbranched polyether polyols as cross-linking agent. Effects of reaction conditionssuch as material temperature, catalyst system on the foaming reaction wereinvestigated. The results showed that foaming time could be significantly shortenedby rising material temperature. From TGA analysis, the heat resistance of foam wasincreased by the introduction of hyperbranched polyether.