Synthesis And End Group Modification Of Hyperbranched Polyesters

There are many advantages of hyperbranched polyesters,such as high branching,low viscosity,symmetrical spherical three-dimensional structure,and no entanglement between molecules.Hyperbranched polyesters carrid lager number of active terminal groups,and it can be used in a wide variety of applications by modifying hyperbranched polyesters.In this experiment,the synthesis of aliphatic hyperbranched polyesters and modification of terminal groups were studied.In this experiment,the selection of hyperbranched polyester core molecules,the type and amount of catalyst and the polymerization temperature were investigated respectively.The hyperbranched polyester products were characterized by FTIR,1H NMR,DSC and Tg analysis.Finally,the terminal groups modification experiments of S-HBPE-2 were carried out.Result shows that the optimal preparation conditions for hyperbranched polyesters with pentaerythritol as a core molecule is that the amount of p-toluene sulphonic acid(p-TSA)is 0.5%,the polymerization temperature is 145 ?,the polymerization time is 180min and the reaction degree of carboxyl groups is 90.36%,the optimal preparation conditions for hyperbranched polyester with trimethylolpropane as a core molecule is that the amount of p-TSA is 0.5%,the polymerization temperature is 145 ?,the polymerization time is 180min and the reaction degree of carboxyl groups is 91.64%,the optimal preparation conditions for hyperbranched polyester with polyethylene glycol-400(PEG-400)as a core molecule is that the amount of p-TSA is 0.5%,the polymerization temperature is 150?,the polymerization time is 180min and the reaction degree of carboxyl groups is 61.29%.The result revealed that S-HBPE-2 is easy to dissolve in polar organic solvents,slightly soluble or insoluble in non-polar solvents.The presence of a large number of ester groups in the product structure can be determined by FTIR analysis.The degree of branching DBfrey and DBfrechet can be determined by nuclear magnetic resonance(1H NMR)analysis.The glass transition temperatures of S-HBPE-2 and S-HBPE-3 were 51.2 ?and 53.4 ? respectively,and it was determined by DSC.It can be concluded by Tg that the thermal stability of S-HBPE-2 and S-HBPE-3 products is perfect,and it begins to decompose above 310 ?.By GPC analysis,the products S-HBPE-2 and S-HBPE-3 PDI were 1.18 and 1.38 respectively,indicating the structure of hyperbranched polyester has reached a relatively regular degree obtained in this experiment.The S-HBPE-4 products were also discussed in this experiment.In this experiment successful modification of hyperbranched polyesters terminal groups.