Synthesis And Characterization Of Oligomers Containing Side Hydroxyl Groups

The oligomers containing side hydroxyl groups is a polymer in which an oligomer is a main chain and a hydroxyl group is introduced in a segment thereof.Its number average molecular weight(Mn)is less than 10,000.The main chain has unique properties due to its relatively low molecular weight.The introduction of hydroxyl reactive groups increases the reactive sites of the oligomers,making it more widely used.In this paper,liquid polyisoprene with low molecular weight were prepared by living anionic polymerization,and its reaction kinetics was studied.The liquid polyisoprene was used as a raw material,and Ene reaction with N-hydroxyethyl maleimide was carried out to synthesize liquid polyisoprene containing side hydroxyl groups.A polyurethane elastomer having low temperature resistance was synthesized by using liquid polyisoprene containing side hydroxyl groupsas a polyol.Then,a isobutylene-maleimide alternate copolymer containing side hydroxyl groups with low molecular weight was prepared by reversible addition-fragmentation chain transfer polymerization.The primary content of the study and the results are shown as follows:1.Using n-BuLi as initiator and cyclohexane as solvent,a pilot-scale amplifica-tion test of isoprene was carried out by living anionic polymerization in a 1 L autoclave to synthesize relative molecules.A liquid polyisoprene having a mass of 9000.The reaction kinetics of the polymerization reaction was studied by weighing method.The influence of polymerization temperature and reaction monomer concentration on the reaction kinetics was studied.The reaction order corresponding to the monomer concentration is obtained as level 1.According to the Arrhenius formula k=A*e^(-Ea/RT),the apparent activation energy of the reaction is Ea=84 KJ/mol.2.N-hydroxyethylmaleimide(NEMI)was used as raw material to react with liquid polyisoprene under nitrogen to prepare liquid polyisoprene containing side hydroxyl groups.Characterization by nuclear magnetic resonance spectroscopy(1H-NMR),fourier transform infrared spectroscopy(FTIR)and gel permeation chromatography(GPC)confirmed the successful synthesis of the product.The effect of the amount of NEMI added on the hydroxyl content of the product was studied.The results show that the hydroxyl content of the product increases linearly with the increase of NEMI.The polyurethane elastomer was synthesized from liquid polyisoprene containing side hydroxyl groups and tested by dynamic mechanical thermal analyzer(DMA)and universal tensile machine.The results show that the Tg of polyurethane synthesized from side hydroxyl liquid polyisoprene is-40 ?,which has good low temperature resistance,and higher content of soft hydroxyl group,the higher the crosslinking density and tensile strength of polyurethane.3.Synthetic method using reversible addition fragmentation chain transfer polymerization,using N-hydroxyethylmaleimide and isobutylene as raw materials,S,S'-Bis(?,?'-dimethyl-?"-acetic acid)-trithiocarbonate is a RAFT chain transfer agent,and a isobutylene-maleimide alternate copolymer containing side hydroxyl groups with low molecular weight is prepared in a 100ml autoclave.Nuclear magnetic resonance spectroscopy(1H-NMR)and fourier infrared spectroscopy(FTIR)was used to characterize the successful synthesis of the product.The effect on the molecular weight of the polymer was investigated by varying the amount of RAFT chain transfer agent added.Characterization was carried out by gel permeation chromatogr-aphy(GPC),and the products were tested for thermal properties using differential scanning calorimeter(DSC)and thermogravimetric analyzer(TGA).The results show that the more the RAFT chain transfer agent is added,the smaller the molecular weight of the product.The Tg of the product was 135 ?,and Td5 and Td10 were 335 ? and 372 ?,respectively,indicating that the polymer has high temperature resistance and good thermal stability.