Preparation Of Polar-branched SIS Containing Polyethylene Oxide

Styrene-isoprene-styrene?SIS?is a widely used thermoplastic elastomer?TPE?material,but due to its small molecular polarity,having a low adhesion with some polar materials.Therefore,polar modification is needed to extend application of SIS in the fields of adhesives,surface coatings and so on.Directly introducing polar blocks in the polymerization process can simply synthesize polar SIS,preparing branched PI-g-PS polymers to make SIS have lower melt viscosity and excellent processing performance.In this thesis,firstly,the polystyrene macromonomer?PS-VB?was synthesized by living anionic polymerization and polyethylene oxide macromonomer?PEO-VB?was synthesized by williamson etherification method using chloromethyl styrene?VBC?as the end-capping agent.The purified macromonomers were characterized by UV?¹H-NMR?FT-IR?GPC and MS,and the emulsification properties of amphiphilic PEO-VB were analyzed.Then,living anionic copolymerization of PS-VB and isoprene using polyethylene glycol diglycidyl ether?PEGDE?as the functional modification agent was studied,the polar comb-shaped PI-g-PS-s-PEO with star-shaped polyethylene oxide at the end of the main chain was prepared by one-pot method.Its molecular structure,thermal and rheological properties were analyzed by FT-IR?GPC?DSC and torque rheometer,and the influencing factors of PEO content?w?PEO?%?in PI-g-PS-s-PEO were investigated.Finally,emulsion copolymerization of PS-VB and Ip using PEO-VB and disproportionated rosin sodium soap?DRS?as composite emulsifier to prepare polar PI-g-PS-g-PEO.The influence of initiator system and emulsifier system on monomer conversion and emulsion performance were investigated.The molecular structure and thermal property of PI-g-PS-g-PEO were analyzed by FT-IR?¹H-NMR and DSC.Experimental results are as follows:?1?The end-capping efficiency of PS-VB is about 95%,its molecular weight can be designed and the distribution is narrow.The end-capping efficiency of amphiphilic PEO-VB is about 92%,and it has a certain emulsifying ability to be used as a reactive emulsifier with its cloud point above 60?,CMC value below 2.4mg/ml and suitable for O/W system.?2?The polar comb-shaped PI-g-PS-s-PEO with polyisoprene as the main chain,polystyrene as ordered side chains,star-shaped polyethylene oxide at the end of the main chain was successfully prepared.The molecular weight of PS-VB has no effect on w?PEO?%,the w?PEO?%is effectively improved when the end-capping reaction time,the amount of modifier are increased and use the smaller molecular weight of PEGDE.PI-g-PS-s-PEO has a certain polarity,and the PEO segment in the molecular chain does not crystallize.Under the same conditions,the melt viscosity of PI-g-PS-s-PEO is significantly lower than that of linear SIS,and as the number of branches increases,the melt viscosity decreases.?3?Using CHP/TEPA=1:1.25 as the initiator and DRS/PEO₈-VB=1:1 as the emulsifier,the polar PI-g-PS-g-PEO copolymer emulsion with monomer conversion over 60%and excellent comprehensive performance can be obtained.PEO₈-VB can reduce the amount of DRS and improve the polarity of the copolymer and its emulsion.The crystallization of PEO segments in the copolymer indicates that PEO is a single phase,and PI-g-PS-g-PEO has a micro-phase separation structure.