Preparation Of PSMA-PS Amphiphilic Block Polymer By RAFT Polymerization And Its Performance In Emulsion Polymerization

In this paper,the RAFT living radical polymerization was used to prepare the styrenemaleic anhydride alternating / homopolymeric amphiphilic block polymer PSMA-PS.According to the kinetic study,the polymerization reaction kinetics of the polymer has firstorder kinetics Reactivity characteristics.The structure of the polymer product was characterized by infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy,which showed that the target product was synthesized.The effects of monomer composition,initiator concentration and chain transfer agent concentration on the relative molecular mass of the polymer were investigated: Changing the monomer composition has little effect on the relative molecular mass of the polymer,and the molecular weight change is not obvious,but it can obviously change the length of the hydrophilic and hydrophobic segments in the polymer molecular chain,increase the initiator concentration,and reduce the chain transfer agent.The concentration can significantly reduce the relative molecular mass of the copolymer.According to the results of gel permeation chromatography,the relative molecular mass of the polymer is between 2000-4000 g / mol and the molecular weight distribution is between 1.109-1.284,which is consistent with the characteristics of living polymerization.The synthesized amphiphilic block copolymer PSMA-PS was subjected to ringopening reaction under the condition of NaOH aqueous solution to obtain a water-soluble polymer PSMAN-PS.The test results show that as the length of the styrene homopolymer segment in the polymer PSMAN-PS increases,the larger the micelle size of the polymer in the aqueous phase,the greater the critical micelle concentration and the weaker the ability to reduce surface tension.The polymer PSMAN-PS is used as a macromolecular emulsifier in the emulsion polymerization of St and MMA.The results of kinetic studies indicate that the macromolecular emulsifier has a certain control effect on the polymerization rate of the emulsion in the emulsion polymerization,and is characterized by infrared spectroscopy The structure of the polymerization product was confirmed,and the anchoring effect between the macromolecular emulsifier and the latex particles was confirmed,indicating that the macromolecular emulsifier is reactive.The effects of emulsion solid content,emulsifier type and monomer type on emulsion stability,conversion rate,latex particle size and nucleation mechanism were investigated.The experimental results show that the emulsion polymerization of PSt takes the form of micelle nucleation,and with the increase of the solid content in the emulsion system,the size of the latex particles in the emulsion gradually increases,and the Zeta potential and conductivity show a downward trend.The length of the hydrophobic segment in the emulsifier increases,the size of the latex particles of the prepared PSt emulsion increases,and the change in Zeta potential and conductivity depends on the amount of charge carried by the hydrophilic group in the macromolecular emulsifier.In PMMA emulsion polymerization,the latex particle size is lower than the emulsifier micelle size and the conductivity is much smaller than the conductivity of PSt emulsion,indicating that the macromolecular emulsifier PSMAN-PS polymerized PMMA emulsion is not in the form of micelle nucleation Polymerization,but to achieve polymerization by homogeneous nucleation.