Preparation And Properties Of Hydrophilic Vinyl Chloride/Acrylate Suspension Copolymer Resins

Polyvinyl chloride(PVC)has excellent all-round properties and is an important polymer for a wide range of applications.However,the lack of polar groups in the molecular backbone of PVC gives it a non-polar surface and a poor hydrophilicity.The problems of easy contamination,infection,and cleaning difficulties occur during the application in the direction of membrane materials,medical products,and construction materials,which greatly reduces the application performance of PVC.Therefore,the hydrophilic modification of PVC is of great importance.To achieve PVC modification from a synthetic point of view,the industrially proven suspension polymerization method is used.However,suspension polymerization uses water as the reaction medium and hydrophilic monomers are readily soluble in water.Therefore,the modifying monomer needs to be able to both copolymerize with vinyl chloride monomer in the aqueous phase and achieve the hydrophilic modification of PVC.In this paper,monomers with good affinity to acrylates were chosen and the vinyl chloride copolymers were prepared by successive dropwise addition of active monomers.Then,different post-treatment methods were used to convert the hydrophobic groups contained in the acrylates into hydrophilic groups,thereby improving the hydrophilicity of PVC,with the following main studies:(1)For the application of PVC in the direction of membrane materials,in order to solve the problems of easy blocking and difficult cleaning of membrane materials due to the poor hydrophilicity of PVC.In this chapter,P(VC-co-t BA)was first synthesized by suspension copolymerization of tert-butyl acrylate(t BA)with vinyl chloride.Taking full advantage of the easy hydrolysis of tert-butyl ester under acidic conditions,the tert-butyl ester was hydrolyzed to obtain P(VC-co-AA)containing carboxyl groups.The structures of P(VC-co-t BA)and P(VC-co-AA)were characterized using infrared spectroscopy and NMR hydrogen spectroscopy,and it was found that tert-butyl ester was almost completely hydrolyzed.After characterization of the properties of P(VC-co-AA)compared to PVC,the glass transition temperature was reduced from 88°C to 78.5°C,the elongation at break was increased from 18% to 42%,the tensile strength was reduced from 45 MPa to 38 MPa and the water contact angle was reduced from 102.76° to 78°.(2)For the application of PVC in the direction of construction materials,in order to solve the problems of easy contamination and difficult coloring of construction materials due to the poor hydrophilicity of PVC.In this chapter,glycidyl methacrylate(GMA)is selected for suspension copolymerization with vinyl chloride,and the epoxy group is introduced into the PVC molecular chain to improve the hydrophilicity of PVC through the hydroxyl group generated by ring opening of the epoxy group during high-temperature processing.The structural characterization and a series of performance characterizations were carried out on P(VC-co-GMA).Compared with pure PVC,the thermal stability of P(VC-co-GMA)was improved,the glass transition temperature was reduced from 85°C to 79°C,the tensile strength increased with increasing GMA content,and the elongation at break reached a maximum of 55.6%at 3 wt % GMA;the P(VC-co GMA9%)specimens,the water contact angle was reduced from 92.32° to58.44° for pure PVC.(3)For the application of PVC in the direction of medical materials,in order to solve the problems of poor hydrophilicity and the use of large amounts of toxic plasticizers in the use of PVC medical materials.In this chapter,glycidyl iso octanoate methacrylate(GMAI)was synthesized using octanoic acid and GMA.GMAI containing hydroxyl groups and long flexible chain segments was introduced directly into the PVC molecular chain by suspension copolymerization to prepare highly efficient internal plasticizing hydrophilic P(VC-co-GMAI)resin.The GMAI structure was first characterized and then the synthesis process was optimized.P(VC-co-GMAI)was then structurally characterized and a series of properties characterized.Compared to pure PVC,the glass transition temperature of P(VC-co-GMAI)was reduced from 84.4°C to 67.2°C;elongation at break reached a maximum at 7 wt % GMAI content,from 21% to 105%of PVC;plasticization time was shortened and equilibrium torque was reduced The water contact angle of the film was reduced from 102.3° to 81.9° and the water contact angle of the test piece was reduced from92° to 69.7°.