Self-Stabilized Precipitation Polymerization of Vinyl Chloride and Maleic Anhydride

Self-stabilized precipitation (2SP) polymerization, a powerful tool for synthesizing and functionalizing uniform polymeric microspheres, is commonly applied in the heterogeneous copolymerization of olefinic compounds with maleic anhydride (MAH). In the present work, we exploited the 2SP polymerization of the vinyl chloride monomer (VCM) with MAH using bis(4-tert-butylcyclohexyl) peroxydicarbonate (TBCP) as the initiator in an isoamyl acetate/n-hexane binary mixture solvent. The effects of polymerization conditions such as the solvent composition, monomer feed ratio, total monomer concentration, and initiator concentration on the size and morphology of the resultant poly[(vinyl chloride)-co-(maleic anhydride)] (PVM) microspheres were investigated systematically. The results showed that clean and well-dispersed PVM microspheres with particle sizes ranging from 185 to 335 nm were successfully prepared when the solubility parameter of the mixture solvent was in the range of 15.92–16.22 MPa1/2. By simply tuning the monomer feed ratios, PVM copolymers (Mn = 14400–21400 g/mol) with a high content of MAH (∼50 mol %) were obtained, which was difficult to achieve either in conventional suspension or in emulsion polymerization. More interestingly, the resultant PVM microspheres showed excellent water solubility in alkaline solution when the molar fraction of MAH in copolymers was more than 40%, making the anhydride-containing PVM microspheres highly attractive as promising functional materials.