Creative Soap-Free Emulsion Polymerization of Vinyl Chloride via Copolymerization With Vinyl Acetate and Maleamic Acid Ammonium Salt

Soap-free emulsion polymerization has superiorities such as better stability, high purity, and being more environmentally friendly than conventional emulsion polymerization. Many soap-free emulsion polymerization systems have been reported on styrene and acrylate monomers, but rarely on vinyl chloride. In this work, we develop a soap-free emulsion polymerization system for poly(vinyl chloride) (PVC) based on the ternary copolymerization between vinyl chloride monomer (VCM), vinyl acetate (VAc), and maleamic acid ammonium salt (MAAS), which can eliminate the undesirable effects of emulsifiers and introduce functional groups on the surface of the PVC latexes. The soap-free emulsion polymerization is achieved successfully by employing MAAS as the hydrophilic unit and VAc as a bridging agent to tailor the reactivity and stability of the polymer latexes. Tuning the feed ratio of MAAS/VAc is the key point to achieve the present soap-free polymerization system. More interestingly, the introduction of a small amount of co-solvent such as ethanol in the soap-free emulsion polymerization system neither destabilizes the emulsion nor hinders the polymerization process; on the contrary, it can significantly improve the polymerization rate and conversion. This new polymerization system provides a broad prospect for high value-added application of PVC and provides supplementary value for the PVC polymerization methods.