The Features of Vinyl Chloride‐Vinyl Acetate‐Maleamic Acid Ammonium Salt Soap‐Free Emulsion Polymerization Under Varied Conditions

ABSTRACT The emulsion polymerization of vinyl chloride monomer (VCM) is one of the quite mature processes to produce poly(vinyl chloride) (PVC) products. The residual emulsifier in PVC products brings some undesirable issues when it is used in some special application scenarios. Soap‐free emulsion polymerization technology provides a strategy to reduce the possible environmental pollution caused by emulsifier residue. Very recently, we have developed a soap‐free emulsion polymerization system for PVC based on the ternary copolymerization between vinyl chloride, vinyl acetate, and maleamic acid ammonium salt. Herein, we mainly investigate the effect of VCM soap‐free emulsion polymerization from five aspects: ionic strength, initiator dosage, monomer concentration, reaction temperature, and stirring speed. Suitable ionic strength is the key to maintaining the stability of the soap‐free system. The initiator dosage, reaction temperature, and monomer concentration are important means to control the reaction rate, number‐averaged molecular weight ( M n ), and particle size. Increasing the stirring speed can accelerate the reaction rate. By tuning the above conditions, PVC latex particles with a particle size of 123–272 nm and M n of 54,000–139,800 g/mol can be prepared. This soap‐free emulsion polymerization is of reference and significance for the preparation of soap‐free emulsions with polar monomers and the production of functional polymers.