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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.

It remains a formidable challenge to explore novel synthetic approaches and realize a high performance for conventional plastics, especially for poly­(vinyl chloride). Herein, we synthesize cross-linked poly­(vinyl chloride) (CL-PVC) microspheres via self-stabilized precipitation (2SP) polymerization by using diallyl maleate (DAM) as a cross-linking agent. The effects of solvent composition, DAM concentration, stirring rate, monomer and initiator concentration, and monomer feeding modes on the particle size, gel content (GC), and morphology of the resultant CL-PVC microspheres are evaluated thoroughly. The mixture solvent of n-hexane and ethanol is suitable for conducting the 2SP polymerization of CL-PVC. Monodisperse microspheres have a linear increase in diameter from 405 to 648 nm with the DAM increasing from 0.25 to 16%. The GC values are highly reliant on both the amount of DAM and its feeding modes. Subsequently, the CL-PVC and dioctyl phthalate-extended CL-PVC (DECL-PVC) microspheres are utilized as functional polymeric fillers in a rigid PVC resin. It is encouraging that both mechanical and impact strengths are enhanced concurrently. When 5 phr DECL-PVC (GC = 30.08%) and DECL-PVC (GC = 76.23%) are added to the rigid PVC resin, the tensile strengths thereof can reach 73 and 78 MPa, respectively, which are much higher than that of the contrast (∼54 MPa). Meanwhile, the highest impact strength can reach 4.36 kJ/m2 by using 5 phr DECL-PVC (GC = 30.08%) as a toughening modifier, which increased by 53.0% than that of CL-PVC (2.85 kJ/m2) at a similar loading content and 209.2% than that of pure PVC (1.41 kJ/m2). This work offers a novel strategy for the synthesis of the CL-PVC microsphere and opens a new scope for its further use.

Owing to the frequent occurrence of diclofenac sodium (DS) in fresh aquatic environments and its potential toxicity towards living organisms, the effective removal of DS has attracted worldwide concern. Herein,...

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