Evolutions of drop/particle size and size distribution in liquid–liquid dispersions and suspension polymerizations of methyl methacrylate (MMA) were monitored by using an online optical reflectance measurement (ORM), and effects of operating parameters such as the agitation rate, concentration of poly(vinyl alcohol) (PVA) dispersant, and initial concentration of poly(methyl methacrylate) (PMMA) in MMA monomer on the Sauter mean diameter (d₃₂) and size distribution of drop/particle were investigated. According to the variations of d₃₂ of drops/particles with time, four characteristic particle formation stages can be identified for suspension polymerization process. The factors that lead to increase the rate of drop break up, such as increasing of concentration of PVA and decreasing of viscosity of dispersed phase, would postpone the particle growth stage. The d₃₂ and size distribution breadth of drops/particles were significant increased when the liquid–liquid dispersions or suspension polymerizations were conducted at low PVA concentrations or MMA/PMMA solutions with high PMMA contents were used as the dispersed phase, in consistent with the scanning electron micrograph observation on final PMMA particles. It is clear that ORM can be effectively applied in online monitoring of size and size distribution of drops/particles in the liquid–liquid dispersions and suspension polymerizations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43632.

Solution and aqueous miniemulsion polymerizations of vinyl chloride (VC) mediated by (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl-2-((ethoxycarbonothioyl)thio) propanoate) (X1) were studied. The living characters of X1-mediated solution and miniemulsion polymerizations of VC were confirmed by polymerization kinetics. The miniemulsion polymerization exhibits higher rate than solution polymerization. Final conversions of VC in the reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization reach as high as 87% and are independent of X1 concentration. Initiation process of X1-mediated RAFT miniemulsion polymerization is controlled by the diffusion–adsorption process of prime radicals. Due to the heterogeneity of polymerization environments and concentration fluctuation of RAFT agent in droplets or latex particles, PVCs prepared in RAFT miniemulsion exhibit relatively broad molecular weight distribution. Furthermore, chain extensions of living PVC (PVC-X) with VC, vinyl acetate (VAc), and N-vinylpyrrolidone (NVP) reveal that PVC-X can be reinitiated and extended, further confirming the living nature of VC RAFT polymerization. PVC-b-PVAc diblock copolymer is successfully synthesized by the chain extension of PVC-X in RAFT miniemulsion polymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2092–2101

An amphiphilic copolymer poly(acrylic acid)-block-poly(styrene) (PAA-b-PS) with a trithiocarbonate reactive group was used in the ab initio reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of vinylidene chloride (VDC). The fast polymerization and high conversion were achieved. The parameters for a good control over the formation of well-defined PAA-b-PS-b-PVDC amphiphilic block copolymers and self-stabilized latexes were identified. To improve the emulsion stability and prevent the desorption of water-soluble initiating radicals, the acid groups of PAA-b-PS were neutralized by NaOH at the later stage of polymerization. The PAA-b-PS-b-PVDC block copolymer with a high molar mass of 30 kg mol⁻¹ and the stable latex with 30 wt % solid content was obtained. The kinetics of RAFT emulsion copolymerization of VDC in a living manner was first investigated. The as-prepared PAA-b-PS-b-PVDC latex particles were further used as seeds in the emulsion polymerization of styrene, enabling the preparation of novel PAA-b-PS-b-PVDC-b-PS tetra-block copolymers with a molar mass of 76 kg mol⁻¹ and a relatively low molecular weight distribution of 1.6. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40391.

Suspension-emulsion combined polymerization process, in which methyl methacrylate (MMA) emulsion polymerization constituents (EPC) were drop wise added to styrene (St) suspension polymerization system, was applied to prepare polystyrene/poly(methyl methacrylate) (PS/PMMA) composite particles. The influences of the feeding condition and the composition of EPC on the particle feature of the resulting composite polymer particles were investigated. It was found that PS/PMMA core-shell composite particles with a narrow particle size distribution and a great size would be formed when the EPC was added at the viscous energy dominated particle formation stage of St suspension polymerization with a suitable feeding rate, whereas St-MMA copolymer particles or PS/PMMA composite particles with imperfect core-shell structure would be formed when the EPC was added at the earlier or later stage of St suspension polymerization, respectively. It was also showed that the EPC composition affected the composite particles formation process. The individual latex particles would exist in the final product when the concentrations of MMA monomer, sodium dodecyl sulfate emulsifier, and potassium persulfate initiator were great in the EPC. Considering the feature of St suspension polymerization and the morphology of PS/PMMA composite particles, the formation mechanism of PS/PMMA particles with core-shell structure was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009