Stabilizer‐Free Dispersion Copolymerization of Maleic Anhydride and Vinyl Acetate. II. Polymerization Features

Abstract

Summary: The polymerization features of the novel stabilizer‐free dispersion copolymerization of MAn and VAc were studied. It was found that the dispersion copolymerization of MAn/VAc is a fairly rapid process, which starts from a slow solution polymerization (below 10% conversion, Stage I) and follows a drastic increase of polymerization rate (10–80% conversion, Stage II) due to the known gel effect. Such process was accompanied by the increase of molecular weight of the copolymer formed ($\overline M _{\rm n}$ from 1.2 × 104 to 3.8 × 104 g · mol−1) and the broadening of the molecular weight distribution ($\overline M _{\rm w} /\overline M _{\rm n}$ from 2.4 to 8.0). Ea of Stage I was determined to be 76.7 kJ · mol−1, while the value of Stage II was 64.7 kJ · mol−1. The lower Ea in Stage II than that in Stage I suggests that there exists a shift of polymerization locus from the solution phase to the particle phase. Moreover, we found that the initial rate of polymerization increased with monomer concentration as well as initiator concentration, following the relationship (Rp)i ∝ [MAn + VAc] · [BPO]. This further implies that the dispersion copolymerization mainly proceeds as a solution polymerization in the very early stage.Evolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.magnified imageEvolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.

Dispersion polymerization of styrene employing lyophilic comonomer in the absence of stabilizer: Synthesis of impurity-free microspheres

“…In other words, the change of those steps means the change of the polymerization loci, namely the continuous and polymer phases. 11 The lines in Figure 2 are achieved by curve-fitting the experimental data using a commercial software (SigmaPlot ® ). As shown in Figure 2, the P(St-co-4VP) microspheres continuously grow with the polymerization time, then become mature after 6 h of polymerization.…”

“…The steric stabilizer brings out environmental pollution, cost increase of the product, change in the ultimate properties of polymer particles, and migration of stabilizer molecules. 10 Therefore, Xing et al 10,11 recently reported a dispersion copolymerization for the preparation of surface-clean polymer particles without any stabilizer or other additives. They performed the novel stabilizer-free dispersion polymerization with maleic anhydride and vinyl acetate in alkyl esters as the reaction medium.…”

Dual‐Functionalized Hollow Polymer Particle as a pH‐Responsive Adsorbent for Selective Removal of Basic Dye

“…The preparation of PMS particles was similar to that of poly(maleic anhydride-alt-vinyl acetate) particles. [40,41] In a typical experiment, the monomers MAH (2.45 g, 25 mmol) and St (1.30 g, 12.5 mmol), the initiator AIBN (0.0375 g, 1 wt% of the monomers), the sol-vent isopentyl acetate (25 mL) and n-heptane (12.5 mL) were charged into a three-necked flask. After all the reagents were dissolved, the solution was purged with N 2 for 20 min.…”

Preparation of core–shell particles by surface-initiated cycloketyl radical mediated living polymerization

“…[48][49][50] This method requires no addition of any stabilizer and produces well-defined particles with their sizes being readily controllable by varying polymerization time and formulations. They were prepared by the self-stable precipitation polymerization developed in our lab.…”