Stabilizer‐free dispersion copolymerization of maleic anhydride and vinyl acetate. I. Effects of principal factors on microspheres

Abstract

A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer‐free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT‐IR and 13C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge‐transfer‐complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n‐butyl acetate, isobutyl acetate, n‐amyl acetate, are desirably fit for this unique stabilizer‐free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760–3770, 2005

Preparation of Styrene–Maleic Anhydride Random Copolymer by Stabilizer-Free Dispersion Polymerization

“…Therefore, it is of practical value to develop a new, easy-to-control and environmentalfriendly productive technology. Recently, we reported a novel and facile method to prepare micro/nano-particles of alternating copolymers of MAH and vinyl acetate (16). These particles can be easily prepared in n-butyl acetate/n-heptane without use of any stabilizer or surfactant.…”

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

“…[9,12,15] This may be attributed to the facile alternating copolymerization of MAn and VAc by a charge transfer complex (CTC) mechanism, as has been discussed in detail in our previous articles. [19,20] However, we found that the ultimate conversion of monomer was hard to be completed (around 80-90%). This can be interpreted from the phenomenon of phase separation in the dispersion polymerization process, which may lead to the ratio imbalance of MAn and VAc (i.e., beyond 1:1).…”

“…[19,20] In comparison, the solution copolymerization of MAn and VAc in methyl propyl ketone was also conducted (with the standard recipe in Table 1, except that the solvent was replaced).…”

“…[12][13][14][15][16][17][18] Recently, we have reported a novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc), which readily yields monodisperse copolymer microspheres in the absence of stabilizer. [19,20] The effects of some principal factors on the morphology of polymer microspheres have been described. This paper will mainly focus on the polymerization features of the unique stabilizer-free dispersion copolymerization of MAn and VAc.…”

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

“…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.…”