Preparation of high molecular weight poly(vinyl alcohol) with high yield by emulsion polymerization of vinyl acetate using 2,2′-azobis(2-amidinopropane) dihydrochloride

• Published in: Journal of applied polymer science Vol. 94; no. 6; pp. 2356 - 2362
• Main Authors: Lyoo, Won Seok, Kwak, Jin Woo, Choi, Kyu Ha, Noh, Seok Kyun
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.12.2004; Wiley
• Subjects: AAPH; Applied sciences; emulsion polymerization; Exact sciences and technology; HMW PVA; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; PVAc; VAc; AAPH; Potassium Peroxodisulfates; Experimental study; Property processing relationship; PVAc; Latex; Optimization; Saponification; Polyvinylalcohol; Azo compound; Radical catalyst; Chemical modification; Free radical polymerization; HMW PVA; Vinyl acetate polymer; Emulsion polymerization; VAc; Kinetics; Molecular mass
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.20731

To prepare high molecular weight (HMW) poly(vinyl acetate) (PVAc) with high yield and high linearity as a precursor of HMW poly(vinyl alcohol) (PVA), vinyl acetate (VAc) was emulsion polymerized using, azo initiator, 2,2′‐azobis(2‐amidinopropane) dihydrochloride (AAPH). This was compared with the polymerization using potassium peroxodisulfate (KPS) as an initiator at various polymerization conditions. PVA, having a maximum number average degree of polymerization (Pn) of 3500 was obtained by the saponification of PVAc with Pn of 13,000–14,000, degree of branching (DB) for the acetyl group of about 3.4–3.5, and a maximum conversion of VAc into PVAc of 95%, which was polymerized by AAPH. These numerical values were superior compared with 14,500–15,000 of Pn of PVAc, obtained by KPS, and 3100 of maximum Pn of resulting PVA, DB of about 3.7–3.8, and maximum conversion of 90%. From the foregoing experimental results, we found that AAPH was a more efficient initiator than KPS in increasing both conversion of PVAc and molecular weight of PVA. In addition, PVAc microspheres, obtained by these emulsion polymerizations, can be converted to PVA / PVAc shell / core microspheres through a series of surface‐saponifications, maintaining their spherical morphology. Various surface morphologies, such as flat or wrinkled and swellable or nonswellable ones formed by the various molecular parameters and saponification conditions, were examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2356–2362, 2004