Interfacial Energy Promotes Radical Heterophase Polymerization

Abstract

Experimental evidence is presented that during the conditions of aqueous heterophase polymerization radical generation and subsequent polymerization are induced by the interfacial energy. A comprehensive study of the emulsion polymerization of styrene at 25 °C with various types of emulsifiers and with different nonredox initiators such as potassium peroxodisulfate, 2,2′-azoisobutyronitrile, dibenzoyl peroxide, and poly(ethylene glycol)-azo-initiator reveals that the particular initiator-stabilizer combination has a strong influence on the achievable final conversion and the latex properties. The deceleration of the polymerization due to the low temperature allowed the recognition of basic differences in the behavior of monomer-and water-soluble initiators, especially at low conversions during the prenucleation period.

Room-temperature decomposition of 2,2′-azobis(isobutyronitrile) in emulsion gels with and without silica

“…At higher temperatures (e.g., 50 • C), aqueous solutions of surfactant micelles increased the rate of decomposition of potassium disulfate [21]. Enhanced room temperature polymerization of styrene has also been reported for other initiators in the presence of surfactants [22]. The AIBN molecule, with its polar and nonpolar moieties, might be expected to partition itself at the interface between the oil and water portions of the emulsion gels.…”

Low-temperature polymerization of methyl methacrylate emulsion gels through surfactant catalysis

“…Surfactant-catalyzed polymerizations at low temperatures were achieved by enhanced decomposition of AIBN when complexed with CTAB in emulsions. Consequently, the temperatures needed for AIBN decomposition are significantly lowered, even as low as room temperature [11,12]. The gelation in the emulsions caused by adding fumed silica particles could further enhance the decomposition for AIBN, but fumed silica alone did not affect the initiator decomposition [11].…”

“…Tauer and Oz have shown that a few different thermal initiators, including water and oil soluble species, decomposed at room temperature with assistance of surfactants [12]. Kinetics data from the cationic surfactant, cetyltrimethylammonium bromide (CTAB) and AIBN system suggested that the AIBN and CTAB formed a complex [10], which accelerates the decomposition of AIBN.…”

An Advanced Approach on the Study of Emulsion Polymerization: Effect of the Initial Dispersion State of the System on the Reaction Mechanism, Polymerization Rate, and Size Distribution of Polymer-Monomer Particles

“…A further development of the mechanism of nucleation of aggregate particles is reflected in the publications of Tauer, Kuhn et al [52][53][54][55][56][57]66]. This theory is indeed a combination of ideas proposed by Fitch et al [39][40][41] and Oganesyan [51] with the difference that the authors consider the surface energy of the particles as an adjustable parameter of the model.…”

“…Later on, these ideas found their development in the investigations of Priest [35], Roe [36], Fitch and Tsai [39,40], Yeliseyeva [37,38], Christiansen [44], Ugelstad [27], Pepard [45] Wilkinson [46][47][48], Oganesyan [49][50][51], Tauer [52][53][54][55][56][57], etc.…”