Murali Sumi, Agirre Amaia, Tomovska Radmila
POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa, Tolosa hiribidea, 72, 20018, Donostia, Spain.
IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009, Bilbao, Spain.
Sci Rep. 2024 Dec 3;14(1):30030. doi: 10.1038/s41598-024-79774-5.
The anti-polyelectrolyte effect, a characteristic unique to polymer chains containing zwitterions, was investigated for its impact on colloidal stabilization during emulsion polymerization and on the resulting polymer characteristics. The zwitterionic monomer (ZM) 3-[(3-Acrylamidopropyl)dimethylammonio]propane-1-sulfonate (A3361) was selected for the synthesis of 30 wt% emulsifier-free methyl methacrylate/n-butyl acrylate (MMA/n-BA) polymer latex. Three pH conditions were examined: neutral, where the zwitterionic chains are in a collapsed state, and acidic and basic, where these chains adopt an extended conformation, leading to the anti-polyelectrolyte effect. The study of the anti-polyelectrolyte phenomenon on colloidal stability was challenging due to the increased ionic strength in the dispersions. Nevertheless, films cast from the acidic latex demonstrated enhanced mechanical properties, water resistance, and humidity barrier compared to films produced at neutral pH. This improvement is attributed to the anti-polyelectrolyte phenomenon, where the extended polymer chains rich in zwitterions offer enhanced ionic complexation, resulting in a denser and thicker ionic complexed network within the MMA/n-BA matrix. Under basic pH conditions, these improvements were modest, indicating that the anti-polyelectrolyte mechanism is influenced by pH. Furthermore, the high incorporation of A3361 facilitated, for the first time, the synthesis of 50% solids content emulsifier-free latexes, highlighting practical importance of this technology.
研究了两性离子聚合物链所特有的抗聚电解质效应，考察其在乳液聚合过程中对胶体稳定性以及所得聚合物特性的影响。选择两性离子单体（ZM）3-[(3-丙烯酰胺基丙基)二甲基铵]丙烷-1-磺酸盐（A3361）来合成30 wt%的无乳化剂甲基丙烯酸甲酯/丙烯酸正丁酯（MMA/n-BA）聚合物胶乳。考察了三种pH条件：中性条件下两性离子链处于塌陷状态，酸性和碱性条件下这些链呈伸展构象，从而产生抗聚电解质效应。由于分散体中离子强度增加，研究抗聚电解质现象对胶体稳定性的影响具有挑战性。然而，与在中性pH下制备的薄膜相比，由酸性胶乳流延而成的薄膜表现出增强的机械性能、耐水性和防潮性。这种改善归因于抗聚电解质现象，富含两性离子的伸展聚合物链提供了增强的离子络合作用，导致在MMA/n-BA基质中形成更致密、更厚的离子络合网络。在碱性pH条件下，这些改善并不显著，表明抗聚电解质机制受pH影响。此外，A3361的高掺入量首次促进了50%固含量无乳化剂胶乳的合成，突出了该技术的实际重要性。
