In this work, caffeine was used as a natural additive in the emulsion polymerization of methyl methacrylate with cetyltrimethylammonium bromide (CTAB) or sodium dodecyl sulfate (SDS). Mean particle size and ζ-potential of the particles, glass transition temperature, and molecular weight of polymer chains were not affected by caffeine. However, caffeine improved considerably the colloidal stability of polymer dispersions at ionic strength of 1.0 mol L −1 NaCl. Fourier transform infrared vibrational spectra in the attenuated total reflectance mode (FTIR-ATR) of PMMA synthesized with CTAB or SDS in the presence of caffeine showed shifts of caffeine bands assigned to isolated and conjugated carbonyl groups to higher wavenumbers, indicating favorable interactions. Density functional theory (DFT) calculations revealed interactions between the negatively charged sulfate and the caffeine imidazole ring and between positively charged ammonium group and the isolated carbonyl of the caffeine. Such interactions are responsible for the improved colloidal stability of polymer dispersions synthesized with caffeine. Cell viability assays showed that adding caffeine at 26 × 10 −3 mol L −1 in the polymerization reaction is enough to prevent C. albicans growth in waterborne polymer dispersions.

中文翻译：

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咖啡因合成的水性聚合物纳米粒子的理化和抗真菌性能

在这项工作中，咖啡因被用作甲基丙烯酸甲酯与十六烷基三甲基溴化铵 (CTAB) 或十二烷基硫酸钠 (SDS) 的乳液聚合中的天然添加剂。颗粒的平均粒径和 ζ 电位、玻璃化转变温度和聚合物链的分子量不受咖啡因的影响。然而，在离子强度为 1.0 mol L -1 NaCl 时，咖啡因显着提高了聚合物分散体的胶体稳定性。在咖啡因存在下用 CTAB 或 SDS 合成的 PMMA 的衰减全反射模式 (FTIR-ATR) 中的傅立叶变换红外振动光谱显示分配给孤立和共轭羰基的咖啡因谱带向更高波数移动，表明有利的相互作用。密度泛函理论 (DFT) 计算揭示了带负电荷的硫酸盐与咖啡因咪唑环之间以及带正电荷的铵基与咖啡因的分离羰基之间的相互作用。这种相互作用是提高用咖啡因合成的聚合物分散体胶体稳定性的原因。细胞活力测定表明，在聚合反应中加入 26 × 10 -3 mol L -1 的咖啡因足以防止白色念珠菌在水性聚合物分散体中生长。