Abstract

Microwave irradiation (MWI) is introduced as a novel trigger to aggregate CO₂-switchable latexes. The polystyrene (PS) latexes were synthesized through emulsion polymerization in two ways (using polar monomer 2-dimethylaminoethyl methacrylate (DMAEMA) (as in situ copolymerization), and a well-defined block copolymer, poly(dimethylaminoethyl methacrylate-block-methyl methacrylate), PDMAEMA-b-PMMA as positively charged stabilizing moieties in the presence of 4,4'-(diazene-1,2-diyl) bis(N-(3-(dimethylamino) propyl)-4-methylpentanamide) (DABPA) as an “inistab” (initiator + colloidal stabilizer). Since the polymerization was conducted in acidic media using hydrochloric acid (HCl) to protonate stabilizers, PS latexes could be simply destabilized by adding NaOH. The destabilized latexes were redispersed by introducing CO₂ plus sonication to yield CO₂-switchable latexes. The particle size of the resultant latexes after redispersion was very similar to that of primary latexes, as measured by dynamic light scattering. MWI and conventional heating (CH) stimuli were applied to aggregate the CO₂-switchable PS latex particles. The influence of different factors on the time required for aggregation and particle size changes of the synthesized latexes was studied. These two methods of destabilization of PS latexes produce completely different switching behavior. Findings revealed that microwave-assisted aggregation (MAA) relative to CH required less time, but an increase in particle size of the redispersed particles in comparison to the original latexes was observed. Therefore, MAA can be assumed as a promising trigger for the aggregation of CO₂-responsive latexes. This facile aggregation process, which could reduce time and energy input, might be of high interest and importance in various applications.

Graphical Abstract

中文翻译：

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使用阳离子稳定剂通过乳液聚合制备二氧化碳可转换聚苯乙烯胶乳的微波辅助聚集

摘要

微波辐射（MWI）被引入作为聚集CO ₂可转换乳胶的新触发因素。聚苯乙烯（PS）乳胶通过乳液聚合以两种方式合成（使用极性单体甲基丙烯酸2-二甲氨基乙酯（DMAEMA）（原位共聚）和明确的嵌段共聚物，聚（甲基丙烯酸二甲氨基乙酯-嵌段-甲基丙烯酸甲酯）） , PDMAEMA- b -PMMA 在 4,4'-(二氮烯-1,2-二基) 双( N- (3-(二甲氨基)丙基)-4-甲基戊酰胺) (DABPA)存在下作为带正电荷的稳定部分“inistab”（引发剂 + 胶体稳定剂）。由于聚合反应是在酸性介质中进行，使用盐酸 (HCl) 质子化稳定剂，因此可以通过添加 NaOH 来简单地使 PS 乳胶去稳定。通过引入 CO ₂加超声处理，使去稳定的乳胶重新分散。产生CO ₂ -可转换乳胶。通过动态光散射测量，再分散后所得乳胶的粒径与原始乳胶的粒径非常相似。MWI和常规加热（CH）刺激用于聚集CO ₂ -可转换乳胶PS乳胶颗粒。研究了不同因素对合成胶乳聚集所需时间和粒径变化的影响。这两种破坏 PS 乳胶稳定性的方法会产生完全不同的转换行为。研究结果表明，相对于 CH，微波辅助聚集 (MAA) 需要的时间更少，但与原始乳胶相比，再分散颗粒的粒径有所增加。因此，MAA可以被认为是CO ₂响应性乳胶聚集的有希望的触发剂。这种简便的聚合过程可以减少时间和能量输入，在各种应用中可能会引起人们的高度兴趣和重要性。

图形概要