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首页> 外文期刊>Polymers >Synthesis of Stimuli-responsive, Water-soluble Poly[2-(dimethylamino)ethyl methacrylate/styrene] Statistical Copolymers by Nitroxide Mediated Polymerization
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Synthesis of Stimuli-responsive, Water-soluble Poly[2-(dimethylamino)ethyl methacrylate/styrene] Statistical Copolymers by Nitroxide Mediated Polymerization

机译：一氧化氮介导的聚合反应合成刺激性的水溶性聚[2-（二甲基氨基）乙基甲基丙烯酸乙酯/苯乙烯]统计共聚物

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2-Dimethylamino)ethyl methacrylate/styrene statistical copolymers (poly(DMAEMA-stat-styrene)) with feed compositions fDMAEMA = 80–95 mol%, (number average molecular weights Mn = 9.5–11.2 kg mol−1) were synthesized using succinimidyl ester-functionalized BlocBuilder alkoxyamine initiator at 80 °C in bulk. Polymerization rate increased three-fold on increasing fDMAEMA = 80 to 95 mol%. Linear Mn increases with conversion were observed up to about 50% conversion and obtained copolymers possessed monomodal, relatively narrow molecular weight distributions (polydispersity = 1.32–1.59). Copolymers with fDMAEMA = 80 and 90 mol% were also cleanly chain-extended with DMAEMA/styrene mixtures of 95 and 90 mol% DMAEMA, respectively, confirming the livingness of the copolymers. Copolymer phase behavior in aqueous solutions was examined by dynamic light scattering and UV-Vis spectroscopy. All copolymers exhibited lower critical solution temperature (LCST)-type behavior. LCST decreased with increasing styrene content in the copolymer and with increasing solution concentration. All copolymers were completely water-soluble and temperature insensitive at pH 4 but were more hydrophobic at pH 10, particularly copolymers with fDMAEMA = 80 and 85 mol%, which were water-insoluble. At pH 10, LCST of copolymers with fDMAEMA = 90 and 95 mol% were more than 10 °C lower compared to their solutions in neutral, de-ionized water. Block copolymers with two statistical blocks with different DMAEMA compositions exhibited a single LCST, suggesting the block segments were not distinct enough to exhibit separate LCSTs in water.
机译：进料组成为f DMAEMA = 80-95 mol％，（数均分子量M n < / sub> = 9.5-11.2 kg mol -1 ）是在80°C下使用琥珀酰亚胺基酯官能化的BlocBuilder烷氧基胺引发剂合成的。随着f DMAEMA = 80至95 mol％的增加，聚合速率增加了三倍。观察到线性转化率随转化率的增加而线性增加，直至达到约50％的转化率，所获得的共聚物具有单峰，相对窄的分子量分布（多分散度= 1.32–1.59）。 f DMAEMA = 80和90 mol％的共聚物也分别与95和90 mol％DMAEMA的DMAEMA /苯乙烯混合物进行了干净的扩链，确认了共聚物的活性。通过动态光散射和UV-Vis光谱检查水溶液中的共聚物相行为。所有共聚物均表现出较低的临界溶液温度（LCST）型行为。 LCST随着共聚物中苯乙烯含量的增加和溶液浓度的增加而降低。所有共聚物在pH 4时完全是水溶性的，并且对温度不敏感，但在pH 10时更疏水，特别是f DMAEMA = 80和85 mol％的共聚物是不溶于水的。在pH 10时，与f DMAEMA = 90和95 mol％的共聚物的LCST相比，它们在中性去离子水中的溶液要低10°C以上。具有两个具有不同DMAEMA组成的统计嵌段的嵌段共聚物表现出单一的LCST，这表明嵌段的截然不同，不足以显示出水中的单独LCST。

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