Effect of Polystyrene Synthesis Method on Water Sorption and Glass Transition.
Effect of Polystyrene Synthesis Method on Water Sorption and Glass Transition.
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DOI：
10.3390/membranes12111059
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发表时间：
2022-10-28
期刊：
影响因子：
4.2
通讯作者：
中科院分区：
文献类型：
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作者：
商品PS通过自由基聚合合成，而嵌段共聚物（BCP）中的PS通常通过活性阴离子聚合合成。这项工作的目的是研究合成方法如何影响重要的性能，如吸水性和玻璃化转变温度（Tg）。水吸附是重要的，因为已知纳米结构聚合物膜在各种应用中的性能受环境条件如湿度的影响。Tg很重要，因为它决定了商品PS以及BCP如热塑性弹性体的加工条件。在商业PS中的吸水被发现是0.5 mgwater/gpolymer在最高湿度调查（约80%），与文献一致。另一方面，在低温下阴离子合成的间同立构PS吸收更多的水，高达1.5 mgwater/g聚合物，由于更高的自由体积。对吸水性的最大影响是由于在无规PS中加入亲水性羟基链端，这导致吸水性高达2.3 mgwater/gpolymer。除了分别测量吸水性和干燥Tg之外，还检查了相对湿度对PS Tg的影响。结合差示扫描量热法和动态力学分析表明，从干燥状态到高湿状态，PS的Tg降低了5 °C。此外，PS的拉伸储能模量从0% RH下的1.58 GPa降低到40% RH下的0.53 GPa。除了本研究的实际相关性，本报告填补了实验文献中的空白，使用不良溶剂系统，PS/水，检查纯聚合物的塑化限制。
Commodity PS is synthesized via free radical polymerization, whereas PS in block copolymers (BCPs) is typically synthesized via living anionic polymerization. The purpose of this work is to investigate how the synthesis method impacts important properties such as water sorption and glass transition temperature (Tg). Water sorption is important because the performance of nanostructured polymer membranes in various applications is known to be affected by environmental conditions such as humidity. Tg is important because it dictates processing conditions, both for commodity PS as well as BCPs such as thermoplastic elastomers. Water sorption in commercial PS was found to be 0.5 mgwater/gpolymer at the highest humidities investigated (about 80%), in agreement with literature. On the other hand, syndiotactic PS synthesized anionically at low temperature absorbed more water, up to 1.5 mgwater/gpolymer, due to higher free volume. The greatest impact on water sorption was due to addition of hydrophilic hydroxyl chain ends to atactic PS, which resulted in water sorption of up to 2.3 mgwater/gpolymer. In addition to measuring water sorption and dry Tg separately, the impact of relative humidity on PS Tg was examined. Combined differential scanning calorimetry and dynamic mechanical analysis show that on going from the dry state to high humidity, the Tg of PS decreases by 5 °C. Moreover, the tensile storage modulus of PS decreases from 1.58 GPa at 0% RH to 0.53 GPa at 40% RH. In addition to the practical relevance of this study, this report fills a gap in experimental literature by using a poor solvent system, PS/water, to examine plasticization in the pure polymer limit.
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影响因子：
3.2
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
DAY, AG