Effect of Synthesis Temperature on Size, Structure, and Volume Phase Transition of Polysaccharide Microgels
Effect of Synthesis Temperature on Size, Structure, and Volume Phase Transition of Polysaccharide Microgels
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DOI：
10.1021/acs.macromol.0c01605
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发表时间：
2020-11-10
期刊：
影响因子：
5.5
通讯作者：
Streletzky, Kiril A.
中科院分区：
文献类型：
--
作者：
Freeman, Krista G.;Adamczyk, Jacob;Streletzky, Kiril A.
高分子量的多糖微凝胶的合成温度范围高于聚合物的低临界溶解温度（LCST）（Δ T = 0.6-18.1摄氏度），和Δ T被发现强烈影响的结构，动力学，和体积相变温度的所得颗粒。静态和动态光散射研究和平均场理论分析的微凝胶以下和以上体积相变揭示了几个不同的制度。在小的Δ T下，合成了密度较低、体积较大且多分散性更高的微凝胶，其体积溶胀为10倍。在中间Δ T = 5-8 ℃下，形成的微凝胶在转变点以下是最小的、致密的和最单分散的，但在转变点以上仅表现出5倍的去溶胀。在高Δ T下的合成导致形成具有小密度、高度多分散性和在某些情况下未交联聚合物的表观存在的不均匀微凝胶。此外，随着Δ T的增加，体积相变温度显著下降。这项工作表明，合成温度可以用来调整的大小，去溶胀能力，和体积相变温度的聚合物微凝胶。
High-molecular-weight polysaccharide microgels were synthesized at a range of temperatures above the polymer lower critical solution temperature (LCST) (Delta T = 0.6-18.1 degrees C), and Delta T was found to strongly influence the structure, dynamics, and volume phase transition temperature of the resulting particles. Static and dynamic light scattering studies and mean field theory analysis of the microgels below and above volume phase transition revealed several distinct regimes. At small Delta T, lower density, larger, and more polydisperse microgels that deswell by a factor 10 in volume were synthesized. At intermediate Delta T = 5-8 degrees C, the formed microgels were the smallest, densest, and most monodisperse below the transition, but exhibited deswelling only by a factor of 5 above the transition. Synthesis at high Delta T led to the formation of nonuniform microgels with small density, a high degree of polydispersity, and in some cases the apparent presence of the un-cross-linked polymer. Furthermore, the volume phase transition temperature dropped significantly as Delta T increased. This work suggests that synthesis temperature can be used to tune the size, deswelling capacity, and volume phase transition temperature of the polymeric microgels.