Lu Jianlei, Xu Mengdi, Lei Yi, Gong Lihao, Zhao Chuanzhuang
Ningbo Key Laboratory of Specialty Polymers, Faculty of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang, 315211, China.
Macromol Rapid Commun. 2021 Apr;42(7):e2000661. doi: 10.1002/marc.202000661. Epub 2021 Jan 22.
The synthesis of thermo-responsive polymers from non-responsive and water-soluble monomers has great practical advantages but significant challenges. Herein, the authors report a novel aqueous copolymerization strategy to prepare polymers with tunable upper critical solution temperature (UCST) or lower critical solution temperature (LCST) from non-responsive monomers. Acrylic acid (AAc), N-vinylpyrrolidone (NVP), and acrylamide (AAm) are copolymerized in water, yielding copolymers with UCST behavior. Interestingly, by simply replacing AAm with its methylated homologue, dimethyl acrylamide (DMA), the thermo-responsiveness of the copolymers is converted into LCST-type. The cloud points of the copolymers can be tuned rationally with their monomer ratios and the condition of the solvent. The UCST property of the poly(AAc-NVP-AAm) comes from the AAc-AAm and AAc-NVP hydrogen-bonds, while the LCST property of poly(AAc-NVP-DMA) originates from the hydrophobic aggregation of AAc-NVP complex and DMA, as indicated by temperature-dependent H NMR and dynamic light scattering.
由无响应的水溶性单体合成热响应性聚合物具有很大的实际优势，但也面临重大挑战。在此，作者报道了一种新型的水溶液共聚策略，用于从无响应单体制备具有可调上临界溶液温度（UCST）或下临界溶液温度（LCST）的聚合物。丙烯酸（AAc）、N-乙烯基吡咯烷酮（NVP）和丙烯酰胺（AAm）在水中共聚，得到具有UCST行为的共聚物。有趣的是，通过简单地用其甲基化同系物二甲基丙烯酰胺（DMA）取代AAm，共聚物的热响应性转变为LCST型。共聚物的浊点可以通过其单体比例和溶剂条件进行合理调节。聚（AAc-NVP-AAm）的UCST性质来自于AAc-AAm和AAc-NVP氢键，而聚（AAc-NVP-DMA）的LCST性质则源于AAc-NVP络合物和DMA的疏水聚集，这由温度依赖的1H NMR和动态光散射表明。
