UCST还是LCST？聚（<i>N-</i>丙烯酰基甘氨酰胺-<i>共-二</i>丙酮丙烯酰胺）的成分依赖性热响应行为,Macromolecules

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UCST还是LCST？聚（N-丙烯酰基甘氨酰胺-共-二丙酮丙烯酰胺）的成分依赖性热响应行为
Macromolecules ( IF 5.1 ) Pub Date : 2017-03-02 00:00:00 , DOI: 10.1021/acs.macromol.7b00020
Wenhui Sun ₁ , Zesheng An ₂ , Peiyi Wu ₁

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共聚已被广泛用于调节水溶性聚合物的热响应行为。但是，尚未报道从仅包含一种均聚物为热敏单体而另一种均聚物为非热敏单体的相同类型共聚物观察到的临界溶液温度的上限和下限（UCST和LCST）。在这项工作中，通过可逆的加成-断裂链转移（RAFT）聚合，使N-丙烯酰基甘氨酰胺（NAGA）和双丙酮丙烯酰胺（DAAM）共聚，合成了具有可调组成的定义明确的热响应性共聚物。使用比浊法，动态光散射（DLS），质子核磁共振（¹ H NMR）和傅里叶变换红外（FTIR）光谱。这些共聚物的溶解度显示出对组成的明显依赖性。虽然具有高达30 mol％的NAGA的共聚物基本上是不溶的，但具有35–55 mol％的NAGA或90–100 mol％的NAGA的共聚物分别具有LCST型或UCST型转变，而获得的可溶性共聚物的含量为60–85 mol％娜迦关于组成，聚合度，聚合物浓度，同位素效应和电解质的存在，LCST型和UCST型过渡是可调的。可变温度¹ H NMR和FTIR光谱学的见解揭示了NAGA和DAAM单元之间氢键在确定热转变中的关键作用。

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UCST or LCST? Composition-Dependent Thermoresponsive Behavior of Poly(N-acryloylglycinamide-co-diacetone acrylamide)

Copolymerization has been widely used to tune the thermoresponsive behavior of water-soluble polymers. However, the observation of both upper and lower critical solution temperature (UCST and LCST) from the same type of copolymer comprising only one monomer whose homopolymer is thermosensitive and the other monomer whose homopolymer is nonthermosensitive has not been reported. In this work, well-defined thermoresponsive copolymers with tunable compositions have been synthesized by copolymerization of N-acryloylglycinamide (NAGA) and diacetone acrylamide (DAAM) via reversible addition–fragmentation chain transfer (RAFT) polymerization. The thermal transitions of these copolymers are investigated using a combination of turbidimetry, dynamic light scattering (DLS), proton nuclear magnetic resonance (¹H NMR), and Fourier transform infrared (FTIR) spectroscopy. The solubility of these copolymers shows a distinct dependence on the composition. While copolymers with up to 30 mol % NAGA are essentially insoluble, copolymers with 35–55 mol % NAGA or 90–100 mol % NAGA have either LCST- or UCST-type transitions respectively, and soluble copolymers are obtained with 60–85 mol % NAGA. The LCST- and UCST-type transitions are tunable with respect to composition, degree of polymerization, polymer concentration, isotope effect and the presence of electrolyte. Insights from variable-temperature ¹H NMR and FTIR spectroscopies reveal the key role of hydrogen-bonding between the NAGA and DAAM units in determining the thermal transitions.

更新日期：2017-03-02

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