Well-defined temperature-responsive cellulose acetate (CA) grafted with a temperature-responsive polymer (TRP) was synthesized using a grafting-to approach. The TRP obtained by reversible addition–fragmentation chain transfer polymerization (RAFT), with M_n = 17 700 and dispersity Đ = 1.10, is a random copolymer of di(ethylene glycol) methyl ether methacrylate (MEO₂MA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA), containing terminal azide groups introduced by addition of an azide-modified methacrylate monomer in the final stage of the polymerization. For the comonomer ratio used, the volume phase transition temperature of the TRP is T_VPT = 33 °C. After modification of CA with propargyl groups using the remaining hydroxyl groups of the glucopyranose rings, the TRP was grafted to the CA by an azide-propargyl click reaction. The CA-g-TRP copolymer was then used to prepare fibers by electrospinning, for application as temperature-responsive scaffolds in cell culture. The fibers were found to change their average diameter from 2.0 ± 0.4 μm to 1.3 ± 0.3 μm upon heating in water, above the T_VPT, and subsequently drying. When cooled in water below the T_VPT, the average diameter increases to 1.8 ± 0.3 μm. Experiments in thin films of the same copolymer show that the change in temperature does not translate into a significative change in the hydrophobic character, possibly due to a conformation rearrangement of the copolymer chains.

中文翻译：

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纤维素共聚物的温度响应纤维†

使用接枝方法合成了定义良好的温度响应型醋酸纤维素（CA），接枝了温度响应型聚合物（TRP）。通过可逆加成-断裂链转移聚合（RAFT）获得的TRP，M _n = 17 700，分散度Đ = 1.10，是二（乙二醇）甲基醚甲基丙烯酸甲酯（MEO ₂ MA）和低聚（乙二醇）的无规共聚物）甲基丙烯酸甲酯甲基醚（OEGMA），其包含在聚合反应的最后阶段通过添加叠氮化物改性的甲基丙烯酸酯单体而引入的末端叠氮化物基团。对于所用的共聚单体比率，TRP的体积相变温度为T _VPT= 33°C。在使用吡喃葡萄糖环的剩余羟基对炔丙基进行CA修饰后，通过叠氮-炔丙基点击反应将TRP接枝到CA。然后将CA- g- TRP共聚物用于通过电纺制备纤维，以用作温度敏感的支架在细胞培养中。发现在水中加热至高于T _VPT并随后干燥后，纤维的平均直径从2.0±0.4μm更改为1.3±0.3μm 。在低于T _VPT的水中冷却时，平均直径增加到1.8±0.3μm。在相同共聚物的薄膜中进行的实验表明，温度的变化不会转化为疏水性的显着变化，这可能是由于共聚物链的构象重排所致。