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首页> 外文期刊>Polymers for advanced technologies >Synthesis of poly(cystine bisamide)-PEG block copolymers grafted with 1-(3-aminopropyl)imidazole and their phase transition behaviors
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Synthesis of poly(cystine bisamide)-PEG block copolymers grafted with 1-(3-aminopropyl)imidazole and their phase transition behaviors

机译：1-（3-氨基丙基）咪唑接枝的聚（胱氨酸双酰胺）-PEG嵌段共聚物的合成及其相变行为

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摘要

New biodegradable and pH-sensitive block copolymers were prepared by grafting 1-(3-aminopropyl) imidazole onto a backbone polymer formed via condensation polymerization between L-cystine and EDTA-dianhydride. The copolymer with a graft ratio of 79% exhibited a good buffering capacity and pH sensitivity. These are attributed to protonation-deprotonation of the imidazole ring at around pH 7. The copolymers with less imidazole content did not show any apparent responses to changes in pH. The particle size of the copolymer aggregate formed under basic conditions was around 200 nm and increased with decreasing pH. The critical aggregation values at pH 6.0 and 8.0, derived from the changes of intensity ratios (I{sub}1/I{sub}3) in the emission spectrums of pyrene, were approximately 0.17 and 0.05 mg/ml, respectively. The surface charge of the aggregates increased with the decreasing pH as a result of the increase in protonation of imidazole and the tertiary amine in the polymer chain. The microviscosity of hydrophobic domains was estimated using 1,6-diphenyl-1,3,5-hexatriene. The decrease of the anisotropy value under acidic conditions reflects a disruption of hydrophobic interaction.
机译：通过将1-（3-氨基丙基）咪唑接枝到通过L-胱氨酸和EDTA-二酐之间的缩聚反应形成的主链聚合物上，制备了新型的可生物降解的，对pH敏感的嵌段共聚物。接枝率为79％的共聚物表现出良好的缓冲能力和pH敏感性。这些归因于在pH 7附近咪唑环的质子化-去质子化。具有较少咪唑含量的共聚物没有显示出对pH变化的任何明显响应。在碱性条件下形成的共聚物聚集体的粒径约为200 nm，并且随着pH值的降低而增加。由6.0发射光谱的强度比（I {sub} 1 / I {sub} 3）的变化得出的pH 6.0和8.0的临界聚集值分别约为0.17和0.05 mg / ml。由于咪唑和聚合物链中叔胺质子化的增加，聚集体的表面电荷随pH值的降低而增加。使用1，6-二苯基-1,3,5-己三烯估计疏水域的微粘度。酸性条件下各向异性值的降低反映了疏水相互作用的破坏。

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