In-situ thermoreversible gelation of block and star copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) of varying architectures
In-situ thermoreversible gelation of block and star copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) of varying architectures
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DOI：
10.1021/ma001852m
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发表时间：
2001-05-22
期刊：
影响因子：
5.5
通讯作者：
Cheng, YL
中科院分区：
文献类型：
--
作者：
Lin, HH;Cheng, YL
我们报道了一种新的凝胶化机制和一种新的聚合物家族的发展，这种聚合物家族以热可逆的方式自组装形成凝胶。该聚合物是具有中心亲水性聚（乙二醇）（PEG）链段（A）和温度响应性聚（N-异丙基丙烯酰胺）（PNIPAAm）末端链段（B）的嵌段或星星共聚物。合成了AB、A（B）（2）、A（B）（4）和A（B）（8）等不同结构的共聚物，研究了结构与性能的关系。在5 ° C下，20重量%溶液的粘度在700和950 cP之间，并且它们可以容易地通过25 G针头注射。当升温至体温时，A（B）（2）、A（B）（4）和A（B）（8）形成强缔合网络凝胶，PNIPAAm链段的聚集体充当物理交联，而AB通过胶束堆积和缠结形成较弱的凝胶。弹性模量、损耗角正切和屈服强度的值分别为1000-2500 Pa、0.24-0.62和200-860 Pa。凝胶化动力学是快速的;对于体积为5 mt的溶液，典型的凝胶化时间小于一分钟。在37 ℃下2个月后没有观察到显著的脱水收缩。DSC结果表明，材料的热行为在30次冷热循环后仍是完全可逆的。这些材料是有前途的候选人原位凝胶化应用，如注射药物输送，组织工程支架，解剖屏障。
We report the development of a new gelation mechanism and a new family of polymers that self-assembles to form gels in a thermoreversible fashion. The polymers are block or star copolymers with a central hydrophilic poly(ethylene glycol) (PEG) segment (A) and temperature responsive poly(N-isopropylacrylamide) (PNIPAAm) terminal segments (B). Copolymers of various architectures, AB, A(B)(2), A(B)(4), and A(B)(8), were synthesized to investigate the structures and properties relationship. At 5 degreesC, the viscosities of 20 wt % solutions were between 700 and 950 cP, and they could be easily injected through a 25 G needle. Upon warming to body temperature, A(B)(2), A(B)(4), and A(B)(8) formed a strong associative network gel with aggregates of PNIPAAm segments acting as physical cross-links, whereas AB formed a weaker gel by micellar packing and entanglement. The values of elastic modulus, loss tangent, and yield strength were 1000-2500 Pa, 0.24-0.62, and 200-860 Pa, respectively. The gelation kinetic was fast; a typical gelation time for a solution of 5 mt in volume was less than a minute. No significant syneresis was observed after 2 months at 37 degreesC. DSC results indicated that the thermal behavior of material was completely reversible even after 30 heat-and-cool cycles. These materials are promising candidates for in-situ gelation applications such as injectable drug delivery, tissue engineering scaffolds, and anatomical barriers.