Thermomechanics of the shape memory effect in polymers for biomedical applications
Thermomechanics of the shape memory effect in polymers for biomedical applications
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DOI：
10.1002/jbm.a.30296
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发表时间：
2005-06-01
影响因子：
4.9
通讯作者：
Anseth, KS
中科院分区：
文献类型：
--
作者：
Gall, K;Yakacki, CM;Anseth, KS
我们研究了用于生物医学，特别是心血管应用的聚合物网络的形状记忆效应。该聚合物由丙烯酸叔丁酯单体与二乙二醇二丙烯酸酯交联剂通过光聚合合成。采用三点弯曲试验系统地研究了形状存储（预变形）和形状恢复的热力学特性。聚合物的玻璃化转变温度T-g测定为约65 ℃。聚合物在低和高预变形温度下显示出100%的应变恢复，最大应变高达~ 80%。聚合物显示出S形的自由应变恢复响应作为在恒定加热速率下增加温度的函数。自由应变恢复取决于预变形过程中的温度;较低的预变形温度（T < T-g）降低了自由应变恢复所需的温度。在预变形过程中，约束应力恢复随温度的变化呈现出复杂的演化过程，并依赖于温度。低温预变形（T < T-g）后的应力恢复在所产生的恢复应力中显示出峰值，而高温预变形（T > T-g）后的应力恢复为S形。等温自由应变回复率随温度的升高或预变形温度的降低而增大。热机械的结果进行了讨论，在潜在的生物医学应用，并提出了一个原型装置。(c)2005年威利期刊有限公司。
We examine the shape memory effect in polymer networks intended for biomedical, and specifically cardiovascular, applications. The polymers were synthesized by photopolymerization from a tert-butyl acrylate monomer with a diethyleneglycol diacrylate crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape storage (predeformation) and shape recovery. The glass transition temperature, T-g, of the polymers was determined to be approximately 65 degrees C. The polymers show 100% strain recovery, at low and high predeformation temperatures, up to maximum strains of -80%. The polymers show a sigmoidal free strain recovery response as a function of increasing temperature at a constant heating rate. Free strain recovery was determined to depend on the temperature during predeformation; lower predeformation temperatures (T < T-g) decreased the temperature required for free strain recovery. Constrained stress recovery shows a complex evolution as a function of temperature and also depends on the temperature during predeformation. Stress recovery after low-temperature predeformation (T < T-g) shows a peak in the generated recovery stress, whereas, stress recovery after high-temperature predeformation (T > T-g) is sigmoidal. The isothermal free strain recovery rate was found to increase with increasing temperature or decreasing predeformation temperature. The thermomechanical results are discussed in light of potential biomedical applications, and a prototype device is presented. (c) 2005 Wiley Periodicals, lnc.