Xu Haikun, Budhlall Bridgette Maria
Department of Plastics Engineering and Nanomanufacturing Center, University of Massachusetts Lowell MA 01854 USA
RSC Adv. 2018 Aug 17;8(51):29283-29294. doi: 10.1039/c8ra06715e. eCollection 2018 Aug 14.
In this study, modified poly(ε-caprolactone) (PCL) tri-block copolymers were successfully synthesized through ring opening polymerization. The nanocomposite films containing either colloidal gold nanorods (AuNRs) or gold nanospheres (AuNSs) in the polymer matrix were fabricated without chemical modification to realize light-responsive shape memory behaviors. The localized surface plasmon resonance of AuNPs was utilized by irradiating the selective wavelength of light to create a photothermal effect. The polymer microstructures were investigated by NMR, and the thermal properties of the polymer networks were studied by TGA and DSC. The addition of AuNPs did not change the melting temperature, ( ) of the SMP. The AuNRs were fairly well dispersed within the PCL matrix as observed using SEM-EDAX analysis and as indicated from the uniform shape memory transitions of the SMP/AuNR nanocomposites. The shape memory behavior was quantitatively analyzed by cyclic thermomechanical tests using DMA. The laser-triggered shape memory properties of the nanocomposites were analyzed and the shape recovery process from a rectangular shaped film to a helical coil was demonstrated. The speed of SMP recovery was found to be dependent on the geometry and concentration of the AuNPs in the nanocomposite, as well as on the laser wavelength and intensity.
在本研究中，通过开环聚合成功合成了改性聚（ε-己内酯）（PCL）三嵌段共聚物。在聚合物基体中制备了包含胶体金纳米棒（AuNRs）或金纳米球（AuNSs）的纳米复合薄膜，无需化学改性即可实现光响应形状记忆行为。通过照射选择性波长的光利用金纳米颗粒的局域表面等离子体共振来产生光热效应。通过核磁共振（NMR）研究聚合物微观结构，并通过热重分析（TGA）和差示扫描量热法（DSC）研究聚合物网络的热性能。金纳米颗粒的加入并未改变形状记忆聚合物（SMP）的熔点。如扫描电子显微镜-能量散射X射线分析（SEM-EDAX）观察以及SMP/AuNR纳米复合材料均匀的形状记忆转变所示，AuNRs在PCL基体中分散良好。通过动态热机械分析（DMA）使用循环热机械测试对形状记忆行为进行了定量分析。分析了纳米复合材料的激光触发形状记忆性能，并展示了从矩形薄膜到螺旋线圈的形状恢复过程。发现SMP的恢复速度取决于纳米复合材料中金纳米颗粒的几何形状和浓度，以及激光波长和强度。
