Gupta Arvind, Kim Beom Soo
Department of Chemical Engineering, Chungbuk National University, Cheongju, Chungbuk 28644, Korea.
Nanomaterials (Basel). 2019 Feb 7;9(2):225. doi: 10.3390/nano9020225.
The distinctive ability to remember their original form after partial or complete deformation makes shape memory polymers remarkable materials for several engineering and biomedical applications. In the present work, the development of a polycaprolactone based toughened shape memory polyurethane biocomposite promoted by in situ incorporation of chitosan flakes has been demonstrated. The chitosan flakes were homogeneously present in the polymer matrix in the form of nanoflakes, as confirmed by the electron microscopic analysis and probably developed a crosslinked node that promoted toughness ( > 500% elongation at break) and led to ~130% increment in ultimate tensile strength, as analyzed using a universal testing machine. During a tensile pull, X-ray analysis revealed the development of crystallites, which resulted from a stress induced crystallization process that may retain the shape and melting of the crystallites stimulating shape recovery (with ~100% shape recovery ratio), even after permanent deformation. The biodegradable polyurethane biocomposite also demonstrates relatively high thermal stability ( at ~360 ). The prepared material possesses a unique shape memory behavior, even after permanent deformation up to > 500% strain, which may have great potential in several biomedical applications.
在部分或完全变形后仍能记住其原始形状的独特能力，使形状记忆聚合物成为多种工程和生物医学应用中的非凡材料。在目前的工作中，已经证明了通过原位掺入壳聚糖薄片来开发基于聚己内酯的增韧形状记忆聚氨酯生物复合材料。电子显微镜分析证实，壳聚糖薄片以纳米薄片的形式均匀地存在于聚合物基体中，并且可能形成了促进韧性（断裂伸长率>500%）的交联节点，并导致极限拉伸强度增加约130%，这是使用万能试验机分析得出的结果。在拉伸过程中，X射线分析显示出微晶的形成，这是由应力诱导结晶过程导致的，即使在永久变形后，微晶的形状和熔化也可能保留，从而刺激形状恢复（形状恢复率约为100%）。这种可生物降解的聚氨酯生物复合材料还表现出相对较高的热稳定性（约360时）。即使在高达>500%应变的永久变形后，所制备的材料仍具有独特的形状记忆行为，这在多种生物医学应用中可能具有巨大潜力。
