Block Copolymer Elastomers for Stretchable Electronics.
Block Copolymer Elastomers for Stretchable Electronics.
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DOI：
10.1021/acs.accounts.8b00488
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发表时间：
2019-01
影响因子：
18.3
通讯作者：
Insang You;Minsik Kong;Unyong Jeong
中科院分区：
文献类型：
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作者：
Insang You;Minsik Kong;Unyong Jeong
随着医疗传感器、电子皮肤和柔性/可拉伸显示器的工业需求增加，对可拉伸材料的兴趣也在增加。近年来，对可拉伸材料的研究已经扩展到各种枢轴部件，例如电极、电路、衬底、半导体、介电层、膜和活性纳米复合膜。嵌段共聚物（BC）弹性体在可拉伸材料的发展中起着相当大的作用。由于BC是基于物理交联的软弹性体，因此它们显示出与用化学交联形成的正常弹性体的物理性质的差异。BC弹性体不需要额外的化学交联过程，因此它们可以在溶解于各种溶剂后容易地加工。它们的粘弹性和热塑性使BC变得可模塑和粘性。虽然它们独特的物理性质在某些情况下可能会成为缺点，但它们已被积极应用于制造各种可拉伸电子材料，并且它们的用途预计将比以往任何时候都扩大。在这个帐户中，我们总结了最近成功的应用BC的可伸缩电子设备，并讨论进一步使用的可能性和实际应用中要解决的挑战。对BC基可拉伸材料的研究最初集中在可拉伸导体的制造过程上;将导电填料与BC物理混合，在导电填料层中渗透BC，并将金属前体转化为BC内的金属纳米颗粒。当使用具有高纵横比的导电填料（例如纳米线或纳米片）时，填料可以在沉积后被BC渗透。由于在渗透过程中保持了填料之间的接触，即使是薄的复合膜也具有高的导电性和拉伸性。金属前体溶液印刷被认为是一种有前途的方法，因为它与传统的印刷技术兼容，而不会堵塞喷嘴，并允许高填料装载效率。当使用BC作为基材时，由于BC的粘弹性和热塑性，建议使用BC/PDMS双层。如果BC/PDMS双层与厚得多的PDMS层一起使用而不是单独使用粘弹性BC，则双层基底可以显示出完美的弹性体行为，并且BC基底的优点得以保留。另外，使用常规制造技术对于可拉伸装置的商业化是重要的。在其表面上具有预形成的微纤维网络的BC衬底通过在衬底上通过掩模直接沉积金属来促进高分辨率电路的制造。最近的成功制造可拉伸的有机晶体管获得的基础上，在原位相分离的聚合物半导体形成纳米纤维束的表面上的BC基板。它们导致了大面积印刷的高分辨率晶体管阵列的实现。BC有望扩大其适用性，包括可拉伸电池，因为它们使制造各种混合纳米复合材料，孔径控制膜和微结构表面变得可行。然而，有必要确保在热、溶剂和UV下的长期稳定性;此外，需要合成用于可拉伸植入生物医学装置的功能性BC。
As industrial needs for healthcare sensors, electronic skin, and flexible/stretchable displays increase, interest in stretchable materials is increasing as well. In recent years, the studies on stretchable materials have spread to various pivot components, such as electrodes, circuits, substrates, semiconductors, dielectric layers, membranes, and active nanocomposite films. The block copolymer (BC) elastomers have been playing considerable role in the development of stretchable materials. Since BCs are soft elastomers based on physical cross-links, they show differences in physical properties from normal elastomers formed with chemical cross-linking. BC elastomers does not require additional chemical cross-linking procedure, so they can be easily processed after dissolved in various solvents. Their viscoelasticity and thermoplasticity enable the BCs to become moldable and sticky. Although their unique physical properties may serve as disadvantages in some cases, they have been actively applied to create various stretchable electronic materials and their uses are expected to be enlarged more than ever. In this Account, we summarize recent successful applications of BCs for the stretchable electronic devices and discuss the possibility of further uses and the challenges to be addressed for practical uses. Studies on BC-based stretchable materials have focused initially on the fabrication process of stretchable conductors; mixing conductive fillers physically with BCs, infiltrating BCs in a conductive filler layer, and converting metal precursors into metal nanoparticles inside BCs. When conductive fillers with high aspect ratios, such as nanowires or nanosheets are used, the fillers can be infiltrated by the BCs after deposited. Since the contacts between the fillers are maintained during the infiltration process, even thin composite films possess high conductivity and stretchability. The metal precursor solution printing is suggested as a promising approach because it is compatible with traditional printing techniques without clogging the nozzles and allows high filler loading efficiency. When using a BC as a substrate, it is advisable to use a BC/PDMS double layer because of viscoelastic and thermoplastic properties of BCs. If BC/PDMS double layer is used with much thicker PDMS layer instead of viscoelastic BC alone, the double layer substrate can show a perfect elastomeric behavior, and the advantages of the BC substrate are preserved. Additionally, the use of conventional manufacturing techniques is important for commercialization of the stretchable devices. BC substrates having preformed microfibril network on their surfaces facilitate the fabrication of high-resolution circuitry by directly depositing metals through a mask on the substrate. Recent successes of fabricating stretchable organic transistors were obtained based on in situ phase separation of polymer semiconductors to form nanofibril bundles on the surface of a BC substrate. They have led to the achievement of high resolution transistor array printed in large area. BCs are expected to expand their applicability, including stretchable batteries, since they make it feasible to fabricate various hybrid nanocomposites, pore size-controlled membranes, and microstructured surfaces. However, it is necessary to secure long-term stability under heat, solvent, and UV; in addition, there is a need for the synthesis of functional BCs for use in stretchable implanted biomedical devices.