Kim Kyungtae, Grummon Benjamin C, Thrasher Carl J, Macfarlane Robert J
Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Department of Chemistry, Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Adv Mater. 2025 Mar;37(10):e2410493. doi: 10.1002/adma.202410493. Epub 2025 Jan 28.
Polymer-brush-grafted nanoparticles (PGNPs) that can be covalently crosslinked post-processing enable the fabrication of mechanically robust and chemically stable polymer nanocomposites with high inorganic filler content. Modifying PGNP brushes to append UV-activated crosslinkers along the polymer chains would permit a modular crosslinking strategy applicable to a diverse range of nanocomposite compositions. Further, light-activated crosslinking reactions enable spatial control of crosslink density to program intentionally inhomogeneous mechanical responses. Here, a method of synthesizing composites using UV-crosslinkable brush-coated nanoparticles (referred to as UV-XNPs) is introduced that can be applied to various monomer compositions by incorporating photoinitiators into the polymer brushes. UV crosslinking of processed UV-XNP structures can increase their tensile modulus up to 15-fold without any noticeable alteration to their appearance or shape. By using photomasks to alter UV intensity across a sample, intentionally designed inhomogeneities in crosslink density result in predetermined anisotropic shape changes under strain. This unique capability of UV-XNP materials is applied to stiffness-patterned flexible electronic substrates that prevent the delamination of rigid components under deformation. The potential of UV-XNPs as functional, soft device components is further demonstrated by wearable devices that can be modified post-fabrication to customize their performance, permitting the ability to add functionality to existing device architectures.
可在后处理过程中进行共价交联的聚合物刷接枝纳米颗粒（PGNP）能够制备出具有高无机填料含量、机械性能强且化学稳定的聚合物纳米复合材料。通过沿着聚合物链修饰PGNP刷以连接紫外线激活的交联剂，将实现一种适用于多种纳米复合材料组成的模块化交联策略。此外，光激活交联反应能够对交联密度进行空间控制，从而有意地设计出不均匀的机械响应。本文介绍了一种使用可紫外线交联的刷涂纳米颗粒（称为UV-XNP）合成复合材料的方法，通过将光引发剂掺入聚合物刷中，该方法可应用于各种单体组成。对加工后的UV-XNP结构进行紫外线交联，可使其拉伸模量提高至15倍，而外观或形状不会有任何明显变化。通过使用光掩膜改变样品上的紫外线强度，交联密度中有意设计的不均匀性会导致在应变下出现预定的各向异性形状变化。UV-XNP材料的这种独特能力被应用于具有刚度图案的柔性电子基板，可防止刚性部件在变形时发生分层。可穿戴设备进一步证明了UV-XNP作为功能性软设备组件的潜力，这些设备在制造后可进行修改以定制其性能，从而能够在现有设备架构中添加功能。
