Printable multi-stage variable stiffness material enabled by low melting point particle additives
通过添加低熔点金属颗粒实现可打印弹性体的多级刚度变化
Fei Long, Yingchun Shao, Zihui Zhao, Mingquan Fang, Zhiyu Zhang, Jianjun Guo, Aihua Sun, Yong Ren*, Yuchuan Cheng*, Gaojie Xu
龙菲，邵迎春，赵自辉，方明权，Zhiyu Zhang，郭建军，孙爱华, 任勇*，程昱川*，许高杰
全文链接：Journal of Materials Chemistry C, 2023, 11, 1285 - 1297
Abstract
软体机器人的基体通常采用低模量的高弹性材料，形变程度高，但负载能力低。传统变刚度软材料通常只能实现刚度软-硬的两相变化，而无法实现多级、连续地调控。我们通过弹性体与模块化组合的低熔点合金颗粒的复合，制备了一种具有多稳态的变刚度材料。由于组合的低熔点合金颗粒具有多个熔点，该材料表现出温度响应的多重力学转换性质，通过调控温度，该材料可以实现多级模量调控功能。通过3D打印制得的网格结构承重能力可达到自身重量的250倍，且在室温至100oC结构的模量变化率可超过2000%，该工作为变刚度智能材料的设计提供了新的思路。
A majority of biological organisms in nature can adjust their biomechanical energy to adapt the complex environments, but most of the current synthetic composites have limited rigid and flexible states that cannot achieve multi-level and continuous regulation on altering mechanical stiffness. Herein, the direct ink printing (DIW) approach for forming a 4D printable phase-changing elastomer that achieves multi-stable stages in response to a thermal stimulus has been developed. This composite consists of low melting point alloy (LMPA) microparticles incorporated into silicone elastomer (PDMS) using a facile composite manufacturing process. The particles with different melting points amplify the steady stage in flexural modulus under the thermal response, which is desirable for stiffness-changing applications, particularly relevant to soft robotics. Moreover, the composites possess the improved printability in three-dimensional direct printing via adjusting the volume ratio of the raw materials, which circumvents the dilemma that most sample structures are restricted between one- and two-dimensional transformations as well as the conventional craftsmanship are limited by complex production. It is demonstrated as well that the utility of LMPA/PDMS composites has an advantage of multiple stiffness changing at the set-transition temperature for unveiling its brilliant prospects for soft actuators with 4D printing technology.
