Shape memory technology : working mechanisms, modeling and surface patterning application

Abstract

A new way to classify shape memory materials (SMMs) was proposed based on the underlying working mechanisms behind the shape memory effect (SME). Three categories, namely dual-state mechanism, dual-component mechanism, and partial-transition mechanism, were discussed in details. Based on this, the concept of advanced shape memory technology was proposed to enable the SME in materials, to design/synthesize new SMMs with tailored features, and to optimize the SME in materials. Previously, SME is considered as a unique behavior in some certain materials. In this study, based on ASMT, SME can be achieved in a range of materials, which are not the traditional SMMs. A generic 3-D model was developed to simulate the shape memory behavior in polymeric SMMs. This model was verified by a series of experiments. In addition, this model was applied for optimization of the SME. The thermo-/chemo-responsive SME in poly(methyl methacrylate) (PMMA) were systematically studied by experiments and simulation. Based on above study on the fundamentals, different surface patterning methods were developed to fabricate micro/nano-sized surface features, including well-controllable wrinkled patterns, PMMA microlens arrays, reversible surface patterns and 3-D surface patterns.

Heating/ethanol-response of poly methyl methacrylate (PMMA) with gradient pre-deformation and potential temperature sensor and anti-counterfeit applications

“…It is pointed out in [21] that the penetration of ethanol into PMMA follows the case II theory, i.e., the transition layer between ethanol-wetted and dry PMMA is very narrow. A numerical analysis of the wrinkled surface based on the data of 3D scanning reveals that the expansion ratio of PMMA due to swelling in ethanol is about 20%, which agrees well with the value reported in [24].…”

Reply to “Comment on ‘Mechanisms of the multi-shape memory effect and temperature memory effect in shape memory polymers’” by H. Lu, Soft Matter, 2013, 9, DOI: 10.1039/c3sm51720a

“…1, recently Dr Yong Zhao has simulated both the multiple-SME and TME in poly(methyl methacrylate) (PMMA) using a nite element method, in which the applied thermo-mechanical properties of the hard component and transition component and the transition progress function were obtained experimentally. 4 It was found that the simulation agrees well with the experimental curves.…”

Temperature memory effect/triple-shape memory effect in niti shape memory alloys and shape memory effect in keratin

“…Theoretically, partial-transition mechanism is not only applicable to polymeric materials but also metallic materials [78].…”