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Mills AS, Chou E, Baierl Z, Daltorio KA, Wnek GE. Elastic/viscoelastic polymer bilayers: a model-based approach to stretch-responsive constructs. SOFT MATTER 2024; 20:407-420. [PMID: 38108205 DOI: 10.1039/d3sm01004j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The use of polymers in the fabrication of bilayers for stimuli-responsive systems is well-known, yet viscoelasticity and viscoelastic models representing bilayer behavior have received surprisingly little attention. Of particular recent interest to us are simple polymeric bilayers in which one material, such as styrene-ethylene-propylene-styrene (SEPS) or styrene-isobutylene-styrene (SIBS), shows typical rubbery elastic response upon extension and retraction, and the other, an unvulcanized, low-Tg polymer such as butyl rubber (butyl), exhibits a viscoelastic response. When such a bilayer strip is extended to a fixed strain and held for several seconds followed by sudden release of this strain, rapid curling is observed, achieving a maximum curvature within 1 second, with a gradual uncurling, typically taking 300-600 seconds to eventually return to a flat strip. Attention has been directed to modeling the observed bilayer behavior. We compare predicted curvature and relaxation time constants from finite element analysis (FEA) simulations using Maxwell, Zener, Generalized Maxwell, and Parallel Rheological Framework (PRF) viscoelastic models to the experimentally measured values. We find that the Generalized Maxwell model predicts curvature over time with the lowest overall mean absolute scaled error (MASE) of 0.519, corresponding to a 4.9% difference from the second lowest error model and a 76.8% difference from the highest error model. Building upon an understanding of the material mechanics in simple bilayer strips, more complex bilayer systems can be designed. Samples of cross and weave geometries were fabricated from bilayer films and initial testing demonstrates how these materials can be used in potential applications.
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Affiliation(s)
- Austin S Mills
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
| | - Evan Chou
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
| | - Zachary Baierl
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
| | - Kathryn A Daltorio
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
| | - Gary E Wnek
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
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Lopes JPT, Vistulo de Abreu F, Simoes R. Modeling the mechanisms for formation of helices and perversions in elastic nanofilaments through molecular dynamics. Polym Bull (Berl) 2022. [DOI: 10.1007/s00289-021-04013-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Meena RK, Rapaka SD, Pratoori R, Annabattula RK, Ghosh P. An embedded interface regulates the underwater actuation of solvent-responsive soft grippers. SOFT MATTER 2022; 18:372-381. [PMID: 34889930 DOI: 10.1039/d1sm01229k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, we report the role of an embedded interface between two polymer thin films in determining the overall folding and actuation characteristics of a bilayer system applied for gripping submerged objects. Along with the material properties and geometry of the individual films involved, the strength of the embedded interface governs the folding behaviour of the bilayer when exposed to a solvent. The concentration gradient developed across the film thickness when exposed to the solvent results in the deformation of the film. The evolution of concentration through the film thickness as a function of time is closely related to the interface strength. It affects various aspects of the deformation, such as the direction of folding, curvature attained, and actuation rate. In this work, we have varied the strength of the interface between solvent responsive chitosan and hydrophobic Poly(methyl-methacrylate) (PMMA) by treating the substrate (chitosan) with varying concentrations of silane before coating. Experimentally, the folding characteristics of the solvent responsive bilayer films have been investigated for four different interfacial strengths. A coupled diffusion-deformation model for the film and a cohesive zone model for the interface is developed to provide insights into the underlying mechanism behind the observations made. Finally, the application of the bilayer as a gripper for submerged objects for two different types of interfaces is demonstrated. Interestingly, in this approach, the medium where the object is immersed acts as a trigger for folding the grippers.
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Affiliation(s)
- Rajesh Kumar Meena
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Sri Datta Rapaka
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Raghunandan Pratoori
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
| | - Ratna Kumar Annabattula
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
- Center for Responsive Soft Matter, Indian Institute of Technology Madras, Chennai 600036, India
| | - Pijush Ghosh
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
- Center for Responsive Soft Matter, Indian Institute of Technology Madras, Chennai 600036, India
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Basu A, Wong J, Cao B, Boechler N, Boydston AJ, Nelson A. Mechanoactivation of Color and Autonomous Shape Change in 3D-Printed Ionic Polymer Networks. ACS APPLIED MATERIALS & INTERFACES 2021; 13:19263-19270. [PMID: 33866782 DOI: 10.1021/acsami.1c01166] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Stimuli-responsive materials can enhance the field of three-dimensional (3D) printing by generating objects that change shape in response to external cues. While temperature and pH are common inputs for initiating a response in a 3D-printed object, there are few examples of using a mechanical input to afford a response. Herein, we report a suite of mechanochromic ionic liquid gel inks that can be used to fabricate 3D-printed objects that use a single mechanoactivation event to elicit both a mechanochromic response and an autonomous shape change. Direct-ink write 3D printing was used to deposit ionic liquid gel inks to create multimaterial objects that underwent a predetermined mechanoactivated shape change (mechanomorphic) when the sample was pulled and then released. When spiropyran was incorporated into the inks, the onset of spiropyran isomerization into its purple merocyanine form occurred at strains dependent upon the particular ion gel ink formulation. We suggest that the color onset could be used as a simple indicator for when the strain required to achieve a predetermined change in shape has been reached, potentially serving as real-time visual cue for the user. Such morphing 3D-printed structures with integrated instructions have potential application to areas including stowable structures as well as multiresponsive autonomous components and sensors.
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Affiliation(s)
- Amrita Basu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Jitkanya Wong
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Bo Cao
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Nicholas Boechler
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Andrew J Boydston
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Alshakim Nelson
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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Emile J, Emile O, Gaudriault P. Resonant vibration of a thin polymer film under optical excitation. SOFT MATTER 2021; 17:3923-3928. [PMID: 33710231 DOI: 10.1039/d1sm00016k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report on the mechanical excitation of a 220 μm thick thermoplastic film in its amorphous state by the radiation pressure of light. By modulating a low power visible laser (from 100 to 600 mW) at low frequencies (below 100 Hz), we observe a deformation of the film interfaces. The phenomenon, that is independent of the laser wavelength, is amplified at a resonant frequency and reaches 0.68 μm. The deformation is reversible and varies linearly with the optical power. Using the damped oscillator model, we show that the resonant frequency depends on the surface tension of the film. The associated free energy is then compared with the energy lost, taking into account the contribution of the damping corresponding to the imaginary part of the Young's modulus.
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Affiliation(s)
- Janine Emile
- Université de Rennes 1, CNRS IPR UMR 6251, F-35000 Rennes, France
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Lutz-Bueno V, Bolisetty S, Azzari P, Handschin S, Mezzenga R. Self-Winding Gelatin-Amyloid Wires for Soft Actuators and Sensors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004941. [PMID: 33103302 DOI: 10.1002/adma.202004941] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/21/2020] [Indexed: 05/20/2023]
Abstract
The origin of self-winding mechanisms in plants' tendrils has fascinated scientists for centuries and continues to inspire developments in material science and nanotechnology. Here, bioinspired water-responsive wires that replicate these mechanisms, including the formation of coils and chiral perversions, are presented. A right-handed gelatin matrix is loaded with rigid left-handed amyloid fibrils and roll-dry-spun into wires in which self-winding activation emerges from simultaneous bending and twisting deformations. Wire bending is a consequence of amyloid fibrils' concentration and distribution within the wire, whereas twisting is controlled by amyloid fibrils' orientation. The resultant wires can be functionalized by organic molecules and inorganic nanoparticles, and potential applications in magnetic actuators and sensors are demonstrated. The simple fabrication method and the remarkable spontaneous self-winding response of these gelatin-amyloid wires exemplify how biomaterials based on mixed proteins have striking potential to develop advanced and tunable properties that can serve robotics, soft machines, and engineering systems.
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Affiliation(s)
- Viviane Lutz-Bueno
- Department of Health Sciences and Technology, ETH Zürich, Zürich, 8092, Switzerland
| | - Sreenath Bolisetty
- Department of Health Sciences and Technology, ETH Zürich, Zürich, 8092, Switzerland
| | - Paride Azzari
- Department of Health Sciences and Technology, ETH Zürich, Zürich, 8092, Switzerland
| | - Stephan Handschin
- Department of Health Sciences and Technology, ETH Zürich, Zürich, 8092, Switzerland
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology, ETH Zürich, Zürich, 8092, Switzerland
- Department of Materials, ETH Zurich, Zurich, 8093, Switzerland
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Waters JT, Li S, Yao Y, Lerch MM, Aizenberg M, Aizenberg J, Balazs AC. Twist again: Dynamically and reversibly controllable chirality in liquid crystalline elastomer microposts. SCIENCE ADVANCES 2020; 6:eaay5349. [PMID: 32258400 PMCID: PMC7101207 DOI: 10.1126/sciadv.aay5349] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 01/02/2020] [Indexed: 05/23/2023]
Abstract
Photoresponsive liquid crystalline elastomers (LCEs) constitute ideal actuators for soft robots because their light-induced macroscopic shape changes can be harnessed to perform specific articulated motions. Conventional LCEs, however, do not typically exhibit complex modes of bending and twisting necessary to perform sophisticated maneuvers. Here, we model LCE microposts encompassing side-chain mesogens oriented along a magnetically programmed nematic director, and azobenzene cross-linkers, which determine the deformations of illuminated posts. On altering the nematic director orientation from vertical to horizontal, the post's bending respectively changes from light-seeking to light-avoiding. Moreover, both modeling and subsequent experiments show that with the director tilted at 45°, the initially achiral post reversibly twists into a right- or left-handed chiral structure, controlled by the angle of incident light. We exploit this photoinduced chirality to design "chimera" posts (encompassing two regions with distinct director orientations) that exhibit simultaneous bending and twisting, mimicking motions exhibited by the human musculoskeletal system.
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Affiliation(s)
- James T. Waters
- Chemical Engineering Department, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Shucong Li
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Yuxing Yao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michael M. Lerch
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Michael Aizenberg
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Joanna Aizenberg
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Anna C. Balazs
- Chemical Engineering Department, University of Pittsburgh, Pittsburgh, PA 15261, USA
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