Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

McCracken, Joselle M.; Tondiglia, Vincent P.; Auguste, Anesia D.; Godman, Nicholas P.; Donovan, Brian R.; Bagnall, Brody N.; Fowler, Hayden E.; Baxter, Chance M.; Matavulj, Valentina M.; Berrigan, John D.; White, Timothy J.

doi:10.1002/adfm.201903761

Cited by 33 publications

(37 citation statements)

References 46 publications

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“…This was nicely shown on liquid crystal elastomers. [ 26–29 ] However, these methods are often labor intense such that they cannot fabricate soft materials with structures that are similar to those of natural models. A contributing reason for the discrepancy in the structure and local composition of soft natural versus synthetic materials is the difference in their processing.…”

Section: Introductionmentioning

confidence: 99%

3D Printing of Strong and Tough Double Network Granular Hydrogels

Hirsch

Charlet

Amstad

2020

Adv Funct Materials

103

127

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Many soft natural tissues display a fascinating set of mechanical properties that remains unmatched by manmade counterparts. These unprecedented mechanical properties are achieved through an intricate interplay between the structure and locally varying the composition of these natural tissues. This level of control cannot be achieved in soft synthetic materials. To address this shortcoming, a novel 3D printing approach to fabricate strong and tough soft materials is introduced, namely double network granular hydrogels (DNGHs) made from compartmentalized reagents. This is achieved with an ink composed of microgels that are swollen in a monomer‐containing solution; after the ink is additive manufactured, these monomers are converted into a percolating network, resulting in a DNGH. These DNGHs are sufficiently stiff to repetitively support tensile loads up to 1.3 MPa. Moreover, they are more than an order of magnitude tougher than each of the pure polymeric networks they are made from. It is demonstrated that this ink enables printing macroscopic, strong, and tough objects, which can optionally be rendered responsive, with high shape fidelity. The modular and robust fabrication of DNGHs opens up new possibilities to design adaptive, strong, and tough hydrogels that have the potential to advance, for example, soft robotic applications.

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Section: Introductionmentioning

confidence: 99%

3D Printing of Strong and Tough Double Network Granular Hydrogels

Hirsch

Charlet

Amstad

2020

Adv Funct Materials

103

127

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“…First of all, we verified that the laser writing direction does not perturb the alignment of the LC cell impressed by the sacrificial layers. [ 57 ] In Figure S16 (Supporting Information), 3D photonic structures have been polymerized in a homogeneous planar cell (Figure S16a, Supporting Information) and in an homeotropic cell (Figure S16b, Supporting Information) showing that the laser writing direction does not affect the final alignment of the structures. Indeed, both polarized optical microscope images and the contraction of the structures (Figure S16c, Supporting Information) are ruled by the LC alignment preimpressed by the alignment layer of the cell and not the laser writing direction.…”

Section: Resultsmentioning

confidence: 99%

Two‐Photon Laser Writing of Soft Responsive Polymers via Temperature‐Controlled Polymerization

Bellis

Nocentini

Santi

et al. 2021

Laser & Photonics Reviews

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Enhancing the resolution of 3D patterning techniques in functional soft polymers enlarges the application areas of responsive shape‐changing materials, for tunable nanophotonics and nanorobotics. Thanks to the recent advances of polymer science, the palette of available materials for nanomanufacturing is becoming wider and wider—although the comprehension of their polymerization process by two‐photon polymerization is still incomplete. In this work, both shrinking of the minimal polymerizable unit and a significant improvement of the mechanical stability of microstructured soft polymers, in particular of liquid crystalline networks, are demonstrated. To this aim, temperature control enhances the resolution and reduces the swelling of the polymerized structures, thus avoiding deviations of the final structure from the intended design. This fine control on the nanoscale features enables the use of soft responsive materials not only for bulky microelements, but also for high‐resolution structures with more complex design.

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“…Motility was observed to light exposure. White and co‐workers used similar methods to prepare hybrid actuators via multimaterial compositions in LCEs 584. The cationic epoxy polymerization used by these authors is particularly suited for printing high‐resolution structures in oxygen‐rich environments.…”

Section: Liquid Crystal Elastomers and Networkmentioning

confidence: 99%

Materials as Machines

2020

Self Cite

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of responsive materials as machines is in robotics. The vision, leadership, and research of Bar-Cohen is seminal in both invigorating and focusing current-day research activities to develop responsive materials [2] and implement [3] them as lightweight, dexterous, and gentle (e.g., soft) robotic elements. In this spirit, this review exhaustively details the materials, the nature of their stimuli-response, and discusses considerations for their implementation in robotic systems and subsystems.Robotics is a well-established but growing field of research. Sustained progress in both performance and functionality continue to be realized in commercial robotic systems largely based on conventional materials and their integration with mechanisms. A recent example is the Atlas robot from Boston Dynamics [4] (Figure 1a). The incorporation of stimuli-responsive materials in robotics has largely focused on component-level demonstrations to extend the performance of a subsystem (such as a hand or gripper).Stimuli-responsive materials, spanning nearly all classes of materials and size scales, are currently subject to widespread examination in corporate, government, and academic research laboratories (Figure 1b-d). [5][6][7] In some cases, these materials have already found widespread commercial implementation in end use and are comparatively mature. The materials and fundamentals of their responses are summarized in Figure 2. Shape memory alloys (SMAs) and ceramic piezoelectric materials are distinctive in that they are hard, stimuli-responsive materials. Deformation of these materials can produce large energy densities due to their inherent stiffness. Electroactive polymers (EAPs) remain a topic of considerable interest, particularly dielectric elastomer actuators (DEAs). Engineered systems are rapidly emerging and enabling performance gains in robotics, largely based on pneumatic or fluidic (such as HASEL [8] actuators) transport processes that localize deformation to generate force or produce motion. Soft materials, such as shape memory polymers (SMPs), hydrogels, and liquid crystalline polymer networks (LCNs) and elastomers (LCEs) may offer distinctive functional performance to robotic systems in allowing local control of deformation without the need for complex interfacing with mechanisms. As will be evident, each of these materials has inherent advantages and performance tradeoffs that must be considered in functional implementations. However, responsive material systems have a common obstacle to widespread use: the performance and Machines are systems that harness input power to extend or advance function. Fundamentally, machines are based on the integration of materials with mechanisms to accomplish tasks-such as generating motion or lifting an object. An emerging research paradigm is the design, synthesis, and integration of responsive materials within or as machines. Herein, a particular focus is the integration of responsive materials to enable robotic (machine) functions such as gripping, lifting, or motility (walk...

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Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

Cited by 33 publications

References 46 publications

3D Printing of Strong and Tough Double Network Granular Hydrogels

3D Printing of Strong and Tough Double Network Granular Hydrogels

Two‐Photon Laser Writing of Soft Responsive Polymers via Temperature‐Controlled Polymerization

Materials as Machines

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