4D Printing of Reversible Shape Morphing Hydrogel Structures

Naficy, Sina; Gately, Reece D.; Gorkin, Robert; Xin, Hai; Spinks, Geoffrey M.

doi:10.1002/mame.201600212

Cited by 216 publications

(173 citation statements)

References 40 publications

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“…As mentioned, heat transport and diffusion are fundamental limitations for thermal and fluidic-based triggers, respectively. [212][213][214][215] Laser cutting provides a rapid means to pattern materials and can control adhesion between layered materials, [216,217] providing multiple avenues for future control of switchable adhesives. Multimaterial printing can create material and structural layouts, providing design tools for well-controlled interfacial properties.…”

Section: Discussionmentioning

confidence: 99%

Switchable Adhesives for Multifunctional Interfaces

Croll

Hosseini

Bartlett

2019

Adv Materials Technologies

132

107

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The reliable bonding or attachment of materials is critical in many industries, is a common necessity of daily life, and is key to functionality in numerous biological settings. [1][2][3][4][5][6][7][8][9][10][11] Adhesives Joining two materials with an adhesive is an extremely common activity, but is most often irreversible. However, emerging and current applications ranging from consumer and medical products to soft robotics and wearable bio-monitoring devices demand strong adhesives which can be easily removed on-demand and subsequently reused. This requires new paradigms in adhesive science and engineering, resulting in the emergence of new classes of multifunctional switchable adhesives. Here summarized is the current state of the art in switchable adhesive systems, focusing on how devices fit into the basic science of adhesion while providing performance metrics for comparison across current approaches. Using fracture mechanics as a guide, systems are classified as functioning under one of three basic mechanisms: near-interface, contact area, or mechanical. These mechanisms must be initiated or "triggered" by a specific input, which can include mechanical, electromagnetic, fluidic, or thermal stimuli. Triggers and adhesion switching performance are compared through the use of a "switching ratio," the interfacial energy release rate, and an estimate of mechanism timing. Finally, it is discussed that how the fundamental mechanisms relate to challenges and opportunities for switchable interfaces in future applications and adhesive systems.

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Section: Discussionmentioning

confidence: 99%

Switchable Adhesives for Multifunctional Interfaces

Croll

Hosseini

Bartlett

2019

Adv Materials Technologies

132

107

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“…Stimuli‐responsive hydrogels physically reconfigure in response to external triggers such as heat, light, pH, and electromagnetic fields . One such hydrogel is poly( N ‐isopropylacrylamide) (pNIPAM), which shows a rapid and reversible volumetric change at critical temperature known as lower critical solution temperature (LCST) .…”

Section: Methodsmentioning

confidence: 99%

“…At temperature T > LCST, pNIPAM molecules undergo coil‐to‐globule transition that leads to shrinking of the hydrogel. Despite excellent thermoresponsive characteristics, pNIPAM lacks in mechanical strength when the size of printed structures is less than 1 mm . Although higher concentrations of NIPAM monomer can enhance stiffness of pNIPAM, volumetric change in response of temperature changes and the resolution of printed structures are compromised .…”

Section: Methodsmentioning

confidence: 99%

“…Despite excellent thermoresponsive characteristics, pNIPAM lacks in mechanical strength when the size of printed structures is less than 1 mm. [30,33] Although higher concentrations of NIPAM monomer can enhance stiffness of pNIPAM, volumetric change in response of temperature changes and the resolution of printed structures are compromised. [28] Here we demonstrate that such manufacturing limitations can be overcome by addition of nanoparticles to NIPAM, which enhances the mechanical properties of the printed structures, while retaining the thermoresponsiveness of the polymer backbone.…”

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confidence: 99%

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Directed Printing and Reconfiguration of Thermoresponsive Silica‐pNIPAM Nanocomposites

Guo

Belgodere

et al. 2019

Macromol. Rapid Commun.

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Printing of polymeric composites into desired patterns and shapes has revolutionized small‐scale manufacturing processes. However, high‐resolution printing of adaptive materials that change shape in response to external stimuli remains a significant technical challenge. The article presents a new approach of printing thermoresponsive poly(N‐isopropylacrylamide) into macroscopic structures that dynamically reconfigure in response to heating and cooling cycles. The printing process is performed using an external laser source, which enables thermal cross‐linking of the polymer ink consisting of monomer, cross‐linker, initiator, and inorganic nanoparticles. It is shown that the addition of silica nanoparticles enhances the mechanical properties of poly(N‐isopropylacrylamide) while maintaining its thermoresponsiveness at micrometer‐scale resolution, which otherwise is not feasible by extrusion‐based three‐dimensional printing techniques. It is demonstrated that spatial reconfiguration of the printed monolayers upon increasing temperature is governed by the local geometry, which enables mimicking the reconfiguration of plant leaves in a natural environment. The study lays a foundation for developing a new fabrication platform to print thermoresponsive structures that may find applications in biomedical implants, sensors, and other multi‐responsive materials.

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“…Unfortunately, most reported materials have been designed for non-biomedical applications, and exterior stimuli are extremely harsh for tissue and organ function. For a long period of time, the biomedical field has concentrated on the study of hydrogels which are also a material of focus for 4D printing[114, 115]. Novel and multi-functional 4D inks are no doubt highly desirable for further expansion of 4D printing.…”

Section: Perspective and Conclusionmentioning

confidence: 99%

4D printing of polymeric materials for tissue and organ regeneration

et al. 2017

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Four dimensional (4D) printing is an emerging technology with great capacity for fabricating complex, stimuli-responsive 3D structures, providing great potential for tissue and organ engineering applications. Although the 4D concept was first highlighted in 2013, extensive research has rapidly developed, along with more-in-depth understanding and assertions regarding the definition of 4D. In this review, we begin by establishing the criteria of 4D printing, followed by an extensive summary of state-of-the-art technological advances in the field. Both transformation-preprogrammed 4D printing and 4D printing of shape memory polymers are intensively surveyed. Afterwards we will explore and discuss the applications of 4D printing in tissue and organ regeneration, such as developing synthetic tissues and implantable scaffolds, as well as future perspectives and conclusions.

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4D Printing of Reversible Shape Morphing Hydrogel Structures

Cited by 216 publications

References 40 publications

Switchable Adhesives for Multifunctional Interfaces

Switchable Adhesives for Multifunctional Interfaces

Directed Printing and Reconfiguration of Thermoresponsive Silica‐pNIPAM Nanocomposites

4D printing of polymeric materials for tissue and organ regeneration

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