Rapid Volumetric Additive Manufacturing in Solid State: A Demonstration to Produce Water-Content-Dependent Cooling/Heating/Water-Responsive Shape Memory Hydrogels

Salvekar, Abhijit Vijay; Nasir, Faqrul Hasif Bin Abdul; Chen, Ya Hui; Maiti, Sharanya; Ranjan, V.; Chen, Hong Mei; Wang, Han; Huang, Wei Min

doi:10.1089/3dp.2021.0279

Cited by 5 publications

(6 citation statements)

References 22 publications

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“…Recently, rapid VAM in solid state has been demonstrated using a special thermal gel [ 4 ]. For a hard polymeric version, UV cross-linkable vitrimer has been suggested as the material [ 6 ].…”

Section: Potential Applications In Additive Manufacturingmentioning

confidence: 99%

“…Different from current VAM [ 2 ], UV cross-linking in solid-state VAM is carried out on a solid piece of polymer. This concept has been realized using a UV cross-linkable thermal gel [ 4 ], which is solid at room temperature, and becomes an easy-to-flow liquid upon cooling to below 10 °C. Thus, after cross-linking at room temperature in the solid state, the un-cross-linked part can be removed by washing in iced water.…”

Section: Introductionmentioning

confidence: 99%

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Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

Chen

Zeng

et al. 2022

Polymers

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In this paper, a UV cross-linkable vitrimer-like polymer, ureidopyrimidinone functionalized telechelic polybutadiene, is reported. It is synthesized in two steps. First, 2(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1H]-pyrimidinone (UPy-NCO) reacts with hydroxy-functionalized polybutadiene (HTPB) to obtain UPy-HTPB-UPy, and then the resulted UPy-HTPB-UPy is cross-linked under 365 nm UV light (photo-initiator: bimethoxy-2-phenylacetophenone, DMPA). Further investigation reveals that the density of cross-linking and mechanical properties of the resulting polymers can be tailored via varying the amount of photo-initiator and UV exposure time. Before UV cross-linking, UPy-HTPB-UPy is found to be vitrimer-like due to the quadruple hydrogen-bonding interactions. The UPy groups at the end of the chain also enable for rapid solidification upon the evaporation of the solvent. The unsaturated double bonds in the HTPB chains enable UPy-HTPB-UPy to be UV cross-linkable in the solid state at room temperature. After cross-linking, the polymers have good shape memory effect (SME). Here, we demonstrate that this type of polymer can have many potential applications in additive manufacturing. In the cases of fused deposition modelling (FDM) and direct ink writing (DIW), not only the strength of the interlayer bonding but also the strength of the polymer itself can be enhanced via UV exposure (from thermoplastic to thermoset) either during printing or after printing. The SME after cross-linking further helps to achieve rapid volumetric additive manufacturing anytime and anywhere.

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Section: Potential Applications In Additive Manufacturingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

Chen

Zeng

et al. 2022

Polymers

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“…Thermally reversible gelatin-based hydrogels have been utilized in VAM, including for production of biological constructs and shape-memory materials. [7,[19][20][21][22] Particularly for bioprinting, light delivery occurs while the precursor material is in gel state which prevents sedimentation of embedded cells and after printing supports the polymerized structure. On the other hand, thermoplastic binders added to monomer mixtures have been utilized to record volume holograms as the spatial variation in density of sensitizers or in refractive index of the affected material for data storage applications, albeit, typically in thin films.…”

Section: Introductionmentioning

confidence: 99%

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Toombs

Shan

Taylor

2023

Macromol. Rapid Commun.

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Liquid photoresists are abundant in the field of light‐based additive manufacturing (AM). However, printing unsupported directly into a vat of material in emerging volumetric AM technologies―typically a benefit due to fewer geometric constraints and less material waste―can be a limitation when printing low‐viscosity liquid monomers and multimaterial constructs due to part drift or sedimentation. With ethyl cellulose (EC), a thermoplastic soluble in organic liquids, a simple three‐component transparent thermoreversible gel photoresist with melting temperature of ≈64 °C is formulated. The physically crosslinked network of the gel leads to storage moduli in the range of 0.1−10 kPa and maximum yield stress of 2.7 kPa for a 10 wt% EC gel photoresist. Nonzero yield stress enables sedimentation‐free tomographic volumetric patterning in low‐viscosity monomer without additional hardware or modification of apparatus. In addition, objects inserted into the print container can be suspended in the gel material which enables overprinting of multimaterial devices without anchors connecting the object to the printing container. Flexural strength is also improved by 100% compared to the neat monomer for a formulation with 7 wt% EC.

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“…Analogously, hydrogels can also be designed to be dynamic, that is, the chemical/physical structures are adjustable, leading to tunable mechanical properties, morphology, and other characteristics . Shape-memory hydrogels, as an emerging kind of dynamic materials, are capable of returning their initial shapes from a temporary state in response to certain stimuli, including temperature, light, solvent, magnetism, electricity, and others. − Currently, noncovalent bonds are popular in shape-memory hydrogel, such as ionic bonds, − host–guest interactions, , and metal coordination. , Huang and co-workers developed a fibriform strain sensor with shape-memory properties; the sensing performance can be retained almost totally after recovery to its original state from 50% deformation in length; meanwhile, the shape-memory effect could enable the sensor to reversibly tightly fit to a nonplanar irregular subject …”

Section: Introductionmentioning

confidence: 99%

Cryopolymerized Polyampholyte Gel with Antidehydration, Self-Healing, and Shape-Memory Properties for Sustainable and Tunable Sensing Electronics

Guo

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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Hydrogel-based wearable flexible electronics are attracting tremendous interest for use in human healthcare. However, many of the existing hydrogel electronics are often susceptible to dehydration, leading to weakened stretchability and inaccurate signal extraction. Besides, hydrogels are desired to be much smarter for self-repairing physical damage and enabling performance manipulation. Herein, we develop a kind of cryopolymerized polyampholyte gels with the multifunctionality of antidehydration, self-healing, and shape-memory for wearable sensing electronics. The antidehydration property is enabled by the incorporation of glycerol, endowing the sensing electronics with excellent stretchability and strain-sensing performance in long-term monitoring. The ionic bonds in the polyampholyte gel possess a dynamic feature regulated by alternant NaCl(aq) and H2O treatments, laying the foundation for self-healing and shape-memory. As a result, the sensing electronics can automatically repair physical damages without any sacrifice in sensing performance, after healing both conductivity and strain-sensing performance could return to the initial levels. The shape-memory function enables the temporal adjustment of the initial state of the sensing electronics; both the conductivity and sensing performance, for instance, signal intensity, can be manually manipulated. In all, the cryopolymerized polyampholyte gels with antidehydration, self-healing, and shape-memory properties can be an inspiration to develop sustainable and tunable gel-based electronics for human motion monitoring.

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Rapid Volumetric Additive Manufacturing in Solid State: A Demonstration to Produce Water-Content-Dependent Cooling/Heating/Water-Responsive Shape Memory Hydrogels

Cited by 5 publications

References 22 publications

Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

Ethyl Cellulose‐Based Thermoreversible Organogel Photoresist for Sedimentation‐Free Volumetric Additive Manufacturing

Cryopolymerized Polyampholyte Gel with Antidehydration, Self-Healing, and Shape-Memory Properties for Sustainable and Tunable Sensing Electronics

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