Three-Dimensional-Printed Shape Memory Biomass Composites for Thermal-Responsive Devices

Programmable and Shape-Color Synchronous Dual-Response Wood with Thermal Stimulus

Stimuli-responsive materials exhibit huge potential in sensors, actuators, and electronics; however, their further development for reinforcement, visualization, and biomass-incorporation remains challenging. Herein, based on the impregnation of thermochromic microcapsule (TCM)-doped dynamic covalent vitrimers, a programmable shape-color dual-responsive wood (SRW-TC) was demonstrated with robust anisotropic structures and exchangeable covalent adaptable networks. Under mild conditions, the resultant SRW-TC displays feasible shape memorability and programmability, resulting from the rigidity-flexibility shift induced by the glass-transition temperature (34.99 °C) and transesterification reaction triggered by the topology freezing transition temperature (149.62 °C). Furthermore, the obtained SRW-TC possesses satisfactory mechanical performance (tensile strength of 45.70 MPa), thermal insulation (thermal conductivity of 0.27 W/m K), anisotropic light management, and benign optical properties (transmittance of 51.73% and haze of 99.67% at 800 nm). Importantly, the incorporation of compatible TCM enables SRW-TC to visualize shape memory feasibility and rigidity/flexibility switching and respond to the external thermal stimulus through the thermal-induced shape-color synchronous dual-responsiveness, which successfully demonstrates the applications of sensing temperature, grasping objects, encrypting/decoding icon messages, and so on. The proposed facile and highly effective strategy could serve as a guideline for developing high-performance multifunctional wood composite with promising intelligent applications in performance visualization, environmental sensing, materials interactivity, information dual-encryption, local precision shape and color regulation, etc.

Biomass 3D Printing: Principles, Materials, Post-Processing and Applications

Under the background of green and low-carbon era, efficiently utilization of renewable biomass materials is one of the important choices to promote ecologically sustainable development. Accordingly, 3D printing is an advanced manufacturing technology with low energy consumption, high efficiency, and easy customization. Biomass 3D printing technology has attracted more and more attentions recently in materials area. This paper mainly reviewed six common 3D printing technologies for biomass additive manufacturing, including Fused Filament Fabrication (FFF), Direct Ink Writing (DIW), Stereo Lithography Appearance (SLA), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM) and Liquid Deposition Molding (LDM). A systematic summary and detailed discussion were conducted on the printing principles, common materials, technical progress, post-processing and related applications of typical biomass 3D printing technologies. Expanding the availability of biomass resources, enriching the printing technology and promoting its application was proposed to be the main developing directions of biomass 3D printing in the future. It is believed that the combination of abundant biomass feedstocks and advanced 3D printing technology will provide a green, low-carbon and efficient way for the sustainable development of materials manufacturing industry.

Nanocomposite Bioprinting for Tissue Engineering Applications

Bioprinting aims to provide new avenues for regenerating damaged human tissues through the controlled printing of live cells and biocompatible materials that can function therapeutically. Polymeric hydrogels are commonly investigated ink materials for 3D and 4D bioprinting applications, as they can contain intrinsic properties relative to those of the native tissue extracellular matrix and can be printed to produce scaffolds of hierarchical organization. The incorporation of nanoscale material additives, such as nanoparticles, to the bulk of inks, has allowed for significant tunability of the mechanical, biological, structural, and physicochemical material properties during and after printing. The modulatory and biological effects of nanoparticles as bioink additives can derive from their shape, size, surface chemistry, concentration, and/or material source, making many configurations of nanoparticle additives of high interest to be thoroughly investigated for the improved design of bioactive tissue engineering constructs. This paper aims to review the incorporation of nanoparticles, as well as other nanoscale additive materials, to printable bioinks for tissue engineering applications, specifically bone, cartilage, dental, and cardiovascular tissues. An overview of the various bioinks and their classifications will be discussed with emphasis on cellular and mechanical material interactions, as well the various bioink formulation methodologies for 3D and 4D bioprinting techniques. The current advances and limitations within the field will be highlighted.