Recent progress on polymer materials for additive manufacturing

Breakthrough in the printing tactics for stimuli-responsive materials: 4D printing

4D printing and stimuli-responsive materials in biomedical aspects

Three-dimensional printing (3DP) has attracted a considerable amount of attention during the past years, being globally recognized as one of the most promising and revolutionary manufacturing technologies. Although the field is rapidly evolving with significant technological advancements, materials research remains a spotlight of interest, essential for the future developments of 3DP. Smart polymers and nanocomposites, which respond to external stimuli by changing their properties and structure, represent an important group of materials that hold a great promise for the fabrication of sensors, actuators, robots, electronics, and medical devices. The interest in exploring functional materials and their 3DP is constantly growing in an attempt to meet the ever-increasing manufacturing demand of complex functional platforms in an efficient manner. In this review, we aim to outline the recent advances in the science and engineering of functional polymers and nanocomposites for 3DP technologies. The report cove...

Functional Polymers and Nanocomposites for 3D Printing of Smart Structures and Devices

Design and direct fabrication of high-performance thermosets and composites via 3D printing are highly desirable in engineering applications. Most 3D printed thermosetting polymers to date suffer from poor mechanical properties and low printing speed. Here, a novel ink for high-speed 3D printing of high-performance epoxy thermosets via a two-stage curing approach is presented. The ink containing photocurable resin and thermally curable epoxy resin is used for the digital light processing (DLP) 3D printing. After printing, the part is thermally cured at elevated temperature to yield an interpenetrating polymer network epoxy composite, whose mechanical properties are comparable to engineering epoxy. The printing speed is accelerated by the continuous liquid interface production assisted DLP 3D printing method, achieving a printing speed as high as 216 mm h-1 . It is also demonstrated that 3D printing structural electronics can be achieved by combining the 3D printed epoxy composites with infilled silver ink in the hollow channels. The new 3D printing method via two-stage curing combines the attributes of outstanding printing speed, high resolution, low volume shrinkage, and excellent mechanical properties, and provides a new avenue to fabricate 3D thermosetting composites with excellent mechanical properties and high efficiency toward high-performance and functional applications.

High-Speed 3D Printing of High-Performance Thermosetting Polymers via Two-Stage Curing.

Four-dimensional printing, a new process to fabricate active materials through three-dimensional (3D) printing developed by MIT’s Self-Assembly Lab in 2014, has attracted more and more research and development interests recently. In this paper, a type of epoxy-acrylate hybrid photopolymer was synthesized and applied to fabricate shape memory polymers through a stereolithography 3D printing technique. The glass-to-rubbery modulus ratio of the printed sample determined by dynamic mechanical analysis is as high as 600, indicating that it may possess good shape memory properties. Fold-deploy and shape memory cycle tests were applied to evaluate its shape memory performance. The shape fixity ratio and the shape recovery ratio in ten cycles of fold-deploy tests are about 99 and 100%, respectively. The shape recovery process takes less than 20 s, indicating its rapid shape recovery rate. The shape fixity ratio and shape recovery ratio during 18 consecutive shape memory cycles are 97.44 ± 0.08 and 100.02 ± 0.05%,...

Three-Dimensional Printing of Shape Memory Composites with Epoxy-Acrylate Hybrid Photopolymer.

4D printing of shape memory polyurethane via stereolithography

In this study, reactive oxygen species (ROS)-mediated antibacterial activity with high efficiency in the dark was achieved by modulating the active sites of MIL-101(Fe) nanoparticles. The ROS production over x-MIL-101(Fe) nanoparticles was intensively enhanced by tuning the unsaturated iron sites (FeII/FeIII, the ratio was marked as x%). Electron paramagnetic resonance (EPR) analysis confirmedmore ROS generation on x-MIL-101(Fe) surface than that on MIL-101(Fe), due to more electrons shifting from benzene rings to FeII/FeIII sites. Among all samples, 8.9-MIL-101(Fe) displayed the highest inactivation efficiency (> 99.99%) against Escherichia coli within 2 h in the dark. ROS reacted with cell wall components to generate carbon-centered radicals via H abstraction, leading to the disruption of cell wall, intracellular ROS, and DNA damage. Antibacterial performance of 8.9-MIL-101(Fe) in air filters indicated 8.9-MIL-101(Fe) can be applied to prevent the spread of airborne pathogens. The results are promising for the ambient antibacterial application of MOF materials. 

Tuning the Unsaturated Iron Sites in MIL-101(Fe) Nanoparticles for Reactive Oxygen Species-Mediated Bacterial Inactivation in the Dark

The invention relates to spinning oil for preparing high-performance carbon fibers, in particular to a low-surface-tension organosilicon spinning oil for preparing high-performance polyacrylonitrile-based carbon fibers. The organosilicon spinning oil is 15 to 45 mass percent emulsion which is prepared from active ingredients and water; based on amino-polysiloxane, the active ingredients comprise the following components in part by weight: 100 parts of amino-polysiloxane, 10 to 25 parts of trisiloxane surfactant, 10 to 50 parts of polyoxyethylene phosphate, 20 to 150 parts of alkyl alcohol ethoxylate propoxylate, and 0.5 to 10 parts of hindered phenol antioxygen; and the surface tension of the low-surface-tension organosilicon spinning oil for preparing the high-performance polyacrylonitrile-based carbon fibers is 20 to 25dyn/cm. The carbon fibers prepared by using the organosilicon spinning oil have few broken filaments and are high in intensity.

Yulei Zhao

Papers

Three-Dimensional Printing of Shape Memory Composites with Epoxy-Acrylate Hybrid Photopolymer.

4D printing of shape memory polyurethane via stereolithography

Tuning the Unsaturated Iron Sites in MIL-101(Fe) Nanoparticles for Reactive Oxygen Species-Mediated Bacterial Inactivation in the Dark

Low-surface-tension organosilicon spinning oil for preparing polyacrylonitrile-based carbon fibers

Effect of Warm Rolling on the Grain-Refining Performance of Al-5Ti-1B Grain Refiner in Al