Junfei Tian

Multivalent cations-triggered rapid shape memory sodium carboxymethyl cellulose/polyacrylamide hydrogels with tunable mechanical strength

A novel multivalent cations-triggered shape memory hydrogels were synthesized in a one-pot method, and interpenetrating double network was formed by chemically cross-linked polyacrylamide (PAM) network and physically cross-linked sodium carboxymethyl cellulose network. The temporary shape was fixed by complexation between a native biopolymer, sodium carboxymethyl cellulose (CMC), and transition metal ions, specifically Fe3+, Ag+, Al3+, Cu2+, Ni2+, and Mg2+. In particular, CMC-Fe3+ hydrogel exhibits excellent shape fixity ratio (95%). Therefore, we chose PAM/CMC1.0-Fe3+ hydrogel as the model material and further investigated its shape recovery process. It was found that a wide range of molecules and anions could be applied to break off the temporary cross-links between CMC and Fe3+. The PAM/CMC composite hydrogels also exhibited excellent tunable mechanical properties. The mechanical properties of the composite hydrogel can be adjusted by changing the cross-linking densities. The presented strategy could enrich the construction as well as application of biopolymers based shape memory hydrogels.

Ionic Gel Paper with Long-Term Bendable Electrical Robustness for Use in Flexible Electroluminescent Devices

Conductive paper has low-cost, lightweight, sustainability, easy scale-up, and tailorable advantages, allowing for its promising potential in flexible electronics, such as bendable supercapacitors, solar cells, electromagnetic shields, and actuators. Ionic gels, exhibiting a lower Youngs modulus together with facile manufacturing, can fully serve as the conductive component to prepare conductive paper. Herein we report a low-cost (∼1.3 dollars/m2), continuous, and high-throughput (up to ∼30 m/min) fabrication of reliable and long-term (stable for more than two months) conductive paper. As-prepared conductive paper shows a high electrical durability with negligible bending-recovering signal changes over 5000 cycles. Using this ionic gel paper (IGP) as a key component, we build a variety of proof-of-principle demonstrations to show the capacity of IGP in constructing flexible electroluminescent devices with diverse patterns, including a square, an alphabetic string, and a laughing face. Our methodology has the potential to open a new powerful route to fabricate bendable conductive paper for a myriad of applications in future flexible electronics.

Engineering Biocompatible Hydrogels from Bicomponent Natural Nanofibers for Anticancer Drug Delivery

Natural hydrogels have attracted extensive research interest and shown great potential for many biomedical applications. In this study, a series of biocompatible hydrogels was reported based on the self-assembly of positively charged partially deacetylated α-chitin nanofibers (α-DECHN) and negatively charged 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF) for anticancer drug delivery. The formation mechanisms of the α-DECHN/TOCNF hydrogels with different mixing proportions were studied, and their morphological, mechanical, and swelling properties were comprehensively investigated. Additionally, the drug delivery performance of the hydrogels was compared via sustained release test of an anticancer drug (5-fluorouracil). The results showed that the hydrogel with higher physical cross-linking degree exhibited a higher drug loading efficiency and drug release percentage.

Patternable transparent and conductive elastomers towards flexible tactile/strain sensors

Transparent conductive elastomers are an emerging platform for stretchable electronics, attractive due to their ability to sustain high physical deformations while still fulfilling optical/electrical functions. Poly(deep eutectic solvent)s (DESs) can serve as a new type of transparent conductive elastomers as a result of their low cost, green fabrication, non-toxicity and post-treatment-free advantages. Here, we report a 3D patternable (starfish type), transparent (transmittance of ∼81%), stretchable (strain up to 150%), and conductive (∼0.2 S m−1) elastomer based on the photopolymerization of the acrylic-acid/choline-chloride DES. The combination of transparency, elasticity, conductivity and patternability allows the poly(DES) elastomers to serve as flexible tactile/strain sensors. Our methodology has the potential to exploit the new application of poly(DESs), and opens up a new powerful route to fabricate all-organic transparent, conductive elastomers for a myriad of applications in future flexible electronics.

Influences of Paper on 3D Printing Quality in UV Ink-jet Printer

The paper intended to research the influences of paper in UV ink-jet printer, mainly including the height and glossiness. Results proved that infiltrations had all appeared between three selected substrates of paper, on which the paper roughness and bulkiness had a linear effect. And the infiltration on the first layer of ink was bigger than those on other layers of ink. It is too stable to not be changed by the paper that the infiltrations between two layers of ink. As we knew, paper roughness and bulkiness would reduce the glossiness. There existed ink sticks on the third layer of ink and more, even some ink holes when the infiltrations were too big because of the substrate of paper had a bigger roughness and bulkiness. Therefore, the substrates used for UV ink-jet 3D printing should have a property of tight and smooth, and the first layer of ink must not be calculated in the whole height of model, so that the printing result would be satisfied.