Highly transparent, hydrophobic, and durable anisotropic cellulose films as electronic screen protectors.

Cellulose films have attracted extensive interest in the field of burgeoning electronic devices. However, it remains a challenge to simultaneously address the difficulties including facile methodology, hydrophobicity, optical transparency, and mechanical robustness. Herein, we reported a coating-annealing approach to fabricate highly transparent, hydrophobic, and durable anisotropic cellulose films, where poly(methyl methacrylate)-b-poly(trifluoroethyl methacrylate) (PMMA-b-PTFEMA) as low surface energy chemicals was coated onto regenerated cellulose films via physical (hydrogen bonds) and chemical (transesterification) interactions. The resultant films with nano-protrusions and low surface roughness exhibited high optical transparency (92.3 %, 550 nm) and good hydrophobicity. Moreover, the tensile strength of the hydrophobic films was 198.7 MPa and 124 MPa in dry and wet states, respectively, which also showed excellent stability and durability under various conditions, such as hot water, chemicals, liquid foods, tape peeling, finger pressing, sandpaper abrasion, ultrasonic treatment, and water jet. This work provided a promising large-scale production strategy for the preparation of transparent and hydrophobic cellulose-based films for electronic device protection as well as other emerging flexible electronics.

Biocompatible Chitin Hydrogel Incorporated with PEDOT Nanoparticles for Peripheral Nerve Repair.

The nerve guidance conduit (NGC) is a promising clinical strategy for regenerating the critical-sized peripheral nerve injury. In this study, the polysaccharide chitin is used to fabricate the hydrogel film for inducing the impaired sciatic nerve regeneration through incorporating the conductive poly(3,4-ethylenedioxythiophene) nanoparticles (PEDOT NPs) and modifying with cell adhesive tetrapeptide Cys-Arg-Gly-Asp (CRGD) (ChT-PEDOT-p). The partial deacetylation process of chitin for exposing the amino groups is performed to (i) improve the electrostatic interaction between chitin and the negatively charged PEDOT for enhancing the composite hydrogel strength and (ii) offer the active sites for peptide modification. The as-prepared hydrogel remarkably promotes the in vitro RSC-96 cell adhesion and proliferation, as well as the Schwann cell activity-related gene S100, NF-200, and myelin basic protein (MBP) expression. Function of gastrocnemius muscle and thickness of myelinated axon in chitin/PEDOT groups are analogous to the autograft in 10 mm rat sciatic nerve defect. Immunofluorescence, immunohistochemistry, western blotting, and toluidine blue staining analyses on the regenerated sciatic nerve explain that the attachment and proliferation enhancement of Schwann cells and angiogenesis are the vital factors for the chitin/PEDOT composite to facilitate the nerve regeneration. This work provides an applicable chitin-based NGC material for accelerating the peripheral nerve restoration.

Insight into Morphology Change of Chitin Microspheres using Tertiary Butyl Alcohol/H2 O Binary System Freeze-Drying Method.

The morphology of materials usually plays a significant role in their applications; the mechanical properties of the materials and characteristics such as specific surface area, surface energy, adsorbability, and wettability are dependent on the morphology. This study is focused on studying the effects of different tertiary butyl alcohol (TBA) aqueous solutions on the freeze-dried morphologies of chitin microspheres (CMs). By constructing a TBA/H2 O phase diagram, the underlying mechanisms of morphology change are explored. It is found that by freeze drying the CMs with 20 and 100 wt% TBA, a fine nanofiber weaved pore structure can be obtained. Away from these two ratios, the nanofibers are oppressed by the large crystals formed during the precool process or bind together due to the existence of water in the secondary drying stage, poor morphology and pore characteristics appearing. Moreover, the 20 wt% TBA freeze-drying route is conducive to split the CMs and other polysaccharide (PS) microspheres. The split method is also helpful for exploring the internal structure of the microspheres. Therefore, this study makes it possible to simplify the morphology control of CMs, which helps in the characterization of porous PS-based microspheres.