Approaches to Preceramic Polymer Fiber Fabrication and On-Demand Applications.

The demand for lightweight, high-modulus, and temperature-resistant materials for aerospace and other high-temperature applications has contributed to the development of ceramic fibers that exhibit most of the favorable properties of monolithic ceramics. This review demonstrates preceramic-based polymer fiber spinning and fiber classifications. We discuss different types of fiber spinning and the advantages of each.

Direct and Divergent Solid-Phase Synthesis of Azobenzene and Spiropyran Derivatives.

Here, we report a solid-phase approach to synthesize azobenzene and spiropyran derivatives. The divergent synthesis process requires no purification steps to obtain the desired product with a 28-55% yield, depending on the specific compound. For the spiropyran compounds, solid-phase resin cleavage is performed under mild conditions to minimize spiropyran ring opening.

Stimulus-Responsive Biopolymeric Surface: Molecular Switches for Oil/Water Separation.

In this work, we fabricated a stimulus-responsive biopolymeric material and demonstrated the reversible character of a hydrophilic/hydrophobic interface upon exposure to UV light. Importantly, this stimulus-responsive material exhibited excellent features in an oil/water separation system. Cellulose was functionalized on both sides of the surface with a dopamine polymer and further modified with an azobenzene-fluorosilane material.

Super Mechanical Stimuli Responsive Hydrogel: Dynamic Cues for Cell Applications.

In this work, we fabricated a thermosensitive hydrogel based on NIPAM that incorporated an oxygen-permeable hyaluronic acid (HA) polysaccharide unit. The interpenetrating network (IPN) of NIPAM-HA-MA hydrogel was fabricated by using an ultraviolet (UV) cross-linking process. Importantly, we explored the real behavior kinetics of the hydrogel via the mechanical properties of Young's modulus and the shear strain.

Modulating Noncovalent Cross-links with Molecular Switches.

Spiropyran molecular switches, in conjunction with transition metal ions, are shown to operate as reversible polymer cross-linkers. Solutions containing a spiropyran-functionalized polymer and transition metal ions underwent reversible thermally triggered (light-triggered) transient network formation (disruption) driven by the association (dissociation) of metal-ligand cross-links. Heat triggers metal-ion-mediated cross-linking via thermal isomerization of spiropyran to its open, merocyanine form, and exposure to visible light triggers dissociation of polymer cross-links.