Bio-Inspired Soft Responsive Coatings for Natural and Synthetic Fibers | AIChE

Bio-Inspired Soft Responsive Coatings for Natural and Synthetic Fibers


Conference Presentation

Conference Type

AIChE Annual Meeting

Presentation Date

November 8, 2021


18 minutes

Skill Level




Marine biological organisms use binding of
transition metal ions in metal-ligand coordination complexes as a transient or permanent cross-linking mechanism to provide materials and coatings with extraordinary properties. Inspired by these mechanisms, we have synthesized bio-friendly polymers and molecules that can be used in hydrogel coatings to provide the underlying structure with desirable features. Specifically, we have synthesized multi-arm PEG
(polyethylene glycol) molecules that are functionalized with DOPA (dihydroxy-phenylalanine), a catechol side-group that is also found within biological structures such as mussel byssus threads. In this talk, we show how metal coordination bonds between DOPA molecules can be effectively used for shape-memory applications. These bonds are reversibly triggered by external stimuli, such as pH, and, despite their transient nature, are only second in strength to permanent covalent interactions. By engineering the underlying network for these polymers, we fabricate a bio-inspired dual-network hydrogel coating that exhibits shape-memory effects upon exposure to external stimuli such as pH. Our results indicate that by changing pH we control the transient bonds within the gel and, by arresting the underlying network, transform the hydrogel from a rubbery state to a glassy state (similar to cooling below Tg in elastomers). This reversible control on the rubbery/glassy state of the gel leads to shape-memory effects for both the hydrogel coating and coated fibers, such as human hair. By performing mechanical spectroscopy, we characterize the glassy/rubbery nature of the hydrogels and study their corresponding effects on the coated fibers. Rheological measurements on the bulk hydrogels and torsional pendulum tests on coated fibers help us to understand the underlying physics of the observed shape-memory effect. We utilize this novel shape-memory mechanism in the hydrogel coating to switch the form of biological fibers, such as human hair, from curly to smooth with safe external stimuli that, unlike traditional methods, do not harm or modify the properties of the cuticle layers within the hair fibers. By developing these bio-inspired soft materials and understanding their mechanical response, we can address challenges in crucial applications for human life and health.


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