Biological materials display great adaptability to their environment, as is the case of bones, muscles and skin which can adapt in response to mechanical stimuli by changing their composition and structure through a process called mechanotransduction. These cellular systems efficiently convert mechanical stimuli into chemical signals that can drive reactions leading to structural changes, deposition and removal of material. These adaptive properties give them great advantage in terms of efficiency and durability. Currently, synthetic polymeric materials mostly lack similar adaptability, resulting in mismatches in their physical properties and the need to replace them repeatedly. Recently, we and others have started investigating methods to use mechanical energy, in the form of ultrasound, to conduct controlled chain-growth, step-growth and crosslinking polymerization reactions. Our approach relies on activating piezoelectric nanoparticles with ultrasound to initiate or promote polymerization reactions. Previously, we used ultrasonic agitation of piezoelectric BaTiO3 nanoparticles to mechanically generate a CuILn catalyst that then promoted atom transfer radical polymerization (ATRP) of acrylate monomers. We have since demonstrated mechanically activated step-growth polymerization and crosslinking reactions mediated by the copper-catalyzed azide-alkyne cycloaddition (CuAAC), commonly known as copper ‘Click’ reaction. These results showed great promise in using piezochemically-mediated polymerization strategies to develop adaptive synthetic polymeric materials that strengthen themselves with mechanical force. Our current goals include demonstrating that the above mentioned mechano-activated chemistries can indeed reinforce a gel/solid polymeric composite, thus conferring adaptability to a synthetic polymeric material; and exploring alternative piezo-polymerization reactions to expand the repertoire of materials that can be reinforced.

Piezoelectrically-mediated mechanochemical reactions for adaptive materials

2019 Fall National Meeting

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