Transformable surface properties in the class of stimulus-responsive polymers are results of clever design of chemical structures and the control of the physics of polymer chain dynamics. In solution states, polymer chains dynamics can be controlled with relatively lower energy input via an optimal coupling between polymer molecular structure and the solvent medium. However, in solid state, there are fewer design freedoms for the engineering of stimulus responsive dynamics. Figure 1 illustrates a qualitative relationship between energy barrier and polymer chain mobility for various states of polymeric materials. One of the challenges in tuning the dynamics of surface property in solid state polymer is the balance between mechanical stability and energy required for transformation to occur. Generally, polymers with high molecular weight, more rigid molecular structures lead to higher mechanical stabilities; however, the same parameters would result in higher energy barrier to effect polymer chain mobilities consequently requires higher energy input for surface property change.<br/>In this work, through the synergy of polymer blend and scaling in micro-nano surface patterning via NIL, the tunability of response amplitudes (a measure of the degree of change for a given energy input) has been achieved. Polymer blends with shape memory properties such as polycaprolactone (PCL), poly(ethylene), PE and polymers with stimulus responsive such as poly (N-isopropyl acrylamide), PNIPAM and poly (vinylene fluoride) PVDF are thermo-formable polymers in which thermal nanoimprinting (NIL) has been successfully used to fabricate micro and nano-scale uniform surface patterns. Surface topographical change and surface property change of PCL/PE blends, and PNIPAM/PVDF blends as function of blend compositions and the effects of scaling in surface patterning have been shown to greatly influence the response amplitudes.

Tuning solid state surface transformation in polymeric materials

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.