High molecular mass polymer-grafted nanoparticles (PGNPs) have attracted significant attention in the past few decades with the potential to design next-generation polymer nanocomposites with enhanced mechanical properties and thermal stabilities of nanopatterned surfaces. A critical requirement for these new nanoparticles and their associated applications is the control of the polymer morphology and the PGNP dispersion and orientation in the system. Recent research from our group reveals that the entropic forces from the topographic confinement can induce the selective partitioning of low molecular mass PGNPs to the less confined 'mesa' region via thermal annealing soft lithography (TA-SL). However, subsequent studies have demonstrated that the mobilities of the high molecular mass PGNPs decrease significantly due to the ‘solid-like’ ‘jammed state’, which leads to poor or no selective partitioning of these high molecular mass PGNPs through TA-SL. We developed a solvent vapor annealing soft lithography (SVA-SL) to overcome this scientific challenge and revealed that the minimization of the entropic free energy from the topographic pattern along with the increased mobilities from solvent vapor drives the high molecular mass PGNPs to the ‘mesa’ region of patterned films. We further demonstrated that the degree of selective partitioning (quantified by the partition parameter, Kp) can be easily controlled as a function of the initial film thickness and the molecular mass difference between the PGNPs and the matrix. The newly developed SVA-SL allows us to extend the application of topographic confinement to a wider range of polymer nanocomposites and design advanced materials with enhanced electrical and mechanical properties.

Tunning the partitioning of patterned high molecular mass polymer-grafted nanoparticles blends via topographic confinement

ACS Spring 2022

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