Two Nanoparticle Populations Simultaneously Directed Using Triptych Triblock Terpolymers

Abstract

Multicomponent nanocomposites are important for diverse fields spanning energy conversion to optoelectronics and catalysis. Polymer structure-directing agents typically direct the placement of hydrophilic nanoparticles (HNPs) using hydrophilic interactions; however, this approach is generally limited to random mixtures when combining two types of HNPs. A new approach is shown where two distinct intermolecular interaction modalities enable independent control of two, respectively, functionalized nanoparticle populations. Specifically, the orthogonal interactions of the hydrophilic-fluorophobic structure-directing agents enabled independent control of the placement of both HNPs and fluorophobic nanoparticles (FNPs). This dual-nanoparticle assembly was first examined using a diblock poly(hydrophilic-b-fluorophobic) structure-directing agents where achieving well-defined assemblies required >32 wt % HNPs to preserve micelle templates. The addition of a glassy lipophilic block led to a triptych triblock poly(hydrophilic-b-lipophilic-b-fluorophobic) design that enabled vitrification of FNP-loaded micelles for robust dual-nanoparticle control with well-defined assemblies regardless of the FNP/HNP fractions. A novel micelle-chain morphology occurred with ≥ 89 wt % FNPs which may support unique transport applications. This micelle-chain morphology was associated with the depletion of chains at the core–corona interface, promoting micelle aggregation. Equilibration experiments were used to probe for dynamic exchange processes during various stages of processing from sequential solvent conditions. These mixing experiments identified that polymer chains and FNPs underwent dynamic exchange in acetone (plasticizer) but did not after transferring to water (nonplasticizer), thus confirming glassy kinetic entrapment at the final stage of processing. This collection of experiments highlights how triptych block polymers offer a new approach toward independent control over two types of nanoparticles.