Transforming the Self-Assembled Structures of Diblock Copolymer/POSS Nanoparticle Composites Through Complementary Multiple Hydrogen Bonding Interactions

Main Chain-Type Block Copolymers through Atom Transfer Radical Polymerization from Double-Decker-Shaped Polyhedral Oligomeric Silsesquioxane Hybrids

In this study, we synthesized two main chain-type block copolymers featuring hydrogen bond donor and acceptor segments through atom transfer radical polymerization (ATRP) using a bifunctionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the initiator. Hydrosilylation of vinylbenzyl chloride at the two corners of a double-decker silsesquioxane (DDSQ) provided the bifunctionalized benzyl chloride initiator VBC-DDSQ-VBC, which we applied as a platform to prepare a main chain-type polystyrene homopolymer (PS-DDSQ-PS), the diblock copolymer poly(styrene-b-4-vinylpyridine) (P4VP-b-PS-DDSQ-PS-b-P4VP), and the diblock copolymer poly(styrene-b-tert-butoxystyrene) (PtBuOS-b-PS-DDSQ-PS-b-PtBuOS) through sequential ATRP. Selective hydrolysis of the tert-butoxyl units of PtBuOS-b-PS-DDSQ-PS-b-PtBuOS yielded the strongly hydrogen bonding diblock copolymer poly (styrene-b-vinylphenol) (PVPh-b-PS-DDSQ-PS-b-PVPh). We used Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, mass-analyzed laser desorption ionization mass spectrometry, and transmission electron microscopy to investigate the chemical structures, thermal behavior, and self-assembled nanostructures formed by these main chain-type block copolymers based on DDSQ.

Hydrogen bonding strength of diblock copolymers affects the self-assembled structures with octa-functionalized phenol POSS nanoparticles

In this study, the influence of the functional groups by the diblock copolymers of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), poly(styrene-b-2-vinylpyridine) (PS-b-P2VP), and poly(styrene-b-methyl methacrylate) (PS-b-PMMA) on their blends with octa-functionalized phenol polyhedral oligomeric silsesquioxane (OP-POSS) nanoparticles (NPs) was investigated. The relative hydrogen bonding strengths in these blends follow the order PS-b-P4VP/OP-POSS > PS-b-P2VP/OP-POSS > PS-b-PMMA/OP-POSS based on the Kwei equation from differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopic analyses. Small-angle X-ray scattering and transmission electron microscopic analyses show that the morphologies of the self-assembly structures are strongly dependent on the hydrogen bonding strength at relatively higher OP-POSS content. The PS-b-P4VP/OP-POSS hybrid complex system with the strongest hydrogen bonds shows the order-order transition from lamellae to cylinders and finally to body-centered cubic spheres upon increasing OP-POSS content. However, PS-b-P2VP/OP-POSS and PS-b-PMMA/OP-POSS hybrid complex systems, having relatively weaker hydrogen bonds, transformed from lamellae to cylinder structures at lower OP-POSS content (<50 wt%), but formed disordered structures at relatively high OP-POSS contents (>50 wt%).

Multiple hydrogen bonding mediates the formation of multicompartment micelles and hierarchical self-assembled structures from pseudo A-block-(B-graft-C) terpolymers

Different multi-compartment micelle structures: raspberry-like spheres, core–shell–corona cylinders, nanostructured vesicles, onion-like structures, and woodlouse-like structures was found dependent upon selective solvent concentration.

Functional groups on POSS nanoparticles influence the self-assembled structures of diblock copolymer composites

The influence of the functional groups presented by polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs) on the self-assembled structures formed by diblock copolymer composites were detail discussed.