Polymer brushes refer to polymer chains that are end-grafted to surfaces or interfaces at high grafting density. Polymer brushes are able to make surface self-assembly or surface coassembly with free block copolymer (BCP) chains, and surface nanostructures with different morphologies are formed on the surfaces. The formation of the surface nanostructures endows materials with new surface properties. To develop a simple and versatile approach to the synthesis of polymer brushes and surface nanostructures, the synthesis of polymer brushes and surface nanostructures on tannic acid (TA) coatings was investigated in this research. TA molecules were coated on the surfaces of amino-modified silica particles (SiO2-NH2) through noncovalent bonds. Quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (qPDMAEMA-b-PS) chains were anchored onto the TA coatings through electrostatic interaction between qPDMAEMA blocks and TA coatings, and PS brushes are formed on the particle surfaces. Thermo gravimetric analysis demonstrates the grafting of the BCP chains on the TA coatings, and the calculation results indicate that the PS chains on the silica particles are in the polymer brush regime. PS brushes on TA coatings are able to make surface coassembly with free BCP chains, and surface nanostructures with different sizes and morphologies are produced on TA coatings. The grafting density of PS blocks and BCP concentration both exert significant influences on the formation of the surface nanostructures. The surface nanostructures can be removed from the particle surfaces in the aqueous solution of sodium chloride. This research provides a simple and versatile method for the fabrication of polymer brushes and removable surface nanostructures on any solid substrates, which have specific interactions with TA molecules.

Thermoresponsive phospholipid–poly­(N-isopropylacrylamide) (PL-PNIPAM) conjugates were synthesized via reversible addition fragmentation chain transfer polymerization mediated by a phospholipid-modified trithiocarbonate. Temperature triggered the micellization of the PL-PNIPAM conjugate to form phosphate group-decorated micelles in the aqueous solution. Driven by the chelation of phospholipids and Ca2+, the PL-PNIPAM conjugate and Ca2+ ions formed size-tunable nanoclusters at a temperature beyond the lower critical solution temperature. To fabricate cross-linked nanogels, NIPAM was copolymerized with N-succinimidyl acrylate (NSA) to obtain the PL-P­(NIPAM-co-NSA) conjugate bearing pendent cross-linkable functionalities. Subsequently, the size-controllable nanogels containing disulfide linkages were generated at 37 °C by cross-linking the PL-P­(NIPAM-co-NSA)/Ca2+ nanoclusters with cystamine through modulation of Ca2+ concentrations. These negatively charged nanogels demonstrate temperature/pH/reduction triple responsiveness. The nanogels can be efficiently loaded with doxorubicin (DOX) and proteins with various isoelectric points. The DOX-loaded nanogels exhibited a temperature/pH/reduction triple-responsive release profile. The immobilized RNase A, BSA, and GOx retained the protein bioactivity. The release of RNase A-loaded nanogels possesses a temperature-responsive profile. The immobilization of Lys and cytochrome C in nanogels inhibited protein bioactivity. However, the addition of NaCl triggered the recovery of bioactivity. These multistimuli-responsive nanogels can provide a versatile platform applicable in biotechnology and drug/protein delivery.