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Sequential and one-pot post-polymerization modification reactions of thiolactone-containing polymer brushesThiolactone chemistry has garnered significant attention as a powerful post-polymerization modification (PPM) route to mutlifunctional polymeric materials. Here, we apply this versatile chemistry to the fabrication of ultrathin, multifunctional polymer surfaces via aminolysis and thiol-mediated double modifications of thiolactone-containing polymer brushes. Polymer brush surfaces were synthesized via microwave-assisted surface-initiated polymerization of dl -homocysteine thiolactone acrylamide. Aminolysis and thiol-Michael double modifications of the thiolactone-functional brush were explored using both sequential and one-pot reactions with bromobenzyl amine and 1 H ,1 H -perfluoro- N -decyl acrylate. X-ray photoelectron spectroscopy and argon gas cluster ion sputter depth profiling enabled quantitative comparison of the sequential and one-pot PPM routes with regard to conversion and spatial distribution of functional groups immobilized throughout thickness of the brush. While one-pot conditions proved to be more effective in immobilizing the amine and acrylate within the brush, the sequential reaction enabled the fabrication of multifunctional, micropatterned brush surfaces using reactive microcontact printing.
Fabrication of single-chain nanoparticles through the dimerization of pendant anthracene groups via photochemical upconversionWe report on the use of visible light as the driving force for the intramolecular dimerization of pendant anthracene groups on a methacrylic polymer to induce the formation of single-chain nanoparticles (SCNPs). Using a 532 nm green laser light source and platinum octaethylporphyrin as a sensitizer, we first demonstrated the use of TTA-UC to dimerize monomeric anthracene, and subsequently applied this concept to dilute poly((methyl methacrylate)- stat -(anthracenyl methacrylate)) samples. A combination of triple-detection size-exclusion chromatography, atomic force microscopy, and UV-visible spectroscopy confirmed the formation of the SCNPs. This report pioneers the use of TTA-UC to drive photochemical reactions in polymeric systems, and showcases the potential for TTA-UC in the development of nanoobjects.
Post-polymerization modification (PPM) has been broadly employed to achieve functional polymer brush surfaces via immobilization of functional moieties on the brush using efficient organic tranformations. Here, we demonstrate the amine-anhydride reaction as a modular PPM route to functional brush surfaces using poly(styrene–maleic anhydride) (pSMA) copolymer brushes as a platform. The amine-anhydride reaction on pSMA surfaces proceeds to high conversions, with rapid kinetics, under ambient reaction conditions, and exploits a readily available library of functional amines. Using cystamine as a modifier, a convenient route to thiol-functionalized brushes was developed that enables sequential PPM modifications with a large library of alkenes using both base-catalyzed thiol-Michael and radical-mediated thiol–ene reactions. The high fidelity PPM reactions were demonstrated via the development of multifunctional, micropatterned brush surfaces.