A convergent synthesis of amphiphilic polymers with a polystyrene (PS) core and a polyelectrolytic poly(1-methyl-4vinylpyridinium iodide) (P4VPMe + I-) shell is reported. The polymers were obtained by reversible addition-fragmentation chaintransfer (RAFT) polymerization in water using a trithiocarbonate chain transfer agent [R0-SC(S)SPr, R0 =-C(Me)(CN)CH2CH2-COOH)]. Two types of particle structure, both having spherical morphology and diameters in the 85-150 nm range, have been obtained as stable latexes with polymer content up to 10% in weight. The first structure consists of core-cross-linked micelles (CCMs), where amphiphilic P4VPMe + I-b-PS arms are cross-linked at the hydrophobic end by the use of diethylene glycol dimethacrylate (DEGDMA). The Coulombic repulsion between the outer shells of the precursor micelles ensures the absence of macrogelation during the cross-linking step. The second structure consists of nanogels (NGs), where the entire hydrophobic core is cross-linked during the last step of simultaneous chain extension and cross-linking of a P4VPMe + I-b-PS intermediate with a short PS block. The lack of radical polymerization for the 4VPMe + Imonomer and the lack of chain extension with styrene for a R0-P4VPMe + I-SC(S)SPr intermediate were circumvented by the synthesis of R0-P4VP-b-PS-SC(S)SPr containing a short PS block by sequential RAFT polymerization of 4-vinylpyridine (4VP) and styrene, followed by quantitative cationization of the P4VP block by MeI, and subsequent sequential (for the CCMs) or simultaneous (for the NGs) chain extension and cross-linking. ASSOCIATED CONTENT Supporting Information. Experimental details, NMR spectra, polymerization kinetics, GPC, DLS and TEM characterization of polymer products and intermediates (23 pages). This material is available free of charge via the Internet at http://pubs.acs.org.
Unimolecular amphiphilic nanoreactors with a poly(4‐vinyl‐N‐methylpyridinium iodide) (P4VPMe+I−) polycationic outer shell and two different architectures (core‐cross‐linked micelles, CCM, and nanogels, NG), with narrow size distributions around 130–150 nm in diameter, were synthesized by RAFT polymerization from an R0‐4VPMe+I−140‐b‐S50‐SC(S)SPr macroRAFT agent by either chain extension with a long (300 monomer units) hydrophobic polystyrene‐based block followed by cross‐linking with diethylene glycol dimethacrylate (DEGDMA) for the CCM particles, or by simultaneous chain extension and cross‐linking for the NG particles. A core‐anchored triphenylphosphine (TPP) ligand functionality was introduced by using 4‐diphenylphosphinostyrene (DPPS) as a comonomer (5–20 % mol mol−1) in the chain extension (for CCM) or chain extension/cross‐linking (for NG) step. The products were directly obtained as stable colloidal dispersions in water (latexes). After loading with [RhCl(COD)]2 to yield [RhCl(COD)(TPP@CCM)] or [RhCl(COD)(TPP@NG)], respectively, the polymers were used as polymeric nanoreactors in Rh‐catalyzed aqueous biphasic hydrogenation of the model substrates styrene and 1‐octene, either neat (for styrene) or in an organic solvent (toluene or 1‐nonanol). All hydrogenations were rapid (TOF up to 300 h−1) at 25 °C and 20 bar of H2 pressure, the biphasic mixture rapidly decanted at the end of the reaction (<2 min), the Rh loss was negligible (<0.1 ppm in the recovered organic phase), and the catalyst phase could be recycled 10 times without significant loss of catalytic activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.