Straightforward synthesis of complex polymeric architectures with ultra-high chain density

• Published in: Chemical science (Cambridge) Vol. 15; no. 32; pp. 12739 - 12753
• Main Authors: Gupta, Sachin, Janata, Miroslav, Čadová, Eva, Raus, Vladimír
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 14-08-2024; The Royal Society of Chemistry
• Subjects: Chains (polymeric); Chemical synthesis; Chemistry; Copolymers; Cyclodextrins; Density; Graft copolymers; Initiation (polymerization); Initiators; Isocyanates; Molecular chains; Molecular weight; NMR; Nuclear magnetic resonance; Polymer coatings; Polymerization; Polymers; Prepolymers; Substrates; Tags
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d4sc01739k

Synthesis of complex polymeric architectures (CPAs)
reversible-deactivation radical polymerization (RDRP) currently relies on the rather inefficient attachment of monofunctional initiation/transfer sites onto CPA precursors. This drawback seriously limits the overall functionality of the resulting (macro)initiators and, consequently, also the total number of installable polymeric chains, which represents a significant bottleneck in the design of new polymeric materials. Here, we show that the (macro)initiator functionality can be substantially amplified by using trichloroacetyl isocyanate as a highly efficient vehicle for the rapid and clean introduction of trichloroacetyl groups (TAGs) into diverse precursors. Through extensive screening of polymerization conditions and comprehensive NMR and triple-detection SEC studies, we demonstrate that TAGs function as universal trifunctional initiators of copper-mediated RDRP of different monomer classes, affording low-dispersity polymers in a wide molecular weight range. We thus unlock access to a whole new group of ultra-high chain density CPAs previously inaccessible
simple RDRP protocols. We highlight new opportunities in CPA synthesis through numerous examples, including the
one-pot synthesis of a novel "star-on-star" CPA, the preparation of β-cyclodextrin-based 45-arm star polymers, and facile grafting from otherwise problematic cellulose substrates both in solution and from surface, obtaining effortlessly ultra-dense, ultra-high-molecular weight bottle-brush copolymers and thick spatially-controlled polymeric coatings, respectively.