Abstract
New branched polymerisations offer previously inaccessible macromolecules and architectural understanding is important as it provides insight into the branching mechanism and enables the determination of structure–property relationships. Here we present a detailed inverse gated 13C NMR characterisation of materials derived from the very recently reported Transfer-dominated Branching Radical Telomerisation (TBRT) approach to quantify branching and provide an insight into cyclisation.
Highlights
Inverse gated 13C nuclear magnetic resonance spectroscopy (NMR) spectroscopy has been employed previously for structural analysis of branched polymers formed by self-condensing vinyl polymerisation under atom transfer radical polymerisation (ATRP) microemulsion polymerisation conditions.[71,72]
The structures of polymers resulting from Transfer-dominated Branching Radical Telomerisation (TBRT) are fundamentally different to those formed by the homopolymerisation of inimers and a relatively simple approach was adopted to calculate the molar ratio of the different contributions of the reacted vinyl groups to branching, linear and terminal structures within the complex architecture
The inverse gated quantitative 13C NMR spectra of TBRT polymers derived from ethylene glycol dimethacrylate (EGDMA) and dodecanethiol (DDT; telogen) present several resonances that are unaffected by overlap from other carbon environments; these allow quanti cation of key structural units, Fig. 2
Summary
The synthesis of branched polymers has intrigued polymer chemists from the earliest days of polymer science including establishing paradigms for their synthesis and characterisation,[1,2] controlling their structure,[3,4,5] avoiding gelation,[6,7] theoretical considerations[8] and methods for their scale-up[9,10,11] and application.[12,13] Several excellent reviews[14,15,16] have been published that highlight the versatility of this polymer topology, and the bene ts and complexities of branched architectures that may range from perfectly branched and monodisperse dendrimers through to macromolecules that are essentially linear in their nature and have low branching densities.Branched polymer synthesis strategies can be divided into two categories of resulting products: (1) materials that have backbones that resemble step-growth polymers (heteroatoms within the backbone); and (2) materials with predominantly C–C backbone chemistries.[17,18,19] a slight oversimpli cation, branched materials with backbones resembling step-growth chemistries are most o en produced using ABn monomers and employ conventional step-growth chemistries such as esteri cation and amide formation.[20]. We present a detailed inverse gated 13C NMR characterisation of materials derived from the very recently reported Transfer-dominated Branching Radical Telomerisation (TBRT) approach to quantify branching and provide an insight into cyclisation.
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