Polycondensation polymers typically follow step-growth kinetics assuming all functional groups are equally likely to react with one another. If the reaction rates with the chain end can be selectively accelerated, living polymers can be obtained. Here we report on two chlorophosphonium iodide reagents that have been synthesized from triphenylphosphine and tri(o-methoxyphenyl)phosphine. The former activates aromatic carboxylic acids as acid chlorides in the presence of secondary aromatic amines and the latter even in the presence of primary aromatic amines. These reagents allow p-aminobenzoic acid derivatives to form solution-stable activated monomers that polymerize in a living fashion in the presence of amine initiators. Other aryl amino acids and even dimers of aryl amino acids can be polymerized in a living fashion when slowly added to the phosphonium salt in the presence of an amine initiator. Diblock copolymers and triblock terpolymers of aryl amino acids can be prepared even in the presence of electrophilic functional groups.
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All data generated and analysed during this study are included in this article and its Supplementary Information. Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition nos. CCDC 1983404 (PHOS1) and 1983405 (PHOS2). Copies of the data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif. Source data are provided with this paper.
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We thank A. Coskun and S. Salentinig for helpful comments and F. Karasu Kilic for GPC measurements. Funding was provided by the National Center for Competence in Research (NCCR) Bio-Inspired Materials.
The authors declare no competing interests.
Peer review information Nature Chemistry thanks Tsutomu Yokozawa and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Materials and instrumentation. Syntheses of monomers, initiators, activation reagents and polymers. NMR, GPC, MALDI-TOF MS, high-resolution mass spectra, AFM analyses, ultraviolet absorption and fluorescence spectra, circular dichroism spectra and ab initio calculations. Supplementary Scheme 1, Figs. 1–323 and Tables 1–9.
CIF file for PHOS1 (CCDC reference: 1983404).
CIF file for PHOS2 (CCDC reference: 1983405).
Raw data including number average molecular weight, dispersity and monomer/initiator ratio as shown in Fig. 2a–f.
Raw SEC data including time and number average molecular weight of the first polymer block and the diblock copolymer as shown in Fig. 3a–h.
Raw data including number average molecular weight, dispersity and monomer/initiator ratio for both, the N-protected and N-deprotected polymer as shown in Fig. 4.
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Pal, S., Nguyen, D.P.T., Molliet, A. et al. A versatile living polymerization method for aromatic amides. Nat. Chem. 13, 705–713 (2021). https://doi.org/10.1038/s41557-021-00712-3