Synthesis of a Diethyl-protected Cyclic Lysine Monomer and Its Copolymerization with ε-Caprolactam
As potential alternatives to fossil raw materials,bio-based materials have stimulated the exploration of novel monomer architectures and synthesis strategies in polymer science.Herein,we report the synthesis of a novel diethyl-protected cyclic lysine monomer M1 with a seven-membered ring from lysine,which was subsequently copolymerized with ε-caprolactam to produce innovative copolyamide.Comprehensive characterizations including nuclear magnetic resonance hydrogen spectra(1H-NMR),carbon spectra(13C-NMR),and diffusion ordered nuclear magnetic resonance spectroscopy(DOSY-NMR)confirmed that the resulting copolymers were homogeneous rather than a blend of multiple polymers.By adjusting the feed ratio of the monomers,it was possible to control the composition of the copolymers and manipulate properties of these copolymers effectively.Furthermore,this synthesis process demonstrated scalability as laboratory-scale production yielding quantities of up to 50 g.The number-average molecular weight of the copolyamide can reach up to 40 kDa,with a high tensile strength and a high elongation at break((105±8)％),indicating that the polymer exhibits exceptional characteristics akin to general polyamides.This work expands the application of lysine,a biological-based molecule,in polyamide general materials.It is expected to reduce the fossil energy dependence of bulk polyamide materials production and lower the full life cycle carbon footprint of related production processes.
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