Synthesis of poly(glutamic acid-co-aspartic acid) VIA combination of N-carboxyanhydride ring opening polymerization with debenzylation

• Published in: Chinese journal of polymer science Vol. 31; no. 12; pp. 1706 - 1716
• Main Authors: Yang, Wei-xi, Wang, Ling-ling, Zhu, Han, Xu, Ri-wei, Wu, Yi-xian
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2013
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Industrial Chemistry/Chemical Engineering; Polymer Sciences; Ring opening polymerization; Glutamic acid; Aspartic acid; Copolymer; Peptide
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-013-1363-z

The random copolymers of glutamic acid (LG) and aspartic acid (ASP), poly(LG- co -ASP), with designed compositions could be successfully synthesized via combination of N -carboxyanhydride ring opening copolymerization with debenzylation. Ring opening copolymerizations of β -benzyl-L-glutamate N -carboxyanhydride (BLG-NCA) and -benzyl-Laspartate N -carboxyanhydride (BLA-NCA) were carried out by using different amines including triethylamine (TEA), diethylamine, n -hexylamine (NHA), triphenylamine, diphenylamine or aniline as initiators. All the 6 amines were highly efficient to get well-defined poly(BLG- co -BLA) copolymers with designed compositions although the polymerizations proceeded via different mechanisms (normal amine mechanism or/and activated monomer mechanism), which are based on chemical structure of amines. The molecular weights of poly(BLG- co -BLA) copolymers could be mediated by both TEA concentration and polymerization time. Then, debenzylation of poly(BLG- co -BLA) copolymers was conducted to prepare the corresponding hydrophilic random copolymers of poly(LG- co -ASP) with α -subunit structure in ASP structural units. The contents of LG structural units in poly(LG- co -ASP) copolymers matched with those of BLG-NCA in NCA-monomer feeds in ring opening copolymerizations initiated by NHA or TEA and were closed to the theoretical line. The diblock copolymer of poly(BLG- b -BLA) could also be synthesized via living NCA ring opening copolymerization by sequential addition of BLGNCA and BLA-NCA.