| Abstract: | New alternating poly(amide-ester)s derived from β-hydroxy acids and α-amino acids 3a,b or ϵ-aminocaproic acid 4a-c were prepared. Two approaches were considered: (i) polycondensation of N-(β-hydroxyacyl)-amino acids 1a,b and 2b,c and (ii) ring-opening polymerization of cyclic amide-esters 5a-c and 6a-c . For all the linear precursors polycondensation reactions result in oligomers with number average molecular weights lower than 5000. The ring-opening polymerization of the cyclic precursors is substrate specific and is sensitive to changes in the polymerization conditions. For N-(3-hydroxybutyroyl)-ϵ-aminocaproic acid lactone c(3HB-ϵAC); 5b ] (IUPAC nomenclature: 2-methyl-5-aza-1-oxa-cycloundecan-4,11-dione) bulk and solution polymerizations result in oligomers with an alternating ester amide microstructure. Polymerization of N-(3-hydroxypropionyl)-ϵ-aminocaproic acid lactone c(3HP-ϵAC); 5a ] (IUPAC nomenclature: 5-aza-1-oxa-cycloundecan-4-11-dione) in dimethylformamide solution and with Bu2Sn(OMe)2 as initiator high molecular weight linear, semi-crystalline polymers were obtained (Tm = 145.9°C). Polymerization of N-(hydroxypivaloyl)-ϵ-aminocaproic acid lactone c(HPv-ϵAC); 5c ] (IUPAC nomenclature: 3,3-dimethyl-5-aza-1-oxa-cycloundecan-4-11-dione) in bulk results in amorphous alternating poly(amide-ester)s with cyclic structure (Tg = 6.8°C). The fourteen membered cyclo(diamide-diester)s 6a-c (IUPAC nomenclatures:: 4,11-diaza-1,8-dioxa-cyclotetradecan-2,5,9,12-tetraone ( 6a ), 7,14 dimethyl-4,11-diaza-1,8-dioxa-cyclotetradecan-2,5,9,12-tetraone ( 6b ), 3,10-dimethyl-4,11-diaza-1,8-dioxa-cyclotetradecan-2,5,9,12-tetraone ( 6c ) based on β-hydroxy acids and α-aminoacids could not be polymerized. |
