Hydroxy-telechelic copolyesters with well defined sequence structure through ring-opening polymerization

Abstract

New well‐defined macrodiols were prepared by ring‐opening copolymerization of lactones and cyclic diesters with a low molecular weight diol. Suitable monomers are diglycolide, L,L‐dilactide, ε‐caprolactone, and rac‐β‐butyrolactone. With exception of rac‐β‐butyrolactone, the reaction can be performed with or without a catalyst. The use of a catalyst influences the sequence structure of the telechelics. Copolyesterdiols from ε‐caprolactone, diglycolide, and ethylene glycol with random, blocky, and intermediate structure were synthesized and characterized. The analogous copolyesterdiols from L,L‐dilactide, ε‐caprolactone, and ethylene glycol were also prepared. The sequence structure of the random chains with diglycolide corresponds to a random distribution of glycolate units, that of the corresponding chains with L,L‐dilactide exhibit a random distribution of L,L‐dilactate units.

Hydrolytic Degradation of Phase-Segregated Multiblock Copoly(ester urethane)s Containing Weak Links

“…[20] These macrodiols are of random, block, and statistical distribution of glycolate and 6-hydroxycaproate units, respectively (the denotation stat is used here to designate a distribution that lies between random and blocky). [19] We depart from the hypothesis [19] that the glycolyl-glycolate ester linkage (the connection between two glycolate monomer units in sequence) is the most rapidly hydrolyzable linkage in our polymers. This diad is most frequently present in segments with a blocky sequence structure, i.e.…”

“…b The synthesis and structure of these polymers have been reported earlier [19,20] and we will only give a synopsis here. The block copolymers are built up from hard segments of poly[(3-(R)-hydroxybutyrate)-co-(3-(R)-hydroxyvalerate)] and a copolyester soft segment.…”

“…As soft segments, copolyester diols from ethylene glycol, diglycolide and e-caprolactone are used. We expect [19] the different ester linkages in these copolyesters to have very dissimilar rates of hydrolytic cleavage, and assume that the bonds in glycolyl-glycolate are the most easily hydrolyzable and may serve as weak links for chain scission.…”

Correspondence of high-frequency ultrasound and histomorphometry of healing rabbit Achilles tendon tissue

“…Polymer A biodegradable polyester urethane polymer (trade name DegraPol Õ ) with poly-hydroxy-butyrate as a crystalline segment and "-caprolactone as a soft segment was produced according to given protocols (11)(12)(13)(14).…”

Regenerative Medicine: Reconstruction of Tracheal and Pharyngeal Mucosal Defects in Head and Neck Surgery

“…The analyses of the mechanisms of the integration of the implant material in the adjacent tissues as well as the mechanisms of material degradation and tissue regeneration are topics of currently ongoing examinations. It was recently found that by introducing glycolide -glycolide diads as weak links [105,137,138] in the macrodimethaycrylate precursors, a faster and adjustable degradation rate of the rather slowly degrading AB -copolymer networks can be achieved. For semicrystalline partially degradable AB -copolymer networks from oligo([ ε -caprolactone] -co -glycolide) dimethacrylates and n -butylacrylate of different molar glycolide contents in vitro higher degradation rates of AB networks with higher χ G were measured by mass loss, decrease of G, and increase of Q due to the glycolide containing ester bonds and especially glycolide -glycolide diades in the oCG, which can be considered as weak links [105,137] .…”