Synthesis of degradable, biocompatible, and tough block‐copolyesterurethanes

Abstract

We describe the synthesis of micro-phase-segregated block-copolyesterurethanes from telechelic hydroxyterminated poly [ [(R)-3-hydroxybutyric acid]-co-[(R)-3-hydroxyvaleric acid]] (PHB-diol) as "hard segments" (i. e., crystallizable chain sections) and hydroxyterminated poly(ecapro1actone)-diethylene glycol-poly(8-caprolactone) (PCL-diol) or telechelic .hydroxyterminated pol y [(adipic acid)-alt-( 1,4-butanediol; diethylene glycol; ethylene glycol)] (Diorez") as "soft segments", with 2,2,4-triethylhexamethylene diisocyanate (TMDI) or methyl (S)-2,6-diisocyanatohexanoate (LDI). High molecular weights were obtained with or without catalyst, the properties of the polymers depending only slightly on the presence or absence of the catalyst. The materials thus obtained were investigated also with respect to their mechanical properties and it was found that Young's modulus directly depends on the fraction of crystallizable PHB-diol in the block copolymer while the type of non-crystallizable segment or diisocyanate had only a minor influence: Generally, the tensile strength increases and the elongation at break decreases with increasing content of PHB-diol. Around body temperature, these polymers exhibit only mild changes in their mechanical behavior. The chain length of the non-crystallizable segment indirectly influences the morphology and the mechanical properties of the polymers through changes in the phase-segregation behavior.

A review of biodegradable polymers: uses, current developments in the synthesis and characterization of biodegradable polyesters, blends of biodegradable polymers and recent advances in biodegradation studies

“…Hirt et al 57 have described the synthesis of microphase-segregated block copoly(ester-urethane)s from telechelic hydroxy-terminated poly(PHB-diol) (hard segments) and hydroxy-terminated PeCL or telechelic hydroxy-terminated poly(adipic acid)-alt-(1,4-butanediol ; diethylene glycol ; ethylene glycol) (Diorez}) (soft segments), with either 2,2,4-triethylhexamethylenediisocyanate (TMDI) or methyl (S)-2,6-diisocyanatohexanoate (LDI). High-molecular-weight copolymers were obtained with or without a catalyst and the mechanical properties of the copolymer were investigated.…”

Tuning electrospinning parameters for production of 3D-fiber-fleeces with increased porosity for soft tissue engineering applications

“…These different polymerizations lead to polymers with different mechanical properties, some with very high elasticity. Several compositions have been produced and compared by Hirt et al (1996). The elasticity can be varied between 20-1250 MPa and covers most of biological tissues that might need to be replaced by tissue engineering approaches.…”

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

“…Moreover, nonbiodegradable PEG-PPG-PEG triblock copolymers have been reported to show hyperlipidemia and high plasma level of cholesterol in rabbits and rats [92], and less cells (L929 mouse fibroblasts) attachment [93], suggesting that introducing a hydrophilic, biodegradable and biocompatible soft phase in the PHAs block copolymers is an effective way to design novel biomaterials. Other diisocyanate, including toluene diisocyanate [94], 2,2,4-trimethylhexamethylene diisocyanate [95][96][97], and L-lysine methyl ester diisocyanate [96][97][98] have also been applied to synthesize block copolymer. The coupling reaction via diisocyanate must be carried out under anhydrous conditions and an argon or nitrogen atmosphere due to the moisture sensitivity of the coupling agent.…”