Abstract
The effect of sequence on copolymer properties is rarely studied, especially the degradation behavior of the biomaterials. A series of linear-comb block, gradient, random copolymers were successfully achieved using hydroxylated polybutadiene as the macroinitiator by simple ring-opening polymerization of l-lactide (l-LA) and 1,3-trimethylene carbonate (TMC). The hydrolytic degradation behaviors of the copolymers were systemically evaluated by using nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM) to illustrate the influences of comonomer compositions and sequence structures. The linear-comb block copolymers (lcP(TMC-b-LLA)) with different compositions had different degradation rates, which increased with l-LA content. Thermal property changes were observed with decreased Tm and increased ΔHm in all block copolymers during the degradation. To combine different sequence structures, unique degradation behaviors were observed for the linear-comb block, gradient and random copolymers even with similar comonomer composition. The degradation rates of linear-comb PLLA-gradient-PTMC (lcP(LLA-grad-TMC)) and linear-comb PLLA-random-PTMC (lcP(LLA-ran-TMC)) were accelerated due to the loss of regularity and crystallinity, resulting in a remarkable decrease on weight retention and molar mass. The hydrolysis degradation rate increased in the order lcP(TMC-b-LLA), lcP(LLA-ran-TMC), lcP(LLA-grad-TMC). Therefore, the hydrolytic degradation behavior of comb-like graft copolymers depends on both the compositions and the sequences dramatically.
Highlights
Synthetic biodegradable polymers, such as polylactide (PLA), polyglycolide (PGA), polycaprolactone (PCL) as well as their copolymers, have been proverbially studied and widely used in biomedical applications [1,2,3]
Linear-comb PLLA and linear-comb PTMC homopolymers were applied as comparison samples
Two groups of graft copolymers were analyzed during hydrolytic degradation: a series of linear-comb PLLA/PTMC block copolymer with different comonomer compositions (TMC/l-LA = 3/7, 5/5, 7/3), and three kinds of linear-comb PLLA/PTMC copolymers with similar composition (TMC/l-LA = 5/5) in block, gradient and random sequences
Summary
Synthetic biodegradable polymers, such as polylactide (PLA), polyglycolide (PGA), polycaprolactone (PCL) as well as their copolymers, have been proverbially studied and widely used in biomedical applications [1,2,3]. PLA is a very promising material because it combines biodegradability, biocompatibility, and excellent processability, while it is derived from natural resources [4]. PLA has been considered as an ideal biomaterial for biomedical and pharmaceutical applications, especially in tissue engineering and controlled drug delivery. To be used in the biomedical field, polymers must generally meet strictly property requirements. The improvement of properties appears necessary for most application fields
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.