Microstructure, thermal and rheological properties of poly(L‐lactide‐co‐ε‐caprolactone) tapered block copolymer for potential use in biomedical applications

Abstract

This work investigates the thermal and rheological properties of the poly(L-lactide-co-ε-caprolactone), PLC, tapered block copolymer synthesized by ringopening polymerization (ROP) using stannous octoate (Sn [Oct] 2 ) as an initiator. The PLC copolymer (LL: CL = 48.9:51.1 mol% from 1 H-NMR) was obtained as a transparent, elastomeric material with a tapered monomer sequencing (R = 0.38 from 13 C-NMR data) due to randomizing effect of transesterification. The M n , M w , and Đ M of the PLC copolymer from GPC are 8.04 Â 10 4 , 1.36 Â 10 5 , and 1.69 respectively. The obtained moduli of the copolymer at 100% and 300% strain are rather low at 0.91 and 1.16 MPa. The rheological properties of the PLC melt are studied in terms of steady and oscillatory shear flow. The master curves at a reference temperature of 150 C with 5% and 100% strain suggest that the copolymer melt may contain some regular microstructures, such as small crystalline domains of poly(L-lactide), which remained intact at high strain deformation. The flow curve of the PLC melt at 150 C constructed from a cross model shows a Newtonian viscosity (η 0 ) of 6754 Pa-s, a consistency index (k) of 0.59, and a Power Law index of 0.35 where the onset of Power Law behavior is observed at around 10 s À1 . For the fabrication of the PLC nerve tubes, the best result is observed from the extruded PLC tubes with a combination of PEG porosifying agent leaching and phase immersion precipitation at 2 C using DMF/1,4-dioxane (1:1) as a mixed solvent and ethanol/chloroform (9:1) as a non-solvent. The porous tube obtained under this condition has a pore diameter and pore depth of approximately 2.3-2.5 and 30 μm respectively.

Effect of Degradation in Small Intestinal Fluids on Mechanical Properties of Polycaprolactone and Poly-l-lactide-co-caprolactone

“…The stress in the PCL sample is reduced by roughly 13% while the stress reduction in PLCL is 30%, and is sustained over a longer time. This difference can be explained by the semi-crystalline nature of PCL, while PLCL exhibits microphase separations due to the presence of the L-Lactide units [25]. Table S3 lists the coefficients of the Prony expansion of the dimensionless relaxation modulus (Equation ( 1)) and these can readily be used in finite element software packages for both PCL and PLCL.…”

“…The premature failure of PLCL can be attributed to the presence of the L-Lactide units. Surrounded by the more hydrophobic Caprolactone chains, they are more prone to hydrolysis, increasing the rate of the polymer chain scission [25]. In contrast, PCL is a hydrophobic semi-crystalline polymer, exhibiting a high resistance to hydrolysis.…”

Conductive and antibacterial scaffold with rapid crimping property for application prospect in repair of peripheral nerve injury

“…Although autologous nerve or allogeneic nerve transplantation is known as the gold standard, 4 this is not able to meet the demands of all cases due to the lack of donor nerve, the difficulty of tissue size matching and the immune response of allogeneic nerve transplantation. As proven to be the best alternative way for nerve repair and regeneration, nerve scaffolds can enhance proliferation and adhesion of Schwann cell (SCs) based on their favorable mechanical property, biocompatibility and biodegradation, 5 and further expedite the growth of axons 6,7 . For better repair effects, active materials are generally loaded on tissue engineered nerve conduits, such as growth factors, antibacterial regents and electroactive materials 8…”