Preparation and properties of biomedical segmented polyurethanes based on poly(ether ester) and uniform-size diurethane diisocyanates

Abstract

This study describes the preparation and properties of a novel aliphatic cost-effective segmented polyurethanes (SPUs) based on poly(ether ester) (poly-(ε-caprolactone-co-l-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-co-l-lactide), PECLA) and uniform-size diurethane diisocyanates (HDI-BDO-HDI). PECLA was synthesized via bulk ring-opening polymerization with poly(ethylene glycol) (PEG) as an initiator and ε-caprolactone, l-lactide as monomers. By chain extension of PECLA diol with HDI-BDO-HDI, three SPUs with different hydrophilic segments content and hard segments content were obtained. The chemical structures of the chain extender, PECLA and SPUs were confirmed by H NMR,C NMR, FT-IR, HR-TOF-MS and GPC. The influences of PEG content and uniform-size hard segments on in vitro degradability and mechanical properties of SPU films were researched. Similar thermostability observed in TGA curves of SPU films indicated that the hard segments and PEG content had little influence on the thermostability. The formation of microsphase-separated morphologies, which were demonstrated by the results of DSC and XRD, and physical-linking (H-bonds) network structures led to better mechanical properties of SPU films (ultimate stress: 23.1-17.9 MPa; elongation at break: 840-1130%). The results of water absorption and water contact angle showed that the bulk and surface hydrophilicity were closely related with the hydrophilic PEG content in SPU backbone. And the water absorption being less than 10 wt% indicated that the SPU films had low swelling property. In vitro hydrolytic degradation studies showed that the time of the SPU films becoming fragments was 34-19 days and the degradation rate increased with the increasing content of hydrophilic segments in SPUs, indicating that the degradation rate of SPU films could be controlled by adjusting PEG content. Cytotoxicity test of film extracts were conducted using L929 cells, and the relative growth rate exceeded 90% after incubation for 24, 48 and 72 h, showing excellent cytocompatibility. The acceptable mechanical properties, controllable biodegradability and excellent cytocompatibility of the polyurethanes can make them good candidates for further biomedical applications.

Degradation and stabilization of polyurethane elastomers

“…This bulk property change results in faster cleavage of unstable ester bonds [453]. In contrast, a higher PCL content, or a lower In some studies [472,473] where a PCL-PEG-PCL triblock copolymer or a poly(CL-co-LA)-PEG-poly(CL-co-LA) was used as the macrodiol component, increasing the PEG chain length or decreasing the PCL chain length in the triblock segment could increase the water absorption and degradation rate of the resulting PUU in PBS (pH 7.4). Hydrolysis-sensitive chemical bonds in the segment could further influence the hydrolytic stability of PUs [474].…”

A Mild Method for Surface-Grafting PEG Onto Segmented Poly(Ester-Urethane) Film with High Grafting Density for Biomedical Purpose

“…The blank SPEU film exhibited outstanding mechanical properties with a strain at break of 896% and an ultimate stress of 38.1 MPa. The excellent mechanical properties should be attributed to the compact physical-linking network structure formed by multiple H-bonds existing among urethane groups and between urethane and ester groups, as per the description in our previous report [36]. The modified films, including SPEU-NH 2 , SPEU-PEG-a, SPEU-PEG-b, and SPEU-PEG-c films displayed analogous stress-strain behaviors with the strain at break of 866–884% and ultimate stress of 35.5–36.4 MPa (Table 2), which were only slightly lower than that of parent SPEU film.…”

Preparation, Physicochemical Properties, and Hemocompatibility of the Composites Based on Biodegradable Poly(Ether-Ester-Urethane) and Phosphorylcholine-Containing Copolymer

“…From the curves, it could be found that the composite films with PMEH content increasing from 0 to 20 wt% (PMPU-0~PMPU-20) behaved as soft elastic materials, displaying a smooth transition from the elastic to plastic deformation regions [42]. The pure PEEU (PMPU-0) containing uniform-size hard segments exhibited good tensile properties with ultimate stress of 20.8 MPa, strain at break of 930% and initial modulus of 19.5 MPa, which was due to the compact physical-linking network structure formed by denser H bonds existing not only among carbamate groups but between carbamate and ether/ester groups [43]. When the PMEH was blended in PEEU, the strain at break decreased gradually.…”