Blends of novel L‐tyrosine‐based polyurethanes and polyphosphate for potential biomedical applications

Abstract

Elastomeric biodegradable polyurethanes and polyphosphate have been developed using an Ltyrosine-based diphenolic monomer desaminotyrosinetyrosine hexyl ester (DTH). Soft segments, which are polycaproloctone diol (PCL) and polyethylene glycol (PEG) have been used for the synthesis of two biodegradable Ltyrosine polyurethanes (LTUs), which are PEG-C-DTH and PCL-C-DTH. An investigation of the physico-chemical properties shows that these polymers have dramatically different properties. By blending LTUs with Ltyrosine polyphosphate (LTP), we hope to produce a family of materials with a wide range of thermal, morphological, surface, and degradative properties. Examination of the blends shows a smooth surface morphology with a partially phase-separated structure. These findings are consistent with the results obtained from thermal analysis of the blends. Hydrophilic nature of PEG imparts the PEG-based blends (PEG-C-DTH/LTP) with a significantly higher surface and bulk hydrophilicity compared with the PCL-based blends (PCL-C-DTH/LTP).Finally, the blends demonstrate a rapid initial hydrolytic degradation in phosphate buffered saline (PBS) followed by a significantly slower, prolonged degradation. The observed trend may occur due to the rapid hydrolytic degradation rate of the polyphosphate polymer followed by the degradation of the polyurethane component. Thus, tuning the physical properties by blending LTUs with LTP may be useful for drug delivery device and soft tissue engineering scaffold applications.

Approach to Fabricating Thermoplastic Polyurethane Blends and Foams with Tunable Properties by Twin‐Screw Extrusion and Microcellular Injection Molding

“…Polymer blends and composites have been extensively studied in recent decades in both the academic and industrial communities to develop new materials with desirable properties at low cost and in a short period of time. 16 However, reports on blends of TPUs with different properties are scarce, especially by melt blending. 12 Those polyurethane blends can supply different enhancements such as improvement of mechanical properties, 13 decrease of flammability, 14 improvement of water resistance, 15 and use in biomedical applications.…”

“…12 Those polyurethane blends can supply different enhancements such as improvement of mechanical properties, 13 decrease of flammability, 14 improvement of water resistance, 15 and use in biomedical applications. 16 However, reports on blends of TPUs with different properties are scarce, especially by melt blending. Fromstein and Woodhouse 17 synthesized four kinds of polyurethane blends with polycaprolactone and polyethylene oxide with soft segments at different ratios, which had different mechanical properties and degradation rates.…”

Cellular interactions with biodegradable polyurethanes formulated from L-tyrosine

“…These studies are consistent with similar experiments conducted by Sarkar et al 14 Furthermore, the surface morphology of the polymer films becomes progressively rougher upon hydrolytic degradation, and the formation of surface defects, such as pores and crevices, can be observed. 14,30 Since a reasonable amount of mass loss is observed to occur by hydrolytic degradation of LTUs, the products that were obtained have been used for cell viability studies. Figure 2 shows a representative image of cells exposed to a 20-mg PEG-L-DTH film for a period of 24 h. The viability of primary human dermal fibroblasts after direct-contact exposure to 20 mg of four different LTU films and PLGA control films for a period of 24 h is summarized in Figure 3.…”

Degradation of crosslinked poly(ester‐urethanes) elastomers in distilled water: Influence of hard segment

“…Crosslinked polyurethanes may thus have high water‐resistance and high mechanical strength which are required in many applications 20, 21. There have also been studies focusing on the dependence of hydrolytic degradation on the nature of the polymeric chain, degradation which was conducted in buffered saline solutions22–24 or seawater 13, 25, 26…”

“…[17][18][19] Crosslinked polyurethanes may thus have high water-resistance and high mechanical strength which are required in many applications. 20,21 There have also been studies focusing on the dependence of hydrolytic degradation on the nature of the polymeric chain, degradation which was conducted in buffered saline solutions [22][23][24] or seawater. 13,25,26 The objective of this work is to analyze the effect of structural variation of the chemical crosslinked hard segments on the hydrolytic degradation behavior of the crosslinked polyurethanes that were subjected to degradation at 37 C in distilled water in a specific environment: in the dark without exposure to enzymatic conditions and under the continuous circulation of water.…”