Seawater degradable thermoplastic polyurethanes

Abstract

Degradable thermoplastic polyurethane (TPU) elastomers incorporating poly(D,L-lactide-co-glycolide) (PLGA) were synthesized and characterized. The soft segments consisted of a mixture of poly(butylene adipate) (PBA) and PLGA with PBA/PLGA ratios of 100/0, 75/25, and 50/50 wt %. Two PLGA polyesters were used. BD-PLGA was initiated from butanediol; whereas BHMBA-PLGA was initiated from 2,2-bis-(hydroxymethyl)butanoic acid. The hard segments consisted of dicyclohexylmethane-4,4 0 -diisocyanate (H 12 MDI) and 1,4-butanediol (BD). The hard segment content, expressed as the weight ratio of BD to polyol used in the TPU formulation, was set either at 8 or 12% (31.2 or 38.1% hard segment by weight, respectively). In all cases initial [NCO]/[OH] ratio was 1.03. The tensile modulus of the TPUs ranged from 9 to 131 MPa and ultimate strains ranged from 100 to 750%. DMA was used to probe the thermomechanical transitions of the TPUs and indicated useful application temperatures from well below zero up to 60-80 C depending on the formulation. Hydrolytic degradation of the TPUs was tested in seawater at 37 C. All of the PLGA-containing TPUs showed enhanced degradation compared to those with only PBA as the soft segment. The latter compositions remained essentially unchanged throughout the test while the PLGAcontaining TPUs lost as much as 45% of their initial mass in 153 days. Molecular weights of TPUs containing degradable polyols were lower than those derived from 100% PBA polyol.

Multiscale approach to the morphology, structure, and segmental dynamics of complex degradable aliphatic polyurethanes

“…Polyurethane (PU) elastomers, their blends and nanocomposites are very popular and frequently used polymeric materials thanks to broad versatility of their functional properties . For a longer time, they have been amply used as automotive accessories, sport devices, in furniture, packaging, and so forth, but at present, they have also been tested in modern medical applications . Although these materials have been attracting the interest of scientists and manufacturers for more than 6 decades, they are still appealing from the academic point of view, especially if a non‐conventional combination of starting components have been used in PU formulation.…”

“…The development of synthetic degradable materials with appropriate mechanical and targeted functional properties (suitable compatibility, non‐toxicity, high surface area, tailored degradation speed from weeks to years) is the focal point of material science, especially in the last decade . Degradable polymeric materials are not only interesting as potential biomaterials for applications in medicine and related branches, but they are suitable candidates replacing the non‐degradable plastics accumulating in the environment.…”

Thermal, mechanical, and thermo‐mechanical properties of thermosets produced using low Mw functionalized polyolefins and polyamines

“…Dynamic mechanical analysis is a technique widely used to characterize the morphology of polymeric materials. 14,[16][17][18][19] Phase separated polymeric blends and elastomers 20 show distinct glass transition temperatures (T g ) corresponding to the each component in the multi phase system, whereas a single T g that is intermediate in temperature between the glass transition temperatures of the components, is taken as evidence of miscibility or partial miscibility of such polymeric systems. Temperature sweep data for the three thermoset materials representing NH 2 /MA molar ratios of 1.5, 2.0, and 3.0 are presented in Figure 5.…”

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

“…It is also known that polyurethanes have faster degradation rates under the influence of heat, ultraviolet radiation, humidity, etc 13, 14. Thus, many applications require polyurethanes which maintain their mechanical stability even after exposure to water, water solutions, water dispersions, seawater, etc.…”

“…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…”