Polyurethane-Based Composites: Effects of Antibacterial Fillers on the Physical-Mechanical Behavior of Thermoplastic Polyurethanes

Abstract

The challenge to manufacture medical devices with specific antibacterial functions, and the growing demand for systems able to limit bacterial resistance growth, necessitates the development of new technologies which can be easily produced at an industrial level. The object of this work was the study and the development of silver, titanium dioxide, and chitosan composites for the realization and/or implementation of biomedical devices. Thermoplastic elastomeric polyurethane was selected and used as matrix for the various antibacterial functions introduced during the processing phase (melt compounding). This strategy was employed to directly incorporate antimicrobial agents into the main constituent material of the devices themselves. With the exception of the composite filled with titanium dioxide, all of the other tested composites were shown to possess satisfactory mechanical properties. The best antibacterial effects were obtained with all the composites against Staphylococcus aureus: viability was efficiently inhibited by the prepared materials in four different bacterial culture concentrations.

Polyurethane-Based Coatings with Promising Antibacterial Properties

“…As in our previous work [ 12 ], we elected to use silver, titanium dioxide and chitosan for their recognized antibacterial properties. In the present study, however, the use of these compounds in the form of coatings is presented with the idea of providing a direct comparison with alternative preparation techniques (i.e., melt processing and post-processing).…”

“…TPU films with fixed dimensions (5 × 5 cm 2 ) were prepared by compression molding following the procedure presented in our previous work [ 12 ] and used as substrates for the coating employed.…”

“…The molecular, structural, thermal, mechanical and rheological properties together with surface morphology characteristics of the TPU have been widely reported in our previous work [ 12 ].…”

“…This efficiency derives from the possibility to concentrating the antibacterial charge on the surface. Compared to other procedures used to incorporate antibacterial agents (i.e., melt compounding [ 12 , 13 , 14 , 15 , 16 ], where antibacterial agents are trapped between layers of the material constituting the device and are not all exposed to the surface) better antibacterial properties can be achieved. This maximized surface/charge ratio is obtained by starting from a lower amount of charged species and by keeping the processing simple, versatile and low-cost.…”

“…To address these issues and to develop innovative coatings with specific antibacterial functions, we selected silver, chitosan and titanium dioxide. These antibacterials have already used as fillers for thermoplastic polyurethane (TPU)-based composites by us in a previous work [ 12 ]. Here, we use them to prepare TPU-based dispersions/solutions through a simple and versatile preparation method to produce efficient antibacterial coatings.…”