Fluorinated Polymers as Smart Materials for Advanced Biomedical Applications

Abstract

Fluorinated polymers constitute a unique class of materials that exhibit a combination of suitable properties for a wide range of applications, which mainly arise from their outstanding chemical resistance, thermal stability, low friction coefficients and electrical properties. Furthermore, those presenting stimuli-responsive properties have found widespread industrial and commercial applications, based on their ability to change in a controlled fashion one or more of their physicochemical properties, in response to single or multiple external stimuli such as light, temperature, electrical and magnetic fields, pH and/or biological signals. In particular, some fluorinated polymers have been intensively investigated and applied due to their piezoelectric, pyroelectric and ferroelectric properties in biomedical applications including controlled drug delivery systems, tissue engineering, microfluidic and artificial muscle actuators, among others. This review summarizes the main characteristics, microstructures and biomedical applications of electroactive fluorinated polymers.

Keywords: biomedical applications; electroactive; fluorinated polymers; piezoelectric; poly(vinylidene fluoride).

Figure 1

Free radical vinyl polymerization of the monomer vinylidene fluoride to obtain PVDF. Different chain conformations of PVDF in the apolar α-phase and in the polar β- and γ-phases.

Figure 2

(a) Schematic illustration of a flexible piezoelectric sensor configuration including a P(VDF-TrFE) nanofibre mat sandwiched between a layer of PDMS and PVA-PDMS; (b) SEM image of the cross-section of the integrated sensor; (c) photographs of the integrated sensor applied on skin and (d) real-time sensor output waveforms at three consecutive body conditions before and after exercise. Reproduced with permission [196].

Figure 3

Graphical representation of the biomaterial implantation surgery protocol and representative section of Hematoxylin and Eosin (H&E) staining the healing defects 4 weeks after implantation on a poled β-PVDF film. Reproduced with permission [203].

Figure 4

Movie frames of the experimental qualitative evaluation of a mixture between water and a dye with and without acoustic actuation. As proof of concept, a cuvette with dimensions of 8 mm width × 7 mm height × 2 mm thickness was used and actuated by PZT and β-PVDF transducers placed underneath, driven by a 24 Vpp sinusoidal voltage. Reproduced with permission [220].

Figure 5

Preparation of drug-loaded PVDF fibres by electrospinning. Reproduced with permission [230].