Synthesis of Novel Shape Memory Thermoplastic Polyurethanes (SMTPUs) from Bio-Based Materials for Application in 3D/4D Printing Filaments

Bio-based thermoplastic polyurethanes have attracted increasing attention as advanced shape memory materials. Using the prepolymer method, novel fast-responding shape memory thermoplastic polyurethanes (SMTPUs) were prepared from 100% bio-based polyester polyol, poly-propylene succinate derived from corn oil, diphenyl methane diisocyanate, and bio-based 1,3-propanediol as a chain extender. The morphologies of the SMTPUs were investigated by Fourier transform infrared spectroscopy, atomic force microscopy, and X-ray diffraction, which revealed the interdomain spacing between the hard and soft phases, the degree of phase separation, and the intermixing level between the hard and soft phases. The thermal and mechanical properties of the SMTPUs were also investigated, wherein a high hard segment content imparted unique properties that rendered the SMTPUs suitable for shape memory applications at varying temperatures. More specifically, the SMTPUs exhibited a high level of elastic elongation and good mechanical strength. Following compositional optimization, a tensile strength of 24-27 MPa was achieved, in addition to an elongation at break of 358-552% and a hardness of 84-92 Shore A. Moreover, the bio-based SMTPU exhibited a shape recovery of 100%, thereby indicating its potential for use as an advanced temperature-dependent shape memory material with an excellent shape recoverability.

Utilizing Radio Frequency Plasma Treatment to Modify Polymeric Materials for Biomedical Applications

Studies that utilize radio frequency plasma modification as a strategy to tune the surface properties of polymeric constructs with the goal of enhancing their use as biomedical devices have grown considerably in number over the past decade. In this Review, we present the importance of plasma surface treatment to biomedical applications, including tissue engineering and wound healing. First, we introduce several key polymeric materials of interest for use as biomaterials, including those that are naturally derived and synthetic. We, then, provide an overview of possible outcomes of plasma modification, such as surface activation, etching, and deposition of a thin film, all of which can be used to alter the surface properties of a given polymer. Following this discussion, we review the methods used to characterize plasma-treated polymer surface properties, as well as the techniques used to evaluate their interactions with biological species of interest such as mammalian cells, bacteria, and blood components. To close, we provide a perspective on future outlooks of this exciting and rapidly evolving field.