Chapter 8 - Multifunctional polymer composites for 3D and 4D printing

Abstract

Tailored multifunctional capabilities, demanded in domains ranging from aerospace to biomedical fields, are achieved through judicious combinations of structural/nonstructural fibers, matrices, and coatings. Multifunctional composite structures are thus designed to perform a variety of secondary functions (sensing, actuation, energy storage/harvesting, etc.) apart from their primary structural functions (strengthening, stiffening, and stabilizing). In realizing such multifunctional capabilities, complex stress-prone assemblies of low-length-scale components/coatings of materials with distinct properties are essential. Fortunately, additive manufacturing has demonstrated the potential to efficiently and effectively enable such robust assemblages. Apart from such three-dimensional (3D)-printed spatial nonuniformity, four-dimensional (4D) printing renders time-dependent properties to be triggered by various stimuli; 3D/4D printing of multifunctional composites possesses advantages over conventional manufacturing (where even feasible!) in term of time, mass, volume, overall cost, and efficiency. This chapter reviews various printing methods, candidate materials, and characterization of multifunctional printed components. The emphasis is on structural members integrated with electronic components, photovoltaic solar cells, piezoelectric materials, and battery fiber composites. A short review of 4D structures due to various stimuli is also carried out. Such 3D/4D printed flexible/wearable electronics, smart devices, and adaptive structures could find applications all the way from household appliances to satellites.