UCLA

Stretchable and conductive hydrogels compatible with 3D printing techniques are of critical importance for electronics applications. A wide range of mechanical properties are desired with specific ranges required for different devices such as soft and tissue-like mechanical properties for applications relating to the human body and stronger mechanical properties for applications in soft robotics. Ease of fabrication to obtain complex configurations is a desirable trait for these materials. However, being able to quickly pattern them while still maintaining a high degree of electrical conductivity and stretchability is often hard to achieve. Here we developed UV-crosslinkable hydrogels that can reach high electronic conductivity (>10 S/m) and good stretchability (>150%) based on the combination of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS), ionic liquid, and a hydrogel matrix. In Chapter 1 the fundamentals of conductive hydrogels are discussed. In Chapter 2 the work done to obtain a 3D printable conductive hydrogel with tissue-like mechanical properties (1-100 kPa) is presented. In brief, a polyacrylamide hydrogel matrix is employed and exhibits soft mechanical properties in addition to working in conjunction with the PEDOT:PSS to obtain high electronic conductivities. The resulting material is UV-crosslinkable and achieved in a one-pot synthesis method, capable of producing complex 2D and 3D structures by digital light processing (DLP) printing. In Chapter 3 A poly(vinyl alcohol) methacrylate is utilized and further strengthened to obtain higher mechanical properties (>1 MPa). The resulting material is also UV-crosslinkable and achieved in a one-pot synthesis method. Future directions are outlined for both works.