Recently, we successfully fabricated a series of poly(dimethyl acrylamide-co-stearyl acrylate and/or lauryl acrylate) (PDMAAm-co-SA and/or LA) based mechanically tunable thermally induced shape memory type hydrogels (SMGs) via stereolithographic 3D printing process (Shiblee et al., Soft Matter, 2018). By utilizing anisotropic swelling and mechanical properties of the SMGs, we also developed 3D printed SMG-based soft actuator (Shiblee et al., Adv Mat Technol., 2019) using the bimetal thermostat concept (S. Timoshenko, J Opt Soc Am., 1925) using heat and swelling as external stimuli.
Self-healing polymers (SHP), developed for extending the life and reducing costs, could be used with external stimulus to repair damage (crack or fracture). Generally, it is challenging to endow the two functions (shape memory and self-healing) of a single polymer; the same polymer is not only able to change its shape but also optically healable.
Therefore, in this project we aim to develop a novel light triggered shape memory assisted self-healable engineering gel materials from macro to micro scale 3D dimension with multipurpose application focusing in soft robotics.
Engineering polymeric materials with multifunctionality scarce in facile and programmable fabrication processes and in soft machine development. Depending on the target application we will exploit this shape memory based self-healing material’s (SH-SMGs) full potential in soft robotics (soft actuators, sensors and integrated robots) where degree of freedom (DOF) and machine deep learning will be considered as extensively. Fabrication process will be done with three-dimensional printing (3D printing) considering freedom of designability and fine resolution. And then finally these biomimetic soft robotic functionalities will be used in smart textiles, biomedical devices, autonomous robotics, drug delivery and tissue engineering etc.
We propose a novel engineering material that shows light trigger shape memory and self-healing property. In principle, photothermally induced shape-memory effect can be activated in polymer network (embedded crystal monomers) using fillers (Au nano particles, carbon nanotubes, graphene etc.) that has high efficiency in converting optical energy to heat through non-radiative energy decay of excited electrons. Self-healing property can be achieved by recrystallize the crystalline domains that are across the boundary between the separate strips at glass transition temperature (Ttr) in the physically crosslinked gel network.
The two year implementation of the study are given below:
First Year: Development of materials, 3D printing of materials and Physical characterization
Development of materials: As a first step, we will develop light triggered SH-SMG material via physical crosslinking of DMAAm (amorphous main chain)) and SA (crystalline side chain) where AuNPs will be used as a filler that will activate the shape memory and self-healing property through light trigger. Due to the advantageous surface plasmon resonance of AuNPs, they are highly efficient in transforming optical energy to heat that will melt the SA monomers to rejoin the raptured part. Gel solutions for printing will be prepared by mixing the monomers, cellulose fibers, fillers, initiator and UV absorber in particular ratios. The gel solutions will be stirred for 15 minutes at 60 ℃ with a continuous supply of N2 gas to create an inert environment.