Ultrafast Digital Printing Of Shape Changing Materials

Stimuli-responsive shape-changing polymers have vast technological potential(e.g.biomedical and aerospace).Their geometric shapes play essential roles towards their ultimate functions,yet they are to a large extent limited by traditional processing techniques like liquid molding.The digital nature of 3D printing has led to its unparalleled flexibility in producing complex shapes,but its typical layer by layer process severely limits its printing speed and material properties consequently its practical potential.We introduce a concept to digitally encode arbitrary spatio-chemical heterogeneity into a two dimensional polymer film using visible light triggered polymerization of commercial monomers.Subsequent swelling and/or desolvation releases the stresses from the heterogeneity,turning the planar film into highly controllable three dimensional designer shape(s).The process is highly versatile in that it permits the use of a wide variety of printing precursors,enabling thus ease incorporation of a fourth dimension in its stimuli-responsiveness.The overall printing process employs fast light curing and does not involve any speed limiting mechanical movement,leading to ultrafast printing in the 30 sec range compared to hours for typical 3D printing.At first,we use the method of 4D printing to ultrafast "printing" the 3D structures of stimuli-responsive hydrogel,wax-based gel and shape memory polymers.Then the application of these kinds of materials are studied.We investigate the method for adjusting corneal curvature through digital corneal crosslinking,ultrafast construction of molding for lost wax casting,and shape memory polymer based substrate for soft stretchable eletronics.