SELF-ASSEMBLY OF SHAPE MEMORY POLYMER PRINTED BY FUSED DEPOSITION MODELING

We demonstrated the method for self-assembly of a polyurethane based shape memory polymer (SMP) printed by a fused deposition modeling (FDM) 3D printer. SMP transfers between a rubber state and a glass state by the change of temperature, and this characteristic is usually used for memorizing a 3D shape. In this study, we used this characteristic not for shape memory but for self-assembly. When a SMP filament is printed in a rubber state by FDM, some internal stress is introduced to the printed SMP structure. Above the glass transition temperature (T-g), the SMP structure transfers to a rubber state and releases internal stress and shrinks. Utilizing bi-layer structure with different shrink rate, we demonstrated that 2D SMP structures can transform into 3D structures. We achieved to control the rate and direction of shrinking by varying printing temperatures and patterns, which then allowed defining bending directions to form 3D structures.