Since the introduction of shape memory polymers, this field of research has undergone dramatic changes from simple to more complex material response such as multi/tripe shape behavior. Thus far, proposed methods to achieve such complex behavior require elaborate material synthesis and processing. Seeking to achieve triple shape behavior with a simpler route to materials synthesis, we introduce here a method that utilizes polymerization induced phase separation (PIPS) to yield a requisite combination of amorphous epoxy matrix and semicrystalline thermoplastic. A large range of morphologies can be obtained by PIPS in a controlled manner, with the two major types being particle/matrix (or sea/island) morphology and co-continuous morphology. These two morphologies were achieved by altering the weight fraction and molecular weight of the semicrystalline thermoplastic in the composite. All composites showed two transitions and three modulus-plateaus, a necessary factor for triple shape memory behavior.  Mechanical properties, bulk shape memory and surface shape memory properties of the composites were investigated by characterizing the ability of the composites to fix and subsequently undergoing the shape changes: temporary shape 1 to temporary shape 2 to permanent shape. This work enabled determination of the best morphological structures for triple shape behavior. Finally we fabricated open cell foams with triple shape memory properties that can be deformed to high strains under relatively low stresses. Given the simplicity of our composite fabrication method, we envision several applications such as film adhesives and coatings.

New triple shape memory composites

248th National Meeting (2014)

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