Triple‐shape‐memory polymer films created by forced‐assembly multilayer coextrusion

Abstract

Triple‐shape‐memory polymers are capable of memorizing two temporary shapes and sequentially recovering from the first temporary shape to the second temporary shape and eventually to the permanent shape upon exposure to a stimulus. In this study, unique three‐component, multilayered films with an ATBTA configuration [where A is polyurethane (PU), B is ethylene vinyl acetate (EVA), and T is poly(vinyl acetate) (PVAc)] were produced as a triple‐shape‐memory material via a forced‐assembly multilayer film coextrusion process from PU, EVA, and PVAc. The two well‐separated thermal transitions of the PU–EVA–PVAc film, the melting temperature of EVA and the glass‐transition temperature of PVAc, allow for the fixing of the two temporary shapes. The cyclic thermomechanical testing results confirm that the 257‐layered PU–EVA–PVAc films possessed outstanding triple‐shape‐memory performance in terms of the shape fixity and shape‐recovery ratios. This approach allowed greater design flexibility and simultaneous adjustment of the mechanical and shape‐memory properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44405.

Electromechanical deformation and failure of multilayered films

“…The forced assembly multilayer coextrusion process enables many polymeric systems having unique architectures to be produced including multilayer films, 10 cellular film/foam materials, 11–14 and fibrous membrane systems 9,15–18 . In addition, there has been numerous studies on the multilayered coextruded polymer systems directed toward applications including gas barrier films, 8,19 optical films, 20 shape memory films, 21–24 packaging film/foams, 25 fibrous membranes for filtration, 18,26 antibacterial membranes, 27,28 cellular membranes having through pores 12 and multilayer films with unique dielectric properties 29–36 . These investigations have emphasized the importance of scale within the multilayer films relative to enhanced performance characteristics.…”

Shape memory polymers for self‐folding via compression of thermoplastic sheets

“…Heating an unaltered amorphous polymer sheet above its T g , stretching the material, and cooling the sheet below T g stores strain in the polymer . Industrially, strained polymer sheets are made through numerous methods including blown film extrusion, roll‐to‐roll processing, or film casting . These processes impart uniaxial or biaxial strain within the sheet to alter the overall geometry based on the intended application.…”