Tunable Multiple‐Shape Memory Polyethylene Blends

Abstract

Shape memory polymers (SMPs) are an important class of smart materials. Usually, these polymers can be switched between two shapes. Recently, the possibility of switching more than two shapes was introduced for SMPs with relatively low strain storage capability. In this work, a lightly cross-linked polyethylene blend comprising 80 wt% EOC, 15 wt% LDPE, and 5 wt% HDPE is prepared in order to obtain a tunable multiple-shape memory polymer with high strain storage capacity. It is found that depending on the programming procedure, this SMP obtains a dual-, triple-, or quadruple-shape memory effect, with well-defi ned intermediate temporary shapes (retraction < 0.5% K −1 ) over a signifi cantly broad temperature range (up to 30 K), large storable strains (up to 1700%), and nearly full recovery of all shapes ( > 98.9%). transition range. [14][15][16][17][18] For instance, Xie [ 19 ] obtained a tunable multiple-shape memory for PFSA (perfl uorosulfonic acid ionomer), which possesses a broad glass transition from 55 to 130 ° C, by correlating certain temporary shapes to different temperatures within its glass transition range. Kolesov and Radusch [ 20 ] showed a triple-shape memory for cross-linked polyethylene blends of HDPE and two different ethylene-1-octene copolymers (EOC), by correlating different temporary shapes to distinct temperatures within a broad melting range. With this system, they were able to store strains of up to 100% with an intermediate shape at 44%. In general, multiple-shape memory polymers store strains of up to 240%, which limit the relative retraction response. We have recently found that the stored strain of PE-SMPs can be greatly enhanced by lowering the degree of cross-linking in a way that the resulting network is at the borderline between thermoplastics and elastomers. [ 21 ] In the present manuscript, this concept is extended to polyethylene blends in order to obtain a tunable multiple-shape memory polymer with large strain storage capability. Experimental Section MaterialsHigh density polyethylene (HDPE) (Lupolen 6021D, M w = 220 000 g mol −1 , PDI = 10, 0.5 branches per 1000 C atoms) [ 22 ]

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

“…Polybutylene succinate (PBS) was grafted onto maleated-polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (m-SEBS) [150]. The poly(ethylene-co-butylene) segments within the Blending two (or more) polymers with different transition temperatures followed by crosslinking is a versatile approach to prepare a multi-SMP [152,153]. Doping small molecules into a dual-SMP network represents another interesting approach to introduce an additional transition phase [154,155].…”

Environmental Memory of Polymer Networks under Stress

“…[ 10 ] The set of properties can be greatly enhanced by blending, [11][12][13][14][15] functional groups, [16][17][18] and additives. [ 10 ] The set of properties can be greatly enhanced by blending, [11][12][13][14][15] functional groups, [16][17][18] and additives.…”

Cellulose Acetate for Shape Memory Polymer: Natural, Simple, High Performance, and Recyclable

“…16,17 The reversible phase can be crystalline or amorphous which is responsible for shape fixation, while fixing phase can be either physically or chemically cross-linked point which determines the permanent shape. Based on this structure principle, many methods have been used to realize shape memory effect, such as two-segment polyurethane (PU), 18,19 chemically cross-linked polyester or polyolefin, [20][21][22] ionic cross-linked polymer networks, 23 and p-p cross-linked polymer networks. 24 Although these materials could show high shape memory properties, there still exist some drawbacks for them in some degree: low mechanical strength, absence of biocompatibility or biodegradation.…”