Dually Actuated Triple Shape Memory Polymers of Cross-Linked Polycyclooctene–Carbon Nanotube/Polyethylene Nanocomposites

Abstract

In this work, electrically and thermally actuated triple shape memory polymers (SMPs) of chemically cross-linked polycyclooctene (PCO)-multiwalled carbon nanotube (MWCNT)/polyethylene (PE) nanocomposites with co-continuous structure and selective distribution of fillers in PCO phase are prepared. We systematically studied not only the microstructure including morphology and fillers' selective distribution in one phase of the PCO/PE blends, but also the macroscopic properties including thermal, mechanical, and electrical properties. The co-continuous window of the immiscible PCO/PE blends is found to be the volume fraction of PCO (vPCO) of ca. 40-70 vol %. The selective distribution of fillers in one phase of co-continuous blends is obtained by a masterbatch technique. The prepared triple SMP materials show pronounced triple shape memory effects (SMEs) on the dynamic mechanical thermal analysis (DMTA) and the visual observation by both thermal and electric actuations. Such polyolefin samples with well-defined microstructure, electrical actuation, and triple SMEs might have potential applications as, for example, multiple autochoke elements for engines, self-adjusting orthodontic wires, and ophthalmic devices.

Development of zwitterionic copolymers with multi-shape memory effects and moisture-sensitive shape memory effects

“…The key factor to realize multi-SMEs is the integration of two or more reversible phases into a polymer network. 32 Another strategy relies on a single broad thermal transition since the broad thermal transition could be thought to multiple distinct transitions. 1 For instance, triple-memory properties could be achieved by designing two thermal transitions in multi-block segmented polyurethanes, [24][25][26] grafting polymers, 27,28 semi-interpenetrating polymer networks, 29 polymer blends, 30,31 or polymer composites.…”

Triple-shape memory effects of modified semicrystalline ethylene–propylene–diene rubber/poly(ε-caprolactone) blends

“…All of the blends showed abrupt drops in the modulus at $56°C and $112°C, which were attributed to the crystalline melting transition of PCL and A-EPDM phase, respectively. Moreover, the A-EPDM and A-EPDM/PCL blend showed a plateau above the crystalline melting temperature ($112°C) of A-EPDM, indicating that the A-EPDM and A-EPDM/PCL blend can form a crosslinked network structure [17,28]. These observations suggest that the A-EPDM/PCL blends can show triple-shape memory properties.…”

“…Triple-shape memory effect (T-SME) can be manifested in a crosslinked multiphase polymer system having two distinct and well-defined crystalline melting and/or glass transition temperatures [17][18][19][20][21][22][23][24]. Zhou and coworkers [10] developed a molecular composite that exhibit T-SME by incorporating a mesogenic unit, cholesteryl isonicotinate (INCh), into the shape memory polyurethane (SMPU) containing carboxylic groups.…”

Triple shape memory effect of foamed natural Eucommia ulmoides gum/high‐density polyethylene composites

“…Recent developments in the field of SMP have generally centered around obtaining triple or multiple shape memory effects (SMEs) mainly by synthesizing polymers with broad or several discrete reversible phase transitions, blending materials with different reversible phase transitions, or special structure design . Compared with chemical synthesis methods, these blending methods are efficient, simple to operate, convenient for manipulating product properties, environmentally friendly, and yield products with equal or better performance.…”