Controlling the Actuation Rate of Low‐Density Shape‐Memory Polymer Foams in Water

Abstract

SMPs have been shown to actuate below their dry glass transition temperatures in the presence of moisture due to plasticization. This behavior has been proposed as a self-actuating mechanism of SMPs in water/physiological media. However, control over the SMP actuation rate, a critical factor for in vivo transcatheter device delivery applications, has not been previously reported. Here, a series of polyurethane SMPs with systematically varied hydrophobicity is described that permits control of the time for their complete shape recovery in water from under 2 min to more than 24 h. This control over the SMP actuation rate can potentially provide significant improvement in their delivery under conditions, which may expose them to high-moisture environments prior to actuation.

Particulate Release From Nanoparticle-Loaded Shape Memory Polymer Foams

“…These results are attributed to increased water uptake and reduced modulus of HDI-containing foams [7]. As foams increase their water uptake (due to increased hydrophilicity) during the wash cycles, it is likely that the washing will be more effective at removing foam debris.…”

“…SMP foams are materials capable of maintaining a temporary shape and, upon application of a thermal, chemical, or optical stimulus, recovering their primary shape [6]. These materials possess tunable thermal and mechanical properties [7][8][9] and are deliverable via catheter [10]. Other potential applications of SMP foams include peripheral vascular occlusion for disease treatment.…”

Mechanical and in vitro evaluation of an experimental canine patent ductus arteriosus occlusion device

“…The SMP foam composition used in these devices was the 0TM composition described and synthesized in a similar way to those reported by Singhal et al (2013). These foams were chosen for their rapid expansion in water (~2 min in 37 °C water) (Singhal et al, 2013) allowing for fast occlusion of the PDA ductus, similar to the occlusion times of the ACDO (5–20 min) (Gordon et al, 2010; Singh et al, 2012).…”

“…These foams were chosen for their rapid expansion in water (~2 min in 37 °C water) (Singhal et al, 2013) allowing for fast occlusion of the PDA ductus, similar to the occlusion times of the ACDO (5–20 min) (Gordon et al, 2010; Singh et al, 2012). These foams were post processed following the protocol described by Hasan et al (2014).…”

Reticulation of low density shape memory polymer foam with an in vivo demonstration of vascular occlusion

“…Two versions of SMP foam were fabricated by the method described by Singhal et al, in 2012 and 2013 7,10 . One version contained 100% hexamethylene diisocyanate (HDI) and the other contained 20% HDI and 80% trimethyl- 1,6-hexamethylene diisocyanate (TMHDI) for the isocyanate monomer in the polyurethane reaction.…”