title: 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.
authors.affiliation: Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX-77843, USA.
authors.forename: Pooja
authors.initials: P
authors.lastname: Singhal
authors.affiliation: Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX-77843, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Boyle
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA-94550, USA.
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Brooks
authors.affiliation: Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX-77843, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Infanger
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA-94550, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Letts
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA-94550, USA.
authors.forename: Ward
authors.initials: W
authors.lastname: Small
authors.affiliation: Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX-77843, USA.
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Maitland
authors.affiliation: Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA-94550, USA.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Wilson
keywords: actuation rate; biomaterials; hydrophobicity; polyurethanes; shape-memory foams