A Processable Shape Memory Polymer System for Biomedical Applications.
Polyurethane shape memory polymers (SMPs) with tunable thermomechanical properties and advanced processing capabilities are synthesized, characterized, and implemented in the design of a microactuator medical device prototype. The ability to manipulate glass transition temperature (Tg ) and crosslink density in low-molecular weight aliphatic thermoplastic polyurethane SMPs is demonstrated using a synthetic approach that employs UV catalyzed thiol-ene "click" reactions to achieve postpolymerization crosslinking. Polyurethanes containing varying C=C functionalization are synthesized, solution blended with polythiol crosslinking agents and photoinitiator and subjected to UV irradiation, and the effects of number of synthetic parameters on crosslink density are reported. Thermomechanical properties are highly tunable, including glass transitions tailorable between 30 and 105 °C and rubbery moduli tailorable between 0.4 and 20 MPa. This new SMP system exhibits high toughness for many formulations, especially in the case of low crosslink density materials, for which toughness exceeds 90 MJ m(-3) at select straining temperatures. To demonstrate the advanced processing capability and synthetic versatility of this new SMP system, a laser-actuated SMP microgripper device for minimally invasive delivery of endovascular devices is fabricated, shown to exhibit an average gripping force of 1.43 ± 0.37 N and successfully deployed in an in vitro experimental setup under simulated physiological conditions.
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Keith
K
Hearon
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Mark A
MA
Wierzbicki
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Landon D
LD
Nash
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Todd L
TL
Landsman
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Christine
C
Laramy
Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, TX, 77842-3012, USA.
Alexander T
AT
Lonnecker
Building 13, Room 263, Biomedical and General Engineering Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
Michael C
MC
Gibbons
Building 13, Room 263, Biomedical and General Engineering Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
Sarah
S
Ur
Building 13, Room 263, Biomedical and General Engineering Department, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
Kristen O
KO
Cardinal
7000 East Avenue, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
Thomas S
TS
Wilson
Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, TX, 77842-3012, USA.
Karen L
KL
Wooley
5045 Emerging Technologies Building, Department of Biomedical Engineering, 3120 Texas A&M University, College Station, TX, 77843-3120, USA.
Duncan J
DJ
Maitland
D006358:Hot Temperature; D011140:Polyurethanes / Q000737:chemistry*
D011140:Polyurethanes
biomedical devices; polyurethane; shape memory polymers; structure-property relationships; thiol-ene “click” chemistry