Abstract
This paper investigates the shape memory capabilities of semicrystalline networks, focusing the attention on poly(ε-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large “temporary” shape configurations, and the easy tailoring of the transformation temperatures. The materials were prepared with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicrystalline systems was prepared by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biological tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystallization temperatures. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mechanical cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory experiments were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a constant load and of a heating/cooling cycle from above melting to below the crystallization temperature, leading to a reversible elongation/contraction effect, involving maximum strain changes up to about 80%, whose extent may be controlled through the crosslink density.
Similar content being viewed by others
References
A. Lendlein and S. Kelch, Shape-Memory Polymers, Angew. Chem. Int. Ed., 2002, 41(12), p 2034–2057
A. Lendlein and R. Langer, Biodegradable, Elastic Shape-Memory Polymers for Potential Biomedical Applications, Science, 2002, 296(5573), p 1673–1676
C.M. Yakacki, R. Shandas, D. Safranski, A.M. Ortega, K. Sassaman, and K. Gall, Strong, Tailored, Biocompatible Shape-Memory Polymer Networks, Adv. Funct. Mater., 2008, 18, p 2428–2435
J. Leng, X. Lan, Y. Liu, and S. Du, Shape-Memory Polymers and Their Composites: Stimulus Methods and Applications, Prog. Mater. Sci., 2011, 56(7), p 1077–1135
A. Lendlein, M. Behl, B. Hiebl, and C. Wischke, Shape-Memory Polymers as a Technology Platform for Biomedical Applications, Expert Rev. Med. Dev., 2010, 7(3), p 357–379
L. Xue, S. Dai, and Z. Li, Biodegradable Shape-Memory Block Co-polymers for Fast Self-Expandable Stents, Biomaterials, 2010, 31, p 8132–8140
G.M. Baer, T.S. Wilson, W. Small, IV, J. Hartman, W.J. Benett, D.L. Matthews, and D.J. Maitland, Thermomechanical Properties, Collapse Pressure, and Expansion of Shape Memory Polymer Neurovascular Stent Prototypes, J. Biomed. Mater. Res. B Appl. Biomater., 2009, 90(1), p 421–429
G.M. Baer, W. Small, T.S. Wilson, W.J. Benett, D.L. Matthews, J. Hartman, and D.J. Maitland, Fabrication and In Vitro Deployment of a Laser-Activated Shape Memory Polymer Vascular Stent, BioMed. Eng. Online, 2007, 6, p 43
M.A. Woodruff and D.W. Hutmacher, The Return of a Forgotten Polymer—Polycaprolactone in the 21st Century, Prog. Polym. Sci., 2010, 35, p 1217–1256
F. Sanda, H. Sanada, Y. Shibasaki, and T. Endo, Star Polymer Synthesis from ε-Caprolactone Utilizing Polyol/Protonic Acid Initiator, Macromolecules, 2002, 35(3), p 680–683
K. Paderni, S. Pandini, S. Passera, F. Pilati, M. Toselli, and M. Messori, Shape-Memory Polymer Networks from Sol-Gel Cross-Linked Alkoxysilane-Terminated Poly(Epsilon-Caprolactone), J. Mater. Sci., 2012, 47(10), p 4354–4362
M. Messori, M. Degli Esposti, K. Paderni, S. Pandini, S. Passera, T. Riccò, and M. Toselli, Chemical and Thermomechanical Tailoring of the Shape Memory Effect in Poly(ε-Caprolactone)-Based Systems, J. Mater. Sci., 2013, 48(1), p 424–440
H. Tamai, K. Igaki, E. Kyo, K. Kosuga, A. Kawashima, S. Matsui, H. Komori, T. Tsuji, S. Motohara, and H. Uehata, Initial and 6-Month Results of Biodegradable Poly l-Lactic Acid Coronary Stents in Humans, Circulation, 2000, 102(4), p 399–404
C.M. Yakacki, R. Shandasa, C. Lanning, B. Rech, A. Eckstein, and K. Gall, Unconstrained Recovery Characterization of Shape-Memory Polymer Networks for Cardiovascular Application, Biomaterials, 2007, 28, p 2255–2263
T. Chung, A. Romo-Uribe, and P.T. Mather, Two-Way Reversible Shape Memory in a Semicrystalline Network, Macromolecules, 2008, 41, p 184–192
J. Zotzmann, M. Behl, D. Hofmann, and A. Lendlein, Reversible Triple-Shape Effect of Polymer Networks Containing Polypentadecalactone- and Poly(ε-Caprolactone)-Segments, Adv. Mater., 2010, 22, p 3424–3429
S. Pandini, F. Baldi, K. Paderni, M. Messori, M. Toselli, F. Pilati, A. Gianoncelli, M. Brisotto, E. Bontempi, and T. Riccò, One-Way and Two-Way Shape Memory Behaviour of Semi-Crystalline Networks Based on Sol-Gel Cross-Linked Poly(ε-Caprolactone), Polymer, 2013, 54(16), p 4253–4265
A. Lendlein, A.M. Schmidt, M. Schroeter, and R. Langer, Shape-Memory Polymer Networks from Oligo(ε-Caprolactone) Dimethacrylates, J. Polym. Sci. Polym. Chem., 2005, 43(7), p 1369–1381
K.K. Westbrook, V. Parakh, T. Chung, P.T. Mather, L.C. Wan, M.L. Dunn, and H.J. Qi, Constitutive Modeling of Shape Memory Effects in Semicrystalline Polymers with Stretch Induced Crystallization, J. Eng. Mater. Technol., 2010, 132, p 041001–041010
G. Barot and I.J. Rao, Constitutive Modeling of the Mechanics Associated with Crystallizable Shape Memory Polymers, Z. Angew. Math. Phys., 2006, 57, p 652–681
Acknowledgments
The authors gratefully acknowledge INSTM (Firenze, Italy), Regione Lombardia, and the Department of Mechanical and Industrial Engineering of the University of Brescia for providing financial support to this research, Mrs. Gloria Spagnoli for the support for the materials characterization, and Mr. Luca Dassa for the design of the folding equipment.
Author information
Authors and Affiliations
Corresponding author
Additional information
This article is an invited paper selected from presentations at the International Conference on Shape Memory and Superelastic Technologies 2013, held May 20-24, 2013, in Prague, Czech Republic, and has been expanded from the original presentation.
Rights and permissions
About this article
Cite this article
Pandini, S., Riccò, T., Borboni, A. et al. Tailored One-Way and Two-Way Shape Memory Capabilities of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications. J. of Materi Eng and Perform 23, 2545–2552 (2014). https://doi.org/10.1007/s11665-014-1033-5
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11665-014-1033-5