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A latent crosslinkable PCL-based polyurethane: Synthesis, shape memory, and enzymatic degradation

  • Wenbin Kuang (a1) and Patrick T. Mather (a1)


Seeking a latent-crosslinkable, mechanically flexible, fully thermoplastic shape memory polymer, we have developed a simple but effective macromolecular design that includes pendent crosslinking sites via the chain extender of a polyurethane architecture bearing semicrystalline poly(ε-caprolactone) (PCL) soft segments. This new composition was used to prepare fibrous mats by electrospinning and films by solvent casting, each containing thermal initiators for chemical crosslinking. The one-step synthesis strategy proved successful, and the crosslinking sites within PCL segments resulted in two-way (reversible) shape memory: repeatable elongation (cooling) and contraction (heating) under constant tensile stress. Being fully characterized, the crosslinked fiber mats revealed promising one-way and two-way (reversible) shape memory phenomena, with lower storage moduli though, compared to uncrosslinked films. We observed for both fibrous mats and films that increasing the applied tensile stress led to greater crystallization-induced elongation upon cooling as well as smaller strain hysteresis, particularly for covalently crosslinked samples. Relevant to medical applications, the materials were observed to feature unique, two-stage enzymatic degradation that was sensitive to differences in crystallinity and microstructure among samples.


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1.Lendlein, A. and Kelch, S.: Shape memory polymers. Angew. Chem., Int. Ed. 41, 2034 (2002).
2.Ratna, D. and Karger-Kocsis, J.: Recent advances in shape memory polymers and composite: A review. J. Mater. Sci. 43, 254 (2008).
3.Liu, C., Qin, H., and Mather, P.T.: Review of progress in shape memory polymers. J. Mater. Chem. 17, 1543 (2007).
4.Xie, T.: Tunable polymer multi-shape memory effect. Nature 464, 267 (2010).
5.Yu, K., Xie, T., Leng, J., Ding, Y., and Qi, H.J.: Mechanisms of multi-shape memory effects and associated energy release in shape memory polymers. Soft Matter 8, 5687 (2012).
6.Mather, P.T., Luo, X., and Rousseau, I.A.: Shape memory polymer research. Annu. Rev. Mater. Res. 39, 445 (2009).
7.Li, J., Rodgers, W.R., and Xie, T.: Semi-crystalline two-way shape memory elastomer. Polymer 52, 5320 (2011).
8.Westbrook, K.K., Mather, P.T., Parakh, V., Dunn, M.L., Qi, Q., Lee, B.M., and Qi, H.J.: Two-way reversible shape memory effects in a free-standing polymer composite. Smart Mater. Struct. 20, 065010 (2011).
9.Shenoy, D.K., Thomsen, D.L. III, Srinivasan, A., Keller, P., and Ratna, B.R.: Carbon coated liquid crystal elastomer film for artificial muscle applications. Sens. Actuators, A 96, 184 (2002).
10.Leng, J., Lan, X., Liu, Y., and Du, S.: Shape memory polymers and their composites: Stimulus methods and applications. Prog. Mater. Sci. 56, 1077 (2011).
11.Yu, Y. and Ikeda, T.: Soft actuators based on liquid-crystalline elastomers. Angew. Chem., Int. Ed. 45, 5416 (2006).
12.Ohm, C., Brehmer, M., and Zentel, R.: Liquid crystalline elastomers as actuators and sensors. Adv. Mater. 22, 3366 (2010).
13.Krause, S., Zander, F., Bergmann, G., Brandt, H., Wertmer, H., and Finkelmann, H.: Nematic main-chain elastomers: Coupling and orientational behavior. C. R. Chim. 12, 85 (2009).
14.Chung, T., Romo-Uribe, A., and Mather, P.T.: Two-way reversible shape memory in a semicrystalline network. Macromolecules 41, 184 (2008).
15.Baker, R.M., Henderson, J.H., and Mather, P.T.: Shape memory poly(ε-caprolactone)-co-poly(ethylene glycol) foams with body temperature triggering and two-way actuation. J. Mater. Chem. B 1, 4916 (2013).
16.Behl, M., Kratz, K., Zotzmann, J., Nőchel, U., and Lendlein, A.: Reversible bidirectional shape memory polymers. Adv. Mater. 25, 4466 (2013).
17.Zhou, J., Turner, S.A., Brosnan, S.M., Li, Q., Carrilo, J.Y., Nykypanchuk, D., Gang, O., Ashby, V.S., Dobrynin, A.V., and Sheiko, S.S.: Shape-shifting: Reversible shape memory in semicrystalline elastomers. Macromolecules 47, 1768 (2014).
18.Teramoto, N., Kogure, H., Kimura, Y., and Shibata, M.: Thermal properties and biodegradability of the copolymers of L-lactide, ε-caprolactone, and ethylene glycol oligomer with maleate units and their crosslinked products. Polymer 45, 7927 (2004).
19.Ping, P., Wang, W., Chen, X., and Jing, X.: The influence of hard-segments on two-phase structure and shape memory properties of PCL-based segmented polyurethanes. J. Polym. Sci., Part B: Polym. Phys. 45, 557 (2007).
20.Kim, B.K. and Lee, S.Y.: Polyurethanes having shape memory effects. Polymer 37, 5781 (1996).
21.Senador, A.E. Jr., Shaw, M.T., and Mather, P.T.: Electrospinning of polymeric nanofibers: Analysis of jet formation. Mater. Res. Soc. Symp. Proc. 661, 5.9.1 (2001).
22.Greiner, A. and Wendorff, J.H.: Electrospinning: A fascinating method for the preparation of ultrathin fibers. Angew. Chem., Int. Ed. 46, 5670 (2007).
23.Demir, M.M., Yilgor, I., Yilgor, E., and Erman, B.: Electrospinning of polyurethane fibers. Polymer 43, 3303 (2002).
24.Odian, G.: Principles of Polymerization, 4th ed. (A John Wiley & Sons, Inc., New Jersey, 2004); p. 619.
25.Gȕven, O.: Crosslinking and Scission in Polymers (Springer, Netherlands, 1990); p. 1.
26.Boire, P.C., Gupta, M.K., Zachman, A.I.L., Lee, S.H., Balikov, D.A., Kim, K., Bellan, L.M., and Sung, H.: Pendant allyl crosslinking as a tunable shape memory actuator for vascular applications. Acta Biomater. 24, 53 (2015).
27.Lawton, M.I., Tillman, K.R., Mohammed, H.S., Kuang, W., Shipp, D.A., and Mather, P.T.: Anhydride-based reconfigurable shape memory elastomers. ACS Macro Lett. 5, 203 (2016).
28.Gan, Z., Liang, Q., Zhang, J., and Jing, X.: Enzymatic degradation of poly(ε-caprolactone) film in phosphate buffer solution containing lipases. Polym. Degrad. Stab. 56, 209 (1997).
29.Zeng, J., Chen, X., Liang, Q., Xu, X., and Jing, X.: Enzymatic degradation of poly(L-lactide) and poly(ε-caprolactone) electrospun fibers. Macromol. Biosci. 4, 1118 (2004).
30.Gu, X., Wu, J., and Mather, P.T.: Polyhedral oligomeric silsesquioxane (POSS) suppresses enzymatic degradation of PCL-based polyurethanes. Biomacromolecules 12, 3066 (2011).
31.Luo, X. and Mather, P.T.: Preparation and characterization of shape memory elastomeric composites. Macromolecules 42, 7251 (2009).
32.Robertson, J.M., Nejad, H.B., and Mather, P.T.: Dual-spun shape memory elastomeric composites. ACS Macro Lett. 4, 436 (2015).
33.Burke, K.A., Rousseau, I.A., and Mather, P.T.: Reversible actuation in main-chain liquid crystalline elastomers with varying crosslink densities. Polymer 55, 5897 (2014).
34.Rice, M.A., Samchez-Adams, J., and Anseth, K.S.: Exogenously triggered, enzymatic degradation of photopolymerized hydrogels with polycaprolactone subunits: Experimental observation and modeling of mass loss behavior. Biomacromolecules 7, 1968 (2006).
35.Saraf, V.P., Glasser, W.G., Wilkes, G.L., and McGrath, J.E.: Structure-property relationships of PEG-containing polyurethane networks. J. Appl. Polym. Sci. 30, 2207 (1985).
36.McMullin, E., Rebar, H.T., and Mather, P.T.: Biodegradable thermoplastic elastomers incorporating POSS: Synthesis, microstructure, and mechanical properties. Macromolecules 49, 3769 (2016).
37.Valério, A., Conti, D.S., Araújo, P.H.H., Sayer, C., and da Rocha, S.R.P.: Synthesis of PEG-PCL-based polyurethane nanoparticles by miniemulsion polymerization. Colloids Surf., B 135, 35 (2015).
38.Lee, B.S., Chun, B.C., Chung, Y.C., Sul, K.I., and Cho, J.W.: Structure and thermomechanical properties of polyurethane block copolymers with shape memory effect. Macromolecules 34, 6431 (2001).
39.Ahmad, M., Xu, B., Purnawali, H., Fu, Y., Huang, W., Miraftab, M., and Luo, J.: High performance shape memory polyurethane synthesized with high molecular weight polyol as the soft segment. Appl. Sci. 2, 535 (2012).
40.Barkoula, N., Peijs, T., Schimanski, T., and Loos, J.: Processing of single polymer composites using the concept of constrained fibers. Polym. Compos. 26, 114 (2005).
41.Kim, N.K., Fakirov, S., and Bhattacharyya, D.: Polymer–polymer and single polymer composites involving nanofibrillar poly(vinylidene fluoride): Manufacturing and mechanical properties. J. Macromol. Sci., Part B: Phys. 53, 1168 (2014).
42.Jiang, S., He, C., Men, Y., Chen, X., An, L., Funari, S.S., and Chan, C.: Study of temperature dependence of crystallization transitions of a symmetric PEO–PCL diblock copolymer using simultaneous SAXS and WAXS measurements with synchrotron radiation. Eur. Phys. J. E: Soft Matter Biol. Phys. 27, 357 (2008).
43.Krumova, M., López, D., Benavente, R., Mijangos, C., and Pereňa, J.M.: Effect of crosslinking on the mechanical and thermal properties of poly(vinyl alcohol). Polymer 41, 9265 (2000).
44.Park, J., Ye, Q., Topp, E.M., Lee, C.H., Kostoryz, E.L., Misra, A., and Spencer, P.: Dynamic mechanical analysis and esterase degradation of dentin adhesives containing a branched methacrylate. J. Biomed. Mater. Res., Part B 91, 61 (2009).
45.Song, L., Ye, Q., Ge, X., Misra, A., Laurence, J.S., Berrie, C.L., and Spencer, P.: Synthesis and evaluation of novel dental monomer with branched carboxyl acid group. J. Biomed. Mater. Res., Part B 102, 1473 (2014).
46.Liu, C., Chun, S.B., and Mather, P.T.: Chemically cross-linked polycyclooctene: Synthesis, characterization, and shape memory behavior. Macromolecules 35, 9868 (2002).
47.Nair, L.S. and Laurencin, C.T.: Biodegradable polymers as biomaterials. Prog. Polym. Sci. 32, 762 (2007).
48.Christenson, E.M., Patel, S., Anderson, J.M., and Hiltner, A.: Enzymatic degradation of poly(ether urethane) and poly(carbonate urethane) by cholesterol esterase. Biomaterials 27, 3920 (2006).


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A latent crosslinkable PCL-based polyurethane: Synthesis, shape memory, and enzymatic degradation

  • Wenbin Kuang (a1) and Patrick T. Mather (a1)


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