## 第29回数学連携サロン　Tough hydrogels based on double network concept

2013年 　 4月 24日 10時 00分 ～ 2013年 　 4月 24日 12時 00分

グン　剣萍　教授　(北海道大学先端生命科学研究院、数学連携研究センター兼務教員）

タイトル：　Tough hydrogels based on double network concept
アブストラクト：

Hydrogels draw great　attention as biomaterials due to their soft and wet nature in similar to
biotissues. Recent inventions of several tough hydrogels show
their high potential as structural biomaterials, such as cartilages. Studies on the double network (DN) hydrogel, an
extraordinarily tough hydrogel consisting of interpenetrating brittle and
ductile networks, has clarified that the toughness is due to the internal
fracturing of the brittle network, which effectively dissipates energy and
concept revealed a novel principle of the toughness, that is, the existence of
an easily fractured, brittle internal structure makes the material as a whole
mechanically tough[1]. Thus, the brittle network acts as a ‘sacrificial bond’,
a term originally used to describe the toughening of bones [2]. This principle
naturally suggests a new strategy for designing high-strength materials:
incorporating, on purpose, a mechanically fragile structure to toughen the
material as a whole. Since the rupture of the brittle network causes permanent
damage, a DN gel softens and does not recover after experiencing large
deformation. To address this problem, several recent works have replaced the
covalent bonds with non-covalent bonds to allow the fractured bond to be
reformed [3, 4]. Studies along these lines have successfully produced tough
hydrogels with partial or full self-recovery after internal rupture. Reversible
bonds also bring about other functions of the materials, including
self-healing, shape memory, viscoelasticity, and damping. In this talk, we
present several novel tough hydrogels and their mechanical functions based on
the reversible sacrificial bonds.

References

1)     Gong, J. P. Why are double network hydrogels so tough? Soft Matter 6, 2583 (2010).

2)     Fantner, G. E. et al. Sacrificial bonds and hidden length dissipate energy as mineralized fibrils separate during bone fracture. Nat. Mater. 4, 612(2005).

3)     Haque, M. A., Kurokawa, T., Kamita, G. & Gong, J. P. Lamellar bilayers as reversible sacrificial bonds to toughen hydrogel: hysteresis, self-recovery, fatigue resistance, and crack blunting. Macromolecules 44, 8916(2011).

4)     Sun, J. Y., Zhao, X. H., Illeperuma, W. R. K.; Chaudhuri,O., Oh, K. H., Mooney, D. J., Vlassak, J. J, Suo, Z. G. Highly stretchable and tough hydrogels. Nature 489, 133(2012).