Water swollen polymer networks, generally referred to as
hydrogels, have received a great deal of attention for a wide variety
of biomedical applications such as tissue engineering, cell encapsulation,
wound dressing and drug delivery [1]. The hydrophilic
polymer network of hydrogels allows a high water content similar
to natural tissues. Their swelling properties, as well as their
biocompatibility, makes hydrogels ideal candidate materials for the
repair and regeneration of soft tissues.Application of hydrogels as load-bearing components is often
limited by their mechanical properties. Accordingly, a special
emphasis is given in the literature to the synthesis of hydrogels
with enhanced mechanical performance [2e4]. It iswell recognized
that the stiffness of the polymer networks can be tailored with the
cross-link density. Such an approach however results in an inverse
proportionality between stiffness and toughness as described by
the LakeeThomas model [5].Most methods developed to increase hydrogels' stiffness and
toughness simultaneously require a chemical modification of the
polymer and/or synthesis with several steps. This complexity in
hydrogel synthesis is a drawback in cases where in situ formation of
the hydrogel is required, such as injectable implants and cell
seeding for cell encapsulations applications.
Designing a hybrid hydrogel is an effective approach to address
the aforementioned issue while keeping a simple and fast processing
routes. Yet, such a design clearly involves the choice of
material components, their scale and shape. On this matter, the
concept of composite hydrogels reinforced with an interpenetrated
phase is introduced as a promising solution [6e9].