hydrogels involve hydrophobic bonds between fluoro(meth)acrylate groups that
associate into 2–6-nm-diameter core–shell nanodomains that represent
multifunctional crosslinks. These hydrogels exhibit exceptional mechanical properties and fracture toughness values approaching 10
4 J/m
2 , are extrudable, and show
self-healing behavior of the microstructure. This chapter reviews the characteristics
of these microphase-separated, hydrophobically associating hydrogels and discusses
potential applications of these materials as injectable in situ forming hydrogels,
electrospun fiber mats suitable for tissue scaffolds, controlled drug release, antifreeze
materials, and shape memory hydrogels.
Keywords Amphiphilic copolymers · Microphase separation · Physical hydrogels ·
Supramolecular hydrogels
1 Introduction
Supramolecular hydrogels (SMHs) are of contemporary interest due to the reversibility of the polymer network from which they are derived and properties such as
processability, toughness, and self-healing that result from having reversible
crosslinks. SMHs have been developed from a variety of non-covalent chemistries,
including hydrogen bonds, ionic bonds, ligand–receptor complexation, and hydrophobic interactions [1, 2]. This chapter concerns SMHs based on hydrophobic
interactions, specifically those based on fluorinated monomers.
Hydrophobically modified hydrogels have been primarily derived from
hydrocarbon-containing monomers [3]. The motivation for synthesizing and studying the fluorocarbon-based hydrogels discussed in this chapter was the work of
Hogen-Esch and coworkers [4–7], who studied aqueous solutions of water-soluble
copolymers containing fluorinated co-monomers. The objective of their work was to
compare the viscosity enhancement of fluorocarbon hydrophobically associating
water-soluble polymers to that of hydrocarbon hydrophobically associating watersoluble polymers. The greater viscosification effect of the former was attributed to
much stronger hydrophobic associations for the fluorinated species. In those studies,
however, the concentration of the hydrophobic monomer in the copolymer was
restricted to less than 3 mol% to ensure that the copolymers were water-soluble.
When the concentration of the hydrophobic moiety is increased to greater than about
5 mol%, the copolymers are no longer water-soluble, though they may be highly
swollen with water. That is, swelling the copolymers with water produces supramolecular hydrogels [8, 9], which are the focus of this chapter.
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associate into 2–6-nm-diameter core–shell nanodomains that represent
multifunctional crosslinks. These hydrogels exhibit exceptional mechanical properties and fracture toughness values approaching 10
4 J/m
2 , are extrudable, and show
self-healing behavior of the microstructure. This chapter reviews the characteristics
of these microphase-separated, hydrophobically associating hydrogels and discusses
potential applications of these materials as injectable in situ forming hydrogels,
electrospun fiber mats suitable for tissue scaffolds, controlled drug release, antifreeze
materials, and shape memory hydrogels.
Keywords Amphiphilic copolymers · Microphase separation · Physical hydrogels ·
Supramolecular hydrogels
1 Introduction
Supramolecular hydrogels (SMHs) are of contemporary interest due to the reversibility of the polymer network from which they are derived and properties such as
processability, toughness, and self-healing that result from having reversible
crosslinks. SMHs have been developed from a variety of non-covalent chemistries,
including hydrogen bonds, ionic bonds, ligand–receptor complexation, and hydrophobic interactions [1, 2]. This chapter concerns SMHs based on hydrophobic
interactions, specifically those based on fluorinated monomers.
Hydrophobically modified hydrogels have been primarily derived from
hydrocarbon-containing monomers [3]. The motivation for synthesizing and studying the fluorocarbon-based hydrogels discussed in this chapter was the work of
Hogen-Esch and coworkers [4–7], who studied aqueous solutions of water-soluble
copolymers containing fluorinated co-monomers. The objective of their work was to
compare the viscosity enhancement of fluorocarbon hydrophobically associating
water-soluble polymers to that of hydrocarbon hydrophobically associating watersoluble polymers. The greater viscosification effect of the former was attributed to
much stronger hydrophobic associations for the fluorinated species. In those studies,
however, the concentration of the hydrophobic monomer in the copolymer was
restricted to less than 3 mol% to ensure that the copolymers were water-soluble.
When the concentration of the hydrophobic moiety is increased to greater than about
5 mol%, the copolymers are no longer water-soluble, though they may be highly
swollen with water. That is, swelling the copolymers with water produces supramolecular hydrogels [8, 9], which are the focus of this chapter.
166
B. D. Vogt and R. A. Weiss