285
alcohol) using epichlorohydrin and epoxy ethers in the late 1970s. Poly(vinyl alcohol) was intended to provide a “skeleton” for the cyclodextrin polymer, in order to
improve the mechanical properties of the resin. This procedure cannot be fully considered as a grafting modification, but it is not exactly a cross-linking process either
since the cyclodextrin units are attached to a previously formed polymer. Hirayama
et al. (1984) used epichlorohydrin to prepare a β-cyclodextrin/starch composite gel.
The tosylation of cyclodextrins does produce reactive units that can be attached to
pre-existing polymers by grafting. Thus, poly(allylamine) with cyclodextrin pendant groups was produced in the late 1980s and 1990s. In the 1990s, Pöpping and
Deratani (1992) reported the production of monochlorinated cyclodextrins, and,
later on, other derivatives containing heterocycles were synthesized (Reuscher et al.
1998). Earlier, in 1981, Tanaka and co-workers had immobilized derivatives of αand β-cyclodextrin on polyurethane and also onto a polyacrylamide support after
activating it with succinyl hydrazide (Tanaka et al. 1981, 1982) with the aim of
obtaining stationary phases for the separation of benzene derivatives. About 20 years
ago, Crini’s group used cyclodextrin tosyl derivatives to produce macroporous polyamines (Crini et al. 1998a) or to modify poly(ethyleneimines) in order to coat silica
beads (Crini et al. 1995). Cyclodextrin side-chain polyesters were also obtained in
those years, for instance, by reacting poly(N-vinyl-2-pyrrolidone-co-maleic anhydride) with deprotonated β-cyclodextrin (Weickenmeier and Wenz 1996), and the
interaction of this polymer with anionic or cationic adamantyl guests was studied.
The authors also reported the synthesis of interesting associative thickeners based
on the specific interaction between complementary cyclodextrin polymers and guest
polymers (Weickenmeier and Wenz 1996).
So far, we have presented some examples of cyclodextrin polymers produced
during the first years after the first announcement of this particular type of cyclodextrin derivatives. A more comprehensive collection can be found, for instance, in the
review of cyclodextrin-containing adsorbents by Crini and Morcellet (2002). In the
last two decades, more complex cyclodextrin polymer structures have been produced, namely, interpenetrated networks, molecular imprinted polymers, dendrimers, nanogels, polymer assemblies, and nanocomposites. The following
subsection will be devoted to describe in detail each of these types of structures,
with some examples found in the literature of the evolution of the synthetic procedures and the characterization techniques employed to analyze them, irrespective of
their potential applications in food and pharmacy, separation technologies, chemical
recognition, or other areas. The especial cases of the feasible uses of these materials
in these two sectors will be the goal of the last section of this chapter.
6.2.2 Covalent and Supramolecular Architectures
Cyclodextrin Cross-Linked in Covalent Networks
Cyclodextrin cross-linked with epichlorohydrin polymers, the most abundant in the
literature, were also the first type known, synthesized by Solms and Egli (1965).
Epichlorohydrin is one of the oldest and most widely used cross-linking agents in
6 Cyclodextrin-Based Polymers for Food and Pharmaceutical Applications…
alcohol) using epichlorohydrin and epoxy ethers in the late 1970s. Poly(vinyl alcohol) was intended to provide a “skeleton” for the cyclodextrin polymer, in order to
improve the mechanical properties of the resin. This procedure cannot be fully considered as a grafting modification, but it is not exactly a cross-linking process either
since the cyclodextrin units are attached to a previously formed polymer. Hirayama
et al. (1984) used epichlorohydrin to prepare a β-cyclodextrin/starch composite gel.
The tosylation of cyclodextrins does produce reactive units that can be attached to
pre-existing polymers by grafting. Thus, poly(allylamine) with cyclodextrin pendant groups was produced in the late 1980s and 1990s. In the 1990s, Pöpping and
Deratani (1992) reported the production of monochlorinated cyclodextrins, and,
later on, other derivatives containing heterocycles were synthesized (Reuscher et al.
1998). Earlier, in 1981, Tanaka and co-workers had immobilized derivatives of αand β-cyclodextrin on polyurethane and also onto a polyacrylamide support after
activating it with succinyl hydrazide (Tanaka et al. 1981, 1982) with the aim of
obtaining stationary phases for the separation of benzene derivatives. About 20 years
ago, Crini’s group used cyclodextrin tosyl derivatives to produce macroporous polyamines (Crini et al. 1998a) or to modify poly(ethyleneimines) in order to coat silica
beads (Crini et al. 1995). Cyclodextrin side-chain polyesters were also obtained in
those years, for instance, by reacting poly(N-vinyl-2-pyrrolidone-co-maleic anhydride) with deprotonated β-cyclodextrin (Weickenmeier and Wenz 1996), and the
interaction of this polymer with anionic or cationic adamantyl guests was studied.
The authors also reported the synthesis of interesting associative thickeners based
on the specific interaction between complementary cyclodextrin polymers and guest
polymers (Weickenmeier and Wenz 1996).
So far, we have presented some examples of cyclodextrin polymers produced
during the first years after the first announcement of this particular type of cyclodextrin derivatives. A more comprehensive collection can be found, for instance, in the
review of cyclodextrin-containing adsorbents by Crini and Morcellet (2002). In the
last two decades, more complex cyclodextrin polymer structures have been produced, namely, interpenetrated networks, molecular imprinted polymers, dendrimers, nanogels, polymer assemblies, and nanocomposites. The following
subsection will be devoted to describe in detail each of these types of structures,
with some examples found in the literature of the evolution of the synthetic procedures and the characterization techniques employed to analyze them, irrespective of
their potential applications in food and pharmacy, separation technologies, chemical
recognition, or other areas. The especial cases of the feasible uses of these materials
in these two sectors will be the goal of the last section of this chapter.
6.2.2 Covalent and Supramolecular Architectures
Cyclodextrin Cross-Linked in Covalent Networks
Cyclodextrin cross-linked with epichlorohydrin polymers, the most abundant in the
literature, were also the first type known, synthesized by Solms and Egli (1965).
Epichlorohydrin is one of the oldest and most widely used cross-linking agents in
6 Cyclodextrin-Based Polymers for Food and Pharmaceutical Applications…