Synthesis of Hydrogel

FIG. 7. Schematic representation of the synthesis of hydrogels by cross-linking polymeric precursors (adapted from Ref. 93). 

Ulanski P, Pawlowska W, Kadlubowski S, Henke A, Gottlieb R, Arndt KF, Bromberg L, Hatton TA, Rosiak JM (2006) Synthesis of hydrogels by radiation-induced cross-linking of Pluronic F127 in NjO-saturated aqueous solution. Polym Adv Technol 17(9—10) 804—813... 

Another form of polymeric synthesis is by free-radical polymerization. These types of polymers are macromolecules formed by the incorporation of unsaturated monomer molecules, in other words, with a double bond, to the active center of a chain in growth. In most cases, these macromolecules are vinyl polymers. In Fig. 1, the chemical structure of some monomers used in the synthesis of hydrogels is shown. 

Fig. 1 Chemical structures of some monomers used in the synthesis of hydrogels.

Regarding the initiation process of polymerization, it can be started by y-radiation. It is a method that has been used for the synthesis of hydrogels of PEO as well as hydrogels based on vinyl monomers " in this latter case, azo-compounds such as 2,2-azo-isobutyroni-trile (AIBN)f or 2,2 -azobis (2-amidine-propane) dihydrochloride or V-SO, and aqueous salt solutions such as aqueous ammonium peroxodisulfate are also used. Among the monomers most used in the preparation of hydrogels through free-radical polymerization are 2-hydroxyethyl methacrylate (HEMA) and A-vinyl-2-pyrrolidone (VP). ... 

Gong JP, Kurokawa T, Narita T, Kagata K, Osada Y, Nishimura G, Kinjo M (2001) Synthesis of hydrogels with extremely low surface friction. J Am Chem Soc 123 5582-5583... 

An often applied method for the synthesis of hydrogels, especially for applications in medicine and pharmaceutics, is based on radiochemistry. The hydrogel can be formed by irradiation of monomers, polymers dissolved in water, or polymers in dry state. Electrons of different energies or y-rays are used as high-energy radiation. The possibilities of the radiation-chemical synthesis of smart hydrogels are discussed on different examples. The technique is applied to bulk polymers, to micro- and nanogel particles, and to patterned layers on different materials. The basics and fundamentals of irradiation techniques as well as the equipment are described. 

Chen C, Imanishi Y, Ito Y (1998) Photolithographic synthesis of hydrogels. Macromolecules 31 4379 381... 

Figure 9 shows the temperature dependence of the elastic part of the complex Young s modulus E a>) for various poly(vinyl methyl ether) hydrogel samples in water at a selected frequency of 20.1 rad/s. The polymer was cross-linked by electron beam irradiation (see Sect. 2.4, chapter Synthesis of hydrogels ). These data were compared with the temperature shrinking behaviour of sample PVME 20/80... 

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