General Properties of Hydrogels

Part of the Springer Series on Chemical Sensors and Biosensors book series (SSSENSORS, volume 6)


In the application areas of polymer hydrogels, precise information on their molecular constitution as well as their elastic properties is required. Several interesting molecular features control the elastic properties of the hydrogels. In this chapter, we describe general properties of hydrogels formed by free-radical cross-linking copolymerization of vinyl/divinyl monomers in aqueous solutions. Special attention is paid to the relationships between the formation conditions of hydrogels and their properties such as swelling behaviour, elastic modulus, and spatial inhomogeneity. New developments achieved in the design of hydrogels with a good mechanical performance and a fast response rate is also presented.


Hydrogels Elasticity Swelling Inhomogeneity 





Na sodium salt of 2-acrylamido-2-methylpropane sulfonic acid






N, N-methylene bisacrylamide


Poly(acrylic acid)




Poly(N, N-dimethylacrylamide)


Poly(ethylene glycol) of molecular weight 300 g mol−1


Poly(N-isopropyl acrylamide)





Initial monomer concentration (g monomer / 100 mL solution)

\( f\; \)

Effective charge density of the network


Reduced elastic modulus


Modulus of elasticity after gel preparation


Number of segments between two successive cross-links


Volume swelling ratio (swollen gel volume / dry gel volume)


Excess scattering intensity at the scattering vector q


Gel volume at a given degree of swelling


Equilibrium swollen normalized gel volume


Gel volume in after-preparation state


Normalized gel volume


Equilibrium swollen gel volume in solution


Equilibrium swollen gel volume in water


Ionic monomer mole fraction in comonomer feed


Linear deformation ratio


Gibbs free energy of elastic deformation


Ionic contribution to Gibbs free energy


Cross-linking efficiency of cross-linker

\( \varphi_2\)

Volume fraction of cross-linked polymer in gel

\( \varphi_2^0 \)

Volume fraction of cross-linked polymer after gel preparation


Effective cross-link density


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  1. 1.Department of ChemistryIstanbul Technical UniversityIstanbulTurkey

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