General Properties of Hydrogels

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

Abstract

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.

Keywords

Hydrogels Elasticity Swelling Inhomogeneity 

Abbreviations

AAm

Acrylamide

AMPS

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

DMSO

Dimethylsulfoxide

FH

Flory–Huggins

MBAAm

N, N-methylene bisacrylamide

PAAc

Poly(acrylic acid)

PAAm

Poly(acrylamide)

PDMAAm

Poly(N, N-dimethylacrylamide)

PEG-300

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

PNIPAAm

Poly(N-isopropyl acrylamide)

TBA/AAm

Poly(N-t-butylacrylamide-co-AAm)

Symbols

Co

Initial monomer concentration (g monomer / 100 mL solution)

\( f\; \)

Effective charge density of the network

Gr

Reduced elastic modulus

Go

Modulus of elasticity after gel preparation

Ns

Number of segments between two successive cross-links

Qv

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

Rex,q

Excess scattering intensity at the scattering vector q

V

Gel volume at a given degree of swelling

Veq

Equilibrium swollen normalized gel volume

Vo

Gel volume in after-preparation state

Vr

Normalized gel volume

Vsol

Equilibrium swollen gel volume in solution

Vw

Equilibrium swollen gel volume in water

xi

Ionic monomer mole fraction in comonomer feed

α

Linear deformation ratio

ΔGel

Gibbs free energy of elastic deformation

ΔGion

Ionic contribution to Gibbs free energy

εxl

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

νc

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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