Effect of calcium neutralization on elastic and swelling properties of crosslinked poly(acrylic acid) - correlation to inhomogeneities and phase behaviour
Journal article, 2009

Crosslinked hydrogels of poly(acrylic acid) neutralized with calcium hydroxide were synthesized using free radical co-polymerization. The effects of the amount added calcium on the elastic modulus and swelling properties of the gels and the correlation to phase behaviour and structural changes within the gels were studied using texture analysis, gravimetric analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and atomic force microscopy (AFM). It was found that the elastic modulus decreased nonlinearly with increasing amount of added calcium and that the swelling's dependence on the amount of added calcium was complicated. The maximum swelling increased with increasing amount of added calcium until a critical calcium content was reached, upon which the gels phase separated, with a strong decrease in swelling as a result. The changes in properties are explained by the fact that calcium affects the structure of the polymer network during synthesis and by the phase behaviour of the gels. Changes in the gel structure with the addition of calcium were detected with AFM. Furthermore, AFM revealed different phases on the nanometre scale for the sample with a calcium content around which phase separation is macroscopically observed. Finally, it was shown that the sulphur from the initiator potassium persulfate formed crystal like regions with high sulphur and calcium content upon drying of the hydrogels.

MODULUS

ACRYLIC-ACID

POLYMERS

SALT-SOLUTIONS

KINETICS

NETWORKS

WATER

GELS

LINKING

HYDROGELS

Author

Mikael Larsson

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Pharmaceutical Technology

Stefan Gustafsson

Chalmers, Applied Physics, Microscopy and Microanalysis

SuMo Biomaterials

Eva Olsson

Chalmers, Applied Physics, Microscopy and Microanalysis

Anette Larsson

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Pharmaceutical Technology

E-Polymers

1618-7229 (ISSN)

141 1683-1696

Subject Categories

Pharmaceutical Sciences

Physical Chemistry

Areas of Advance

Materials Science

More information

Created

10/7/2017