Fibrillar morphologies of hydrogels obtained from a lamellar medium

• Published in: European polymer journal Vol. 48; no. 1; pp. 105 - 115
• Main Authors: Pacios, Isabel E., Renamayor, Carmen S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2012; Elsevier
• Subjects: Applied sciences; Correlation; Evolution; Exact sciences and technology; Fibrillar morphology; Hydrogel; Hydrogels; Lyotropic medium; Mesophase; Morphology; Organic polymers; Physical properties; Physicochemistry of polymers; Polymerization; Porosity; Preparation, kinetics, thermodynamics, mechanism and catalysts; Fibrillar morphology; Lyotropic medium; Hydrogel; Lyotropic solvent; Fibrillar structure; Experimental study; Acrylamide derivative polymer; Solution polymerization; Sulfonate; Colloidal gel; Structure processing relationship; Anionic surfactant; Free radical polymerization; Morphology
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2011.10.007

Hydrogels are suitable for multiple applications and their properties are strongly dependent on their morphology. Sponge-like morphologies are obtained in conventional hydrogels when the polymerization is performed in isotropic media. Fibrillar morphologies imparting new properties to hydrogels are expected when the reacting medium is anisotropic. Here, we synthesize such fibrillar hydrogels by polymerization in a lamellar medium formed by 1,4-bis(2-ethylhexyl)sodium sulfosuccinate (AOT) and water. At high surfactant content this objective is achieved, and the thickness of the obtained fibrils (0.1–1
μm) can be correlated with the physical properties of the lamellar system. At intermediate AOT concentrations, the morphology is hierarchical, with primary closed pores containing a secondary fibrillar structure that fills the pores. For low AOT concentrations, the crosslinking process is unhindered, and the hydrogels are mechanically consistent with a sponge-like morphology having large (10–10
2
μm) void pores. The time evolution of the mesophase as polymerization advances is followed by small angle X-ray scattering.