The effect of gel structure on matrix orientation.

Four polymeric gels of different structure, low electroendosmosis (LE) agarose, highest electroendosmosis (HEEO) agarose, beta-carrageenan, and polyacrylamide, were studied by transient electric birefringence to determine the importance of various structural features on the orientation of the gels in an electric field. The two types of agarose, but not the polyacrylamide or beta-carrageenan, exhibited anomalous orientation effects. Both agarose and beta-carrageenan exhibited large birefringence signals, suggesting that the noncovalent hydrogen bonds joining the agarose fibers within the matrix allow the high degree of orientation of the gel. The spatial arrangement of the sugars of the agarose backbone is necessary for the anomalous orientation effects in reversing electric fields.