Comparison of calactomanan crosslinking with organotitanates and borates.

Water-soluble polymers crosslinked with metal ions form stable gels that are used in oil and gas production processes. We present an investigation of the chemistry of the binding between guar galactomanans and both borates and titanates using NMR and dynamic light scattering. The two monosaccharides comprising guar -- methyl-beta-D-galactopyrannoside and methyl-alpha-D- mannopyrannoside -- have been studied as model compounds. High resolution 13 sup C NMR detected complexation of the sugars with borate but displayed no sign of complexation with either of the two titanates even at high titanate concentrations. Dynamic light scattering studies demonstrated the existence of colloidal titanium dioxide particles for both titanate crosslinkers. The loss of free titanium to the colloidal particles reduces the concentration of titanium crosslinking sites to below the detectable limits of NMR.