Gelation kinetics of functionalized silica crosslinked polymeric gels used in conformance control applications

The potential crosslinking of three types of nitrogen-containing functionalized silica (TAAcONa, guanidine, and triamine) with polyacrylamide (PAM) has been investigated. Only triamine silica was able to crosslink with PAM, producing barely flowing gel with storage modulus of around 700 Pa. Micro differential scanning calorimeter (μDSC) analysis illustrated exothermic peaks indicating crosslinking of PAM with triamine and polyethyleneimine (PEI), with crosslinking onset temperatures of 80°C and 84°C. TGA analysis showed the thermal stability of the functionalized silica up to temperatures of more than 200°C. In the domain of study (up to 130°C), TAAcONa silica exhibited the highest weight loss of 5%. Different kinetic models were used to identify the degree of crosslinking and PAM/PEI has shown diffusion-controlled reaction unlike PAM/triamine-functionalized silica. The crosslinking mechanism of the new crosslinker is proposed to be similar to that of the PAM/PEI system. Yet, functionalized silica-based gels are more stable and possess higher strength.