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.The authors would like to acknowledge the support of Qatar National Research Fund (a member of Qatar Foundation) through grant number NPRP10-0125-170240. The findings achieved herein are solely the responsibility of the authors. Special thanks with gratitude to SNF Company for supplying the polymers used in this study. The acknowledgement is also extended to the Central Laboratories Unit in Qatar University for carrying out the SEM tests, and to the University of Oklahoma for supporting this research.Scopu