Comparison of Modified HPAM Using Hyperbranched Brush Macromonomer in Supercritical Carbon Dioxide and Controlled Polymerization

RAMSES SEGUNDO MELEANS; AGUSTÍN IBORRA; JOANA E TASQUE; MIRIAM C. STRUMIA; FACUNDO MATTEA; ISABEL N. VEGA; JUAN M. GIUSSI; JUAN M. MILANESIO

Los cocos

Conferencia; VI Iberoamerican Conference on Supercritical Fluids; 2023

Partially hydrolyzed polyacrylamide (HPAM) has found widespread use in the Oil & Gas industry in recent years, particularly for Enhanced Oil Recovery (EOR) applications. However, the viscosity of its aqueous solution is adversely affected by reservoir conditions, such as high salinity and temperature. Thus, a significant technological challenge is to synthesize HPAM copolymers capable of maintaining and enhancing their viscosifying properties under harsh conditions [1,2]. An effective approach for enhancing the viscosity of HPAM involves the incorporation of associative comonomers within the polymer chain. Hyperbranched molecules like Boltorn H30 with their multiple terminal hydroxyl groups, offer an opportunity for generating multiple associative interactions and for the customization of hyperbranched structures to suit specific applications [3]. These modified hyperbranched molecules can be added to the reactive mixture as co-monomers to obtain modified HPAMs, potentially leading to copolymers with enhanced resistance to high temperatures and salinity[4,5]. In this study, we partially modified the terminal hydroxyl groups (8 ou t of 32) of a hyperbranched molecule (Boltorn H30) using poly(ethylene glycol) methyl ether methacrylate (PEGMA 500) via atom transfer radical polymerization (ATRP) and then, in order to obtain polymerizable methacrylates in the macrostructure for the next step, free hydroxyl groups were derivatized in a considerably smaller proportion with methacrylic anhydride. The aim was to produce a water-soluble hyperbranched comonomer that could be incorporated into the modified HPAM polymer chain through radical polymerization. To obtain the modified HPAMs, two different synthesis pathways were explored: a polymerization in aqueous solution controlled by iodine, and precipitation polymerization controlled by iodine in supercritical carbon dioxide. The latter approach facilitates postreaction purification and separation steps, commonly associated with polymerizations using organic solvents or water solutions. The synthesized polymers were characterized using spectroscopic methods like FTIR and 1HNMR to confirm the incorporation of the hyperbranched monomer, and to evaluate the feasibility and yield of the proposed reactions. Subsequently, the effects of the modification on the rheological properties of aqueous polymer solutions were also studied, and the polymer obtained by both synthetic approaches were compared.