An ITC Study on the Interaction Energy Between Galactomannan Biopolymers and Selected MO₂ Nanoparticles in Hydrogels

Abstract

The interaction of guar gum, a galactomannan polysaccharide, and its derivative hydroxypropyl guar (HPG) with MO2 nanoparticles whereby M exhibits a decreasing metallic character (Ti → Sn → Si) and MO2 different sizes (6 – 15 nm) was studied by applying isothermal titration calorimetry (ITC) and rotational viscosimetry. It was found that the crosslinking ability of the oxide nanoparticles towards galactomannans is controlled by the electropositive character of M and the size of the nanoparticles which should be as small as possible (< 10 nm) to produce extremely viscous gels. The thermodynamic parameters ΔH, ΔS and ΔG for the association reaction obtained from ITC revealed that the interaction generally is entropy driven, slightly stronger for guar gum than for HPG and is decreasing from TiO2 to SnO2 to SiO2. The results explain the observations made in the viscosimetric measurements.

Influence of zirconium crosslinker chemical structure and polymer choice on the performance of crosslinked fracturing fluids

“…The size of colloidal particles in solution has been shown to influence the likelihood of achieving crosslinking viscosity. Hurnaus and Plank [ 6 ] showed that the size of the colloidal particles required to crosslink guar is smaller than those needed to crosslink HPG. In this work, the effect of ligands present in Zr crosslinkers has been shown to influence the crosslinker performance with polyacrylamide and CMHPG in different ways.…”

“…Commonly used elements include boron, aluminium, titanium, and Zr. [ 5,6 ] Boron is typically used to crosslink guar and its derivatives and is generally applied above pH 9 conditions for optimal crosslinking. [ 7 ] Compared to the above‐mentioned metallic crosslinkers, borate crosslinked fluids are more shear tolerant and exhibit re‐healing properties.…”

“…[ 7,12 ] On the other hand, metallic crosslinkers have been found to polymerize into oxide nanoparticles to facilitate crosslinking. [ 5,6 ] These nanoparticles bond with the polymer through multiple hydrogen bonds to form a highly viscous fluid, as shown in Figure 1. However, unlike borate‐polymer bonds, the bonds between the metallic crosslinker and the polymer bonds do not re‐heal.…”

“…In addition, the size and electropositivity of the nanoparticle have also been observed to affect the characteristics of the crosslinked solution. Hurnaus and Plank [ 6 ] compared the crosslinking of TiO 2 , SnO 2 , and SiO 2 with guar and hydroxypropyl guar. From their tests, they reasoned that the efficacy of crosslinking improved with the electropositivity of the metal ion and that a large gain in entropy occurs during crosslinking.…”

Isothermal Titration Calorimetry Reveals Entropy-Driven Bisphenol A Epoxy Resin Adhesion to Metal Oxide Surfaces

“…Isothermal titration calorimetry (ITC) is a powerful technique that directly quantifies the thermodynamic profile ( K a , Δ G , Δ H , Δ S ) of binding interactions in solution from a single experiment. , It involves the incremental titration of an analyte into a macromolecular solution and monitoring the heat released or absorbed upon binding. , Traditionally employed for biomolecular systems, ,, the use of ITC has been expanded to characterize the interaction thermodynamics in nonbiomolecular systems, − including polymer–inorganic interfaces. ,,− Here, we use ITC to quantify the thermodynamic interaction between DGEBA epoxy resins and metal oxide particles in solution. We examine the relative roles of entropy and enthalpy in epoxy-metal oxide interactions by investigating a homologous series of DGEBA resins with increasing pendant –OH groups (Table ) and three metal oxide particles with different -sOH concentrations: tin oxide (SnO 2 ), chromium oxide (Cr 2 O 3 ), and aluminum oxide (Al 2 O 3 ).…”