Improving the mechanical performance of P(N‐hydroxymethyl acrylamide/acrylic acid/2‐acrylamido‐2‐methylpropanesulfonic acid) hydrogel via hydrophobic modified nanosilica

Abstract

Hydrogels with high mechanical strength are essential for its most industrial applications. In this work, the hydrophobic SiO2 nanoparticles (M‐SiO2 NPs) modified with octadecyltrimethoxysilane were used as physical crosslinker to toughen the mechanical properties of hydrogels. The solution of monomers containing M‐SiO2 NPs, N‐hydroxymethyl acrylamide (NHAM), acrylic acid (AA), 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), was polymerized to prepare a P(NHAM/AA/AMPS)‐based composite hydrogel without any chemical cross‐linker. The composition and microstructure of the hydrogel were carefully studied with Fourier transform infrared spectroscopy and scanning electron microscopy. The mechanical properties of the hydrogel were investigated through compressive and tensile tests. Dynamic swelling tests were carried out at different pH values (1.0–12.0) and salinity (2000–20,000 mg/L) to study the acid resistance, alkali resistance, and salt resistance of the hydrogel. The obtained results showed that the hydrogel exhibited excellent mechanical performance, which was attributed to the unique 3D network formed by the hydrogen bond between M‐SiO2 NPs and polymer as well as the hydrophobic association effect between the hydrophobic chains of M‐SiO2 NPs. Furthermore, the hydrophobic association effect was enhanced when contacting with salt, acid, and alkali solutions, thus endowing the hydrogel with intensified salt resistance and wider acid–base adaptability range.

Environmentally Adaptive Polymer Hydrogels: Maintaining Wet‐Soft Features in Extreme Conditions

“…Besides, designing unique 3D network structures can also effectively enhance the adaptability of hydrogels in acidic and alkaline environments. Xu et al [ 95 ] used the octadecyl‐trimethoxy‐silane to hydrophobically modify silica nanoparticles to obtain M‐SiO 2 NPs, and then, M‐SiO 2 NPs were used as cross‐linkers to initiate and participate in the polymerization of n‐hydroxy‐methyl‐acrylamide (NHAM), acrylic acid (AA), and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) monomers (Figure 10e) to prepare hydrogels with high mechanical strength. The hydrogen bonding between the M‐SiO 2 NPs and the polymer forms a unique3D network, and the hydrophobic linkage effect between the hydrophobic chains endows the hydrogel with excellent mechanical properties, acid and alkali resistance (pH 1.0–12.0) (Figure 10f) and high salt resistance (2–20 g L −1 ) (Figure 10g).…”

Strengthening the Hydrogel for Lost Circulation Control through In Situ Self-Assembled Nanocomposite Networks

“…The method of enhancing the affinity between nano-SiO 2 and polymer chains through surface modification has been proven effective in improving the strengthening performance of nano-SiO 2 on the polymer network structure. − In other words, the functional groups grafted on the surface endow nano-SiO 2 with a stronger strengthening effect on hydrogel strength. Cao et al .…”

Synthesis and properties of elevated temperature hydrogels for enhanced oil recovery based on AM/AMPA/NVP copolymer and silica nanoparticles

“…11,12 On the other hand, an economical crosslinker with heat and salt resistance were selected. 13,14 The 2-acrylamido-2-methylpropane sulfonic acid (AMPS) 15,16 and sodium styrene sulfonate (SSS) 17 monomers contained ion groups (sulfonic acid groups) that were not sensitive to Ca 2+ and Mg 2+ , which could increase the polarity of the polymer chain, making it difficult for the polymer chain to rotate freely and improving the salt resistance of the polymer. It was reported that the AM-co-AMPS copolymer in the 5000 mg/L salt solution revealed a high viscosity retention (35%), which was higher than the conventional polymer HPAM.…”