Molecular Weight Dependence of SiO2 Nanoparticle Agglomeration Behavior in Monodisperse PMMA–SiO2 Hybrid Suspension

Abstract

The rapid agglomeration of SiO2 nanoparticles suspended in organic solvents, where the interactions between the PMMA chains and SiO2 are very weak and may be ignored, is, therefore, concluded to be “entanglement agglomeration mechanism” triggered by strong mutual entanglement effects occurring when the polymer chains come into contact, overlap, and mutually intrude each other at higher polymer concentrations, providing the driving force for particle agglomeration.

Effect of SiO2@PEGMA Composites on Mechanical Properties of Oil Well Cement

“… 21 − 23 However, SiO 2 nanoparticles have extremely high surface energy and can easily agglomerate in cement pore solution, which reduces their efficacy significantly, and their application in cementing is limited. 24 The strong agglomeration tendency of SiO 2 nanoparticles is hindered by adding polymeric dispersants in cementing. Polyether-based, polycarboxylate, and phosphate superplasticizers are commonly used superplasticizers.…”

“…Nanomaterials have been shown to affect the hydration process of cement through their unique physicochemical properties, thereby fundamentally affecting the macroscopic properties of oil well cement. − At present, more and more nanomaterials are used to modify oil well cement, such as SiO 2 nanoparticles, TiO 2 nanoparticles, Fe 2 O 3 nanoparticles, Al 2 O 3 nanoparticles, and nano clay . Among them, nano-SiO 2 is a kind of nanomaterial studied earlier and is most widely used in cement. − Compared with other nanomaterials, SiO 2 nanoparticles can not only play a physical filling role but also generate C–S–H via reacting with Ca­(OH) 2 , thereby promoting the hydration process, densifying the microstructure, and improving the macroscopic properties of cement. − However, SiO 2 nanoparticles have extremely high surface energy and can easily agglomerate in cement pore solution, which reduces their efficacy significantly, and their application in cementing is limited . The strong agglomeration tendency of SiO 2 nanoparticles is hindered by adding polymeric dispersants in cementing.…”

Effect of core–shell nanocomposites on the mechanical properties and rheological behaviors of cement pastes

“…16,17 However, SiO 2 nanoparticles have a strong tendency to agglomerate, which can easily form weak zones in oil well cement, reducing the mechanical properties of cement. [18][19][20] As a result, the application of SiO 2 nanoparticles in cementing is restricted. The dispersion of SiO 2 nanoparticles can be improved by surface modication of nano-SiO 2 .…”