Mechanical Engineering Faculty Publications and Presentations
Document Type
Article
Publication Date
9-2022
Abstract
Hypothesis
The shape and quantity of hydrophilic silica nanoparticles (NPs) can be used to tune the microstructure, rheology, and stability of phase-separating polymer solutions. In thermoresponsive polymer systems, silica nanospheres are well-studied whereas anisotropic NPs have little literature precedent. Here, we hypothesize that NP shape and concentration lower the onset of rheological and turbidimetric separation of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions.
Experiments
Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), turbidimetry, and oscillatory rheology are utilized to examine interactions between NPs, PNIPAM, and water and to track changes in phase separation and mechanical properties due to NP concentration and shape.
Findings
NP addition reduces phase separation enthalpy due to PNIPAM-NP hydrogen bonding interactions, the degree to which depends on polymer content. While NP addition minorly impacts thermodynamic and optical properties, rheological transitions and associated rheological properties are dramatically altered with increasing temperature, and depend on NP quantity, shape, and polymer molecular weight. Thus NP content and shape can be used to finely tune transition temperatures and mechanical properties for applications in stimuli-responsive materials.
Recommended Citation
Neal, Christopher AP, Valeria León, Michelle C. Quan, Nondumiso O. Chibambo, and Michelle A. Calabrese. "Tuning the thermodynamic, optical, and rheological properties of thermoresponsive polymer solutions via silica nanoparticle shape and concentration." Journal of colloid and interface science 629 (2023): 878-895. https://doi.org/10.1016/j.jcis.2022.08.139
Publication Title
Journal of colloid and interface science
DOI
10.1016/j.jcis.2022.08.139
Comments
Student publication.
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