Microrheology of thermoresponsive poly(N-isopropylacrylamide) microgel dispersions near a substrate surface
| Autor: | Chuanxin He, Wei Liu, To Ngai, Tong Zhang, Yuwei Zhu, Hui Zhu |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Microrheology
Magnetic tweezers Materials science Total internal reflection microscopy 02 engineering and technology Dynamic mechanical analysis 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Condensed Matter::Soft Condensed Matter Biomaterials Colloid chemistry.chemical_compound Colloid and Surface Chemistry Rheology chemistry Chemical physics Dynamic modulus Poly(N-isopropylacrylamide) 0210 nano-technology |
| Zdroj: | Journal of Colloid and Interface Science. 597:104-113 |
| ISSN: | 0021-9797 |
| DOI: | 10.1016/j.jcis.2021.03.181 |
| Popis: | Hypothesis Relative to the bulk systems, the near-wall ( Experiments The combination of active microrheometry (multipole magnetic tweezers) and total internal reflection microscopy (TIRM) was employed to probe the structure–rheology relationships of microgel dispersions near a substrate surface. The ω, T, and ϕeff-dependences of the storage modulus (G′), loss modulus (G"), and softness (J) were analyzed by power-law and Arrhenius-like scaling theories. The fluctuation of J was further analyzed to give a quantitative description of the inhomogeneity in the near-wall regions. Findings (1) Remarkable differences in the rheological behaviors between the bulk and near-wall cases are revealed, where the latter shows a segmented overlap behavior in ϕeff; (2) Five regimes of ϕeff that correspond to distinct physical states of the microgel dispersions are determined; (3) The near-wall local structures exhibit more heterogeneity in the glass and colloidal gel regimes as compared to the liquid regime. |
| Databáze: | OpenAIRE |
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