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Published on: March 16, 2020
Tethered poly(2-isopropyl-2-oxazoline) chains: temperature effects on layer structure and interactions probed by AFM
Junxue An1, Xiaoyan Liu1, Per Linse2
1†School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden.
Thermoresponsive polymer layers, made of poly(2-isopropyl-2-oxazoline) (PIPOZ), show temperature-dependent interactions. Increasing temperature causes attraction between PIPOZ layers, altering surface forces and chain behavior.
Area of Science:
- Materials Science
- Surface Chemistry
- Polymer Science
Background:
- Thermoresponsive polymers offer tunable surface properties.
- Controlling polymer layer interactions is crucial for advanced materials.
Purpose of the Study:
- To investigate temperature-induced changes in adsorbed poly(2-isopropyl-2-oxazoline) (PIPOZ) layers on silica.
- To understand the effect of solvent conditions on inter-layer forces and friction.
Main Methods:
- Electrostatically driven adsorption of a cationic-nonionic diblock copolymer onto silica surfaces.
- Measurement of normal and friction forces at varying temperatures.
- Self-consistent lattice mean-field theory modeling of polymer segment density and surface forces.
Main Results:
- An attraction develops between adsorbed PIPOZ layers as temperature increases (worsening solvent conditions).
- Mean-field theory accurately predicts this temperature-dependent attraction.
- Increased temperature leads to higher segment density and chain interpenetration under load.
Conclusions:
- Temperature significantly influences the interactions and behavior of PIPOZ polymer layers.
- The findings provide insights into designing surfaces with switchable properties.
- This work validates theoretical models for thermoresponsive polymer systems.
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