Related Experiment Video
Updated: Jul 1, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Light-Controlled Topology Switching Enables Continuous Modulation of Thermally Induced Phase Behavior in Polymer
Zhuoheng Yu1, Jie Zhang1, Jun Liu1
1School of Chemistry and Chemical Engineering, Key Laboratory of Surface and Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Abstract:
Dynamic regulation of polymer solution phase behavior with real-time reversibility remains challenging. Here, we report a light-responsive poly(ethylene glycol) (PEG) system that enables reversible switching between linear and cyclic topologies, allowing continuous modulation of thermally induced phase transitions. Linear PEG functionalized with styrylpyrene end groups undergoes efficient intramolecular [2 + 2] photocycloaddition under visible light to form cyclic polymers, while UV irradiation restores the linear precursor. This reversible topology interconversion allows continuous tuning of the cyclic/linear ratio. As a result, the cloud point temperature of aqueous solutions can be modulated over a wide range from 37 to 65 °C. Aggregation appears to be enhanced in linear polymers through end-group-mediated π-π stacking and intermicellar bridging, whereas it is suppressed in cyclic polymers due to topological constraints and reduced stacking interactions. This work establishes topology switching as a noninvasive strategy for dynamically regulating polymer solution thermodynamics and highlights topology as a tunable parameter for controlling thermoresponsive behavior.
Related Concept Videos
Step-Growth Polymerization: Overview
Many natural and synthetic polymers are produced by...
Polymer Classification: Stereospecificity
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Cationic Chain-Growth Polymerization: Mechanism
Ziegler–Natta Chain-Growth Polymerization: Overview
Phase Transitions: Vaporization and Condensation

