Related Experiment Video
Updated: Aug 14, 2026
11:17
Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
Photo-Thermally Sequentially Responsive Shape Memory Polymers Based on Side-Chain Azobenzene-Functionalized Epoxy
Jinxiong Wen1, Xianhao Mao1, Shaojun Chen1
1College of Materials Science and Engineering, Shenzhen University, Shenzhen 518053, China.
Polymers
|August 13, 2026
Summary
New epoxy-based shape memory polymers (ESMPs) with azobenzene (Azo) side chains exhibit enhanced photothermal sequential response and shape memory stability. This molecular design offers potential for advanced smart actuators and flexible electronics.
Area of Science:
- Materials Science
- Polymer Chemistry
- Nanotechnology
Background:
- Traditional photothermal-responsive epoxy-based shape memory polymers (ESMPs) face limitations in compatibility and cyclical stability.
- Developing advanced materials with improved performance is crucial for smart actuators and flexible electronics.
Purpose of the Study:
- To synthesize and characterize novel side-chain azobenzene (Azo)-functionalized linear ESMPs (EPDm) with enhanced photothermal-responsive and shape memory properties.
- To investigate the effect of Azo content on the glass transition temperature (Tg) and photothermal behavior of the synthesized polymers.
Main Methods:
- Covalent integration of 4-aminoazobenzene (Azodm) units into a Bisphenol A-type epoxy backbone.
- Systematic characterization of synthesized EPDm polymers using techniques to determine Tg, tensile strength, and shape memory performance.
- Evaluation of photothermal sequential behavior under UV irradiation and assessment of shape fixity and recovery ratios over multiple cycles.
Main Results:
- EPDm polymers with tunable Tg (41.53 °C to 53.26 °C) were successfully synthesized via chemical bonding.
- Homogeneous covalent architecture led to superior photothermal sequential behavior and remarkable shape memory stability.
- EPDm films demonstrated rapid macroscopic bending (>150° in 15 s) driven by Azo photoisomerization and excellent shape fixity (>98%) and recovery (>95%) ratios with high anti-fatigue performance.
Conclusions:
- A robust and high-efficiency molecular design strategy for photo-thermally sequentially responsive shape memory polymers was established.
- The synthesized EPDm polymers exhibit significant potential for applications in smart actuators and flexible electronics.
- This work overcomes limitations of traditional ESMPs, paving the way for next-generation responsive materials.
Related Concept Videos
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
02:26Base-Catalyzed Ring-Opening of Epoxides
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...