Interactions affecting the mechanical properties of macromolecular microsphere composite hydrogels
Fangzhi Jiang1, Ting Huang, Changcheng He
1Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University , Beijing 100875, People's Republic of China.
The Journal of Physical Chemistry. B
|October 8, 2013
Summary
Macromolecular microsphere composite (MMC) hydrogels offer superior toughness through combined chemical and physical cross-linking. Their mechanical properties, including fracture energy, are significantly enhanced even when swollen, demonstrating remarkable resilience.
Area of Science:
- Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Macromolecular microsphere composite (MMC) hydrogels are advanced materials known for their toughness.
- Fabrication involves peroxidized macromolecular microspheres acting as polyfunctional initiating and cross-linking centers (PFICC).
- Understanding the interplay of chemical and physical cross-linking is crucial for tailoring hydrogel properties.
Purpose of the Study:
- To investigate the mechanical properties of MMC hydrogels.
- To elucidate the contributions of chemical and physical cross-linking to hydrogel performance.
- To analyze the impact of varying water content on mechanical behavior.
Main Methods:
- Fabrication of MMC hydrogels using PFICC.
- Mechanical testing of hydrogels swollen in water and aqueous urea solutions.
- Cyclic tensile testing to evaluate hysteresis and residual strain.
Main Results:
- As-prepared MMC gels show moderate moduli (60-270 kPa), high fracture stress (up to 0.54 MPa), extensibility (up to 2500%), and fracture energy (270-770 J m(-2)).
- Swollen gels exhibit decreased moduli but maintained or increased fracture strength and strain.
- Significantly enhanced fracture energies (>2000 J m(-2)) were observed in swollen gels, with reduced hysteresis and residual strain.
Conclusions:
- Covalent bonding dictates tensile strength and fracture energy in MMC gels.
- Physical cross-linking (entanglement, hydrogen bonding) primarily influences modulus and hysteresis.
- MMC hydrogels demonstrate tunable mechanical properties and enhanced toughness, particularly when swollen.
