PEG-Based Photo-Cross-Linked Networks with Adjustable Topologies and Mechanical Properties

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials Engineering

Background:

• Polymer networks with tunable properties are crucial for advanced materials.
• Controlling network topology and mechanical characteristics remains a challenge.
• Poly(ethylene glycol) diacrylates (PEG-DA) are versatile building blocks for hydrogels.

Purpose of the Study:

• To develop a simple and robust method for synthesizing polymer networks with adjustable topologies and mechanical properties.
• To investigate the role of monothiols as non-cross-linking transfer agents in tuning network characteristics.
• To optimize PEG-based hydrogels for enhanced adhesive performance.

Main Methods:

• Photopolymerization of poly(ethylene glycol) diacrylates (PEG-DA) in the presence of mono- and multifunctional thiols.
• Systematic variation of the ratio of thiol to acrylate functions and the average thiol functionality.
• Characterization of network properties including gel point, swelling ratio, soluble fraction, viscoelastic moduli, ultimate stress, and strain.

Main Results:

• Introduction of monothiols enables the production of soft, extensible networks with tunable topologies.
• Precise adjustment of network properties (gel point, swelling, moduli, mechanical strength) was achieved by varying thiol/acrylate ratios and thiol functionality.
• The strategy was successfully applied to longer PEG-DA chains (Mn = 2300 and 3200 g·mol−1), optimizing viscoelastic and tensile responses for adhesion.

Conclusions:

• The developed thiol-acrylate polymerization strategy offers a simple and effective route to engineer PEG-based hydrogels with tailored properties.
• This approach expands the application scope of PEG-based hydrogels, particularly in areas requiring tunable mechanical performance and adhesion.
• The findings contribute to the broader field of polymer network synthesis and functional material design.