Evolution of high-temperature molecular relaxations in poly(2-(2-methoxyethoxy)ethyl methacrylate) upon network...

Area of Science:

• Polymer Science
• Materials Science
• Biomaterials

Background:

• Poly(2-(2-methoxyethoxy)ethyl methacrylate) (poly(MEO2MA)) is a bioinert polymer alternative to poly(N-isopropylacrylamide).
• Poly(MEO2MA) can form thermo-responsive hydrogels with varying network architectures.
• Understanding the dynamic mechanical properties of poly(MEO2MA) is crucial for its biomedical applications.

Purpose of the Study:

• To investigate the segmental motions and network relaxation processes in linear poly(MEO2MA) and its different network structures.
• To determine the influence of polymer topology and network formation on the glass transition temperature (Tg) and relaxation dynamics.
• To characterize the sub-Rouse process in poly(MEO2MA) networks using dielectric and mechanical spectroscopy.

Main Methods:

• Dielectric spectroscopy was employed to study segmental motions.
• Dynamic mechanical analysis (DMA) was used to investigate network relaxation processes.
• Linear poly(MEO2MA), bare poly(MEO2MA) networks, and grafted poly(MEO2MA) networks were analyzed.

Main Results:

• The alpha (α) process, attributed to poly(MEO2MA) segmental motions, was found to be independent of polymer topology.
• The glass transition temperature (Tg) associated with the α process remained consistent across all investigated systems (235–236 K).
• The alpha-prime (α') relaxation, assigned to the sub-Rouse process, showed strong dependence on network architecture, slowing down significantly with network formation.

Conclusions:

• The segmental dynamics of poly(MEO2MA) are robust and unaffected by network structure or grafting.
• Network formation significantly impacts higher-order relaxation processes, like the sub-Rouse process.
• Poly(MEO2MA) hydrogels maintain consistent thermal properties regardless of their architectural complexity.