Development of temperature-responsive polymeric gels with physical crosslinking due to intermolecular ��-��...

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Poly(N-isopropylacrylamide) (PNIPAAm) is a well-known thermoresponsive polymer.
• Incorporating moieties that promote physical crosslinking can enhance polymer properties.
• Pi-pi interactions are a key mechanism for physical crosslinking in polymer systems.

Purpose of the Study:

• To synthesize novel thermoresponsive polymers by copolymerizing PNIPAAm with biphenyl-containing monomers.
• To investigate the effect of biphenyl co-monomer content on polymer properties, specifically thermoresponsiveness and physical crosslinking.
• To explore the potential applications of these unique physically crosslinked systems.

Main Methods:

• Synthesis of polymers using 2-phenylphenol monoacrylate (2PPMA) and 4-phenylphenol monoacrylate (4PPMA) as biphenyl co-monomers.
• Characterization using gel permeation chromatography (GPC) to determine molecular weight.
• Swelling studies and mechanical testing to evaluate thermoresponsive behavior and physical crosslinking.

Main Results:

• GPC confirmed a decrease in average molecular weight with increased initiator concentration.
• Swelling studies demonstrated temperature-dependent swelling, with increased biphenyl content reducing swelling ratio due to enhanced physical crosslinking.
• Mechanical tests indicated that biphenyl co-monomer concentration significantly influences the material's mechanical properties.

Conclusions:

• The incorporation of biphenyl moieties effectively creates a thermoresponsive physically crosslinked system in PNIPAAm-based polymers.
• The degree of physical crosslinking, and consequently swelling and mechanical properties, can be tuned by adjusting biphenyl co-monomer content.
• These novel polymers show promise for applications in environmental remediation, sensing, and biomedicine.