Polyaromatic-anion behavior of different polyelectrolytes containing benzenecarboxylate units

Area of Science:

• Polymer Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Polyelectrolytes are polymers with charged groups, widely used in various applications.
• Understanding their interactions with other molecules is crucial for designing new materials.
• Aromatic-aromatic interactions play a significant role in the behavior of polyaromatic-ion systems.

Purpose of the Study:

• To investigate the polyaromatic-ion behavior of specific copolymers: poly(sodium N-maleoyl-2-aminobenzoate-co-sodium acrylate), poly(sodium N-maleoyl-4-aminobenzoate-co-sodium acrylate), and poly(sodium N-maleoyl-4-aminobenzoate-co-N,N-dimethylacrylamide).
• To examine the interactions of these copolymers with model dyes, methylene blue and rhodamine B.
• To compare the behavior of these copolymers with reference polymers like poly(sodium 4-styrenesulfonate) and poly(sodium vinyl sulfonate).

Main Methods:

• Synthesis and characterization of novel copolymers.
• Spectroscopic analysis (UV-vis) to study interactions and spectral shifts.
• Titration methods to determine changes in pK(a) values.
• Comparative studies with reference polyelectrolytes under varying salt concentrations.

Main Results:

• Copolymers exhibit short-range aromatic-aromatic interactions with methylene blue and rhodamine B, causing a bathochromic shift in UV-vis spectra.
• Methylene blue is effectively dispersed on the polymeric domains due to the polyaromatic-anion behavior.
• The pK(a) of rhodamine B increases in the presence of the copolymers, indicating altered protonation states.
• The copolymers show a lower resistance to salt-induced disruption of methylene blue interaction compared to poly(sodium 4-styrenesulfonate).
• Differential effects on the reduction of 2,3,5-triphenyl-2H-tetrazolium chloride by ascorbic acid were observed for the different polyelectrolytes.

Conclusions:

• The studied copolymers demonstrate significant polyaromatic-anion behavior, influencing dye interactions and properties.
• These findings provide insights into the design of functional polyelectrolytes for applications involving molecular recognition and dispersion.
• The comparative study highlights the nuanced role of polymer structure and reference materials in understanding polyelectrolyte complexation.