Polyampholytes consisting of oppositely charged monomer subunits are considered as the synthetic equivalents of naturally occurring biological molecules like proteins or DNA, and have offered many potential applications in industries. Among them, the hydrophobically modified polyampholytes are unique class of these polymers containing both ionizable and hydrophobic moieties. Therefore, the structure, morphology, hydrodynamic and conformational properties of hydrophobic polyampholytes depend on environmental conditions including pH, ionic strength, temperature, water-organic solvents. Two major forces – electrostatic repulsion (or attraction) and hydrophobic interactions – govern self-assembly process of these polymers and decide formation of different structures such as amorphous, ordered, expanded, coiled and globular states.
In this research, the polymeric betaines containing various long alkyl chains were synthesized by Michael addition reaction of hydrophobically modified aminocrotonates and methacrylic acid and characterized by FTIR, NMR, DSC, DLS, viscometry and zeta-potential measurements. Self-assembly of these polymers in different solvents were studied. The average hydrodynamic size and zeta potential of diluted aqueous solutions of hydrophobic polybetainess containing dodecyl-, tetradecyl- and octadecyl groups were studied as a function of pH and solvents. The results from DLS, TEM, and cryo-TEM will be also discussed as function of pH, solvents, and ionic strength. In addition, the effect of hydrophobically modified polbetaines on the crystal growth mechanism of paraffin will be also studied.