Functionalized (X-PEO)2-(PS-Y)2 star block copolymers at the interfaces:: Role of terminal groups in surface behavior and morphology

We focus on the role of functional terminal group combinations for (X-PEO)(2)-(PS-Y)(2) heteroarm star copolymers with respect to their interfacial behavior and surface morphology. We synthesized a series of star copolymers with combinations of bromine, amine, TBDPS, hydroxyl, and carboxylic terminal groups. The study concluded that hydrophilic functional groups attached to hydrophobic chains and hydrophobic functional groups attached to hydrophilic chains resulted in the stabilization of the spherical domain morphology, rather than cylindrical morphology predicted for the given chemical composition of star copolymers. The replacement of functional groups of hydrophobic polymer chains was found to be even more effective in creating stable and very fine circular domain morphology. In addition, for (COON-PEO)(2)-(PS-NH2)(2) star polymer the ionization of carboxylic terminal groups at higher pH led to greater solubility of PEO chains in the water subphase, which along with deionization of amine terminal group prevented the lateral aggregation of PS domains, further promoting the formation of nanoscale circular morphology.