Solution properties of stilbene‐containing sterically crowded alternating polyanions

Abstract

Sterically crowded stilbene-containing alternating polyanions were prepared via an indirect strategy of synthesizing "protected" monomers followed by deprotection and neutralization of the polyanion precursors. The solution properties of these new sterically crowded polyelectrolytes were studied. Steady-state solution shear rheology showed a pronounced polyelectrolyte effect. The persistence lengths of these polyelectrolytes were determined. The dissociation behavior of the polyanions was investigated by pH titration with HCl, and multistep dissociation behavior was observed. Chain size and aggregation were studied by using DLS at varying ionic strengths. Polyelectrolytes behaved like rigid-rods and formed concentrated solutions at the polymer concentration of 1.0 mg mL 21.

Salt‐ and pH‐Responsive Semirigid/Flexible Double‐Hydrophilic Block Copolymers

“…Our group recently reported the synthesis and solution characterization of two different polyampholyte DHBCs with semirigid and flexible segments . The semirigid block segments (persistence lengths of 3–6 nm) comprise stilbene‐maleic acid, strictly alternating, monomer sequences . The semirigid character of these copolymers arises from the steric congestion of the incorporated stilbene monomer derivatives in addition to the stiffening from the ring structures of the maleic anhydride monomers …”

A review of semi-rigid, stilbene-containing alternating copolymers

“…Using steady-state solution shear rheology, reduced viscosity plotted against polymer concentration revealed a prominent polyelectrolyte effect in deionized water for DCSti-alt-MA, CSty-alt-MA, and Sti-alt-MA shown in Fig. 3 [23]. Increasing the sodium chloride (NaCl) concentration suppressed the polyelectrolyte effect by decreasing the Debye Length and electrostatic repulsions as the polymer concentration decreased.…”

“…Further physical aqueous solution properties evaluated using steady-state solution shear rheology, dynamic light scattering (DLS), and titration studies proved critical to understanding effects of polymer rigidity and conformation in aqueous solutions [23]. Using steady-state solution shear rheology, reduced viscosity plotted against polymer concentration revealed a prominent polyelectrolyte effect in deionized water for DCSti-alt-MA, CSty-alt-MA, and Sti-alt-MA shown in Fig.…”

“…For study of the polyanions, deprotection with trifluoroacetic acid followed by neutralization with base and dialysis yielded the pure, well-characterized polyanions. The solution properties of the precursor tert-butyl ester copolymers and the polyanions were studied in detail [23].…”

“…Using the same deprotection strategy above, a family of polyanion and polyampholyte copolymers were prepared with stilbene comonomers and the solution properties arising from the semi-rigid copolymer backbone were studied [22,23,30].…”