In Situ Hydrolysis of Block Copolymers at the Water‐Oil Interface

Abstract

In situ manipulation of the chemical composition of block copolymers at the fluid interfaces affords a route by which the interfacial tension, the packing of the copolymers, and the penetration of the blocks into the two liquids can be controlled. Here, a series of linear block copolymers of poly(solketal methacrylate-bstyrene) (PSM-b-PS) are used, converting hydrophobic PSM block into a hydrophilic glycerol monomethacrylate (GM) block, that results in a marked decrease in the liquid-liquid interfacial tension. The kinetics of the first-order hydrolysis reaction was analyzed by monitoring the time-dependent interfacial tension as a function of pH, polymer concentration, molecular weight, and composition. Fluorescence recovery after photobleaching (FRAP) was used to measure the in-plane dynamics of the copolymers before and after hydrolysis. This work provides insights into a quantitative pathway by which in situ interfacial reactions may be performed and monitored in real time, completely changing the interfacial activity of the molecule.

Amphiphilic Heterografted Molecular Bottlebrushes with Tertiary Amine‐Containing Side Chains as Efficient and Robust pH‐Responsive Emulsifiers

“…Clearly, even if MBB‐B 0.24 E 0.76 and MBB‐B 0.00 E 1.00 at pH 4.0 and all PDEAEMA‐containing MBBs at pH 10.0 decreased γ significantly, the individual bottlebrushes were not strongly bound to the interface and were ejected from the interface when the interfacial area was reduced. Note that the lowering of γ reflects the adsorption of amphiphiles to the water‐oil interface but does not necessarily correlate with emulsion stability, which has been reported in the literature [10a,15b] . The rheological properties of the adsorbed interfacial layer, related to the binding energy per emulsifier species to the interface, play an important role among many factors in determining if emulsion droplets are stable against coalescence [15–18,20,31] …”

Hydrolysis-Induced Morphology Evolution of Linear and Bottlebrush Block Copolymers in Thin Films with Acid Vapor or Photoacid Generators

“…Hydrolysis in solution could be achieved with hydrochloric acid. 56 Before hydrolysis, the segmental interaction parameter (χ) between the two blocks was low, 0.035 at 25 °C using 118 Å 3 as a reference volume. 54 As a result, the BCPs were in a disordered state.…”

“…Solid-state hydrolysis of PSM into PGM in spin-coated thin films was achieved by a previously used TFA vapor strategy and a newly developed PAG route. Hydrolysis in solution could be achieved with hydrochloric acid . Before hydrolysis, the segmental interaction parameter (χ) between the two blocks was low, 0.035 at 25 °C using 118 Å 3 as a reference volume .…”

On the Interfacial Assembly of Anisotropic Amphiphilic Janus Particles

“…To quantitatively understand this relaxation behavior and the time scales associated with the relaxations, the data were fit with a sum of linear exponential decays. The dynamic interfacial tension as a function of time can be expressed as, [70,71]…”