Untitled

Abstract

The desorption behaviour of the diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), preadsorbed on silicon substrates was investigated under the influence of several desorption agents. The investigated polyampholyte is known to adsorb in regular structures directly from aqueous solutions onto silicon substrates While the adsorption process is mainly determined by electrostatic interactions, two kinds of desorp-tion mechanism should be assumed The first mechanism is based on changed electrostatic conditions caused for instance by a strong change in pH of the aqueous solution. The other mechanism is observed after treatment with hydrophobic organic solvent, which leads to the desorption of hydrophobic adsorbed polyampholyte chains, while the electrostatically attached ones will not be influenced. To complete the desorption experiments with organic solvents also adsorption experiments from analogous polyampholytic solutions in the same organic solvents were performed. The amount of polymer at the substrate surface after adsorption or desorption experiments was determined using ellipsometry. Atomic force microscopy (AFM) was used to investigate the surface topography of dried samples after the desorption process.

Self-Assembly and Dual-Stimuli Sensitivities of Hydroxypropylcellulose-graft-poly(N,N-dimethyl aminoethyl methacrylate) Copolymers in Aqueous Solution

“…Figure shows the transmittance of the HPC 0.1 - g -PDMAEMA 20 aqueous solution at different pH values as a function of temperature and the LCST as a function of pH values. It is known that PDMAEMA (p K a ≈ 8.0) can be protonated in an acidic aqueous solution, which leads to the increase in the electrostatic repulsive force and prevent the phase separation . Therefore, the LCST of HPC 0.1 - g -PDMAEMA 20 copolymer shifts to a higher temperature with the decrease in the pH values of the solutions (Figure b), which is similar to tendency of the LCST of PDMAEMA 108 homopolymer that reported in literature .…”

“…Whereas the peaks for the PDMAEMA side chains remains unchanged in all the experimental temperatures ( a , b , c , d in Figure a). It is known that PDMAEMA (p K a ≈ 8.0) is a weak polyelectrolyte and can be protonated in an acidic aqueous solution. , The LCST of PDMAEMA shifts to higher temperature with the decrease in pH due to the protonation of PDMAEMA chain, which lead to the increase in the electrostatic repulsive force and prevent the phase separation. The protonated PDMAEMA will not possess an LCST anymore. , Therefore, when the HPC 0.1 - g -PDMAEMA 20 acid aqueous solutions are heated, the HPC backbone collapse to form the core of the micelles that stabilized by the hydrophilic PDMAEMA side chains as the shell.…”

Modelling the interaction processes between nanoparticles and biomacromolecules of variable hydrophobicity: Monte Carlo simulations

“…[19][20][21] Moreover, stronger affinity is observed with higher protein charge anisotropy. [19][20][21] Moreover, stronger affinity is observed with higher protein charge anisotropy.…”

“…The adsorption dynamics and conformational changes between proteins and nanoparticles are reported to be mainly driven by local electrostatic interactions and pH of solution. [19][20][21] Moreover, stronger affinity is observed with higher protein charge anisotropy. 22 However, van der Waals, hydrophobic, hydrophilic and structural interactions, as well as surface curvature, may also play a role in the adsorption (coating) process on nanoparticles, or more generally nanomaterials.…”

Amphoteric nano-, micro-, and macrogels, membranes, and thin films

“…So far, most of interfacial studies on polyampholytes have reported their adsorption on solid interfaces. 195,196 For example, Mahltig et al [196][197][198][199][200][201] studied the adsorption of poly(methacrylic acid)block-poly(dimethyl aminoethyl methacrylate) (PMAA-b-PDMAEMA) from aqueous solution on silicon substrates. It was found that the adsorbed amount of PMAA-b-PDMAEMA at the solution-substrate interface depended on the solution pH.…”