Reduction of Surface Hydrophobicity Using a Stimulus-Responsive Polysaccharide

Abstract

The adsorption of carboxymethyl cellulose (CMC) onto a hydrophobic self-assembled monolayer has been characterized using the quartz crystal microbalance (with dissipation monitoring, QCM-D). Adsorption was studied as a function of initial solution conditions. CMC adsorbs to a greater extent at high ionic strength (10(-1) M KCl as opposed to 10(-2) M KCl) or low pH (3 as opposed to 9). The solution conditions that yielded the lowest initial adsorbed amount (10(-2) M KCl, pH 9) were used as a reference to investigate the response of the adsorbed layer to a switch in solution conditions after adsorption (i.e., to higher ionic strength (10(-1) M KCl) or lower pH (pH 3)). The adsorbed layer released significant amounts of hydration water after each solution switch, as determined by the QCM-D measurements. This expulsion of hydration water was fully reversible. For the two solution switches, reducing the solution pH resulted in a more pronounced change in the amount of hydration water within the adsorbed CMC, accompanied by a distinct conformational change, as determined from a QCM D-f plot. In addition to studying adsorption using QCM-D, the effect of adsorbed CMC on surface hydrophobicity has been investigated using captive bubble contact angle measurements. The effect of the polymer on the contact angle of the surface was seen to be greatest when adsorbed at low pH or at higher ionic strength. CMC was also seen to have a significantly enhanced ability to reduce the surface hydrophobicity after both the ionic strength and pH switches, lowering the advancing water contact angle by 6 and 23° and the receding water contact angle by 10 and 40° for the ionic strength and pH switches, respectively. As with the change in hydration water content, the change in the contact angle of the polymer-coated surface following the solution switches was reversible.

Adsorption of Hyperbranched Arabinogalactan-Proteins from Plant Exudate at the Solid–Liquid Interface

“…Combining these two techniques can provide information on the sorption mechanisms, structural changes, and obtained state of hydration of the adsorbed film. These techniques have been widely used to investigate the adsorption properties of biopolymers, proteins, and polysaccharides on various type of surfaces with or without grafting [34][35][36][37][38][39][40][41][42][43][44][45][46]. A comparison of the two gums should allow their respective contribution to the surface interactions leading to adsorption to be deciphered.…”

A Survey of the 2010 Quartz Crystal Microbalance Literature

“…The production of surfaces comprising cellulose or modified cellulose was presented in a number of papers with relevance to biological structures, rigidity and layer modulation and control under various conditions. The adsorption of carboxymethyl cellulose onto surfaces can be manipulated by changes in pH and ionic strength and adsorption onto an alkanethiol coated gold surface was investigated by QCM in order to manipulate the conformation, water content and hydrophobicity of the formed surface (Sedeva et al ., ). The formation of planar surfaces of modified cationic hydroxyethyl cellulose on citrated coated gold surfaces was also examined (Pamies et al ., ).…”

Impact of Surface Hydrophobicity and Salinity on the Adsorption of Humic Acids

“…The adsorbed mass also can be determined from the change of the frequencies (Δfn) at different overtone numbers (n), while n is the vibrational resonance overtone numbers (equal to 1, 3, 5, 7, 9, ...) [20,21]. Since the noise at 5 MHz (fundamental overtone, n=1) was particularly large, we followed the practice of literature reports [23,24] and neglected these data and only focused on the overtones larger than one (n=3, 5, 7, 9). The adsorbed mass (Δm) values obtained from overtone numbers n-3, 5, 7, 9 were compared, and the average values of adsorbed mass and standard deviation were presented.…”