Addition Of Concentrated Acid Research Articles

Acid-Enhanced Interfacial Polymer Layer Growth

We report on the growth of interfacial multilayer structures formed from maleimide−vinyl ether alternating copolymers. The thickness and density of these polymer layers can be controlled by adding acid to the interlayer cross-linking reaction. We have demonstrated this control for several different interlayer cross-linking strategies, where amide, ester, urea, and urethane interlayer covalent bonds are formed. For all reactions, the addition of concentrated acid during polymer layer deposition resulted in a 2- to 4-fold increase in the loading density of the polymer relative to the acid-free reaction, depending on the acid used and its concentration. These findings are consistent with acid catalysis (HCl) and/or dehydration (H2SO4).

Isolation of xylogalactans from the Corallinales: influence of the extraction method on yields and compositions

An already studied seaweed, Corallina officinalis and two other species of the red seaweed order Corallinales, i.e. Bossiella orbigniana and Jania rubens, were extracted using three different standard procedures: the method of Usov, which destroys the calcium carbonate cover by the addition of concentrated acid, the method of Cases, which applies controlled acid degradation of this cover, and the method of Takano, which avoids an acid medium, and uses hot water. The three methods extract similar amounts of products, but those using acid give better yields of xylogalactans, without evidence for degradation. However, subsequent hot water extraction shows that the traces of acid present when applying the method of Usov yield partially degraded products at this stage. The characteristics of the xylogalactans of the newly studied seaweeds are similar to those previously studied. However, in Jania rubens significant amounts of 3,6-anhydrogalactose, and in Bossiella orbigniana small amounts of the d-enantiomer of 2- O-methylgalactose were found.