Membranes composed of poly(viny1pyrrolidone)-poly(methacry1ic acid) (PVP-PMAA) complexes appear to be suitable for pervaporation of water-n-propanol mixtures. The membranes are selective to water. The separation factor a increases with increasing content of propanol, w, , , , and reaches a maximum value for wpaH at about 0.8 in the case of PVP-rich membranes, and close to wpaH = 1 for PMAArich membranes. All membranes exhibited maximum swelling at wpaH of ca. 0.4.At constant wpmH of 0.8 the value of a changes in a complicated manner with the composition of the membrane. Under this condition of constant wpaH, a runs parallel with the swelling degree. A tentative explanation is proposed for results pertaining to membranes containing not too high excesses of PVP or PMAA.
ZUSAMMENFASSUNG:Membranen aus Komplexen von Poly(viny1pyrrolidon) und Poly(methacry1saure) (PVP und PMAA) zeigen sich geeignet fur die Pervaporation von Wasser-n-Propanol-Mischungen durch diese Membranen. Die Membranen sind selektiv beziiglich der Permeation von Wasser. Der Trennfaktor a steigt mit zunehmendem Gehalt an Propanol, wproH, und erreicht einen maximalen Wert fiir w, , , = 0,8 fur PVPreiche und nahe w, , , = 1 fur PMAA-reiche Membranen. Alle Membranen zeigen eine maximale Quellung bei Werten fur w, , , von ca. 0,4. Bei einem konstanten wprOH von 0,8 andert sich der Wert fur a in einer komplizierten Weise mit der Zusammensetzung der Membran. Bei diesen Bedingungen andert sich a proportional zum Quellungsgrad. Fur die Ergebnisse bei Membranen mit nicht zu hohen uberschiissen an PVP oder PMAA wird eine vorlaufige Erklarung vorgeschlagen .
Depending on the kind of initiator, anionic polymerization of 4-(a,~dimethylbenzyl)phenyl methacrylate in toluene at -78 "C led either to highly isotactic or predominantly syndiotactic polymers as determined by 13C NMR spectroscopy. The glass transition temperature difference between the syndiotactic and isotactic polymer appeared to be smaller than in case of poly(alky1 methacrylates), probably because of a larger stiffening effect by the bulky aromatic ester group on the isotactic backbone than on the syndiotactic one.
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