POLYALLYL AMINE

A significant number of works are concerned with the development of new membranes for the separation of mixtures of aromatic/alicyclic hydrocarbons [10,11,77-109]. For example, the following works can be mentioned. A mixture of cellulose ester and polyphosphonate ester (50 wt%) was used for benzene/cyclohexane separation [113]. High values of the separation factor and flux were achieved (up to 2 kg/m h). In order to achieve better fluxes and separation factors the attention was shifted to the modification of polymers by grafting technique. Grafted membranes were made of polyvinylidene fluoride with 4-vinyl pyridine or acrylic acid by irradiation [83]. 2-Hydroxy-3-(diethyl-amino) propyl methacrylate-styrene copolymer membranes with cyanuric chloride were prepared, which exhibited a superior separation factor /3p= 190 for a feed aromatic component concentration of 20 wt%. Graft copolymer membranes based on 2-hydroxyethyl methylacrylate-methylacrylate with thickness 10 pm were prepared [85]. The membranes yielded a flux of 0.7 kg/m h (for feed with 50 wt% of benzene) and excellent selectivity. Benzene concentration in permeate was about 100 wt%. A membrane based on polyvinyl alcohol and polyallyl amine was prepared [87]. For a feed containing 10 wt% of benzene the blend membrane yielded a flux of 1-3 kg/m h and a separation factor of 62. 

Covalent coupling. Reactive LB/LS membranes with dense assemblies of am-phiphiles displaying activated ester, anhydride, imide, and disulfide functionalities have been developed for direct or linker-mediated coupling to proteins, especially for biosensors [68,69]. Thus, a-chymotrypsin can be bound to LB films of succinimidyl behenoate to give supported planar monolayers [70]. Alternatively, functionalized polymers such as polyethyleneimine and polyallyl-amine can be adsorbed to fatty acid LB/LS membranes, followed by covalent attachment of proteins to the polymers [68]. However, covalent immobilization suffers from the drawback that it may lead to undesirable conformational disturbances in the protein and partial denaturation. 

---