Support layer polyacrylonitrile

Typical membranes prepared according to this synthesis procedure have chito-san, PVA (polyvinylalcohol), PPO (polyphenylene oxide), PDMS (polydimethyl si-loxane) or Nation top-layers. Typical support layers are made of PAN (polyacrylonitrile), PI (polyimide), PVDF (polyvinylidenedifluoride) or PSf (polysulfone). 

Oh et al. took AFM pictures of TFC nanofiltration membranes, each consisting of a polycimide skin layer formed by in situ polymerization on a polyacrylonitrile (PAN) support layer [29]. PAN support membranes were prepared from casting solutions with different PAN concentrations (10,15, and 20 wt.%) by the phase inversion technique, followed by treatment with a sodium hydroxide solution. The pictares taken for the top surfaces of these membranes are shown in Fig. 4.14. The figme clearly shows that the smface morphology depends on the PAN concentration. 

A composite separator made from three layers a polyolefin fiber support layer, a ceramic coating layer, and a polyacrylonitrile nanofiber layer.The separator possesses high porosity, small pore size, and high tensile strength. The cells showed better rate capabilities, and in a hot box at 150°C, showed higher thermal stability than cells made with conventional separators. 

Oh et al. studied PA composite membranes prepared by the conventional interfacial polymerization of PA active layers on the surface of various microporous polyacrylonitrile (PAN) supports [80]. The PAN supports were prepared by using PAN/NMP solution with various compositions (10/90,15/85, and 20/80 wt.%). The PAN supports were further modified with NaOH solutions of different concentrations for 1 h at40 °Cto form -COOH groups on their surfaces [81]. Figure 4.50 shows AFM photographs of PAN membranes treated with different NaOH concentrations after their formation from a 15 wt.% PAN solution. Figure 4.50 indicates visually the difference in the surface morphology between those membranes. The surface became smoother as the concentration of NaOH increased. 

Asymmetric membranes consist of a thin top layer supported by a porous sublayer and quite often macrovoids can be observed in the porous sublayer. Figure EH - 54 illustrates two ultrafiltration membranes from polysulfone and polyacrylonitrile, where the existence of these macrovoids can be clearly observed. 

Plasma-treated/hydrolized polyacrylonitrile and cellulose acetate, on the other hand, are negatively charged [126,127]. In addition, PES is rather appealing to be used as a supporting material although it is fairly neutral. Hence, the attachment of polyelectrolyte layer is based on hydrophobic interaction [115]. 

The dimerization of isobutene carried out in a forced-flow polymeric catalytic membrane reactor was reported by D. Fritsch and co-workers. The authors prepared composite porous membranes consisting of a catalytic layer made of solid add catalysts, such as siUca supported Naflon , Nafion NR50, Amberlyst 15 and silica supported tungstophosphoric add dispersed in polymeric binders such as Teflon AF, Hyflon AD, polytrim-ethylsilylpropyne, or polydimethylsiloxane (PDMS), cast on microporous support membranes made of polyacrylonitrile (PAN) or Torlon . The membranes were assembled in the membrane reactor into which isobutene was fed in the retentate side with a build-up pressure of 4 bar. The liquid product was collected on the permeate side. 

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