Ion Track Technology

PhysicsConsult

Reimar Spohr

PostHeaderIcon Abstract

Transport properties of thermo-responsive ion track membranes. Reber, N.; Kuchel, A.; Spohr, R.; Wolf, A.; Yoshida, M.. J. Membr. Sci. (2001), 193(1), 49-58

The permeation of orange G (MW 452), methylene blue (MW 319), and bovine albumin (MW 68000), through thermo­responsive ion track membranes was studied. For this purpose, poly-N-isopropylacrylamide (poly-NIPAAm) hydro-gel was chem. grafted onto single/multi-pore ion track membranes of poly(ethylene terephthalate) (PET).The local transport properties were studied by measuring the elec. current through single pore membranes. It was found that the incorporation of the hydro-gel into the pores does not influence the phase transition temp. The switching of the responsive membrane was reversible over 200 switching cycles applied during 30-50 days. The closed pores represent a phys. barrier excluding org. mols. larger than 2.+-.0.2 nm. This fact is based on the size exclusion method using mixts. of polyethylene glycol (PEG) of various mol. wts. and 0.1 N potassium chloride.The global transport properties were studied using multi-pore membranes with 5.times.105 to 5.times.107 pores per cm2 and pore diams. between 0.6 and 4.5 .mu.m. For bovin insulin permeation in the open state was 35 times above the level of the closed state corresponding to the detection limit of the used permeation cell. In the open state the transport rates of the solvent and the solute were identical implying that the free space in the open pores was larger than the size of the permeating bovine albumin mols. (about 7.3 nm). The linear relation between pressure and mass current enabled to det. an effective open-pore diam. between 0.2 and 1 .mu.m. In the open state, the membrane this is not mol. selective.