Asymmetric polyvinylidine chloride membranes and carbon molecular sieve membranes made therefrom

A method of making an asymmetric polyvinylidene chloride copolymer membrane, the method comprising:

• (i) providing a dope solution comprised of a polyvinylidene chloride copolymer and a solvent that solubilizes the polyvinylidene chloride copolymer;
• (ii) shaping the dope solution to form an initial shaped membrane;
• (iii) exposing the initial shaped membrane to a quenching liquid comprised of a solvent that is miscible with the solvent that solubilizes the polyvinylidene chloride copolymer but is immiscible with the polyvinylidene chloride copolymer to form a wet asymmetric polyvinylidene chloride copolymer membrane;
• and
• (iv) removing each of the solvents of step (i) and (iii) to form the asymmetric polyvinylidene chloride copolymer membrane,
• wherein the polyvinylidene chloride copolymer has an amount of comonomer of 3% to 20% by weight of the polyvinylidene chloride copolymer,
• wherein the comonomer is one or more of the following:
• a vinyl monomer;
• a vinyl chloride monomer;
• an acrylate monomer;
• a methacrylate monomer;
• a styrenic monomer;
• acrylonitrile, methacrylonitrile;
• itaconic acid;
• chlorotrifluoroethylene, and
• wherein the polyvinylidene chloride copolymer has a crystallinity ranging from 60% to 85%, as measured by differential scanning calorimetry (DSC) according to ASTM D3418.