Abstract: Disclosed herein are a polyimide-polybenzoxazole copolymer, a method for preparing thereof and a gas separation membrane comprising the same. More specifically, provided are a polyimide-polybenzoxazole copolymer simply prepared through thermal-rearrangement performed by thermally treating a polyimide-poly (hydroxyimide) copolymer as a precursor, a method for preparing the same, and a gas separation membrane comprising the same. The copolymer shows superior gas permeability and gas selectivity, thus being suitable for use in gas separation membranes in various forms such as films, fibers or hollow fibers. The gas separation membrane thus prepared can advantageously endure even harsh conditions such as long operation time acidic conditions and high humidity due to the rigid polymer backbone present in the copolymer.

Abstract: Disclosed herein are a method for preparing a benzoxazole-based polymer by thermal rearrangement, the benzoxazole-based polymer prepared by the method and a gas separation membrane comprising the polymer. More specifically, provided are a method for preparing a benzoxazole-based polymer by subjecting poly(hydroxyamide) as an intermediate to thermal treatment involving dehydration, the benzoxazole-based polymer obtained thereby and gas separation membrane comprising the polymer. The benzoxazole-based polymer of the present invention can be simply prepared by thermally rearrangement via thermal treatment at low temperatures, and thus exhibits superior mechanical and morphological properties and has well-connected microcavities. Due to showing excellent permeability and selectivity for various gases, the benzoxazole-based polymer is suited for application to gas separation membranes, in particular, gas separation membranes for small gases.

Abstract: Disclosed is a method of preparing porous polybenzimidazole. The method includes providing polyaminoimide by reacting aromatic amine including at least two ortho-positioned amino groups and acid dianhydride, obtaining polypyrrolone from the polyaminoimide, subjecting the polypyrrolone to alkaline treatment, and subjecting the alkaline-treated polypyrrolone to heat treatment. The polybenzimidazole shows permeability and selectivity for various gases due to a fractional free volume and well-connected picopores.

Abstract: Disclosed herein are polymer compounds, a method for preparing thereof. More specifically, provided are polymer compounds with well-connected, narrow size distribution free-volume element and a method for preparing the polymer compounds by thermal rearrangement for aromatic polyimides containing ortho-positioned functional groups in the solid state.

Abstract: Disclosed is a hollow fiber that includes a hollow positioned at the center of the hollow fiber, macropores positioned at adjacent to the hollow, and mesopores and picopores positioned at adjacent to macropores, and the picopores are three dimensionally connected to each other to form a three dimensional network structure. The hollow fiber includes a polymer derived from polyimide, and the polyimide includes a repeating unit obtained from aromatic diamine including at least one ortho-positioned functional group with respect to an amine group and dianhydride.

Abstract: Disclosed is a hollow fiber that includes a hollow positioned at the center of the hollow fiber, macropores positioned at adjacent to the hollow, and mesopores and picopores positioned at adjacent to macropores, and the picopores are three dimensionally connected to each other to form a three dimensional network structure. The hollow fiber includes a polymer derived from polyamic acid, and the polyamic acid includes a repeating unit obtained from aromatic diamine including at least one ortho-positioned functional group with respect to an amine group and dianhydride.

Abstract: Disclosed herein are a polyamic acid dope solution composition, a method for preparing a hollow fiber using the composition and a hollow fiber prepared by the method. More specifically, disclosed are a method for preparing a hollow fiber, comprising preparing a polyamic acid dope solution composition comprising polyhydroxyamic acid, polythiolamic acid or polyaminoamic acid, spinning the composition to prepare a hollow fiber, and imidizing and thermally rearranging the hollow fiber, and the hollow fiber prepared by the method. In accordance with the method, a hollow fiber made of a high free volume polymer membrane can be prepared by spinning the dope solution composition to prepare a hollow fiber and thermally rearranging the hollow fiber via thermal treatment. The hollow fiber thus prepared exhibits excellent gas permeability and selectivity, thus being suitable for use as a gas separation membrane.

Abstract: Disclosed herein are a polyimide dope solution composition, a method for preparing a hollow fiber using the composition and a hollow fiber prepared by the method. More specifically, disclosed are a method for preparing a hollow fiber, comprising preparing a polyimide dope solution composition comprising polyhydroxyimide, polythiolimide or polyaminoimide, spinning the composition to prepare a hollow fiber, and thermally rearranging the hollow fiber, and the hollow fiber prepared by the method. In accordance with the method, a hollow fiber made of a high free volume polymer membrane can be prepared by spinning the dope solution composition to prepare a hollow fiber and thermally rearranging the hollow fiber via thermal treatment. The hollow fiber thus prepared exhibits excellent gas permeability and selectivity, thus being suitable for use as a gas separation membrane.

Abstract: The present invention relates to novel aminopeptidase derived from Bacillus licheniformis, a gene encoding the aminopeptidase, an expression vector containing the gene, a cell transformant transfected with the expression vector and a process for preparing a natural type protein using thereof. More particularly, the present invention relates to a gene encoding aminopeptidase which is cloned and manufactured using the recombinant DNA technique, an expression vector containing the gene, a cell transformant transfected with the expression vector and a recombinant aminopeptidase which is necessary to produce recombinant human growth hormone in a natural type protein and can be expressed in a high yield more stably and advantageously, compared with conventional methods for the purification.

Abstract: The present invention relates to novel aminopeptidase derived from Bacillus licheniformis, a gene encoding the aminopeptidase, an expression vector containing the gene, a cell transformant transfected with the expression vector and a process for preparing a natural type protein using thereof. More particularly, the present invention relates to a gene encoding aminopeptidase which is cloned and manufactured using the recombinant DNA technique, an expression vector containing the gene, a cell transformant transfected with the expression vector and a recombinant aminopeptidase which is necessary to produce recombinant human growth hormone in a natural type protein and can be expressed in a high yield more stably and advantageously, compared with conventional methods for the purification.