Organic polymer thin membrane, and method for producing same
|発明の名称 （英語）||Organic polymer thin membrane, and method for producing same|
|発明の概要（英語）||Provided is a technique for fabricating a novel thin membrane with a starting material such as a biocompatible compound that is not easily processible into a membrane, particularly a technique for fabricating a novel thin membrane of a composition that is gradually polymerized from a membrane surface into the membrane in the cross sectional direction of the membrane, and having, for example, different structures on the front and back of the membrane.The technique includes the steps of preparing a solution of a starting material compound; forming a thin membrane of the solution on a base material surface; and forming the organic polymer thin membrane through a polymerization reaction caused by irradiating the exposed surface of the thin membrane with a plasma or an electron beam.|
Among the examples of previously reported water-soluble compound membranes having different structures on the front and back are laminates of langmuir membranes (LB membranes) with a hydrophobic functional group and a hydrophilic functional group arranged at the gas-solid interface and the solid-liquid interface, respectively, and alternate laminate membranes of a cationic polymer and an anionic polymer.
However, fabrication of a self-supporting membrane for functional membrane applications requires laminating LB membranes or alternate laminate membranes of a molecular length thickness in several hundred layers.This is time consuming and costly.
There is a method in which a thin membrane prepared by using an existing technique such as spin casting is crosslinked to become insoluble to water.However, this requires restricting the starting material compounds, or mixing different compounds.It is also difficult to form a self-supporting membrane having different front and back structures because the whole membrane is crosslinked to become insoluble to water.
A plasma process by plasma or electron beam irradiation has been known for many years since it was first reported some 140 years ago (Non Patent Literatures 1 and 2), and plasma irradiation is commonly used in applications such as deposition from a gas phase using intermolecular radical polymerization, a surface hydrophilic treatment, and crosslinking of polymers.For example, Patent Literature 1 describes performing plasma gas phase deposition by heating polysaccharides or methyl silicon resins to evaporate, and introducing the gas onto a substrate with an inert gas or other materials.
19. An organic polymer thin membrane comprising an organic polymer of at least one compound selected from the group consisting of a compound having a hydrophilic functional group, a compound having a polyalkylene glycol chain within the molecule, and a compound having a functional group selected from a hydroxyl group and a carboxyl group, and having a composition that is gradually polymerized from a thin membrane surface into the membrane in a cross sectional direction of the membrane.
20. The organic polymer thin membrane according to claim 19, wherein the gradually polymerized composition reflects a polymerization reaction profile that occurs in a direction from the irradiated surface to the non-irradiated surface during formation of the organic polymer thin membrane in a polymerization reaction caused by irradiating one surface of the thin membrane with a plasma or an electron beam.
21. The organic polymer thin membrane according to claim 19, wherein the gradually polymerized composition is confirmed by using at least one selected from:
transmission electron microscopy of a cross section across the thin membrane from the irradiated surface to the non-irradiated surface after osmium staining of the thin membrane;
energy dispersive X-ray inner composition analysis of the thin membrane from the irradiated surface to the non-irradiated surface;
atomic force microscopy of surface structures on both surfaces of the thin membrane; and
glazing-incidence small angle X-ray scattering orientation analysis of both thin membrane surfaces.
22. The organic polymer thin membrane according to claim 19, wherein the organic polymer thin membrane is a self-supporting membrane.
23. The organic polymer thin membrane according to claim 22, wherein the self-supporting membrane has different structures on the front and back of the membrane, and is similar in structure to the cuticle of a living organism.
24. The organic polymer thin membrane according to claim 23, wherein the self-supporting membrane has a surface having large numbers of polar groups and being easily wettable with water, and a surface having small numbers of polar groups and being less wettable with water.
|参考情報 （研究プロジェクト等）||CREST Establishment of Innovative Manufacturing Technology Based on Nanoscience AREA|
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