Plastic substrate having multi-layer structure and method for preparing the same

A plastic substrate having a multi-layer structure, comprising:

• plastic films attached to each other, and
• a first buffering layer of an organic-inorganic hybrid, a layer of gas barrier, and a second buffering layer of an organic-inorganic hybrid which are stacked on both sides of the plastic films in an orderly manner, each layer forming a symmetrical arrangement centering around the plastic films,
• wherein each of the first organic-inorganic hybrid buffer layer and the second organic-inorganic hybrid buffer layer is prepared from partial hydrolysis of a buffer composition comprising 20-99.99 wt % of at least one organic silane selected from the group consisting of the compounds represented by Chemical Formula 1 below and 0.01-80 wt % of at least one metal alkoxide selected from the group consisting of the compounds represented by Chemical Formula 2:
• (R1)m—Si—X(4-m) (1)
• where X, which may be identical or different, is hydrogen, halogen, C1-12 alkoxy, acyloxy, alkycarbonyl, alkoxycarbonyl, or —N(R2)2 (where R2 is H or C1-12 alkyl);
• R1, which may be identical or different, is C1-12 alkyl, alkenyl, alkynyl, aryl, arylalkyl, alkylaryl, arylalkenyl, alkenylaryl, arylalkynyl, alkynylaryl, halogen, substituted amino, amide, aldehyde, keto, alkylcarbonyl, carboxy, mercapto, cyano, hydroxy, C1-12 alkoxy, C1-12 alkoxycarbonyl, sulfonate, phosphate, acryloxy, methacryloxy, epoxy, or vinyl;
• oxygen or —NR2 (where R2 is H or C1-12 alkyl) may be inserted between R1 and Si to give —(R1)m—O—Si—X(4-m) or (R1)m—NR2—Si—X(4-m);
• and
• m is an integer of 1-3;
• and
• M-(R3)z (2)
• where M is a metal selected from the group consisting of aluminum, zirconium, and titanium;
• R3, which may be identical or different, is halogen, C1-12 alkyl, alkoxy, acyloxy, or hydroxy;
• and
• Z is an integer of 3 or 4.