Patent ID: 8734952

Claim:
An optical film comprising: a substrate having front and rear surfaces, and at least one solid optical retardation layer on the front surface of the substrate, wherein the solid optical retardation layer comprises rigid rod-like macromolecules comprising n organic units of the first type having general structural formula I k organic units of the second type having general structural formula II wherein n is in the range from 0 to 10,000, and k is in the range from 0 to 10,000, sum n+k≧10, R 1 and R 2 are side-groups independently selected from the list comprising —H, alkyl, —(CH 2 ) m SO 3 M, —(CH 2 ) m Si(O-alkyl) 3 , —CH 2 -aryl, —(CH 2 ) m OH, wherein m is a number from 1 to 18, and in case H is one of the side groups, then its fraction does not exceed 50% of total number of side-groups in the macromolecule, and M is a counterion selected from the list comprising H + , Na + , K + , Li + , Cs + , Ba 2+ , Ca 2+ , Mg 2+ , Sr 2+ , Pb 2+ , Zn 2+ , La 3+ , Al 3+ , Ce 3+ , Y 3+ , Yb 3+ , Gd 3+ , Zr 4+ and NH 4-p Q p + , wherein Q is selected from the list comprising linear and branched (C1-C20) alkyl, (C2-C20) alkenyl, (C2-C20) alkinyl, and (C6-C20)arylalkyl, and p is 0, 1, 2, 3 or 4; wherein the organic units of the first type and the organic units of the second type are contained in the rigid rod-like macromolecules in random or orderly sequence, wherein the rigid rod-like macromolecules are isotropically oriented in the plane of the substrate, the solid optical retardation layer is a negative C-type, and the solid optical retardation layer is substantially transparent to electromagnetic radiation in the visible spectral range.