Patent ID: 7671141

Claim:
A process for preparing a second order nonlinear optic polyimide polymer of formula (I), wherein: R 1 is a functionality group selected from —OH and —COOH; R 2 is a group represented by the formula selected from wherein when R 1 is —OH, R 2 is a group represented by the formula: and when R 1 is —COOH, R 2 is a group represented by the formula: wherein R is a phenyl or styryl group that is 3-substituted with a group selected from the —NO 2 , —COCH 3 , —CN, —SO 2 NH 2 , Br and Cl; and x+y+z=100% of the repeating units, x is at least 1%, and either or both of y and z can be zero; the process comprising the steps of: reacting 4,4′-(hexafluoroisopropylidene)diphthalic anhydride with a compound of formula wherein R 1 is the same as that defined for formula (I), optionally in the presence of m-phenylenediamine, so as to form a host polyimide polymer comprising repeating units represented by the formula: wherein R 1 , x, y and z are the same as those defined for formula (I); and grafting the thus formed host polyimide polymer with a compound of formula R 2 ″—H so as to form an intermediate polyimide polymer comprising repeating units represented by the formula (I′), which is processible to form the second order nonlinear optic polyimide polymer of formula (I): wherein: R 1 , x, y and z are the same as those defined for formula (I); when R 1 is —OH, R 2 ″ and R 2 ′ are the same and represent a group of formula when R 1 is —COOH, R 2 ″ represents a group of formula and R 2 ′ represents a group of formula wherein R is a phenyl or styryl group that is 3-substituted with a group selected from —NO 2 , —COCH 3 , —CN, —SO 2 NH 2 , Br and Cl.