Methods of preparing polymer-organoclay composites and articles derived therefrom

A method for preparing a polymer-organoclay composite comprising:

• combining a solvent, an unexfoliated organoclay, a dianhydride component, and a diamine component to form a first mixture, wherein the organoclay comprises alternating inorganic silicate layers and organic layers, and has an initial spacing between the silicate layers;
• exposing the first mixture to an energized condition of a sufficient intensity and duration to increase the initial spacing of the inorganic silicate layers, to form a second mixture;
• polymerizing the dianhydride component and the diamine component to form a polyamic acid;
• and
• removing at least a portion of the solvent from the polyamic acid mixture to provide a polyimide, wherein the inorganic silicate layers remain separated by the polyimide after removal of the solvent.

An article comprising a polymer-organoclay composite prepared by the method of

• combining a solvent and an unexfoliated organoclay to provide a first mixture, wherein the unexfoliated organoclay comprises alternating inorganic silicate layers and organic layers, and has an initial spacing between the silicate layers;
• exposing the first mixture to an energized condition of a sufficient intensity and duration to increase the initial spacing of the inorganic silicate layers, to provide a second mixture;
• contacting the second mixture with a thermoplastic polymer composition so that the polymer composition fills at least one region located between at least one pair of silicate layers, wherein the polymer composition is at least partially soluble in the solvent;
• and
• removing at least a portion of the solvent from the second mixture, wherein the inorganic silicate layers remain separated by the polymer after removal of the solvent,
• wherein the organoclay comprises a quaternary phosphonium cation of formula (2), formula (3), formula (4) or formula (5):
• wherein Ar1, Ar2, Ar3 and Ar4 are independently C6-C50 aromatic radicals;
• “a” is a number from 1 to about 200;
• “c” is a number from 0 to 3;
• R1 is independently at each occurrence a halogen atom, a C1-C20 aliphatic radical, a C5-C20 cycloaliphatic radical, or a C2-C20 aromatic radical;
• and R2 is a C1-C20 aliphatic radical, a C5-C20 cycloaliphatic radical, a C6-C50 aromatic radical, or a polymer chain,
• wherein Ar12, Ar13, Ar14 and Ar15 are independently C6-C50 aromatic radicals;
• and Ar16 is a C6-C200 aromatic radical, or a polymer chain comprising at least one aromatic group,
• wherein Ar6, Ar7, and Ar8 are independently C6-C50 aromatic radicals;
• “b” is a number from 0 to 2;
• R3 is independently at each occurrence a halogen atom, a C1-C20 aliphatic radical, a C5-C20 cycloaliphatic radical, or a C2-C20 aromatic radical;
• and Ar11 is a C6-C200 aromatic radical, or a polymer chain comprising at least one aromatic group,
• wherein Ar6, Ar7, and Ar8 are independently C6-C50 aromatic radicals;
• “b” is a number from 0 to 2;
• “d” is a number from 0 to 4;
• R3 and R4 are independently at each occurrence a halogen atom, a C1-C20 aliphatic radical, a C5-C20 cycloaliphatic radical, or a C6-C20 aromatic radical;
• Z is a bond, a divalent C1-C20 aliphatic radical, a divalent C5-C20 cycloaliphatic radical, a divalent C6-C20 aromatic radical, an oxygen linking group, a sulfur linking group, a SO2 linking group, or a Se linking group;
• and Ar9 is a C10-C200 aromatic radical, or a polymer chain comprising at least one aromatic group.