Reduced viscosity compositions containing polyamideimide polymers

An aromatic polyamic acid/polyamideimide polymer [Polymer (PAI)] which comprises recurring units, more than 50 mol % of said recurring units, [recurring units (RPAI)], are chosen from the group consisting of:

• wherein:
• the symbol → in each formula denotes isomerism so that, in any recurring unit within the aromatic polyamic acid structure, the groups to which the arrows point may exist as shown or in an interchanged position;
• Ar is an aromatic tetravalent group, which may comprise one or more than one aromatic ring, and which is preferably selected from the group consisting of:
• with X being selected from the group consisting of —O—, —C(O)—, —S—, —SO2—, —CH2—, —C(CF3)2—, —(CF2)n— with n=0, 1, 2, 3, 4 or 5;
• R is an aromatic divalent group, which may comprise one or more than one aromatic ring, and which is preferably selected from the group consisting of:
• with Y being selected from the group consisting of —O—, —C(O)—, —S—, —SO2—, —CH2—, —C(CF3)2—, —(CF2)n— with n=0, 1, 2, 3, 4 or 5,
• wherein said aromatic polyamic acid/polyamideimide polymer has a molecular weight distribution, Mw/Mn, from 2.00 to 3.40, and
• wherein the recurring units (RPAI) are chosen from the group consisting of units (i), (ii) and (iii):
• and/or the corresponding imide-group containing recurring unit:
• wherein the attachment of the two amide groups to the aromatic ring as shown in (i-a) will be understood to represent the 1,3 and the 1,4 polyamide-amic acid configurations;
• and/or the corresponding imide-group containing recurring unit:
• wherein the attachment of the two amide groups to the aromatic ring as shown in (ii-a) represent the 1,3 and the 1,4 polyamide-amic acid configurations;
• and/or the corresponding imide-group containing recurring unit:
• wherein the attachment of the two amide groups to the aromatic ring as shown in (iii-a) represent the 1,3 and the 1,4 polyamide-amic acid configurations;
• and
• and/or the corresponding imide-group containing recurring unit:
• wherein the attachment of the two amide groups to the aromatic ring as shown in (iii-a) represent the 1,3 and the 1,4 polyamide-amic acid configurations.