Polyorganosiloxane-polyamide block copolymers

A process for preparing a block copolymer having a polyorganosiloxane block [B] having a number average molecular weight of about 10 kg/mole to about 150 kg/mole of the formula:

• ##STR14## and a polyamide block [A] having a number average molecular weight of about 15 kg/mole to about 130 kg/mole of the formula:
• ##STR15## wherein R.sub.1 and R.sub.2 are the same or different within each organosiloxane block and wherein R.sub.1 and R.sub.2 may vary among the p different organosiloxane blocks and are independently selected from the group consisting of alkyl having from 1 to 18 carbon atoms, aryl, alkenyl having from 1 to 12 carbon atoms and combinations thereof,
• n.sub.k is the number average degree of polymerization of the organosiloxane block and is from about 3 to 7000,
• k is an integer from 1 to p,
• p is the total number of organosiloxane blocks in the polyorganosiloxane block [B] and is an integer greater than or equal to one,
• n is the overall number average degree of polymerization of the entire polyorganosiloxane block [B] and is an integer of from about 3 to 7000,
• Y.sub.m is an alkylene having from 3 to 13 carbon atoms,
• l is the total number of different cyclic lactam monomers in the polyamide block [A] and is an integer greater than or equal to one,
• m is an integer of from 1 to l,
• x is an integer greater than or equal to one, and
• z is the overall polyamide block number average degree of polymerization and is an integer of from about 15 to 1200;
• comprising mixing together an N-acyllactam functionalized homo- or copolyorganosiloxane, one or more cyclic lactam monomers of the formula:
• ##STR16## and a catalyst of the formula:
• LiAl(OR).sub.j H.sub.4-j,
• wherein j=1, 2 or 3 and R is an alkyl having from 1 to 18 carbon atoms or an aryl to form the block copolymer.