ar-(-Lng-ar-(-w (Q)mw wherein w is an integer of 1 to about 20, preferably 1 to about 8, more preferably 1, 2 or 3, ar is as described above with the priviso that there are at least 2 unsatisfied (i.e., free) valences in the total of ar groups, Q and m are as defined hereinbefore, and each Lng is a bridging linkage individually chosen from the group consisting of carbon-to-carbon single bonds, eth