| Popis: |
Metal ions chelated to preformed polymers can produce marked property changes, especially when the metal ion is bonded directly to the polymer backbone. Such metal-chelate polymers can show superior properties over their organic counterparts in certain applications,1 although properties such as thermal stability are quite polymer and metal ion dependent.2 A good example of improved thermal stability Is provided by the zinc chelate of PTO; i.e., poly(terephthaloyloxalic-bis-amidrazone)3,4. This metal-chelate polymer and many others are also good fire retardants. The existence of polymer-anchored metal catalysts is well documented, too. 1,5–11 However, superiority is not always the case. Brittleness and intractability are two properties often associated with metal-containing polymers.12 We are attempting to modify polymers through metal ion chelation and to vary the metal ions therein, in order to learn more about how such chelation modifies the properties of the polymers. The polymeric hydrazones under investigation in our laboratory provide examples of the changes which are possible. |
