| http://www.w3.org/ns/prov#value | - Polymers having the repeating mer unit: ##STR63## wherein n is an integer substantially greater than 10; wherein R1 and R2 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups or may form parts of a cyclic group; R is a quadrivalent organic grouping; R3 and R4 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups
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