 Solution

Reductive ozonolysis cuts the unsaturated backbone into cyclopentane-1,3-dicarbaldehyde units, apart from end fragments. Both alkene carbons carry a hydrogen, so the carbonyl products are aldehydes rather than ketones. Ring substituent stereochemistry is inherited from the polymer repeat; backbone E/Z geometry does not survive cleavage.

Ozone adds across a backbone alkene by cycloaddition, giving a primary ozonide. Its fragmentation produces a carbonyl group and a carbonyl oxide, which recombine to a secondary ozonide. Dimethyl sulfide reduces the peroxide-containing intermediate, forming dimethyl sulfoxide and the two carbonyl termini. Repetition at every backbone double bond liberates the dialdehyde. An oxidizing work-up would instead risk oxidation to carboxylic acids, so the specified reductive work-up is essential.