Alkene-dioxolane alternating copolymers 1 and 4, formed from ethane-1,2-diol and the corresponding alkene-carbon monoxide copolymers, undergo transketalisation reactions with ethane-1,2-dithiol, pyopane-1,3-dithiol and sulfanylethanol to yield novel dithiolane-, dithiane- and oxathiolane-containing polymers 6, 8, 9, 11 and 12.