spiro chain

in a polymer
https://doi.org/10.1351/goldbook.S05880
A @D01849@ consisting of an uninterrupted @ST06775@ of rings, with adjacent rings having only one atom in common. Alternatively, a spiro chain is a double-strand chain with adjacent @C01288@ joined to each other through three atoms, two on one side and one on the other side of each @C01288@.
Source:
PAC, 1996, 68, 2287. (Glossary of basic terms in polymer science (IUPAC Recommendations 1996)) on page 2295 [Terms] [Paper]