Feed-Order-Enabled One-Pot Sequential Polymerization of Cyclopentene and 2,3-Dihydrofuran via Ring-Opening Metathesis Polymerization and Cationic Addition

Abstract Sequential polymerization provides an effective strategy for integrating distinct polymerization mechanisms within a single reaction system and constructing multicomponent polymeric materials. In this work, cyclopentene (CP) and 2,3-dihydrofuran (DHF) were employed as model monomers to investigate feed-order-dependent one-pot sequential polymerization in a WCl6/2,6-di-tert-butylphenol/AlEt2Cl/2,6-di-tert-butylpyridine (DTBP) catalytic system. When CP was introduced first, it underwent ring-opening metathesis polymerization (ROMP) mediated by W/Al active species to afford polycyclopentene (PCP). Subsequent addition of DHF led predominantly to ring-retaining cationic addition polymerization, consistent with the involvement of Brønsted acidic species and a cooperative role of AlEt2Cl, yielding poly(DHF) (PDHF). 1H NMR, 1H–1H COSY, and GPC analyses, together with distinct apparent diffusion coefficients observed by DOSY NMR, supported the assignment of the sequential-addition product as a blend composed predominantly of PCP and PDHF. Control experiments showed that DHF addition strongly suppressed CP ROMP, whereas an additional charge of AlEt2Cl only partially restored CP polymerization. At the same total aluminum loading, staged addition afforded a higher CP conversion than one-shot addition. Preformed PDHF caused much less inhibition under the tested conditions, whereas Et2O also suppressed CP polymerization, suggesting that DHF monomer and ether interactions with the catalytic environment contribute to inhibition. These results demonstrate the importance of monomer feed order and aluminum addition timing. AFM observations further showed that films prepared from the sequential-addition product exhibited heterogeneous surface morphologies. DSC measurements revealed distinguishable thermal transitions associated with the two polymer components. This work reveals distinct polymerization pathways, competitive behavior under simultaneous feeding, and sequential operation enabled by feed-order regulation, providing experimental support for the one-pot polymerization of cycloolefin and cyclic vinyl ether monomers and the preparation of multicomponent polymer systems.