Cationic crosslinking reactions of poly (allenyl ether) s having oligo (oxyethylene) moieties prepared by the radical polymerization of the corresponding allenyl ethers were carried out under some varied reaction conditions. For instance, a crosslinked polymer was obtained in 82% yield by the treatment of poly (ethylene glycol methyl allenyl ether) (1a) with 1.2 mol % of BF3 . OEt, (2) under high concentration in dichloromethane (46 wt %). The gels obtained showed good swelling properties in water, alcohols, and polar organic solvents such as dichloromethane. In particular, the degrees of swelling of these gels in aqueous sodium chloride (1M) were quite similar to those in ion-free water, indicating that these gels served as nonionic hydrogels.