Oligoether branched-and-spaced "acid-in-chain" polymers, with variable length side chains attached to the acidic borons have been prepared by a simple two-step reaction sequence. These may be used as anion-retarding hosts for "salt-in-polymer" electrolytes or, alternatively, may be converted to polyanionic electrolytes by reacting with strong Lewis base anions. High ionic conductivities, reaching 7.6 x 10(-5) S cm(-1) at 25 degreesC have been obtained for the former case, using LiTFSI:B proportions of 1: 1, and optimized side chain and spacer lengths. The electrochemical windows are wide enough ( > 4.5 V) for most applications. (C) 2003 Elsevier Science Ltd. All rights reserved.