Hyperbranched polyether-polyols based on polyglycerol: Polarity design by block copolymerization with propylene oxide

Multiarm block copolymers were synthesized via anionic ring-opening multibr anching polymerization (ROMBP) of glycidol followed by addition of propylen e oxide. The resulting polyether-polyols with molecular weights in the rang e 5000-12 000 g/mol possessed up to five propylene bride units per end grou p and showed narrow molecular weight distributions (MWD < 1.7). Via propoxy lation the polarity of the highly hydrophilic polyglycerols can be varied, resulting in versatile, highly functional branched polyether polyols. The h yperbranched polyglycerols with oligo(propylene oxide) segments were charac terized by C-13 and H-1 NMR, demonstrating complete propoxylation of all en d groups. 1H NMR, SEC, vapor pressure osmometry, and hydroxyl number titrat ion were used to determine molecular weights. The effect of the short poly( propylene oxide) blocks on the flexibility of the polyethers was studied by DSC. The T-g varied between -37 and -71 degrees C, depending on the length of the propylene oxide segments attached.