"Functional poly(ethylene glycol)": PEG-based random copolymers with 1,2-diol side chains and terminal amino functionality

A series of poly(ethylene glycol-co-isopropylidene glyceryl glycidyl ether) (P(EO-co-IGG)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units was synthesized. After acidic hydrolysis a new type of "functional PEGs", namely poly(ethylene glycol-co-glyceryl glycerol) (P(EO-co-GG)) was obtained. Using an initiator that releases a terminal amino moiety after deprotection, functional end groups with orthogonal reactivity to the in-chain groups were obtained. All polymers showed narrow molecular weight distributions (1.07-1.19), and control of the molecular weights was achieved in the range 5000-30 000 g/mol. Random incorporation of both comonomers was verified by monitoring the copolymerization kinetics via real-time ¹H NMR spectroscopy during the polymerization and by characterization of the triad sequence distribution, relying on ¹³C NMR analysis. Using the 1,2-diol component of the side chains allows for attachment and facile acid-catalyzed release of molecules bearing ketone/aldehyde functionalities. This renders the materials potentially useful as support for reagents, drugs or catalysts. This was demonstrated using benzaldehyde as a model compound. DSC was carried out on all samples, showing amorphous structures upon incorporation of IGG fractions exceeding 15%.