“Functional Poly(ethylene glycol)”: PEG-Based Random Copolymers with 1,2-Diol Side Chains and Terminal Amino Functionality

Abstract

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 glycolco-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 1 H NMR spectroscopy during the polymerization and by characterization of the triad sequence distribution, relying on 13 C 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%.

PEG-based Multifunctional Polyethers with Highly Reactive Vinyl-Ether Side Chains for Click-Type Functionalization

“…The key for random incorporation of glycidyl ether comonomers is polymerization at an elevated temperature, which was proven in previous works for other glycidyl ethers. 11,15,16,18 To level the different reactivities of the monomers, the reaction mixture was rapidly heated to 90°C in a sealed system under vacuum. All polymerizations were carried out in THF and stirred for at least 48 h to guarantee full conversion of both monomers.…”

Multifunctional Poly(ethylene glycol)s

“…Only random incorporation leading to a homogenous average PEG homopolymer segment length within the polymer chains results in gradual changes in thermal behavior upon variation of the comonomer ratio. [97,98,100] Nonrandom comonomer incorporation and block formation leads to microphase separation, and the melting point depression is less pronounced.…”

Multifunktionelle Poly(ethylenglycole)

“…[57,70,74,75,[87][88][89][90][91][92][93][94] propylidenglycerylglycidylether (IGG) dar, das je Monomereinheit eine primäre und eine sekundäre Hydroxygruppe zur Verfügung stellt. [96,97] Eine interessante Erweiterung, insbesondere im Hinblick auf Biokonjugation, ist die Verwendung eines Initiators mit einer orthogonalen Funktionalität, die selektiv adressiert werden kann. [97][98][99] Neben Hydroxygruppen wurde bislang nur die Einführung von Aminogruppen durch Einsatz von geschützten Monomeren beschrieben (über N,N-Dibenzylaminoglycidol (DBAG)).…”

“…Nur ein statistischer Einbau, der zu einer homogenen Segment- länge des PEG-Polymersegments führt, resultiert in gleichmäßigen ¾nderungen des thermischen Verhaltens bei Veränderung des Comonomeranteils. [97,98,100] …”