Supramolecular Linear-g-Hyperbranched Graft Polymers: Topology and Binding Strength of Hyperbranched Side Chains

Abstract

Complex, reversible hyperbranched graft polymer topologies have been obtained by spontaneous self-assembly. Well-defined adamantyl-and β-cyclodextrin-functionalized polymers were employed to generate linear-g-(linear−hyperbranched) supramolecular graft terpolymers. For this purpose the synthesis of monoadamantyl-functionalized linear polyglycerols (Ada-linPG) and hyperbranched polyglycerols (Ada-hbPG) as well as poly(ethylene glycol)-block-linear polyglycerol (Ada-PEG-b-linPG) and poly(ethylene glycol)-block-hyperbranched poly-(glycerol) (Ada-PEG-b-hbPG) block copolymers was established. Isothermal titration calorimetry (ITC) with β-cyclodextrin revealed a shielding effect of hyperbranched polyglycerol for the adamantyl functionality, which was significantly less pronounced when using a linear spacer chain between the adamantyl residue and the hyperbranched polyglycerol block. Additionally, welldefined poly(2-hydroxypropylamide) (PHPMA) with pendant β-cyclodextrin moieties was synthesized via RAFT polymerization and sequential postpolymerization modification. Upon mixing of the β-cyclodextrin-functionalized PHPMA with Ada-PEG-b-hbPG, a supramolecular linear-g-(linear−hyperbranched) graft terpolymer was formed. The self-assembly was proven by ITC, diffusion-ordered NMR spectroscopy (DOSY), and fluorescence correlation spectroscopy (FCS).

Activated Ester Containing Polymers: Opportunities and Challenges for the Design of Functional Macromolecules

“…The water-soluble copolymer was used to fabricate reversible linear-graf t-(linear-hyperbranched) supramolecular graft terpolymers by complexation with monoadamantylfunctionalized linear polyglycerols. 94 Nilles and Theato reported RAFT polymerization of PFP4VB with extreme precision and further displayed it as potential macrochain transfer agent (CTA) for diblock copolymerization of styrene derivatives. 95 Remarkably increased reactivity of PFP4VP has been taken advantage of in creating dual-reactive statistical copolymers poly(PFPMA-co-PFP4VP) that offered selective modification with amines of varying reactivity.…”

Aliphatic Polyethers: Classical Polymers for the 21st Century

“…Using “graft on graft” strategies with repeating cycles of deprotonation, polymerization, and acidic deprotection, highly branched polymers with high molecular weights ( M n > 1 800 000 g mol −1 ) have been reported . Since then, different functional initiators as well as termination agents were applied for the preparation of well‐defined polymers with exactly one functional moiety at the chain end …”

Redox‐Switchable Supramolecular Graft Polymer Formation via Ferrocene–Cyclodextrin Assembly

“…Thus, supramolecular brush polymers are accessible either via the combination of a cyclodextrin (CD)‐containing backbone or surface and a guest end‐functionalized polymer or through a guest molecule containing polymer and the addition of an CD‐end‐functionalized polymer . Thereby, the grafting density depends significantly on the association constants and steric factors . In addition to the preferably used adamantyl group as guest molecule, some organic dyes and organometallic compounds such as metallocenes are able to form stable complexes with CDs.…”