Facile synthesis of polyester dendrimer via combining thio‐bromo “Click” chemistry and ATNRC

Abstract

This article reports on developing an efficient synthesis approach to aliphatic polyester dendrimer, poly(thioglycerol-2-propionate) (PTP), by combination of thio-bromo "Click" chemistry with atom transfer nitroxide radical coupling (ATNRC). Through the one-pot two-step method, linear polystyrene with hydroxyl end groups (l-PS-2OH) was obtained by first atom transfer radical polymerization of styrene and following termination using 4-(2,3-dihydroxypropoxy)-TEMPO (DHP-TEMPO) to capture the PS macroradicals via ATNRC method. Using l-PS-2OH as support, the dendritic repeating units divergently were grown from the hydroxyl end groups via esterification and thio-bromo "Click" reaction two-step process. In every generation, the resulting intermediates l-PS-d-PTP (G1-G4) can be easily isolated from the excessive unreacted monomers by simple precipitation in ethanol without help of time, labor and solvent consuming column chromatographic purification. At last, cleavage of the alkoxyamine group between the PS support and dendrimer at elevated temperature (125 C) provided the targeted polyester dendrimer PTP up to the fourth generation.

Thio‐bromo “Click,” post‐polymerization strategy for functionalizing ring opening metathesis polymerization (ROMP)‐derived materials

“…This methodology has been used in combination with controlled radical polymerization techniques like reversible addition‐fragmentation chain‐transfer (RAFT) polymerization, and atom transfer radical polymerization (ATRP) reactions. Hu and coworkers recently reported an interesting study, which combined this chemistry with an atom transfer nitroxide radical coupling (ATNRC) for the preparation of polyester dendrimers . This process could potentially represent a more efficient functionalization method than traditional radical thiol‐ene chemistry as the reactivity of radicals can give rise to byproducts formation .…”

“…Hu and coworkers recently reported an interesting study, which combined this chemistry with an atom transfer nitroxide radical coupling (ATNRC) for the preparation of polyester dendrimers. 23 This process could potentially represent a more efficient functionalization method than traditional radical thiol-ene chemistry as the reactivity of radicals can give rise to byproducts formation. 3,24 Nonetheless, using this approach for side chain functionalization of linear polymers has not been heavily explored.…”

Precise Synthesis of PS‐PLA Janus Star‐Like Copolymer

“…Synthesis of novel macromolecular architecture with well‐defined structures and compositions has been an important research topic in polymer science . Thanks to the advances in polymerization techniques, numerous well‐organized polymers have been prepared over the past few decades . One of these structures is the Janus particle having biphasic geometry of distinct compositions and properties, first coined by Pierre‐Gilles de Gennes in his Nobel Prize address .…”

Postpolymerization modification of polynorbornene side chains via tetramethyl guanidine promoted esterification

“…Various reactive sites and modification reactions have been reported. Among them, as a paradigm of “click” reaction to achieve utmost efficiency, the nucleophilic substitutions between activated bromides and thiols have found wide applications in postpolymerization modification and topology construction . Besides thiols, other nucleophiles such as amines, azides, acids, and pyridine are also selected for functionalization of activated bromide moieties on polymer chains.…”