Synthesis of degradable molecular brushes via a combination of ring‐opening polymerization and click chemistry

Abstract

Acid‐degradable molecular brushes with polycarbonate backbone and densely grafted side chains (∼1.9 SCs per backbone repeating unit) were synthesized for the first time using the grafting‐onto method. Extremely efficient copper‐catalyzed azide‐alkyne cycloaddition click reactions between the polycarbonate backbone containing two pendant azido groups per backbone unit and alkynyl‐terminated poly (methyl acrylate) (ay‐PMA72, average degree of polymerization DP = 72) SCs were demonstrated to finish in 10 min with a quantitative conversion of the azido groups. Similar grafting efficiencies were also achieved when using alkynyl‐terminated polystyrene (ay‐PS), poly(ethylene oxide) (ay‐PEO), and poly (t‐butyl acrylate)‐b‐polystyrene (ay‐PtBA‐b‐PS) to successfully prepare molecular brushes with high grafting density (>1.8 SCs per backbone repeating unit). Under acidic condition, the polycarbonate backbones were completely degradable and the final degraded product of the molecular brushes was a linear polymer chain with molecular weight two times of the SCs. When a mixture of hydrophobic ay‐PS and hydrophilic ay‐PEO chains was used, amphiphilic heterobrushes PC‐g‐(PS‐co‐PEO) were synthesized, which could self‐assemble into micelles or vesicles in selective solvents, depending on the ratio of the two SCs in the brush. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 239–248

Click Chemistry in Functional Aliphatic Polycarbonates

“…This provides a facile platform for the synthesis of functional aliphatic polycarbonates. According this useful approach, palmitate, poly(methyl acrylate), polystyrene, and poly( t ‐butyl acrylate)‐ block ‐polystyrene were successfully grafted to the polycarbonate backbone to generate amphiphilic block‐graft copolymers or degradable molecular brushes. Using monomethoxy poly(ethylene glycol) as an initiator, amphiphilic block copolymer PEG‐ b ‐P(DTC‐ADTC) bearing the pendant azide groups could be synthesized for preparing core‐shell redox‐responsive polymeric micelles in which the cores are crosslinked via click chemistry with the disulfide‐containing dialkyne as the crosslinker to enhance the stability of the micelles and improve the drug‐loading property .…”

When dual and multi-responsiveness meet molecular brushes

“…Thus, the research of molecular brushes is inspired by the biological brushes and they have potential applications in biomimetic field. Thanks to the development of living/controlled radical polymerization, including atom transfer radical polymerization (ATRP) [9,10], reversible addition-fragmentation chain transfer polymerization (RAFT) [11], and nitroxide mediated polymerization (NMP) [12], and robust synthetic routes, like ''click'' chemistries [13][14][15][16][17], the molecular brushes with controlled molecular weight, narrow molecular weight distribution and well-defined structures can be synthesized via ''grafting from'', ''grafting through'' or ''grafting to'' method [18][19][20][21][22][23][24].…”

A UV‐Cleavable Bottlebrush Polymer with o‐Nitrobenzyl‐Linked Side Chains

“…[15a,17] In studies of cleavable/degradable bottlebrush polymers, Müller's group reported core–shell cylindrical brushes with acid‐degradable cores, which were used to prepare hollow nanotubes . Shi et al prepared an acid‐degradable bottlebrush polymer with a polycarbonate backbone and densely grafted side chains . Jiang's group reported a reducible and degradable brushed poly(2‐(dimethylamino) ethyl methacrylate and evaluated its gene delivery .…”