Catalyst-free click cascade functionalization of unsaturated-bond-containing polymers using masked-ketene-tethering nitrile N-oxide

Abstract

We developed a facile protocol for grafting-onto and cross-linking unsaturated-bond-containing common polymers via the formation of masked-ketene-functionalized polymers. The protocol utilizes a cascade functionalization agent 1 that has nitrile N-oxide and masked ketene functionalities. Through the model ligation reactions using 1, it turned out that the 1 facilitates the catalyst-free click introduction of masked ketene moieties to the unsaturated bonds such as C≡N and C=C bonds, capable of undergoing catalyst-free ligation with not only a nucleophilic amine but also a neutral alcohol with low nucleophilicity. On the basis of these results, the catalyst-free grafting reactions of PEG onto EPDM and PAN using 1 were performed to afford the corresponding graft copolymers in excellent conversion yields. In addition, it was also revealed that heating of both PAN and NR with masked ketene moieties at 250 °C for 1 h without catalyst enables the efficient conversion to give the respective cross-linked polymers.

Thermosetting Resins Based on a Self-Crosslinkable Monomer/Polymer Possessing Meldrum's Acid Groups

“…As ketene groups generated from MA thermolysis reaction could undergo self‐cycloaddition reaction and [2+4] or [2+2] cycloaddition reaction with furan group, MA‐bisF itself could be considered as a thermally curable monomer for preparation of the corresponding thermosetting resin (Scheme ) . As the possible melting point and reaction temperature of MA‐bisF are very close to each other, MA‐bisF almost does not have a processing window (the region between melting point and reaction temperature) for molten process.…”

“…Although chemical and physical modification of a resin might alter and enhance could be further functionalized and crosslinked through the ketene-mediated chemistry have been reported with Hawker's group [20][21][22][23][24] and other researchers. [25][26][27] MAbased crosslinked polymers have also been utilized in coatings, [28] anodes for lithium batteries, [29] and gas separation membrane. [30] As MA is an effective precursor to generate the highly reactive ketene group which could undergo self-dimerization and addition reaction to other groups, a new class of thermosetting resins based on MA derivatives as monomers has been explored in our previous work.…”

“…Moreover, MA ring could undergo thermolysis reaction to generate highly reactive ketene group with lose of acetone and CO 2 . Based on this feature, MA‐possessing polymers which could be further functionalized and crosslinked through the ketene‐mediated chemistry have been reported with Hawker's group and other researchers . MA‐based crosslinked polymers have also been utilized in coatings, anodes for lithium batteries, and gas separation membrane…”

Topology-transformable polymers: linear–branched polymer structural transformation via the mechanical linking of polymer chains

“…The integration of structure-transformable units via the highly effective click reaction of nitrile N-oxide is an effective way to synthesize multi-arm star polymers (Figure 21). [83][84][85][86][87][88] The transformable unit (arm) consisting of rotaxane-linked PVL and an alkene group as a reactive group was synthesized via the DPPcatalyzed living ring-opening polymerization of δ-VL initiated by the two hydroxyl groups of a sec-ammonium/crown ether-type pseudo [2] rotaxane with an alkene group on the axle component, as shown in Scheme 13a. The two propagating end groups (−OH) were reacted with 3,5-dimethylphenyl isocyanate that not only acts as the bulky end-cap but also produces the second attractive site for the crown ether wheel as the urethane group at the polymer end.…”

Phototriggered Crosslinking and Surface Modification via Catalyst‐Free Functionalization of a New Orthogonal Agent Containing Nitrile N‐Oxide and o‐Nitrobenzyl Ether Moieties

“…[ 25–32 ] For instance, we reported a thermotriggered orthogonal reagent having two functional groups, i.e., a catalyst‐free clickable nitrile N ‐oxide and masked ketene, which can bond several nucleophiles such as alcohols and amines onto alkene, alkyne, and nitrile‐containing polymers and glass surfaces following a thermotriggered two‐step protocol. [ 25,26 ] However, the activation of the masked ketene required high temperatures (<160 °C). Considering this background, we herein describe a useful and convenient catalyst‐free protocol for the introduction of a photocleavable NB moiety into unsaturated bond‐containing polymers and surfaces.…”