3 research outputs found
Solvent-Selective Reactions of Alkyl Iodide with Sodium Azide for Radical Generation and Azide Substitution and Their Application to One-Pot Synthesis of Chain-End-Functionalized Polymers
Herein,
a new reaction of an alkyl iodide (RâI) with an
azide anion (N<sub>3</sub><sup>â</sup>) to reversibly generate
the corresponding alkyl radical (R<sup>â˘</sup>) is reported.
Via this new reaction, N<sub>3</sub><sup>â</sup> was used as
an efficient catalyst in living radical polymerization, yielding a
well-defined polymerâiodide. A particularly interesting finding
was the solvent selectivity of this reaction; namely, RâI and
N<sub>3</sub><sup>â</sup> generated R<sup>â˘</sup> in
nonpolar solvents, while the substitution product RâN<sub>3</sub> was generated in polar solvents. Exploiting this unique solvent
selectivity, a one-pot synthesis of polymerâN<sub>3</sub> was
attained. N<sub>3</sub><sup>â</sup> was first used as a catalyst
for living radical polymerization in a nonpolar solvent to produce
a polymerâiodide and was subsequently used as a substitution
agent in a polar solvent by simply adding the polar solvent, thereby
transforming the polymerâiodide to polymerâN<sub>3</sub> in one pot. This one-pot synthesis was further applied to obtain
N<sub>3</sub>-chain-end-functionalized polymer brushes on the surface,
uniquely controlling the N<sub>3</sub> coverage (number density).
Using the chain-end N<sub>3</sub>, the obtained linear and brush polymers
were connected to functional molecules via an azideâalkyne
click reaction. The attractive features of this system include facile
operation, access to unique polymer designs, and no requirement for
using excess NaN<sub>3</sub>. In addition to N<sub>3</sub><sup>â</sup>, thiocyanate (<sup>â</sup>SCN) and cyanate (<sup>â</sup>OCN) anions were also studied
Biocompatible Choline Iodide Catalysts for Green Living Radical Polymerization of Functional Polymers
Herein,
nontoxic and metabolizable choline iodide analogues, including
choline iodide, acetylcholine iodide, and butyrylcholine iodide, were
successfully utilized as novel catalysts for âgreenâ
living radical polymerization (LRP). Through the combination of several
green solvents (ethyl lactate, ethanol, and water), this green LRP
process yielded low-polydispersity hydrophobic, hydrophilic, zwitterionic,
and water-soluble biocompatible polymethacrylates and polyacrylates
with high monomer conversions. Well-defined hydrophobicâhydrophilic
and hydrophilicâhydrophilic block copolymers were also synthesized.
The accessibility to a range of polymer designs is an attractive feature
of this polymerization. The use of nontoxic choline iodide catalysts
as well as green polymerization conditions can contribute to sustainable
polymer chemistry
Synthesis of Highly Reactive Polymer Nitrile <i>N</i>âOxides for Effective Solvent-Free Grafting
A one-pot synthesis of polymer nitrile <i>N</i>-oxides
was achieved via the Michael addition of living polymer anions derived
from vinyl monomers to commercially available <i>trans</i>-β-nitrostyrene and subsequent dehydration with concd H<sub>2</sub>SO<sub>4</sub>. The polymer nitrile <i>N</i>-oxides
are effective as grafting agents in catalyst- and solvent-free 1,3-dipolar
cycloadditions to unsaturated-bond-containing polymers with high conversion
and exhibit higher reactivity compared to that of nitrile <i>N</i>-oxides prepared from 1,1-diphenylnitroethene. Application
to the preparation of a functional glass surface was demonstrated
using P<i>t</i>BMA nitrile <i>N</i>-oxide as a
grafting agent