Herein, a new reaction of an alkyl iodide (R-I) with an azide anion (N) to reversibly generate the corresponding alkyl radical (R) is reported. Via this new reaction, N was used as an efficient catalyst in living radical polymerization, yielding a well-defined polymer-iodide. A particularly interesting finding was the solvent selectivity of this reaction; namely, R-I and N generated R in nonpolar solvents, while the substitution product R-N was generated in polar solvents. Exploiting this unique solvent selectivity, a one-pot synthesis of polymer-N was attained. N was first used as a catalyst for living radical polymerization in a nonpolar solvent to produce a polymer-iodide and was subsequently used as a substitution agent in a polar solvent by simply adding the polar solvent, thereby transforming the polymer-iodide to polymer-N in one pot. This one-pot synthesis was further applied to obtain N-chain-end-functionalized polymer brushes on the surface, uniquely controlling the N coverage (number density). Using the chain-end N, the obtained linear and brush polymers were connected to functional molecules via an azide-alkyne click reaction. The attractive features of this system include facile operation, access to unique polymer designs, and no requirement for using excess NaN. In addition to N, thiocyanate (SCN) and cyanate (OCN) anions were also studied.

Molecular weight distribution of polymers,t ermed dispersity (), is af undamental parameter for determining polymer material properties.T his paper reports an ovel approach for controlling by exploiting at emperatureselective radical generation in organocatalyzed living radical polymerization. The polymers with tailored were synthesized in ab atch system without the assistance of an external pump.Aunique aspect of this approach is that was tuneable from 1.11 to 1.50 in any segment in diblock, triblock, and multiblock copolymers and in any form of star and brush polymer without segmental or topological restriction. This approach is amenable to various monomers and free from metals and thus attractive for applications.T he approach also generated polymer brushes on surfaces with tailored .A n interesting finding was that the polymer brushes exhibited unique interaction with external molecules,d epending on the value.Molecular weight distribution of polymers,t ermed dispersity ( = M w /M n ), is afundamental parameter in determining polymer properties such as processability,viscoelasticity,and self-assembly behaviors,w here M w and M n are the weightand number-average molecular weights,r espectively. [1][2][3][4][5][6] Living radical polymerization (LRP) facilitates the synthesis of polymers with small values,a sw ell as pre-determined molecular weights and sophisticated architectures. [7][8][9][10][11][12] However,p olymers with large values are occasionally desired for improved physical properties such as miscibility and processability,a nd the manipulation of in LRP is an important topic but still challenging. Several approaches have been developed to manipulate values.Blending polymers with different molecular weights is often applied. [13][14][15] Thep olymers need to be prepared in multiple independent runs,a nd the blended polymers often have multimodal molecular weight distribution. By optimizing the polymerization conditions such as catalyst loadings, initiators,temperatures,and additional chain-transfer agents, the was modulated at 1.1-2.0 in LRP. [16][17][18] However,t he attained large usually arose from inefficient control in LRP. Thus,t he obtained polymers hardly undergo further chain extension. Recently,F ors et al. elegantly varied and molecular weight distribution "shapes" by metering the addition of an initiator using af eeding pump in anionic and nitroxide-mediated polymerizations. [19][20][21][22] This approach was applied to homopolymers and the first segment of block copolymers but not to the other segments of block copolymers.B oyer et al. recently metered the addition of the polymeric initiator (macro-initiator) in ap hotocontrolled LRP and successfully obtained block copolymers with tailored in the second segment. [23,24] However, the pumpassisted method is always inapplicable to heterogeneous systems,s uch as polymer brush synthesis from solid substrates,a nd thus limits applications.We have developed an organocatalyzed LRP,t hat is, reversible complexation mediated polymerization (RCMP) t...

The paper reports the generation of a carbon-center radical (R • ) from an alkyl iodide (R-I) via a halogen bonding catalysis using pyridine N-oxide (PO) catalysts. The use of this catalysis in organocatalyzed living radical polymerization was systematically studied over a series of substituted POs. A more electron-donating substitute led to a higher catalytic activity, as experimentally observed and theoretically supported by DFT (density functional theory) calcuation. Notably, the polymerization was induced and controlled not only by thermal heating but also photo irradiation. The polymerization was compatible with several functional monomers and afforded block copolymers.

The development and applications of an organocatalyzed living radical polymerization via halogen-bonding catalysis, i.e., reversible complexation mediated polymerization (RCMP), are highlighted.

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