Summary: Well‐defined poly(N‐vinylcarbazole) [poly(NVC)] was synthesized by macromolecular design via interchange of the xanthates (MADIX)/reversible addition‐fragmentation chain transfer (RAFT) polymerization. The homopolymers with controlled molecular weights ($\overline M _{\rm n}$ = 3 000–48 000) and low polydispersities indices ($\overline M _{\rm w} /\overline M _{\rm n}$ = 1.15–1.20) were obtained by the polymerization of NVC with AIBN in the presence of O‐ethyl‐S‐(1‐phenylethyl) dithiocarbonate as a xanthate‐type chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first‐order kinetic plot, the molecular weight controlled by the monomer/CTA molar ratio, linear increase in the molecular weight with the conversion, and the ability to extend the chains by the second addition of the monomer.Radical polymerization of NVC in the presence of CTA and plot of number‐average molecular weight (circles) and polydispersity (squares) as a function of conversion.magnified imageRadical polymerization of NVC in the presence of CTA and plot of number‐average molecular weight (circles) and polydispersity (squares) as a function of conversion.

Poly (N-ethyl-3-vinylcarbazole), in which the carbazole unit is directly bound to the polymer main chain, has been synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The homopolymers with controlled molecular weights and low polydispersities (Mw/Mn ) 1.15-1.29) were obtained by the polymerization of N-ethyl-3-vinylcarbazole (E3VC) with 2,2′-azobis(isobutyronitrile) (AIBN) as an initiator in the presence of benzyl 1-pyrrolecarbodithioate as a chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first-order kinetic plot, linear increase in the molecular weight with the conversion, and the linear relationship between the molecular weight and the monomer/CTA molar ratio. Successful chain extension from dithiocarbamate-terminated poly(E3VC) was also observed. Well-defined block copolymers with poly(E3VC) segment have been synthesized using the dithiocarbamate-terminated polystyrene as a macro-CTA. The resulting polymers, poly(E3VC) and polystyrene-b-poly(E3VC), absorbed light in the range from 300 to 380 nm and exhibited excimer emission at 454 nm with blue fluorescence. These polymers showed thermal stability above 350°C under nitrogen.

Cover: The graphic shows the use of the xanthate-type chain transfer agent for controlled radical polymerization of N-vinylcarbazole. Good control of the polymerization was confirmed by the narrow polydispersity of the products, feasibility to control molecular weight based on the monomer to chain transfer agent ratio (left figure), linear increase in molecular weight with the conversion (middle figure), and ability to extend the chains by the second addition of the monomer (right figure).

Stereospecific polymerization of vinyl alkyl ether was studied; various kinds of compounds, such as metal oxides, metal halides, metal oxyhalides, metal sulfate complexes and organometallic compounds‐Lewis acid complexes, being used at low temperature or room temperature. The relationship between the structures of catalysts and the stereoregularities of polymers is discussed, and it is found that tetrahedral compounds which have one active edge are especially useful for making the stereoregular polymers at room temperature. Also, the shorter the length of active edge, the more suitable the catalyst is for stereospecific polymerization. On the basis of these experimental results, a mechanism of stereospecific polymerization of vinyl alkyl ether is proposed.

The reaction of 2-alkyl or -aryl substituted 5-methoxy-4-(p-nitrophenyl)oxazoles (1) with tetracyanoethylene gave 2-substituted methyl 3,3,4,4-tetracyano-5-(p-nitrophenyl)-4,5-dihydro-3H-pyrrole-5-carboxylates (2) as formal [3 + 21 cycloadducts; these were produced via a zwitterionic mechanism involving oxazole ring opening.