The B all and N all: Soluble, linear, high molecular weight polyaminoborane homopolymers and copolymers have been synthesized by iridium‐catalyzed dehydrocoupling of readily available amine–borane adducts RNH2⋅BH3 (R=H, Me, nBu).

We herein report the formation of two complex nanostructures, toroidal micelles and bicontinuous nanospheres, by the self-assembly of the single structurally simple crystalline-b-coil diblock copolymer poly[bis(trifluoroethoxy)phosphazene]-b-poly(styrene), PTFEP-b-PS, in one solvent (THF) and without additives. The nature of these nanostructures in solution was confirmed by DLS and cryo-TEM experiments. The two morphologies are related by means of a new type of reversible morphological evolution, bicontinuous-to-toroidal, triggered by changes in the polymer concentration. WAXS experiments showed that the degree of crystallinity of the PTFEP chains located at the core of the toroids was higher than that in the bicontinuous nanospheres, thus indicating that the final morphology of the aggregates is mostly determined by the ordering of the PTFEP core-forming blocks.

This Perspective discusses the development of new routes to polyphosphazenes, [R(2)P[double bond, length as m-dash]N](n), that occur at ambient temperature and, in some cases, allow molecular weight control and access to narrow molecular weight distributions and block copolymers. For example, the room temperature silyl-carborane initiated ring-opening polymerisation of (NPCl(2))(3) is described together with chain growth condensation polymerisations of phosphoranimines Cl(3)P[double bond, length as m-dash]NSiMe(3) and BrMePhP[double bond, length as m-dash]NSiMe(3). Recent works on donor-stabilised cationic phosphoranimines are also discussed.

The sequential living polymerization of N-silylphosphoranimines for the synthesis of polyphosphazene-b-polyphosphazene diblock copolymers (PP-b-PP) has been studied both experimentally and theoretically. For the experiments, BrMe 2 PN−SiMe 3 , [Cl 3 PNPCl 3 ][X] (X = PCl 6 − , Cl − ), Cl 3 PN−SiMe 3 , ClMe 2 PN−SiMe 3 , and [Me 3 PNPMe 2 Cl] + were used as representative model reagents. Density functional theory (DFT) calculations in the gas phase adjusted for solvent effects on ClMe 2 PN− SiMe 3 , [Cl 3 PNPCl 3 ] + , Cl 3 PN−SiMe 3 , and ClMe 2 PN−SiMe 3 confirmed the experimental observations. The results have shown the necessity of starting with monoend-capped initiators to avoid the formation of triblock chains. It was also demonstrated that the nature of the nucleophilic N-silylphosphoranimines and the electrophilic cationic end groups of the living polyphosphazenes strongly affects the polymerization reaction, imposing limits to its synthetic potential. Thus, good electron donor N-silylphosphoranimines, i.e. XR 2 PN−SiMe 3 , react better with electron-deficient cationic end groups such as N−PCl 3 + , probably by molecular orbital (MO) control. The results led to the designed synthesis of well-defined PP-b-PP block copolymers with narrow molecular weight distributions of formula [N P(Ph)(Me)] n -b-[NP(OCH 2 CF 3 ) 2 ] m and [NP(Ph)(Me)] n -b-[NP(O 2 C 12 H 8 )] m , which are excellent candidates for micellation studies.

A series of optically active helical polyphosphazene block copolymers of general formula R-[N=P(O2C20H12)]n-b-[N=PMePh]m (R-7 a-c) was synthesized and characterized. The polymers were prepared by sequential living cationic polycondensation of N-silylphosphoranimines using the mono-end-capped initiator [Ph3 P=N=PCl3][PCl6] (5) and exhibit a low polydispersity index (ca. 1.3). The temperature dependence of the specific optical activity ([α]D) of R-7 a,b relative to that for the homopolymers R-[N=P(O2C20H12)]n (R-8 a) and the R/S analogues (R/S-7 a,b), revealed that the binaphthoxy-phosphazene segments induce a preferential helical conformation in the [N=PMePh] blocks through a "sergeant-and-soldiers" mechanism, an effect that is unprecedented in polyphosphazenes. The self-assembly of drop-cast thin films of the chiral block copolymer R-7 b (bearing a long chiral and rigid R-[N=P(O2C20H12)] segment) evidenced a transfer of helicity mechanism, leading to the formation of twisted morphologies (twisted "pearl necklace"), not observed in the nonchiral R/S-7 b. The chiral R-7 a and the nonchiral R/S-7 a, self-assemble by a nondirected morphology reconstruction process into regular-shaped macroporous films with chiral-rich areas close to edge of the pore. This is the first nontemplate self-assembly route to chiral macroporous polymeric films with pore size larger than 50 nm. The solvent annealing (THF) of these films leads to the formation of regular spherical nanostructures (ca. 50 nm), a rare example of nanospheres exclusively formed by synthetic helical polymers.