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.

Despite their ubiquitous presence in synthesis, the use of polar organolithium reagents under environmentally benign conditions constitutes one of the greatest challenges in sustainable chemistry. Their high reactivity imposes the use of severely restrictive protocols (e.g., moisture‐ and oxygen‐free, toxic organic solvents, inert atmospheres, low temperatures, etc.). Making inroads towards meeting this challenge, a new air‐ and moisture‐compatible organolithium‐mediated methodology for the anionic polymerization of different olefins (e.g., styrenes and vinylpyridines) was established by pioneering the use of deep eutectic solvents (DESs) as an eco‐friendly reaction medium in this type of transformation. Fine‐tuning of the conditions (sonication of the reaction mixture at 40 °C in the absence of protecting atmosphere) along with careful choice of components of the DES [choline chloride (ChCl) and glycerol (Gly) in a 1:2 ratio] furnished the desired organic polymers (homopolymers and random copolymers) in excellent yields (up to 90 %) and low polydispersities (IPD 1.1–1.3). Remarkably, the in situ‐formed polystyril lithium intermediates exhibited a great resistance to hydrolysis in the eutectic mixture 1ChCl/2Gly (up to 1.5 h), hinting at an unexpected high stability of these otherwise highly reactive organolithium species in these unconventional reaction media. This unique stability can be exploited to create well defined block‐copolymers.

Self-assembly of block copolymers in block-selective solvents can lead to a variety of different morphologies with shapeand composition-dependent potential applications in areas as diverse as drug delivery and nanolithography.[1] Amorphous block copolymers usually give rise to spherical micelles in selective solvents, but since the mid 1990s various strategies [2] that promote the formation of other morphologies including cylinders [3, 4] or cylinder networks, [5] disks, [6] helices, [7] Janus micelles, [8] toroids, [9] nanotubes, [10] and other complex forms [11][12][13] have been developed. Previous work on the solution self-assembly of diblock copolymers has shown that the presence of crystalline coreforming blocks such as poly(ferrocenyldimethylsilane) (PFS), polyethylene, polyacrylonitrile, polycaprolactone, and poly-(ethylene oxide) promote the formation of morphologies with low interfacial curvature such as cylinders and platelets. [4,14] Moreover, recent studies of PFS block copolymers have revealed that on addition of further unimer, epitaxial growth from the exposed crystalline cores of the ends of cylindrical micelles or the edges of platelets is possible to generate hierarchical micelle architectures such as block co-micelles and scarf structures, respectively.[15] This crystallizationdriven living self-assembly process has enabled the preparation of well-defined self-assembled structures with spatially defined attachment of nanoparticles and oxide surface coatings.[16] Here we report that by using this crystallization-driven living self-assembly approach, the formation of unusual nanoscopic architectures such as pointed ovals and hierarchical pointed-oval-based co-micelle architectures is also possible.We used two types of asymmetric, narrow polydispersity crystalline-coil, PFS core-forming diblock copolymers: firstly, PFS 34 -P2VP 272 (P2VP = poly(2-vinylpyridine)) [17,19] to generate cylindrical micelles, especially short "seed" micelles, and, second, PFS 54 -PP 290 [18,19] (PP = poly[bis(trifluoroethoxy)-phosphazene]; Scheme 1 and Supporting Information Table S1).Previous studies have shown that PFS-P2VP block copolymers such as PFS 34 -P2VP 272 with a long P2VP segment self-assemble to form cylinders with a crystalline PFS core and a P2VP corona in 2-propanol (iPrOH), a selective solvent for the P2VP block. [17] To explore the use of PFS 54 -PP 290 in crystallization-driven living self-assembly, [20] seed micelles of PFS 34 -P2VP 272 were used as initiators. The seed micelles were generated by sonication of long cylindrical micelles (length 3 to 10 mm (by TEM, see Figure S2) and height 8 to 12 nm (by AFM, see Figure S3)). In our first set of exploratory experiments, a solution of the cylinders (0.0625 mg mL À1 ) was subjected to sonication for 5 min. This led to shortened PFS 34 -P2VP 272 seeds that were polydisperse in length (number average length L n = 215 nm (by TEM), L w /L n = 1.63 (Figures 1 a, S4a, S5a, and S7), and uniform in height (ca. 10 nm by AFM; Figure S6)). We took four ali...

A new environmentally-friendly and air-tolerant protocol for the Cu-MOF catalysed ATRP of MMA in a biorenewable deep eutectic solvent is reported, with both the solvent and catalyst being recycled up to six consecutive times.