Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

Cylindrical polymer micelles pack in 3D When you control chemistry, solvents, temperature, and concentration, surfactants and block copolymers will readily assemble into micelles, rods, and other structures. Qiu et al. take this to new lengths through precise selection of longer polymer blocks that self-assemble through a crystallization process (see the Perspective by Lee et al. ). They chose polymer blocks that were either hydrophobic or polar and used miscible solvents that were each ideal for only one of the blocks. Their triblock comicelles generated a wide variety of stable three-dimensional superstructures through side-by-side stacking and end-to-end intermicellar association. Science , this issue p. 1329 ; see also p. 1310 </jats:p

Di-tert-butyl cyclo­hex-2-ene-1,4-diyl dicarbonate

In the title mol­ecule, C16H26O6, the central cyclo­hexene ring is in a half-chair conformation. The carbonyl groups are in a trans arrangement with respect to each other and the dihedral angle between the mean planes of the carbonate groups is 10.8 (2)°

2,5-Dimethyl­hexane-2,5-diyl bis­(4-nitro­phen­yl) dicarbonate

The title structure, C22H24N2O10, contains two independent centrosymmetric mol­ecules. The only significant difference between the mol­ecules is the dihedral angle between the unique carbonate group (–O—CO2–) and the benzene ring, the values being 77.35 (8) and 66.42 (8)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds

trans-Cyclo­hexane-1,4-diyl bis­(4-nitro­phen­yl) dicarbonate

In the title crystal structure, C20H18N2O10, there are two independent mol­ecules, both of which lie on crystallographic inversion centres. In one mol­ecule the 4-nitro­phenyl dicarbonate groups are substituted in equatorial (A eq) positions of the chair-form cyclo­hexane ring while in the other mol­ecule the substitution is axial (B ax). The dihedral angles between the atoms of the symmetry-unique carbonate group (O=CO2—) and benzene ring for each mol­ecule are 47.3 (1)° for A eq and 11.7 (2)° for B ax. In B ax, this facilitates the formation of a weak intra­molecular C—H⋯O hydrogen bond, while the packing is stabilized by weak inter­molecular C—H⋯O inter­actions

Explosive dissolution and trapping of block copolymer seed crystallites

The study of the dissolution of polymer crystals is a challenging task. Here the authors use crystallization-driven self-assembly of coil-crystalline block copolymers as a trapping technique to track the change in length of 1D seed crystallites during annealing

trans-Cyclo­hex-2-ene-1,4-diyl bis­(4-nitro­phen­yl) dicarbonate

Although the title mol­ecule, C20H16N2O10, does not possess mol­ecular inversion symmetry, it lies on a crystallographic inversion centre which imposes disorder on the central cyclo­hexene ring. In addition, the cyclo­hexene ring has non-symmetry-related disorder over two sites, with the ratio of the major and minor components being 0.54:0.46. The overall effect is to produce four disorder components for the atoms of the cyclo­hexene ring. The side chain is perfectly ordered and the dihedral angle between the atoms of the carbonate group (O=CO2—) and the benzene ring is 72.99 (6)°

Cylindrical Micelles with "patchy" Coronas from the Crystallization-Driven Self-Assembly of ABC Triblock Terpolymers with a Crystallizable Central Polyferrocenyldimethylsilane Segment

Solution self-assembly of a series of linear ABC triblock terpolymers with a central crystallizable poly­(ferrocenyldimethylsilane) (PFS) core-forming “B” block and terminal polystyrene (PS) and poly­(methyl methacrylate) (PMMA) “A” and “C” blocks has been investigated. Three PS-<i>b</i>-PFS-<i>b</i>-PMMA triblock terpolymers with different block ratios (<b>1</b>, 3.6:1.0:4.7; <b>2</b>, 7.0:1.0:6.9; and <b>3</b>, 1.1:1.0:1.4) but with similar degrees of polymerization for the central PFS block were prepared through a combination of living anionic and atom-transfer radical polymerization techniques, together with azide/alkyne “click” chemistry. Cylindrical micelles with a crystalline PFS core were formed in solvents selective for the terminal PS and PMMA blocks. In ethyl acetate, a slightly more selective solvent for the PS block, cylinders with significant microphase separation within the corona in the dry state were observed on the basis of TEM analysis. The use of acetone, which is slightly more selective for the PMMA block than the PS block, led to more distinct microphase separation to generate a “patchy” coronal morphology. Living crystallization-driven self-assembly studies in acetone allowed the formation of uniform cylindrical micelles and block comicelles of controlled length with “patchy” coronal segments by seeded growth methods

Bis(4-nitro­phen­yl) 1,3-phenyl­ene­dimethyl­ene dicarbonate

In the title mol­ecule, C22H16N2O10, the dihedral angles between the benzene rings of the 4-nitro­phenyl groups and the central benzene ring are 32.7 (1) and 34.7 (1)°, while the dihedral angle between the two benzene rings of the 4-nitro­phenyl groups is 3.6 (2)°. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds link mol­ecules into centrosymmetric dimers

Uniform patchy and hollow rectangular platelet micelles from crystallizable polymer blends

Growing patterned rectangular objects The growth of patterned objects usually requires a template to aid the positioning of multiple materials. Qiu et al. used the seeded growth of a crystallizable block copolymer and a homopolymer to produce highly uniform rectangular structures (see the Perspective by Ballauff). Chemical etching, or dissolution, of uncross-linked regions of the rectangular structures produced perforated platelet micelles. The sequential addition of different blends and cross-linking/dissolution strategies allowed the formation of well-defined hollow rectangular micelles, which can be functionalized in a variety of ways. Science , this issue p. 697 ; see also p. 656 </jats:p