The epitaxy forced crystallization behavior of thin film olefin block copolymer (OBC) samples was investigated in the presence of benzoic acid (BA). The investigated OBC samples show apparent phase separation in the melt. However, their dissimilar comonomer difference between hard and soft segments (ΔC8) and block lengths results in different segregation strength, which controls their crystallization behavior. Independent of the crystallization conditions, for both OBCs the BA substrate induces highly oriented and epitaxially grown lamellar crystals. In case of the weakly melt segregated OBC, crystallization always breakout the melt separated phase domains, and crystals are homogeneously distributed in the entire sample. For strongly melt segregated OBC, on the other hand, phase separation is maintained when quenching the samples, and only isolated crystalline domains are formed. However, subsequent annealing of quenched samples, slow cooling from the melt, or isothermal crystallization at low supercoolings on the BA substrate forces crystals breakout the initial confinement. Such crystallization experiments help us better understanding the interplay between molecular architecture, segregation strength, and controlled crystallization conditions on the organization of OBCs.

The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(l-lactide) (PS-PLLA) and polystyrene-b-poly(d-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical chains from self-assembly. The handedness of the twisted lamella can be determined by using rotation experiment of polarized light microscopy (PLM). Similar to the self-assembly of BCPs*, the examined results suggest the homochiral evolution in the crystallized chiral polylactides. The results presented in this Account demonstrate the notable progress in the spectral and morphological determination for the examination of molecular, conformational, and hierarchical chirality in self-assembled twisted superstructures of chiral polymers and helical phases of block copolymers and suggest the attainability of homochiral evolution in the self-assembly of chiral homopolymers and BCPs*. The suggested methodologies for the understanding of the mechanisms of the chirality transfer at different length scales provide the approaches to give Supporting Information for disclosing the mysteries of the homochiral evolution from molecular level.

The selective alteration of the cellular genome by laser microbeam irradiation has been extensively applied in cell biology. We report here the use of the third harmonic (355 nm) ofan yttrium-aluminum garnet laser to facilitate the direct transfer of the neo gene into cultured human HT1080-6TG cells. The resultant transformants were selected in medium containing an aminoglycoside antibiotic,

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The nucleation process of poly(lactide) (PLA) on a series of fibers was studied by means of in-situ Polarized Optical Microscope (POM) during crystallization.Several synthetic and natural fibers (PLLA stereocomplex fibers (SC), PET, carbon, Kevlar, glass, hemp, linen and cellulose) were employed, and compared to customspun fiber of stereocomplex enantiomeric PLA blend.Meaningful differences in the nucleating ability towards PLA could be found for all the considered fibers. Stereocomplex PLA fibers display extremely high nucleating efficiency, with the development of a continuous transcrystalline morphology on their surface, up to high crystallization temperatures. Quantitative measurement of the nucleation rate allowed a comparison of the different fiber substrates in the light of classical heterogeneous nucleation theory, by considering the interfacial free energy difference parameter, Δσ, directly related to the nucleation barrier.The topography of the fibers surface was investigated by atomic force microscopy (AFM), and tentatively related to the measured nucleation ability. While a general effect of surface roughness on lowering the heterogeneous nucleation energy barrier can be deduced, deviations can be observed, in particular for carbon and stereocomplex PLA fibers. The different fiber wettability by PLA melt suggests that chemical interactions between the substrate and the crystallizing polymer also play a meaningful role in promoting the nucleation, although this aspect is generally disregarded in the literature -in favor of surface roughness. Moreover, the specific surface topography is shown to largely affect the density of available nucleation sites along the fiber.

A highly active nickel catalyst with a hybrid P,N ligand is successfully used for the first time for the polymerization of a thiophene monomer with sterically very demanding side groups. The performance of this catalyst is by far not achievable with commercially available standard catalysts. Polythiophenes with special side chain patterns can thus be made with predetermined molecular weight, low dispersity, and high regioregularity, which enable the preparation of various large crystalline superstructures for the investigation of anisotropic optoelectronic properties in the absence of π–π interactions.

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