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The amphiphilic diblock copolymers consist of poly(ethylene oxide) (PEO) and poly(methacrylate) (PMA) having azobenzenes as mesogen units in the side chain afford highly ordered phase-segregated nanostructures, in which PEO cylindrical domains are hexagonally arranged and normally oriented in PMA matrix in the thin films. The liquid crystalline ordering in the strongly segregated block copolymers plays one of the most important roles to attain such an excellent arrangement of the nanostructure, potentially leading to practical use. In order to elucidate the role of the mesogen units in the side chain of the PMA segment, a new series of amphiphilic liquid crystalline diblock copolymers were synthesized to tune molecular interaction between mesogen units in liquid crystalline segments by using azobenzene, benzylideneaniline, and stilbene as mesogen cores. All the side-chain liquid crystalline diblock copolymers exhibited smectic phase and gave hexagonally arranged cylindrical nanostructures in the bulk pellets. The block copolymers having 4-(4-butylphenylazo)phenoxy, 4-((E)-(4-butylphenylimino)methyl)phenoxy, or 4-((E)-4-butylstyryl)phenoxy groups as the mesogens units gave the highly ordered hexagonal nanocylinder structures in the thin film, while the copolymers having (E)-4-(4-butylbenzylideneamino)phenoxy mesogen group afforded less ordered nanostructures. The former three kinds of copolymers showed obvious hypsochromic shifts and large hypochromic effects on the UV–vis spectra of annealed film, implying the formation of the strongly H-aggregated and homeotropic alignment of mesogen moieties in the PMA matrix.

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A liquid crystalline block copolymer, composed of poly(ethylene oxide) (PEO) and polymethacrylate (PMA)-bearing azobenzene (Az) mesogen side chains, uniquely forms perpendicularly oriented PEO cylinders in a film on various substrates, independent of the substrate surface energy. In this paper, it is revealed that the perpendicular cylinders are formed at the air interface of the block copolymer film, as the perpendicular cylinders and liquid crystal structures were observed only in the vicinity of the air interface for a block copolymer film annealed for a short period of 5 s. On the basis of this mechanism of air-interface-induced perpendicular cylinder formation, we developed a surface covering method to prevent the perpendicular cylinder formation and instead induce parallel cylinder formation. Moreover, uniaxial cylinder films were fabricated by a combination of the surface covering and substrate rubbing methods. The surface covering layer for controlling cylinder orientation can be removed to utilize the block copolymer film for templating.

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Mesoporous silica thin films have received much attention in applications as diverse as separation devices, sensors, and optoelectronic devices.[1] The evaporation-induced self-assembly method (EISA) has been established as an efficient process for the rapid preparation of mesoporous silica thin films. [2] Usually, beginning with a highly dilute homogenous solution of a soluble silica species and a surfactant in an ethanol/water mixture, preferential evaporation of ethanol concentrates the nonvolatile surfactant and silica species in water, thereby inducing the self-assembly of silica-surfactant micelles and their further organization into liquid-crystalline mesophases. [2] Recently, this efficient EISA method has been applied to prepare ordered mesoporous materials within the confined channels of anodic alumina membranes (AAM), silicon membranes, and other resist molds. [3][4][5][6][7][8][9][10][11][12][13] Compared to mesoporous powders and thin films, a hierarchically ordered mesoporous material is advantageous for self-assembly on a macroscopic scale and allows easy control over the morphology. A reduction in diameter below 50 nm to obtain mesoporous nanowires and -fibers is believed to offer even more benefits. However, studies of this type of materials have been limited so far due to the size limitation of the templates available. This shortcoming can be overcome by using the block copolymer lithography technique, which provides a powerful way to fabricate highly ordered arrays of inorganic nanoparticles with diameters of 5 -50 nm. [14][15][16][17][18][19][20][21][22][23][24][25][26] Both the diameter and interparticle distance of the resulting nanoparticle arrays can be tuned by adjusting the volume fractions of the block copolymer templates. Unfortunately, control of the aspect ratio (or the height) still remains a challenge. Herein, we report for the first time preparation of a highly ordered array of mesoporous silica nanorods with tunable aspect ratios, through an integrated strategy of block copolymer lithography and EISA. Block copolymer thin films with normal, cylindrical domains are used as external scaffolds to define the morphology of SiO 2 nanorods. The surfactant cetyltrimethylammonium bromide (CTAB) is used as an internal template to form mesoporous structures inside the SiO 2 nanorods. The control of the diameter, the center-to-center distance, and the height of SiO 2 nanorods were studied systematically.Microphase-separated diblock copolymer films of amphiphilic PEO m -b-PMA(Az) n (m and n denote repeated units of the individual segments), consisting of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(methacrylate) with azobenzene mesogens (PMA(Az)) in the side chain, [27][28][29] can be prepared by spin-coating 1 ∼ 3 wt % toluene or chloroform solutions thereof on silicon wafers substrates followed by annealing at 140°C for 24 h in vacuum. When the silicate sol was introduced into the PEOm-b-PMA(Az)n thin film, the swollen PEO domains had been selectively doped, which was confirm...

Much more attention has been directed to biodegradable polymers due to their potential applications in the fields related to environmental protection in the last two decades. According to the difference in preparation methods, biodegradable polymers can be classified into two types. One is the biosynthetic polymer, such as bacterial polyhydroxyalkanoates (PHAs). Among them poly(hydroxybutyrate) (PHB) is probably the most extensively studied biodegradable thermoplastic polymer. Ha et al. recently reviewed the miscibility, properties and biodegradability of blends containing either PHB or poly(3-hydroxybutyrate-cohydroxyvalerate).1 The other is the chemosynthetic polymer, such as the aliphatic polyesters. Poly(butylene succinate) (PBSU) and poly(ethylene succinate) (PES) are just two of them. The chemical structures of PBSU and PES are (-OCH The crystal structure, crystallization and melting behaviour of PBSU have been reported in literature. 2-4Polymer blending is often performed in order to improve the physical properties and extend the application fields of PBSU. PBSU was found to be miscible with poly(vinylidene fluoride), poly(vinylidene chloride-co-vinyl chloride), poly(ethylene oxide) (PEO) and poly(vinyl phenol).5-9 On the other hand, PBSU was found to show no miscibility with PHB, poly(3-hydroxybutyrate-co-hydroxyvalerate) and poly("-caprolactone). [10][11][12] We also studied the subsequent melting behavior of PBSU crystallized nonisothermally from the melt. 13The crystal structure, crystallization behaviour and melting behaviour of PES have been reported in literature.14-16 The crystallization and morphology of PES in binary miscible blends of two crystalline polymers have also been reported recently, such as in PES/PHB and PES/PEO blends. 17,18 We also studied the subsequent melting behavior of PES crystallized nonisothermally from the melt and the crystallization kinetics as well as subsequent melting behaviour of PES from the amorphous glassy state. 13,19 Crystallinity is known to play an important role in the physical properties and biodegradability of biodegradable polymers. Meanwhile, the crystalline structure and morphology of semicrystalline polymers are also influenced greatly by the thermal history. Therefore, much more attention should be paid to the crystallization kinetics study since it affects not only the crystalline structure and morphology of semicrystalline polymers but also the final physical properties and biodegradability for the biodegradable polymers. However, to the best of our knowledge, the overall crystallization kinetics studies, especially the nonisothermal crystallization kinetics studies from the melt, of PBSU and PES have not been reported so far in literature. But it is essential to study the nonisothermal crystallization kinetics from the viewpoint of practical application because most polymer processing operations are carried out under nonisothermal conditions.In this note we reported our results on the nonisothermal crystallization kinetics of PBSU and PES from the ...