Conformational properties of cylindrical rod brushes consisting of a flexible polystyrene main chain and poly(n-hexyl isocyanate) (PHIC) rod side chains have thoroughly been studied by static light and small-angle X-ray scattering (SAXS) in tetrahydrofuran (THF) at 25 °C. These rod brushes were prepared by radical homopolymerization of 4-vinylbenzyloxy-ended PHIC macromonomers (1) (VB-HIC-N s , where N s is the weight-averaged degree of polymerization of HIC and in a range from 21 to 80) in n-hexane at 60 °C. The mean-square cross-sectional radius of gyration (〈R c 2 〉 0 ) of the brush at an infinite dilution is determined by SAXS measurement and rationalized as a function of N s . The experimental value of 〈R c 2 〉 0 gradually increases with N s but above N s higher than 20 increases to follow the scaling law of 〈R c 2 〉 0 ∝ N s 0.87 . The experimental N s dependence of 〈R c 2 〉 0 is compared to that from the wormlike comb model whose main and side chains have different stiffness parameters. The molecular weight dependence of z-averaged mean-square radius of gyration (〈R g 2 〉 z ) of the brush is determined and analyzed in terms of the wormlike cylinder model taking into account the end effects. The parameters characteristic of the rod brush in THF solution, such as the main chain stiffness parameter (λ M -1 ), the molecular weight per unit contour length (M L ), and the excluded-volume strength (B), are determined and rationalized as a function of the contour length of the side rod. The polystyrene main chain stiffness of the rod brush remarkably increases by the densely located rod side chains to follow the scaling law of λ M -1 ∝ N s 1 . The backbone stiffness of the rod brush is higher than that of the flexible brush consisting of flexible polystyrene side chains with the corresponding contour length. A single rod brush of poly(VB-HIC-47) deposited on a mica surface is observed by the scanning force microscopy to reasonably demonstrate the cylindrical rod brushes.

Nonlinear fluorescence response, which is particularly important to attain the high signal-to-background ratio, was realized by the aggregation-induced fluorescence increase of guanidinium-tethered tetraphenylethene with ATP.

Self-assembly behaviors of a series of systems (G1, G2, and G3) possessing same organic building blocks based on a substituted anthracene have been investigated in decalin. G2 and G3 are dominated by head-to-tail (ht) and head-to-head (hh) type dimers of G1, respectively. G1 gives a thermoresponsive gel that behaves ideally, showing frequency-independent elastic and viscous moduli. Interestingly, G2 produces a thixotropic gel that shows the signature of structural relaxation, signifying the dynamic nature of the system. In contrast, G3 remains fluidlike. As investigated by scanning electron microscopy (SEM), in the assembly process of G2, first disklike nanoaggregates are formed, and in the second step these aggregates interact to construct the densely packed secondary assembly. A transition from secondary assembly to primary assembly under shear initiates the mechanoresponsive destruction of the gel. In the self-assembly process, G1 propagates in a one-dimensional fashion, whereas G2 and G3 can propagate in a two-dimensionional fashion. The same side orientation of the substituents in G3 facilitates the formation of a compact closed-shell-type structure, which results in the generation of isolated nanocrystals. The long-range weak interaction together with the capability of propagating in two dimensions is found to be essential for the construction of such a mechanoresponsive assembly. C(60) and C(70) could be incorporated successfully in G2 assembly to develop mechanoresponsive fullerene assemblies. The presence of fullerenes not only enhances the elastic properties of G2 but also intensifies the thixotropy. C(70) appears to be a superior guest in terms of property enhancement due to its better size fitting with the concave-shaped host.

Methacrylate-ended rodlike macromonomers consisting of poly(n-hexyl isocyanate) (MA-HIC-n(2), where n is a degree of polymerization of n-hexyl isocyanate (HIC)) with narrow molecular weight distribution have successfully been synthesized in CH2Cl2 at room temperature by living coordination polymerization of HIC using 2-methacrylate ethyloxydichloro(cyclopentadienyl)titanium (IV) (1) as an initiator. The rodlike macromonomers prepared have carefully been characterized by size exclusion chromatography fitted with a multiangle laser light scattering (SEC−MALS) and 1H NMR spectroscopy. The radical copolymerization behavior of the rodlike macromonomers (M2) with methyl methacrylate (MMA) (M1) or styrene (ST) (M1) in benzene at 60 °C has thoroughly been studied and rationalized with a function of degree of polymerization of HIC. In region of degree of polymerization (n) higher than 26, the macromonomer's apparent reactivity (1/r 1) relative to MMA was found to be almost independent of n and macromonomer concentration but lower than MMA (1/r 1 is ca. 0.6). On the other hand, in the macromonomers with n less than 26, the reactivity appeared to steeply increase with decreasing n, because of weak aggregation due to hydrogen bond formation between terminal amide groups in benzene. In the copolymerization with ST (M1), the apparent reactivities (1/r 1) were also lower the reference value reported in the copolymerization of MMA with ST. The copolymerization behavior of MA-HIC-n macromonomers was compared with that of styryl-ended (VB-HIC-n, 1/r 1 ≈ 1.0) and methacryloyl-ended (Bz-HIC-n-MA, 1/r 1 ≈ 0.1) macromonomers and discussed from the structural point of views. The methacrylate functional group was thought to be much more subject to steric hindrance effects than the styrenic group.

The dimensional properties of rod brushes consisting of a flexible polymethacrylate main chain and poly(n-hexyl isocyanate; PHIC) rod side chains have been studied using static light and small-angle X-ray scattering (SAXS) techniques in tetrahydrofuran (THF) at 25 1C. The results are compared with those consisting of a flexible polystyrene main chain and PHIC side chains (VB-HIC-N s-H, where N s is the weight-averaged degree of polymerization of HIC). The rod brushes were prepared through the radical homopolymerizations of a-methacryloyloxyethoxy-x-acetyl-PHIC macromonomer (MA-HIC-61-Ac) in n-hexane at 60 1C. The molecular weight dependence of the z-averaged mean-square radius of gyration (/R g 2 S z) of the brush is quantitatively described in terms of the wormlike cylinder model taking into account the end effects. The main chain stiffness parameter (k M À1) is determined to be 197 nm for poly(MA-HIC-61-Ac), which is approximately three times greater than that for poly(VB-HIC-62-H), which has a polystyrene main chain and the same rod length. The considerably larger stiffness in the polymethacrylate than in the polystyrene is most likely responsible for the larger effective excluded volume effects produced by the freely rotating spacer between the main chain and side rod. A single rod brush of poly(MA-HIC-61-Ac) on a mica surface is clearly observed using atomic force microscopy to reasonably demonstrate the cylindrical rod brushes.

The helix-forming nature of β-1,3-glucan polysaccharides is a characteristic that has potential for producing gene carriers, bio-nanomaterials and other chiral nanowires. Herein, carboxylic curdlan (CurCOOH) bearing the β-1,3-polyglucuronic acid structure was successfully prepared from β-1,3-glucan polysaccharide curdlan (Cur) by one-step oxidation using a 4-acetamido-TEMPO/NaClO/NaClO(2) system as the oxidant. The resulting high-molecular-weight CurCOOH was proved to bear the 6-COOH group in 100% purity. The optical rotatory dispersion (ORD) spectra indicated that the obtained CurCOOH behaves as a water-soluble single-strand in various pH aqueous media. This advantage has allowed us to use CurCOOH as a polymeric host to form various macromolecular complexes. For example, complexation of CurCOOH with single-walled carbon nanotubes (SWNTs) resulted in a water-soluble one-dimensional architecture, which formed a dispersion in aqueous solution that was stable for several months, and much more stable than SWNTs complexes of the similar negatively-charged polyacrylic acid (PAA) and polymethacrylic acid (PMAA). It was shown that in the complex, SWNTs are effectively wrapped by a small amount of CurCOOH, enabling them to avoid electrostatic repulsion. This pH-responsive CurCOOH formed a very stable complex with cationic water-soluble polythiophenes (PT-1), which was stabilized not only by the hydrophobic interaction but also by the electrostatic attraction between trimethylammonium cations in PT-1 and dissociated anionic COO(-) groups in CurCOOH. The included PT-1 became CD-active only in the neutral to basic pH region, and the positive Cotton effect suggested that the conjugated main chain is twisted in the right-handed direction. We also found that CurCOOH can interact with polycytidylic acid (poly(C)) only under high NaCl concentrations, the binding and release of which could be controlled by a change in the salt concentration. We believe, therefore, that CurCOOH bearing a dissociable COOH group can act as a new potential polymeric host to construct novel polymeric complexes applicable for gene carriers, biosensors, chiral polymer assemblies, etc.

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A series of novel poly(n-hexyl isocyanate) (PHIC) rodlike macromonomers having an -methacryloyloxyoligo(oxyethylene) group and an !-acetyl group (MA-EO m -HIC-n-Ac, where m and n are the degrees of polymerization of oxyethylene (EO) and HIC, respectively) have been prepared. They were prepared by living coordination polymerization of HIC using corresponding titanium(IV) alkoxide complexes as an initiator in CH 2 Cl 2 at room temperature, followed by termination with acetic anhydride as a terminator in the presence of BF 3 OEt 2 as a Lewis acid. The radical copolymerization behavior of MA-EO m -HIC-n-Ac (M 2 ) with methyl methacrylate (MMA) (M 1 ) in benzene at 60 C has thoroughly been investigated in order to evaluate an effect of a flexible oligo(oxyethylene) spacer (m) on the copolymerizability. The apparent reactivities (1=r 1 ) of MA-EO m -HIC-n-Ac are lower than for MMA (1/r 1 is ca. 0.52) and decrease slightly with increasing m. The copolymerizability of MA-EO m -HIC-n-Ac was compared with that of -4-vinylbenzyoxy-ended PHIC macromonomers (VB-HIC-n-H). The decrease in the copolymerizability of the methacrylate-ended PHIC macromonomers is most likely due to the incompatibilities among the macromonomer, comonomer, and propagating polymer chain, together with the fact that methacrylate itself is much more influenced by the polymerization conditions than a styrenic monomer.