Research articles

Two series of fluorescent glycopolymers (boronic acid derivatives, PG-PFE, and borate derivatives, PG-PFW) were synthesized through different methods. Compared with the PG-PFE samples, the PG-PFW samples had a higher grafting ratio due to the highly efficient Williamson reaction. The fluorescent glycopolymers possessed good water solubility, low cytotoxicity and selective responsiveness toward H₂O₂. Meantime, the fluorescent glycopolymers were imaged only in cellular mitochondria based on the fact that endogenous H₂O₂ is mainly distributed in cellular mitochondria.

The halogenated polyhedral oligomeric silsesquioxane (POSS) fillers can increase the refractive indices (RIs) of the films. In particular, the degree of increases was larger than those estimated by the theoretical prediction, suggesting that accumulation of polymer chains around the POSS filler plays a key role in the increasing effect. Moreover, critical losses of thermal and mechanical properties were hardly observed. Preparation without the conventional sol‒gel method for the single-molecule-type filler with high-RI polymer hybrids based on the chain assembling can be demonstrated.

In this study, we synthesized and characterized cyclodextrin-based nanoparticles (CDNPs) by polyaddition reactions using epichlorohydrin and three different type of CDs (α-, β-, and γ-CD). We found that cyclodextrin tended to cover surface of our nanoparticles; while epichlorohydrin network enlarged when weight ratio of epichlorohydrin/cyclodextrin increased. Our CDNPs demonstrated a very high loading ratio against α-mangostin (MGS), and getting close to 1:1 ratio.

This work presents a method on tailoring open pores on the patterned surface of polyethersulfone membrane prepared by the phase separation micromolding. By modifying both the thermodynamics of the casting solution and the dynamics of solvent/nonsolvent demixing, micropatterned membrane with average surface open pores in the diameter of 1095 nm and porosity as high as 31.4% was achieved. The size and number of pores were different depending on their locations on the patterned surface, which was caused by different solvent/nonsolvent demixing dynamics resulting from the physical discontinuity of micro-patterned membranes.

To precisely design microwrinkles on a biomimetic hydrogel, a two-step photocrosslinking process with VIS and UV irradiation was developed. Photocurable gelatin was first crosslinked with VIS light in the presence of the water-soluble radical generator to form thick bulk gels. Next, the top surface of the gels was irradiated with UV light in the presence of surface-coated water-insoluble radical generator. This two-step photocrosslinking process enabled to independently control the elastic moduli of the surface and the bulk lower than 100 kPa and to generate several-micron-scale wrinkles on the soft hydrogels.

The thermocompression bonding of conductive polymer films was investigated to achieve a flexible wiring and packaging technique for flexible electronics. Conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films were successfully bonded together by thermocompression, especially through surface activation treatment using ultraviolet light irradiation. After thermocompression, the PEDOT:PSS films maintained their ohmic electrical conductivity even through the adhered interface. The surface state analysis of the PEDOT:PSS indicated that the oxidized species were generated after the surface activation process. These chemical species can interact each other and provide robust bonding interfaces.

A novel method for preparing coal gasification fine slag (CGFS) samples utilized as a reinforcing filler for the SBR matrix through an efficient pneumatic separation technique has been demonstrated. The superior filler–rubber interfacial interaction can contribute to significant reinforcement in the comprehensive performances of composites by the addition of CGFS series fillers into the SBR matrix. CGFS particles have great potential for application in rubber composites, and a new strategy of using CGFS as fillers has been established.

The dilute solution properties of poly(d,l-lactide)s (PDL50) with a weight-averaged molar mass (M_w) ranging from 0.154 × 10⁴ to 75.7 × 10⁴ g mol⁻¹ are thoroughly studied in tetrahydrofuran at 25 °C by static light and small-angle X-ray scattering and intrinsic viscosity ([η]) measurements. The M_w dependences of 〈S²〉_z^1/2 and [η] are quantitatively described by the wormlike cylinder with stiffness parameter λ⁻¹ = 2.9 nm, indicating that the PDL50 chain behaves as a typical flexible polymer but is essentially 1.6−2.1 times stiffer than polystyrene and poly(methyl methacrylate).

Polymeric micelles based on amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(ethylene oxide)(PEO-b-PCL-b-PEO) triblock copolymers improved the solubility of caffeic acid phenethyl ester (CAPE) in aqueous media. Further on, the grafting of pendant cinnamyl moieties to the PCL block enhanced the compatibility between CAPE and the micellar core, thus increasing the encapsulation efficiency and reducing the burst release effect as compared to those of micelles with an unmodified PCL core.

The interfacial adhesion between olefinic double bond- or hydroxyl-terminated telechelic polypropylenes (PPs) and carbon fibers was studied to determine the potential of the telechelic PPs as a candidate for PP matrix resin-coupling agents for carbon fiber-reinforced PP composites. The hydroxyl-terminated PP showed higher interfacial shear strength than that of commercial PP and olefinic double bond-terminated PP. The hydroxyl-terminated PP could be used as a novel coupling agent of the PP matrix.

A cyclic block copolymer allows feasible fabrication of porous films through designed interaction between its macromolecular arms. The morphology of pores is directly determined by the structural features of the block copolymer and can be easily tuned by modification of the length of its ring and arms.

The correlation between mechanical properties and structural changes upon uniaxial stretching was studied by atomic force microscopy observations and two-dimensional small-angle X-ray scattering measurements. For this purpose, coated layers composed of di- and tri-block copolymer blends were prepared by solution coating at different drying temperatures. The packing regularity of spherical microdomains in the stretching direction was enhanced with stretching. We could correlate fracture of the block copolymer film having spherical microdomains with the completion of stretching-induced ordering of spheres in the stretching direction, which sensitively depended on the drying temperature.

Gels containing the medicinal ingredients of licorice were formed by dissolving herbal medicinal plants into a biocompatible zwitterionic cellulose solvent and successive precipitation. The licorice gels gradually released glycyrrhizic acid, the main medicinal ingredient in licorice, within 3 h. Although the licorice gels were mechanically weak, the gel strength was improved just by the addition of cellulose during the preparation of the gels.

Photopolymerization of dodecyl acrylate was conducted using methyl phenylglyoxylate as an initiator. Most polymers had either an acryloyl group or a benzoyl group at one of the chain ends. We investigated the initiation pathways and found out that methyl phenylglyoxylate initiated photopolymerization only by Norrish type II processes.

Transient elongational viscosity for polypropylene (PP)/low-density polyethylene (LDPE) blends was evaluated. Because deformed LDPE droplets act as rigid fibers due to its strain hardening, the blends show a strain hardening behavior. The growth curves are, however, affected by their viscosity ratio. These behaviors are calculated by the Phan–Thien Tanner model by assuming a symmetric geometry with a periodic structure. Based on the simulation, we propose an appropriate LDPE to modify the processability, at which the strain hardening in the elongational viscosity is required.

Core cross-linked star-shaped poly(N-isopropylacrylamide) (PNIPAAm), which was prepared via an arm-first method by reversible addition-fragmentation chain-transfer polymerization, was shown to exhibit unique thermoresponsive behavior in water. Star polymers with ~20–35 arms with narrow molecular weight distributions apparently had a more hydrophilic nature compared with that of linear PNIPAAm, judging from their thermoresponsive behavior. Most importantly, an aqueous solution of the star PNIPAAm with carboxy ends remained transparent even at 70 °C.

The osmotic pressure during the gelation process below the overlapping concentration of prepolymers was investigated using a series of model polymer gels, namely, tetra-polyethylene glycol gels. The osmotic pressure decreased during the gelation reaction and was constant after the sol–gel transition, suggesting that the clusters grow and fill the system, at the sol–gel transition point. This representation of the sol–gel transition at the overlapping condition of the critical clusters corresponds well to the aggregation process prediction.

Low-modulus polypropylene (LMPP) with controlled stereoregularity showed elastic recovery. To understand the underlying mechanism, changes in the morphology of LMPP under cyclic uniaxial elongation were investigated using in situ SAXS and WAXD. During the first cycle, the undulating structure of the crystal lamellae is large, and fragmentation of the lamellae occurs. On the other hand, during the second cycle, the little fragmentation of the lamellae occurs and that only the lamellae were rotating under elongation. Based on these results, lamella fragmentation has a significant effect on the elastic-recovery rate.

Visible light-curable alginate was prepared by coupling alginate with furfurylamine. The prepared furfuryl alginate (F-Alginate) underwent gelation in the presence of a photosensitizer under visible light irradiation. The mechanical and release properties of the visible light-induced gel were similar to that of conventional Ca²⁺-induced cross-linked alginate. The release rate of encapsulated substances depended on their molecular weight. Cell growth was enhanced in response to a sustained release of insulin-like growth factor-1 from the F-Alginate hydrogel.

To understand the roles of mechanical and structural factors in the extracellular matrix on cancer cell migration, elasticity/porosity-tunable gel matrices of gelatinous microfibers were developed. The elasticity of fibers and the porosity of matrix were tuned with photocrosslinking conditions and degree of interfiber bonding, respectively. Highly malignant MDA-MB-231 cells showed the highest degree of MMP-independent invasion into the matrix composed of fibers with a Young’s modulus of 20 kPa and a low degree of interfiber bonding, while nontumorigenic MCF-10A cells did not show invasive behavior under the same matrix conditions.