Analytical chemistry articles within Polymer Journal

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  • Original Article |

    Developing fluorescence anion sensors is important because anions play a significant role in various biological phenomena. Herein, we evaluated the anion binding properties of a polyhedral oligomeric silsesquioxane (POSS) derivative with eight urea groups and a 3D structure. The results revealed that the POSS derivative with urea groups can bind to sulfate ions and exhibits a greater binding ability than that of the model compound because multiple urea groups exhibit cooperative effects. Through the introduction of naphthyl urea groups, the POSS derivative can be used as a fluorescence sensor for quantifying sulfate ions.

    • Hayato Narikiyo
    • , Masayuki Gon
    •  & Yoshiki Chujo

  • Note |

    Surface amino groups (SAGs) on nanochitin materials were quantified using three amino-labeling reagents and two cationic dyes. After binding to SAGs, the excess labeling reagents or generated molecules were assessed by spectrophotometry. The dyes were adsorbed onto SAGs, and the excess was similarly quantified. The obtained values were compared with the titration values. Although the values by labeling reagents were underestimated, some of the values were proportional to those by titration. Reliable results were attained using the two labeling reagents with conversion equations or using Acid Orange 7 adsorption.

    • Jun Araki
    • , Shiori Yoda
    •  & Riku Kudo

  • Original Article |

    Statistical structural analysis was conducted for ternary blends of copolymers composed of two monomers chosen from acrylonitrile, α-methylstyrene, and styrene. Blending parameters, such as the composition and blending fraction of the component copolymer, were predicted by regularized regression analysis of 1H NMR data. Regression models were constructed with the dataset for copolymers and binary blends to predict the blending parameters for ternary blends. The composition and blending fraction were predicted with high accuracies

    • Ryota Kamiike
    • , Tomohiro Hirano
    •  & Koichi Ute

  • Original Article
    | Open Access

    Copolymers of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and acrylamide (AAm) (AETAC-co-AAm) are polyelectrolytes used as flocculants in wastewater purification. Diffusion-ordered dimensional NMR spectroscopy (DOSY) experiments for AETAC-co-AAm samples with Mw ranging from 1.9 to 3.9 million and a polyacrylamide sample with Mw of 1.3 million were carried out in pure D2O and in D2O containing 0.1 or 1 M NaCl using an inverse-geometry diffusion-probe system. Projections of the DOSY contour plots onto the diffusion coefficient (D) dimension gave distributions of D for the AETAC and AAm units in the samples. The D values at the maximum point of the distribution (Dp) agreed fairly well with those determined by dynamic light scattering.

    • Kazuya Watanabe
    • , Hiroyuki Matsushita
    •  & Koichi Ute

  • Original Article |

    In situ infrared spectroscopy and two-dimensional (2D) correlation analysis was applied to research the chemical changes and curing reaction mechanism of epoxy resin and amine curing agents. The curing reaction mechanism can be deeply understood from the results. Due to the nucleophilic addition reaction of amino and epoxy groups, the nitrogen atoms easily combine with the carbon atoms, which forms new C-N groups. Then, the C-O bonds break; finally, as the N-H bonds in primary amines break, the hydrogen atoms combine with the oxygen atoms to form new hydroxyl groups.

    • Zhipeng He
    • , Wei Lv
    •  & Qinwei Yin

  • Focus Review |

    This focus review describes a biosensing strategy called “chemical tongue”, which mimics the human taste system by employing fluorogenic materials containing various chemical structures in conjunction with statistical techniques. The focus is on the design of polymer-based chemical tongues and their applications with various complex biological samples. The chemical-tongue strategy is capable of recognizing biological samples in a unique manner that does not, in contrast to conventional approaches, rely on specific interactions, thereby potentially opening avenues for unexplored uses of polymers in a wide range of research areas.

    • Shunsuke Tomita

  • Original Article |

    A newly synthesized polyurethane (PU) was used to increase the flexibility of Bombyx mori silk fibroin (SF) fiber by making a composite of SF and PU, which is expected to increase applications of SF fiber in biomaterials. Namely, the elongation at break of the fiber increased by 1.3–1.8 times compared with that of regenerated SF fiber. The main reason for the increased flexibility of the SF-PU composite fiber is the increase in the fraction of random coils in SF, which was clearly observed by 13C solid-state NMR.

    • Koto Suganuma
    • , Hironori Matsuda
    •  & Tetsuo Asakura

  • Focus Review |

    Reverse osmosis (RO) membranes are widely used as energy-saving and environmentally friendly materials for water purification. This Focus Review reports on the nanoscale structure and permeation mechanism of crosslinked fully aromatic polyamide RO membranes. First, the research on the morphology of protuberance structures of the polyamide separation functional layer is described. Next, hydrated structure of the functional layer is focused, which was analyzed using neutron scattering and molecular dynamics simulations. Innovative RO membranes are being developed that can obtain higher quality water with less energy by precisely controlling nanostructures.

    • Harutoki Shimura

  • Review |

    In this review, we overview the recent advances associated with seminal findings in the development of nucleic acid-based fluorescent sensor systems aimed at application for exploring intracellular phenomena. We described the fluorescence signal generation mechanisms of each nucleic acid-based fluorescent sensor, including molecular beacon and quencher-free linear probes, as well as aptamer or DNAzyme-based systems. In addition, cascade hybridization chain reaction and catalyzed hairpin assembly are introduced as methods for amplifying fluorescence signals under isothermal conditions.

    • Aya Shibata
    • , Sayuri L. Higashi
    •  & Masato Ikeda

  • Focus Review |

    Water-gated polymer thin-film transistors (WG-PTFTs) fabricated by a simple procedure can be operated at an ultralow voltage, whereby the WG-PTFTs with molecular recognition units allow chemical sensing. Upon the addition of analytes, the electric double layer capacitance of the WG-PTFTs can be changed by accumulation and desorption of charged species at the interface of the semiconductor and electrolytes. For example, the WG-PTFTs have successfully detected biogenic amines and a herbicide glyphosate. In short, our proposed WG-PTFTs are among the most promising platforms for sensing applications based on π-conjugated polymer materials.

    • Tsuyoshi Minami
    • , Wei Tang
    •  & Koichiro Asano

  • Rapid Communication |

    A fluorescent microarray comprising polythiophene-based chemosensors functionalized with pyridinium boronic acid has been developed for the detection of the components of sake such as glucose and pyruvate. The sensor microarray was fabricated on a glass chip for on-site detection utilizing imaging analysis and pattern recognition. The selected four nondiluted sake samples were discriminated by the cross-reactive response pattern. Moreover, the facile chemosensor array realized the prediction of unknown concentrations of glucose and pyruvate in the diluted sake, which indicated its usability for drink analysis.

    • Xiaojun Lyu
    • , Akira Matsumoto
    •  & Tsuyoshi Minami

  • Focus Review |

    We reviewed our recent studies on optical manipulation techniques for microspectroscopic analysis of optically trapped polymers. A focused laser beam exerts an optical force on polymer chains, leading to the microassembly formation of them. We applied the conventional optical tweezers for the concentration determination techniques of phase-separated thermoresponsive polymer chains by combining with microspectroscopies. To overcome the limitations of the conventional optical tweezers, localized surface plasmon has attracted much attention. Finally, we introduced our original manipulation technique based on nanostructured semiconductor-assisted optical tweezers; NASSCA optical tweezers.

    • Tatsuya Shoji
    •  & Yasuyuki Tsuboi

  • Original Article |

    The present work focuses on the development of a system enable to modulate, upon an external stimuli, the amount of metal ions uptake. A photoresponsive compound was used as a functional monomer for the preparation, for the first time, of a photoresponsive ion-imprinted polymer (PIIP) for Pd(II) uptake. The photoisomerization capability of the submicroparticles of PIIP, with conformational changes of the polymer, was demonstrated and an improved binding capacity versus Pd(II) was observed after UV exposure of the polymer with maximum binding capacity near to 22 mg g−1.

    • Lucia Mergola
    • , Tiziana Stomeo
    •  & Roberta Del Sole

  • Original Article |

    The polymerization and crystallization of polyamide 6 (PA6) via anionic polymerization was observed using a combination of in situ wide-angle X-ray scattering (WAXS), temperature measurement, and real-time visualization at 119–182 °C. In-situ WAXS discriminated between polymerization and the crystallization of PA6. The WAXS results indicated that polymerization was fast at 139–155 °C, and crystallization was fast at 148–155 °C. The crystallinity of PA6 decreased with increasing temperature. We concluded that molding temperatures between 148 and 155 °C were suitable for high productivities of PA6 with good properties.

    • Mamiko Narita
    • , Hiroaki Yoneyama
    •  & Masashi Harada

  • Original Article |

    Viscoelasticity of PEG in aqueous solutions containing different concentrations of K2SO4 was studied by QCM-D, after coating a rigid supported lipid bilayer on the silicon oxide substrate. The obtained viscoelastic properties of PEG in K2SO4 solutions agree well with the Zimm model predictions for linear polymer chains. The gradual worsening of solvent quality by adding K2SO4 to aqueous PEG solutions is demonstrated by the obtained excluded volume exponents via QCM-D and the conventional intrinsic viscosity measurements.

    • Xiaoxue Wu
    • , Ziliang Zhao
    •  & Yonggang Liu

  • Focus Review |

    We have successfully developed easy-to-use and rapid immunosensor devices based on extended-gate type polymer field-effect transistors (PFETs). The designed PFET was operated under low-voltage conditions, being able to apply for the detection of proteins in water. As a consequence, label-free detection of glycoproteins was achieved by the extended-gate PFETs functionalized with monoclonal or polyclonal antibodies. We believe that PFET-based immunoassays will be an attractive platform for on-site monitoring devices in healthcare applications in the near future.

    • Tsukuru Minamiki
    • , Yui Sasaki
    •  & Tsuyoshi Minami

  • Original Article |

    Saturation transfer difference (STD) NMR analysis was performed to identify the titanium-binding peptide (TBP) sites that interact with the SiO2 nanoparticle surface, and then Arg1 and Asp5 were identified to be in close contact with the surface. The structure of the TBP bound to SiO2 determined by the NOESY measurement was well defined, and the Arg1 and Asp5 side chains face in the same direction. These results validates that the NH2+ of Arg1 and the COO− of Asp5 interact electrostatically with the SiO− and SiOH2+ on the SiO2 surface, respectively.

    • Yu Suzuki
    •  & Heisaburo Shindo

  • Focus Review |

    Intracellular structures and function are tightly interwoven. Recapitulation of such intracellular microenvironments may enable novel biomimetic material synthesis and bioanalysis. Cell-inspired microanalysis platforms can be constructed by combined top-down microfabrication and bottom-up molecular self-assembly. Microcompartments of phase-separated aqueous solutions also play a critical role in biological processes. The biphasic microdroplets provide a unique analytical platform that conventional homogeneous bulk environments fail to achieve.

    • Taisuke Kojima
    •  & Shuichi Takayama

  • Focus Review |

    Amphiphilic C3-symmetric tris-ureas self-assemble into supramolecular hydrogels in aqueous solution. These supramolecular hydrogels were used as matrices for the electrophoresis of biopolymers (SUGE: SupramolecularGelElectrophoresis). A unique separation mode in comparison to that of SDS–PAGE was found during the electrophoresis of denatured proteins. Native proteins were separated on the basis of their isoelectric points and retained their activities. Large DNA fragments that previously had been separated only by pulsed-field gel electrophoresis were separated using a supramolecular hydrogel matrix and a typical continuous-field electrophoresis apparatus.

    • Masamichi Yamanaka

  • Focus Review |

    Vibrational circular dichroism (VCD) is effective for analyzing the configuration and conformation of various bio(macro)molecules. In addition to a conventional VCD approach using theoretical calculations, this review explains how the use of an exciton-type VCD couplet can be employed to elucidate the structures of bio(macro)molecules, such as carbohydrates, glycerophospholipids, proteins and polyesters.

    • Tohru Taniguchi
    • , Takahiro Hongen
    •  & Kenji Monde

  • Focus Review |

    Because of importance of anions as analyte in diverse fields, a reliable and practical method that allows simple and rapid anion detection has been in increasing demand. To satisfy this requirement, many efforts have been made to develop optical anion sensor materials for sensor applications. This article reviews recent progress in the design and fabrication of conjugated polymer-based anion sensors. Through rational molecular design of the sensor polymers, certain structures have been found to possess desirable anion detection abilities, including enhanced binding affinity, strict size specificity and applicability to anions in an aqueous environment.

    • Ryosuke Sakai

  • Original Article |

    Rubber materials are often used in fluid sealing. Molecular mobility of rubber is one of the important parameter for designing suitable material for rubber seals. Pulsed proton nuclear magnetic resonance (1H-NMR) results showed that crude acrylonitrile–butadiene rubber has two components with long and short spin–spin relaxation time assigned to the altenatively copolymerized acrylonitrile–butadiene and butadiene block sequences, respectively. We conclude that these components with different mobilities in crude rubber originated from a inhomogeneity in the first-order structure of molecular chains.

    • Hiroaki Ono
    • , Hirotada Fujiwara
    •  & Shin Nishimura

  • Original Article |

    The existence of intramolecular CH/π interaction of four soluble polyfluorenes (PFs) and molecular di-n-octylfluorene in chloroform-d1 at 20 °C was first revealed by cross-peaks of the ring with several protons of alkyl groups in 1H–1H NOESY NMR and marked upfield shift of several alkyl proton signals in 1H-NMR spectra. Only the PF bearing β-branched chiral groups at 9,9-positions among three chiral PFs in chloroform at 20 °C showed intense circular dichroism bands in the π−π* region because of the intramolecular CH/π interaction. Conflex7 and Gaussian 03 MP2 calculation results supported this idea.

    • Makoto Taguchi
    • , Nozomu Suzuki
    •  & Michiya Fujiki

  • Original Article |

    The phase-transition point Tc from the low- to high-temperature phase of ethylene-tetrafluoroethylene copolymer is dependent on the type of the third monomeric unit having long (C4F9) or short (CF3) side groups. The existence of side chains affects more or less the unit cell dimension as well as the higher-order structure of stacked lamellae.

    • Atsushi Funaki
    • , Suttinun Phongtamrug
    •  & Kohji Tashiro

  • Original Article |

    129Xe NMR spectra of 129Xe in polyphenyleneoxide, PPO were measured at various temperatures below Tg. From the analysis of 129Xe NMR chemical shifts, the mean volume of individual microvoids in PPO, v could be determined. The temperature when value of v becomes same as a Xe atom, was very close to Tg of PPO. Temperature dependence of individual microvoid’s volume was very similar with that of CH′, which is obtained by dual-mode sorption model from Xe sorption isotherms and is corresponding to the unrelaxed volume of PPO in the glassy state.

    • Hiroaki Yoshimizu
    • , Satoshi Ohta
    •  & Yoshiharu Tsujita

  • Original Article |

    This study demonstrated that synchrotron radiation ultra-small angle X-ray scattering (SR-USAXS) enable us to evaluate the outermost surface and ‘buried’ periodic structure without any pretreatment and sample damage. Surface and ‘buried’ nanostructure were fabricated on poly(lactic acid) film by nanoimprint lithography. The resulting films were characterized by SR-USAXS. The size of surface and ‘buried’ structure were successfully determined by the analysis of scattering pattern.

    • Takamichi Shinohara
    • , Tomoko Shirahase
    •  & Atsushi Takahara

  • Original Article |

    Xe sorption properties of tetramethyl bisphenol A polycarbonate (TMPC)/polystyrene (PS) blends indicated the reduction of microvoids by blending. From the analysis of 129Xe NMR chemical shifts of the 129Xe in these blends, the mean volume of individual microvoids (v) was calculated. The v values for these blends were smaller than those of predicted by a simple additive rule, as well as the cases of variation of density and Xe sorption properties. This fact indicates that the volume contraction induced by blending for TMPC/PS blends is mainly attributed to contraction volume of individual microvoids.

    • Hiroaki Yoshimizu
    • , Takafumi Murakami
    •  & Yoshiharu Tsujita

  • Original Article |

    The hydrogen dissolved in acrylonitrile butadiene rubber due to high-pressure hydrogen exposure was analyzed by solid-state 1H NMR. On the basis of pressure dependency of chemical shift of free hydrogen and relaxation time of dissolved hydrogen, the hydrogen with two different characters at 4.3 and 4.8 p.p.m. were ensured to be with different mobility. Conversion of the ratio of the two states of hydrogen suggested the transition of hydrogen from the state constrained to rubber chemical structure to free volume during hydrogen elimination process.

    • Hirotada Fujiwara
    •  & Shin Nishimura

  • Original Article |

    Multivariate analysis was applied to the 13C nuclear magnetic resonance spectra of homopolymers, homopolymer blends and copolymers of methyl methacrylate (MMA) and tert-butyl methacrylate (TBMA). The first (PC1) and second (PC2) principal components reflected chemical composition of the copolymers and fraction of the MMA-TBMA dyad sequence (fMT), respectively. Dyad and triad sequence distributions of copolymers that were obtained at higher conversions were successfully determined by partial least squares regression with those of copolymers obtained at low conversions as a training set.

    • Hikaru Momose
    • , Tomoya Maeda
    •  & Koichi Ute

  • Original Article |

    The natural rubber (NR) without vulcanization is easily deformed and strained during magic-angle spinning (MAS). The elongated NR during MAS forms molecular orientation. The static 13C NMR spectra of elongated NR became anisotropic, although the static 13C NMR spectra of NR before MAS show isotropic. Angle-dependent 13C NMR spectra of strips cut from the restricted elongation NR were different from those from the maximum elongated NR. The disagreement indicated that 13C chemical shift depends on not only the molecular orientation but also the magnetic susceptibility resulting from the alignment of NR chains.

    • Masashi Kitamura
    • , Yoshiaki Hata
    •  & Atsushi Asano

  • Original Article |

    The relaxation behaviors for several commercial ultra-high molecular weight polyethylene reactor powders were compared. On the basis of the morphological analyses, the reactor powder consisted of particles and fibrils between them, the relative amounts of which depended on the powder preparation conditions. The results of differential scanning calorimetry analysis could not distinguish these powder characteristics because of the remarkable reorganization of these reactor powders during heating scans. In contrast, molecular motions detected by solid-state proton nuclear magnetic resonance techniques characterize the structural differences between these powders.

    • Hiroki Uehara
    • , Hidekazu Tanaka
    •  & Takeshi Yamanobe

  • Original Article |

    Isotactic and syndiotactic poly(lactic acid) dimer model compounds were synthesized, and studied by 1H and 13C NMR in three solvents, CDCl3/CCl4 (20/80 v/v), CDCl3 and DMSO-d6. All the peaks in the 1H and 13C NMR spectra were assigned with the help of two-dimensional NMR. The tacticity splitting of the dimers showed no significant difference among the solvents. The chemical shifts were calculated and compared with the experimental shifts to understand the origin of the tacticity splitting in PLA. The observed tacticity splitting of the chemical shifts between isotactic and syndiotactic 1H and 13C NMR peaks were reproduced particularly well using the combination of Becke’s three parameter hybrid method for conformational energy calculation and Hartree-Fock for chemical shift calculation.

    • Koto Suganuma
    • , Ken Horiuchi
    •  & Tetsuo Asakura

  • Original Article |

    Two topics concerning the utilization of internal and external magnetic field gradients are discussed. The first topic concerns the transport of conformons in the quasi-ordered phase of a regioregular, π-conjugated polymer, poly(4-methylthiazole-2,5-diyl), using a combination of longitudinal and transverse relaxation dispersion measurements. The effects of conformon diffusion on the relaxation exponent were successfully estimated via a numerical approach that used the Fourier spectrum solution of the one-dimensional Bloch-Torrey equation. The second topic demonstrates a low-cost magnetic resonance imaging method using a magnetic field gradient from a neodymium ferromagnet. Spin echo experiments are shown for three-layered thin films of PDMS/PTFE/PDMS under a large magnetic field.

    • Naoki Asakawa
    •  & Toshiki Obata

  • Original Article |

    The crystalline structure and molecular mobility of PVDF blended with PMMA at various fractions were investigated by solid-state 19F MAS NMR spectroscopy. The origin of the characteristic peaks observed for typical polymorphs of PVDF (α-, β- and γ-forms) are explained based on DFT calculations. The dominant crystalline form in the blends of [PVDF/PMMA]=[80/20], [70/20] and [50/50] is α-form containing a small portion of β-form, whereas that of [65/35], [60/40] and [55/45] consists of β-form and γ-form. In contrast, no crystalline structure is found in [45/55], [40/60] and [20/80], indicating that PVDF and PMMA chains are miscible at the molecular level.

    • Yu Koseki
    • , Keitaro Aimi
    •  & Shinji Ando

  • Original Article |

    This paper reports multivariate analyses such as principal component analysis and partial least-squares regression of NMR spectra of poly(N-isopropylacrylamide)s [poly(NIPAAm)s]. Principal component analysis successfully interpreted the assignments of 1H and 13C NMR spectra of methylene protons and methine carbons, respectively, of poly(NIPAAm)s in terms of stereostructures. Furthermore, triad tacticity was successfully predicted by partial least-squares regression of 1H NMR spectra of the methine and methylene groups. Consequently, it is assumed that chemometric analysis of NMR spectra is a promising method for the characterization of synthetic polymers.

    • Tomohiro Hirano
    • , Takuya Anmoto
    •  & Koichi Ute

  • Original Article |

    A microfluidic device with three-dimensional flow channels is fabricated by stereolithography according to a computer-aided design (CAD) model. By injecting water and oil phases into the device, a monodisperse water-in-oil emulsion is formed. We show that monodisperse thermosensitive poly(-isopropylacrylamide) gel particles can be prepared by photopolymerization of a gelation reagent dissolved in the water phase.

    • Toshimitsu Kanai
    • , Kanako Ohtani
    •  & Masatoshi Hayakawa

  • Original Article |

    The static structure of polyrotaxane (PR) possessing a supramolecular structure in which cyclic molecules are threaded into an axial polymer was investigated. Using contrast variation small-angle neutron scattering, the conformation of the axial linear polymer and the alignment of cyclic molecules within the axial polymer in a good solvent were evaluated quantitatively, together with derivation of detailed scattering theory. The entropic origin of the stiffing of PR due to the array of cyclic molecules was also discussed.

    • Hitoshi Endo
    • , Koichi Mayumi
    •  & Mitsuhiro Shibayama

  • Original Article |

    X-ray scattering from an organogel made from discotic triazine triamide was measured at SPring-8 at a quite wide q range of 0.050 nm−1 <q <20 nm−1. Analyses revealed (1) an amorphous nature of the molecular stacking at a distance of 0.32 nm, (2) the presence of a semiflexible rod-like scattering object with a radius of 1.3 nm and a Kuhn length of 55 nm and (3) branching of the cylinder formed at the gel state.

    • Yasuya Kudo
    • , Mina Sakuragi
    •  & Kazuo Sakurai

  • Original Article |

    Liquefied bamboos were multihydroxy compounds and could react with bisphenol-A and epichlorohydrin to prepare a novel epoxy resin. Curing behavior of copolymer epoxy resins prepared with phenol- and polyhydric alcohol-liquefied bamboo could be analyzed by differential scanning calorimetry and dynamic mechanical analysis to obtain more advanced information.

    • Chiou-Chang Wu
    •  & Wen-Jau Lee

  • Original Article |

    Allyl benzoate (ABz) was polymerized using dicumyl peroxide (DCPO) at 130 °C; almost no direct contribution of cumyloxy radical to initiation reaction was observed. This was extended to other organic peroxide initiators; it was confirmed that the initiation by methyl radical generated by β-scission of alkoxy radicals occurred predominantly in allyl polymerization at elevated temperatures.

    • Satoshi Inoue
    • , Takeo Kumagai
    •  & Michirou Shibano

  • Original Article |

    Largely improved strength and abrasion resistance for styrene–butadiene rubber (SBR)/silica composites are demonstrated when sorbic acid (SA) is incorporated in the compounds. The abrupt changes in performance are attributed to the strong interactions between silica and SA and the largely improved dispersion of silica, which are realized by SA-intermediated linkages through grafting copolymerization and hydrogen-bonding mechanisms.

    • Baochun Guo
    • , Feng Chen
    •  & Weiwei Chen

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