Search

Tensile creep property of a die-cast AMXS6020 (Mg–6Al-0.2Mn–2Ca-0.3Si, wt.%) alloy has been investigated. The as-die-cast AMXS6020 alloy consists of α-Mg, Al2Ca and (Mg, Al)2Ca eutectics at grain boundaries. MgCaSi and Al8Mn5 intermetallic particles also exist both inside α-Mg grains and along the grain boundaries. Tensile creep tests, which were carried out at temperatures from 100 to 225 °C and stress range of 30–75 MPa for 100 h, show that the AMXS6020 alloy has excellent creep resistance as compared to commercial Mg alloys. When the temperature is increased from 100 °C to 180 °C or higher, the creep activation energy, Q, changes from 73 to 191 kJ/mol under the applied stress of 50 MPa. The creep results and TEM analysis of the specimens crept at 150 and 200 °C under the applied stress of 50 MPa suggest that the creep is controlled by grain boundary sliding at the temperature below 180 °C, while the creep is controlled by cross slip to non-basal planes at the temperature over 180 °C.

Four patients with non-small-cell lung cancer(NSCLC), diagnosed with cN2 stage III A disease, by using CT and FDG-PET/ CT imaging, received 2 or 3 courses of platinum-based combination chemotherapy.The patients achieved partial response after chemotherapy and underwent surgery.Complete tumor resection was performed via upper lobectomy for 3 patients, but in 1 patient, interlobar metastatic lymph nodes remained after middle and lower bilobectomy.Two courses of postoperative chemotherapy were administered to 3 patients, but 1 patient could not receive postoperative chemotherapy due to complications.One patient, in whom lymph node metastasis completely disappeared after induction chemotherapy, is still alive and without disease recurrence for 7 years.Another patient, with the presence of only one intralobar metastatic lymph node after chemotherapy, died of brain and meningeal metastases, 3 years after surgery.Two other patients, with multiple pN2 lymph nodes after chemotherapy, died of early intrathoracic local relapse, indicating that prognosis is influenced by response to chemotherapy, especially in patients with poor N-downstaging.Improvements in response to induction therapy by using intensive chemotherapeutic regimens, concurrent radiotherapy, and strict patient selection, limited to N-downstaged cases, are needed for successful surgery outcomes in patients with cN2 stage III A NSCLC who have received induction therapy.

A 78-year-old woman developed second, third, and fourth lung tumors at intervals of 1-3 years after left upper lobectomy for primary lung cancer. The tumors were controlled with radiofrequency ablation(RFA)or conventionalconformalradiotherapy for 9 years postoperatively. For the treatment of second primary lung cancer or lung metastasis after surgical resection of the primary lung cancer, reoperation is not recommended because of the impaired respiratory reserve. Thus, local therapy such as radiotherapy or RFA is applied in some cases. Among these, stereotactic body radiotherapy(SBRT)is a feasible option because of its good local control and safety, which is comparable with surgery. On the other hand, for cases of multiple lesions that are not suitable for radiotherapy or combination therapy, RFA could be an option because of its short-term local control, easiness, safety, and repeatability. After surgery for primary lung cancer, a second lung tumor could be controlled with highly effective and minimally invasive local therapy if it is recognized as a local disease but is medically inoperable. Therefore, longterm postoperative follow-up for primary lung cancer is beneficial.

Effect of dislocation behavior on formation of whisker in pure Sn has been investigated. Slip system in β-Sn was determined; slip plane is , and Burgers vector b is . The magnitude of Burgers vector is larger than the smallest interatomic spacing in β-Sn. This means that there is broad space under the extra half plane of edge dislocation. It sould be noted that pipe diffusion along the edge dislocation is enhanced in β-Sn, resulting in easy supply of Sn atoms at the root of Sn whisker [1, 2]. Si-bearing particles, which precipitate on surface of bulk Sn by heat-treatment in quartz tube, suppress the accumulation of both edge and screw dislocations to same area. It is greatly effective for the suppression of the nucleation of Sn whisker.

We retrospectively evaluated the clinical outcomes of 192 consecutive patients with local recurrence after complete resection of non-small cell lung cancer NSCLC). The initial local recurrent site was the resection stump in 5 patients the chest wall in 3 patients, mediastinum in 1 patient, and diaphragm in 1 patient), and the hilar and/or mediastinal lymph node (HMLN) in 17 patients. The sites of distant metastasis were the lungs in 10 patients, pleura in 4 patients, brain in 7 patients, liver in 5 patients, bone in 4 patients, and other sites in 4 patients. Treatments after initial recurrence included surgery in 2 patients, radiotherapy in 5 patients, chemotherapy in 9 patients, and chemo-radiotherapy in 5 patients. Only 1 patient received supportive care. The response to radiotherapy was a complete response (R) in 1 patient, partial response (PR) in 5 patients, stable disease (SD )in 3 patients, and progressive disease (PD )in 1 patient. The best response of all lines of chemotherapy was CR in 3 patients, PR in 4 patients, SD in 3 patients, and PD in 4 patients. The median post-recurrence survival (PRS) time with local recurrence was better than that with distant metastasis (23 vs 14 months); however, the best PRS was obtained in patients with recurrence in the lungs (29 months). A CR for more than 2 years was obtained in 1 patient after surgery, in 1 patient after radiotherapy, and in 2 patients after chemotherapy. Although local recurrence of resected NSCLC can be potentially controlled by using local treatments - such as surgery and radiotherapy - or systemic chemotherapy, curative aggressive treatment should be considered when required.

Calcium alginate fibers were prepared by extruding an aqueous sodium alginate solution into an aqueous calcium chloride solution. The fibers were treated with a saturated aqueous calcium hydroxide solution for various periods and their apatite-forming ability was examined in a simulated body fluid (SBF). The calcium alginate fibers were treated with the aqueous calcium hydroxide solution for periods longer than five days formed apatite on their surfaces in SBF, and their apatite-forming ability improved with increasing calcium hydroxide treatment time. The amount of calcium ions released from the fibers also increased with increasing calcium hydroxide treatment time, resulting in acceleration of nucleation and growth of apatite on the fiber surfaces. The resultant apatite-alginate fiber composite is expected to be useful as a flexible bioactive bone-repairing material.

Chitin fibres constituting a non-woven fabric were carboxymethylated in monochloro acetic acid and treated with saturated Ca(OH) 2 aqueous solution. Within 3 days in a simulated body fluid with pH value and ion concentrations nearly equal to those of human blood plasma, a bonelike apatite layer formed on the surface of fibres of the treated fabric. The apatite–chitin fibre composite thus prepared is expected to be useful as a flexible bioactive bone-repairing material.

Calcium alginate fibres with an average diameter of 5 μm were prepared by extruding an aqueous sodium alginate solution through nozzles with holes of 0.1 mm diameter into an aqueous calcium chloride solution, and then through a calcium chloride methanol solution. The ratio of D-mannuronate (M) to L-gluronate (G) subunits in the calcium alginate ranged from 0.7 to 2.0. The fibres were soaked in an aqueous saturated calcium hydroxide solution for 5 d, and then soaked in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. Fibres with an M/G ratio of 2.0 had apatite deposited on their surfaces within 7 d in SBF, but fibres with M/G ratios of 0.7 and 1.5 did not. The higher apatite-forming ability of the former fibres was attributed to their release of more calcium ions from the fibres, that is, the formation of a larger number of free carboxyl groups, effective for apatite nucleation and more efficient acceleration of the apatite nucleation by increasing the ionic activity product of the apatite in SBF.

Carboxymethylated chitin, gellan gum, and curdlan gels were soaked in a simulated body fluid (SBF) having ion concentrations nearly equal to those of human blood plasma. Some of the gels had been soaked in a saturated Ca(OH) 2 solution, while others had not. The carboxymethylated chitin and gellan gum gels have carboxyl groups, while the curdlan gel has hydroxyl groups. None of the gels formed apatite on their surfaces in the SBF when they had not been subjected to the Ca(OH) 2 treatment, whereas the carboxymethylated chitin and gellan gum gels formed apatite on their surfaces when they had been subjected to the Ca(OH) 2 treatment. The curdlan gel did not form an apatite deposit even after the Ca(OH) 2 treatment. Apatite formation on the carboxymethylated chitin and gellan gum gels was attributed to the catalytic effect of their carboxyl groups for apatite nucleation, and acceleration of apatite nucleation from released Ca 2+ ions. This result provides a guiding principle for obtaining apatite-organic polymer fiber composites. This composite is expected to have an analogous structure to that of natural bone.

The surface of an ethylene-vinyl alcohol copolymer (EVOH) was modified with Ti-OH groups by a silane coupling treatment followed by treatment with a titania solution. The arrangement of the Ti-OH groups formed on EVOH was changed from amorphous into anatase structure by a subsequent HCl solution treatment. Bonelike nanoapatite was successfully formed on the surface-modified EVOH even in a form of fibers as well as plates within 2d at 36.5°C in a simulated body fluid (SBF) with ion concentrations approximately equal to those of human blood plasma. The resultant nanoapatite-polymer fiber composite was similar to that of natural bone in its structure where apatite nanocrystals are deposited on fine organic fibers constituting a composite. Therefore, if the present surface modification can be applied to a three-dimensional fabric with a structure similar to the collagen fibers of natural bone, a composite with an analogous structure to that of natural bone would be obtained. The resultant composite is expected to exhibit mechanical properties analogous to those of natural bone, as well as bone-bonding ability, and hence be truly useful as a new bone substitute.

We attempt to recover the surface properties of wool fibers damaged by physical and/or chemical treatment. For this purpose, two kinds of damaged wool fabric samples are prepared, one damaged by corona discharge treatment and the other oxidized with dichloroisocyanuric acid. We confirm that these treatments decrease the content of covalently bound fatty acids and change the fiber surface properties. To recover the surface properties of damaged wool, a fatty acid chloride, stearoyl chloride, is used to treat both damaged samples. The content of covalently bound fatty acids in treated samples recovers to some degree, and the surface characteristics of the treated wool fibers also recover from hydrophilic to hydrophobic. We also evaluate some mechanical properties with the KES-FB method, and we find they recover almost to the level of the original wool fabric sample.

Silk fibroin (SF) was dissolved in calcium chloride/ethanol/water mixture (1/2/8 in mole ratio) at 70°C for 4 h. The dissolved silk fibroin was regenerated by casting the dialyzed solution into the films. The films were treated with 50% aqueous solution of methanol for different times, and their antithrombogenicity was evaluated byin vitro andin vivo tests.In vivo blood tests were made by a method of peripheral vein indwelling suture. It was found that the silk fibroin had a good anti-thrombogenicity and an absorbability even though the polymer showed foreign body reaction. Finally, the blood compatibilty of silk fibroin films which were subjected to structural change by the methanol treatment, was examined in connection with their interfacial surface energy, and a correlation between these properties was found to be present.

The surface of wool fibers consists of cuticular cells, the surface of which is hydrophobic in nature due to the existence of a lipid layer on the epicuticle. This layer is known to consist of covalently bound fatty acids such as 18-methyl eicosanoic acid. Wool fibers are damaged by physical and chemical treatments during processing. In this study, we investigate changes in the covalently bound surface lipid layer by chemical (chlorination) and physical (corona discharge) treatments, and try to evaluate the covalently bound surface lipid contents of damaged fibers. We also evaluate surface characteristics such as contact angle and hand values by the KES-FB method, and we discuss these results in terms of the covalently bound surface lipid contents.

Amphiphilic block and statistical copolymers of vinyl ethers (VEs) with pendant glucose residues were synthesized by the living cationic polymerization of isobutyl VE (IBVE) and a VE carrying 1,2:5,6-di-O-isopropylidene-D-glucose (IpGlcVE), followed by deprotection. The block copolymer was prepared by a two-stage sequential block copolymerization, whereas the statistical copolymer was obtained by the copolymerization of a mixture of the two monomers. The monomer reactivity ratios estimated with the statistical copolymerization were r 1 (IBVE) = 1.65 and r 2 (IpGlcVE) = 1.15. The obtained statistical copolymers were nearly uniform with the comonomer composition along the main chain. Both the block and statistical copolymers had narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight ∼ 1.1). Gel permeation chromatography, static light scattering, and spin-lattice relaxation time measurements in a selective solvent revealed that the block copolymer formed multimolecular micelles, possibly with a hydrophobic poly(IBVE) core and a glucose-carrying poly(VE) shell, whereas the statistical copolymer with nearly the same molecular weight and segment composition was molecularly dispersed in solution. The surface properties of the solvent-cast films of the block and statistical copolymer were also investigated with the contact-angle measurement.

This study concerns the living cationic polymerization of two vinyl ethers (VEs) having pendant glucose residues, in which the hydroxyl groups are protected by acetyl and isopropylidene functions. Living cationic polymerization of VE having an acetyl-protected glucose was achieved by employing an initiating system consisting of the CF3COOH adduct of isobutyl VE (IBVE) and ethylaluminium dichloride in the presence of an added base at 0 °C. In contrast, the use of the HCl adduct of IBVE in conjunction with zinc iodide at −15 °C was more suitable for the controlled polymerization of VE having an isopropylidene-protected glucose. Polymers obtained under these reaction conditions had narrow molecular weight distributions (Mw/Mn ∼ 1.1) and controlled molecular weights. © 2001 Society of Chemical Industry

In this article, a series of O-2-[2-(2-methoxyethoxy)ethoxy] acetyl celluloses with different degree of substitution (DS) values was synthesized by a homogeneous reaction of cellulose with 2-[2-(2- ...

A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellul ...

The surfaces of ethylene-vinyl alcohol copolymer (EVOH) substrates were modified with silanol (Si-OH) groups, and their apatite forming ability was examined in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma or in a solution with ion concentrations 1.5 times those of SBF (1.5SBF). The surface modification of EVOH was carried out by reacting 3-isocyanatopropyltriethoxysilane, followed by hydrolysis of the ethoxysilyl groups into Si-OH groups. However, no apatite formation was observed on the EVOH substrate thus modified, even after 3 weeks in SBF and 1.5SBF. The Si-OH modified EVOH substrate was further modified by hydrolysis and polycondensation of tetraethyoxysilane (TEOS). It was found that the apatite forms on the TEOS-modified substrate within 3 weeks in 1.5SBF. These results suggest that the presence of a large amount of Si-OH groups (i.e., a cluster of Si-OH groups) on the substrate is prerequisite to apatite formation in the body environment. Apatite-EVOH composites prepared by this process might be useful as hard tissues substitutes.

Controlled free radical polymerization of a sugar-carrying acrylate, 3-O-acryloyl-1,2: 5,6-di-O-isopropylidene-a-D-glucofuranoside (AIpGlc), was achieved in p-xylene at 100°C by using a di-tert-butyl nitroxide (DBN)-based alkoxyamine as an initiator and dicumyl peroxide (DCP) as an accelerator. The polymerization gave low-polydispersity (1.2 < M w /M n < 1.6) polymers with predicted molecular weights. The same approach with a DBN-capped polystyrene (PS-DBN) as an initiator afforded block copolymers of the type PS-b-PAIpGlc. The acidolysis of the homopolymers and block copolymers gave well-defined glucose-carrying polymers PAGlc and PS-b-PAGlc, respectively. These amphiphilic PS-b-PAGlc block copolymers were observed to exhibit microdomain surface morphologies that differ for different copolymer compositions. This success opens up a new, simple route to the synthesis of well-defined sugar-carrying polymers of various architectures.

Amphiphilic block copolymers of vinyl ethers (VEs) having pendant N-acetyl-d-glucosamine (GlcNAc) residues were synthesized by living cationic polymerization of isobutyl VE (IBVE) and a VE carrying...

In order to elucidate the nature of the LiCl/1,3‐dimethy‐2‐imidazolidinone (DMI) solvent system as one of the homogeneous reaction media of cellulose, cellulose acetate (CA) and O‐methylcellulose (MC) were prepared using this solvent system, and the distribution of substituents within anhydroglucose units was examined by 13C‐NMR. It was found that (i) homogeneous cellulose solutions can be easily prepared by heating 2, 5–12 and 100 parts of weight of cellulose, LiCl, and DMI, respectively, and (ii) the relative reactivity of hydroxyl groups is in the order C‐6 > C‐2 > C‐3 for both CA and MC. A remarkable feature of this solvent system is that the reaction efficiency in etherification is very high compared with other homogeneous solvent systems.

Poly(vinyl alcohol) (PVA) was converted into melt flowable derivatives by complexation with a small amount of n-butyl boronic acid (BBA) and phenyl boronic acid (PBA) in dimethylsulfoxide (DMSO), and their thermal properties were examined from a viewpoint of the melt spinning of the complexes. It was found that (1) the melting temperature of the PVA-boronic acid complexes decreases and their degradation temperature increases with increasing the boronic acid content; (2) no gelation occurs for the PVA complexes with BBA and PBA in DMSO; (3) PBA gives a larger melting-temperature depression for PVA than BBA, but the spinnability of the complexes with BBA is much better than that with PBA; and (4) the melt-molded PVA complex fibers can be easily regenerated into PVA fibers with hot water.

The thermoreversible hydrogel of short-chain (unentangled) O-(2,3-dihydroxypropyl)cellulose/Borax aqueous solution was studied by 11B NMR and dynamic viscoelastic measurements. The total number XT of transient cross-links formed by the (diol/ion) 2/1 complexation could be quantitatively estimated by 11B NMR. The dynamic viscoelastic data gave the number NE of elastically effective chains and the relaxation time of the gel. The NE vs XT data were compared to the mean-field theory of transient gels. Agreement between the theory and experiment was very poor at low C but became better as C increased. It was suggested that the ratio of the experimental NE to the theoretical NE is a function only of polymer concentration C. The gel point estimated by the zero extrapolation of the experimental NE vs XT data with a fixed C reasonably agreed with the mean-field prediction only at high C. The relaxation time τ (and hence the viscosity η) of the gel strongly depended on the pH of the system but not explicitly on C o...

In this work, a series of 2,3-O-methylcellulose (MC) with different DS value were prepared. Its phase transition behavior in aqueous solution was studied in terms of DS value, concentration and molecular weight. The the following conclusions were obtained. (1) All the 2,3-O-MC samples show no sol-gel transition in aqueous solution despite the molecular weight. (2) No phase separation was observed for the 2,3-O-MCs with a DS value lower than 1.0, even when the temperature was raised to 95°C. (3) The precipitation temperature is surprisingly different between 2,3-O-MCs. and other MCs possessing comparable total DS value. (4) The precipitation temperature of 2,3-O-MCs depends on the molecular weight rather than on the concentration.

Two series of thermotropic polymethacrylate (PM) samples with pendant cellobiose residues and an alkyl spacer (number of carbon atoms n = 4 and 10) were synthesized, and their mesomorphic properties were investigated to elucidate the function of acylated cellobiose moieties as discotic mesogens by differential scanning calorimetry (DSC), polarization microscopy and X-ray diffraction. The PM-4 samples with a short spacer (n = 4) showed two kinds of mesophases in a wide temperature region up to the degradation temperature of the sample, i.e., about 230 °C, whereas the PM-10 samples with a long spacer (n = 10) showed a single mesophase between 45 and 135°C. X-Ray diffraction data suggested that both the mesophases formed by PM-4 and PM-10 belong to a kind of discotic columnar phases in which the side chain mesogens form the discotic columns around the polymer backbone.

This article shows that intramolecular hydrogen bonds formed at the three hydroxyl group positions of cellulosic glucose unit contribute in determining the handedness of chiral nematic mesophases ethylcellulose in CH2Cl2. Using two series of samples which differed only by increasing the ethyl substitution of the hydroxyl groups at either the C-6 or C-3 positions, the handedness of individual mesophase solutions was investigated using circular dichroism (CD). The CD spectra indicated that free hydroxyls at the C-6 position hindered dissolution in the solvent while hydroxyls at the C-3 position may play an important role in determining the handedness of the EC mesophase in CH2Cl2. Free hydroxyls at the C-3 position are known to easily form intramolecular hydrogen bonds, resulting in enhanced stiffness of the molecular chains. Therefore, these results lead to the conclusion that breaking intramolecular hydrogen bonds by increasing the substitution along the molecular chain causes it to become more flexible, which may account for the change in structural handedness.

The free radical polymerization of p-tert-butoxystyrene (BOS) in the bulk at 125°C initiated with the adduct of 2-benzoyloxy-1-phenylethyl and TEMPO (BS-TEMPO) was found to proceed in a living fashion, providing low-polydispersity PBOS and block copolymers of the type PBOS-b-PS, where TEMPO is 2,2,6,6-tetramethylpiperidin-1-oxyl and PS is polystyrene. The acidolysis of the polymers gave well-defined poly(p-vinylphenol) (PVP) polymers. The PVP-b-PS block copolymers were observed to exhibit lamellar and cylindrical microdomain morphologies depending on the copolymer composition. The rate of BOS polymerization is independent of the initiator (BS-TEMPO) concentration, being essentially equal to the rate of thermal polymerization. The polydispersity of PBOS depends on polymerization time but not on the degree of polymerization, under the studied experimental conditions.

The aim of this work is to develop a basic approach to the preparation of biologically active polymer-apatite composites with various mechanical properties. To this end, a type of hybrid materials bearing silanol groups were prepared from triethoxysilyl-terminated poly(oxyethylene) (PEG) and tetraethoxysilane (TEOS) by using the in-situ sol-gel process. The hybrid materials having different PEG contents were subjected to the biomimetic process for forming the bone-like apatite layer on/in the hybrid materials. It was found that a dense bone-like apatite layer can be prepared in an arbitrary thickness on/in the hybrid materials, indicating that the silanol groups introduced provide the effective sites for the apatite nucleation and formation. The polymer-apatite composites thus obtained are expected to have a great potential in the biomedical applications.

This is the first report of the synthesis of a well-defined glycopolymer by free radical polymerization. N-(p-vinylbenzyl)-[O-β-d-galactopyranosyl-(1→4)]-d-gluconamide (VLA), a styrene derivative w...

A woman in her seventies presented with bilateral hilar and mediastinal lymphadenopathy with high fluorodeoxyglucose (FDG) uptake by positron emission tomography (PET)-computed tomography (CT), small lung nodules, and uveitis. Mediastinoscopic biopsy yielded a histological finding of epithelioid granuloma and a diagnosis of sarcoidosis. A nodule, 1 cm in diameter, in the right middle lobe with moderate FDG uptake was deemed to be a sarcoidosis lesion. Steroid therapy for uveitis resulted in shrinkage of the hilar and mediastinal lymph nodes; however, 1 year later the nodule in the right middle lobe had enlarged to 2 cm in diameter. Right middle lobectomy was performed, and a histological diagnosis of lung squamous cell carcinoma was made. Six months later, right pretracheal lymphadenopathy with high FDG uptake was noted and was proved to be a metastatic squamous cell carcinoma by endobronchial ultrasound-guided transbronchial needle aspiration( EBUS-TBNA). After 7 courses of chemotherapy with docetaxel, the target lesion shrank and its abnormal FDG uptake disappeared. Small-sized lung cancer could be missed when complicated by sarcoidosis because the latter produces a background of multiple lesions, so careful diagnostic imaging and follow-up should be performed in patients diagnosed as having sarcoidosis.

A series of 2,3-O-carboxymethylcelluloses (CMC's), which are regioselectively substituted at the C-2 and C-3 position, were prepared and their water solubility was examined. It was found that the lower limit for the degree of substitution (DS) value of water-soluble 2,3-O-CMC is about 0.3. This value was almost the same as that of CMC prepared in a slurry of isopropyl alcohol/water with isopropyl chloroacetate and sodium hydroxide, showing that the uniform alkylation is rather important to convert cellulose into water-soluble derivatives.

The dissociation rate constant kd related to the homolytic cleavage of the CON bond formed between a polystyrene (PS) and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) is determined by adopting the gel permeation chromatography peak-resolution method to the styrene polymerization with a PS-TEMPO adduct as a probe and the radical initiator tert-butyl hydroperoxide. The result was given by the Arrhenius equation, kd = A exp(−E/(RT)) with A = 3.0 × 1013 s−1 and E = 124 kJ · mol−1.

Previous work from this laboratory has shown that cellobiose octaalkanoate (COA) functions as a thermotropic discotic mesogen, forming a hexagonal ordered columnar phase (D ho ). In this work, we prepared the COA-based discotic twin and triplet derivatives and examined the mesomorphic properties of the derivatives by DSC, polarization microscopy and X-ray diffraction. In the former derivative, two cellobiose heptadecano-ate (CHD) molecules (monomers) are combined through an alkyl spacer of varying length by ether and ester linkages at the C-1 position of the reducing end units of the monomers. Three CHD molecules having an alkyl spacer are connected with a coupling agent for the latter derivative. The results revealed that (i) all the twin derivatives form a distinct discotic columnar phase, (ii) the thermal stability of the mesophases of the twins is enhanced, compared with that of the monomer, when the length of the flexible spacer is appropriate, (iii) the twins with a relatively short spacer form a discotic rectangular ordered (D ro ) phases while those with a longer spacer form a pseudo-D ho , Phase, (iv) thc triplets also form a discotic columnar mesophase, but not a hexagonal ordered columnar (D ho ,) phase, (v) the thermal stability of the mesophases of the triplets strongly depends on the chemical nature of coupling cores, and (vi) the packing structures of the cellobiose cores within the columns of both derivatives are markedly different from that of the monomer.

The aim of this work is to prepare the temperature-responsive cellulosic hydrogels undergoing a large volume change in an aqueous solution on heating or cooling. To this end, we prepared O-methyl cellulose (MC) and O-(2-hydroxy-3-butoxypropyl) cellulose (HBPC) which precipitate out of solution on heating without forming gel. MC and HBPC derivatives prepared by homogeneous reactions were proved to be promising raw materials for the cellulosic hydrogels mentioned above The results on the phase separation of the derivatives were discussed in terms of the distribution of substituents along the cellulose chain and in the anhydroglucose units

D-Glucosamine-containing glycopolymers with well-controlled structure were synthesized by living cationic polymerization. To this end, D-glucosamine-containing vinyl ether(VE) of the type [CH 2 =CH(OCH 2 CH 2 OR)] was prepared, where R denotes a 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimide-β-D-glucopyranoside, i.e., the hydroxyl and amino groups in D-glucosamine residues are protected by acetyl and phthaloyl groups, respectively. It was found that (1) the efficient living cationic polymerization of VE monomer is achieved by a combination of ethylaluminum dichloride (EtAlC1 2 ) with an adduct of trifluoroacetic acid (TFA) and isobutyl VE (IBVE) [CH 3 CH(OiBu)OCOCF 3 ] (i.e., TFA/EtAlC1 2 initiating system); and (2) the polymerization in toluene at the elevated temperature (0°C ) is most suitable to proceed the homogeneous polymerization over the whole conversion range. The molecular weight distribution of the resulting polymers was very narrow (M ω /M n ∼1.1). Quantitative deprotection of the resulting precursor polymers was successfully achieved with hydrazine monohydrate to afford the corresponding water-soluble polymers with pendant D-glucosamine residues.

This study concerns the synthesis of C 6O -capped vinyl ether (VE) oligomers with well-defined structure by living cationic polymerization technique. The VE oligomers bearing C 60 at the chain end were prepared by addition reaction between monooctynylfulleride anions and living cationic VE oligomers. Living oligo(isobutyl vinyl ether) (IBVE) and oligo(methyl vinyl ether) (MVE) were synthesized using CH 3 CH(OiBu)Cl/ZnI 2 as initiating system. The C 60 -capped VE oligomers were obtained as dark brown gummy solid in 28% for IBVE and 34% for MVE. The UV/VIS and 13 C NMR spectra indicated the formation of C 60 -capped oligomers via 1,2-addition reaction. It was also found that the films of blends of C 60 -capped oligomers with poly(IBVE) and polystyrene (5 wt.-% C 60 ) are homogeneous on a micron scale and transparent, resulting from a good dispersion of C 60 in the polymer matrix.

Amphiphilic block copolymers of vinyl ethers (VEs) of the type —[CH2CH(OCH2CH2OR)]m—[CH2CH(OiBu)]n—were synthesized by living cationic polymerization, where R is a D-glucose residue, and m and n are the degrees of polymerization (m = 20–50; n = 11–89). To obtain them, sequential living block copolymerization of isobutyl vinyl ether (IBVE) and the vinyl ether carrying 1,2:5,6-diisopropylidene-D-glucose residue was conducted by using the HCl adduct of IBVE, CH3CH(OiBu)Cl, as initiator in conjunction with zinc iodide. These precursor block copolymers had a narrow molecular weight distribution (Mw/Mn ∼ 1.1) and a controlled composition. Treatment of them with a trifluoroacetic acid/water mixture led to the target amphiphiles. The solubility of the amphiphilic block copolymers in various solvents depended strongly on composition or the m/n ratio. Their solvent-cast thin films were observed, under a transmission electron microscope, to exhibit various microphase-separated surface morphologies such as spheres, cylinders, and lamellae, depending on composition. © 1997 John Wiley & Sons, Inc.

The effect of substituent distribution on the water solubility of O-methylcellulose (MC) was re-examined to elucidate the lower limit of the degree of substitution (DS) in water-soluble MC. To this end, a series of 2,3-MCs which are regioselectively substituted at the C-2 and C-3 hydroxyl groups were prepared by homogeneous methylation. It was found that the lower limit for the DS value of water-soluble 2,3-MC was almost the same as that for MCs having even distributions of substituents along the cellulose chain as well as in the anhydroglucose units.

Comb-shaped, amphiphilic O-(2- hydroxy-3-butoxypropyl) cellulose (HBPC) was prepared by a homogeneous reaction of cellulose with butyl glycidyl ether (BGE) in a 10% (w/w) LiCl--DMAc solution. It was found that: (a) the molar substitution (MS) of water-soluble HBPC ranges from 0.4 to 1.0, and is nearly equal to its degree of substitution (DS), indicating that the HBPC derivatives obtained are comb-shaped polymers; (b) the water-soluble HBPC shows a thermally reversible sol-gel transition in aqueous solution; and (c) the derivative having a DS of 0.6 shows surface activity with critical micelle concentration (cmc) in the order of 0.8 g/l and surface tension of 31.5 dyn/cm

The bulk polymerization of styrene at 125 °C in the presence of a PS−TEMPO adduct was studied with respect to the polymerization rate and the concentration of free TEMPO as a function of time, where PS is polystyrene and TEMPO is 2,2,6,6-tetramethylpiperidinyl-1-oxy. The results were perfectly consistent with the proposed kinetic scheme which assumes the existence of a stationary state with respect to both polymeric and nitroxyl radical concentrations and predicts that the polymerization rate of the nitroxide-mediated system is independent of the adduct concentration, being equal to the polymerization rate of the adduct-free system, i.e., the rate of thermal polymerization in the case of the styrene system studied here. The equilibrium constant K for the PS−TEMPO reversible reaction was estimated to be 2.1 × 10-11 mol L-1 on the basis of the dilatometric and electron spin resonance data. This value of K was indicated to be large enough to set the system under control. This work thus shows that in order fo...

Three co-operative phenomena that are supposed to originate in the orientation-dependent interactions among polymer segments are discussed and attempted to be interpreted in terms of a common set of polymer models.

An amphiphilic diblock copolymer with a narrow molecular weight distribution, which has a glucose residue-carrying vinyl ether subchain and an isobutyl vinyl ether subchain, was studied with its monolayer-forming properties at the air-water interface. The block copolymer and its blends with polyl(isobutyl vinyl ether) homopolymer, spread from a mixture solution of chloroform and methanol onto the water surface, were found to form a stable monolayer. The surface monolayers were successfully transferred onto a substrate by the Langmuir-Blodgett technique, and the built-up film was characterized by surface plasmons and transmission electron microscopy. The surface pressure-area isotherms exhibited a plateau region, suggesting a structural change taking place on the water surface at specific pressures. The observed values of the layer thickness and the occupied area indicated that the hydrophobic segments, which lie essentially flat on the water surface at low surface pressures, aggregate at higher pressures, forming a thicker layer with hydrophobic and hydrophilic segments microphase-separated at the air-water interface. In addition, it was demonstrated that the layered structure of the LB film could be controlled by blending the homopolymer.

A copolymer of 2-(9-anthrylmethoxy)ethyl methacrylate with methyl methacrylate (Mw = 3.1 × 105, anthryl content = 0.8 mol %) and a low-mass model compound were studied with respect to their photodimerization or photo-cross-linking processes in tetrahydrofuran solution. The number of dimers or cross-links formed by ultraviolet (UV) irradiation was determined by UV absorption spectroscopy. A kinetic study on the model compound indicated the existence of a small amount of side reaction, which should be taken into consideration for a quantitative analysis. The concentration dependence of the initial quantum yield of photo-cross-linking of the polymer suggested that, below the overlap concentration c*, the intramolecular cross-linking predominates, while at c > c*, the contribution of intermolecular cross-linking increases with increasing c. This was directly confirmed by the light scattering measurements of the molecular weight and radius of gyration of the irradiated polymer. For a 10 wt % solution (c/c* ≈ 4...

Cellobiose octa(decanoate), a discotic columnar mesogen, was found to form in hexadecane solution various molecular assemblies such as a lyotropic liquid crystal of discotic columnar type, multimolecular micelles, and a thermoreversible gel, depending on the concentration and temperature. The gelation, observed even at very low concentrations, say, < 0.01 weight fraction of the mesogenic compound, is believed to proceed by local coagulation of long threadlike micelles into micro-liquid-crystallites, which work as cross-linking points combining the threadlike micelles. This will be a new type of gel that could be termed a “liquid crystalline gel.”

The α- and β-anomers of cellobiose octa-alkanoates with purities higher than about 95 per cent were prepared from β-cellobiose by two simple esterification methods. The carbon number n of the acyl substituents ranged from 7 to 10 in both anomers. Both α- and β-anomers exhibited two types of discotic columnar phases (Dho and Dro), depending on n and temperature, but their phase diagrams were appreciably different. Generally, the α-anomers formed more stable mesophases than the β-anomers. In the Dro phase of the β-anomers, the column axis was tilted from the normal to the ‘disks’, while no such tilting was observed in the other phases.

The present paper focuses on (i) a new synthetic methodology to prepare vinyl ether-based synthetic glycoconjugates (glycopolymers) with well-controlled structure, and on (ii) the application of glycopolymers bearing modified disaccharide residue as thermotropic liquid crystalline (LC) materials. Two vinyl ethers (VEs) having pendant glucose residues with their hydroxyl functions protected by acetyl and isopropylidene groups, respectively, were found to undergo living cationic polymerization initiated by a HI/ZnI2-initiating system. Deprotection of the resultant monodisperse polymers led to water-soluble polymers bearing a pendant glucose residue. Sequential living block copolymerization of glucose-containing VE and alkyl VE, and subsequent deprotection afforded an amphiphilic block copolymer of well-controlled structure. Transmission electron microscopic observation of its cast thin film revealed microphase-separated surface morphologies that varied with varying segment composition ratio. A VE substituted with a heptadecanoated cellobiose pendant was independently prepared, and was cationically polymerized to give a thermotropic LC polymer. From X-ray analysis, the mesophase was assigned to a discotic columnar in type, in which each main chain, extended due to the steric repulsion between the neighboring bulky pendants, was surrounded by three discotic columns.