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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.

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.

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- ...

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.

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...

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.

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.

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.

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

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.

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.

Main mesomorphic properties of cellulose and cello- and chito-oligosaccharide derivatives are overviewed, and their structuring principles are briefly discussed with some new analyses incorporated.

This paper reviews briefly our preliminary results concerning thermoplastic hydrogels and thermotropic aqueous gels from cellulose. Several kinds of thermoplastic hydrogels and thermotropic aqueous gels were prepared from cellulose and their thermal properties were examined. The former aims at preparing water-insoluble cellulose derivatives having a high water absorbency and a thermal flow temperature of approximately 130°C, while the later aims at preparing water-soluble cellulose derivatives which show a solubility behavior similar to that of synthetic polymers with a lower critical solution temperature (LCST) in aqueous solution. The results will be discussed in terms of the chemical structure of the prepared derivatives and their substituent distributions along the cellulose chain.

A dense, uniform and highly biologically active bone-like apatite layer can be formed in arbitrary thickness on any kind and shape of solid substance by the following biomimetic method at normal temperature and pressure: first, a substrate is set in contact with particles of CaO-SiO2-based glass soaked in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. Second, the substrate is soaked in another solution with ion concentrations 1.5 times those of SBF (1.5 SBF). In the present study, organic polymer substrates were treated with 1 m HCl solution, then subjected to the above mentioned biomimetic process. The induction periods for the apatite nucleation on polyethyleneterephthalate, polymethylmethacrylate, polyamide 6 and polyethersulfone substrates were reduced from 24 to 12 h with the HCl treatment. The adhesive strength of the formed apatite layer to the polyethyleneterephthalate, polymethylmethacrylate and polyamide 6 substrates were increased from 3.5 to 7.0 MPa from 1.1 to 2.8 MPa and from 0.6 to 3.1 MPa, respectively, with the HCl treatment. It is supposed that highly polar carboxyl group formed by the HCl hydrolysis reaction of ester group in polyethyleneterephthalate and polymethylmethacrylate or amide group in polyamide 6 increased the affinity of the substrates with a silicate ion to decrease the induction period, and also increased the affinity of the substrate with the apatite to increase the adhesive strength. The apatite-organic polymer composites thus obtained are expected to be useful as bone-repairing materials as well as soft-tissue-repairing materials.

Fairly narrow fractions of tri-O-heptylcellulose (THC) covering a wide range of degrees of polymerization (DP) were prepared and studied by viscometry and light scattering to determine the wormlike model parameters of the polymer to be q= 43.2 exp(-0.0050T) nm and M L = 880 nm -1 , where q is the persistence length, M L is the shit factor, and T is the absolute temperature. The same fractions were studied with their thermal properties to determine the anisotropic-isotropic transition temperature T i and transition entropy ΔS as a function of DP. Both T i and ΔS increased with increasing DP to approach a limiting value for large enough DP. These trends were favorably compared with the predictions of the statistical models with the above-noted parameter values. It was shown that the main factor that causes the thermotropic transition and the chain-length dependence of T i in bulk THC is the temperature-dependent flexibility of the polymer

Dense and uniform layers of a biologically active carbonate-containing hydroxyapatite can be formed on various kinds of organic polymers by the following biomimetic method. First, a substrate is set in contact with particles of CaO–SiO2-based glass soaked in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma for forming the apatite nuclei on the substrate. Second, the substrate is soaked in another solution highly supersaturated with respect to the apatite, e.g, with ion concentrations 1.5 times those of SBF (1.5SBF) for making the apatite nuclei grow on the substrate in situ. The induction period for the apatite nucleation, which is defined as the time of the first treatment required for forming enough of the apatite nuclei to make the continuous layer after the second treatment, was almost 24 h for most of the examined polymers. The adhesive strength of the formed apatite layer to the polymers was as high as 3 to 4 M Pa for poly(ethylene terephthalate), poly-ether sulfone, and poly (vinyl alcohol) hydrogel. This type of apatite–organic polymer composite is expected to be useful for repairing not only living hard tissues but also soft ones.

n-Alkyl 1-O-β-D-cellobiosides with an alkyl length ranging from 7 to 18 in carbon number m were synthesized, and their thermal properties were studied in comparison with those of the already-known monosaccharide homologues, n-alkyl 1-O-β-D-glucopyranosides. The cellobiosides were found to exhibit a thermotropic mesophase at higher temperatures than the glucopyranosides. Depending on m and thermal history, the cellobiosides showed various textures such as homeotropic, transient bâtonnets, polygonal, and fan-shaped textures. Like in the case of the monosaccharide homologues, the difficulty of aligning the samples prohibited a full classification of the mesophase, but the X-ray diffractograms of the unaligned cellobiosides indicated that their mesophase belongs to smectic A(or less possibly, smectic C). The m dependence of the lamella thickness was much weaker than (about half) that of the monosaccharide homologues. Possible molecular arrangements of the cellobiosides in the mesophase were presented.

The present authors previously reported that a dense and uniform bone-like apatite layer with a desired thickness can be formed on any kind and shape of solid substance by the following biomimetic method at normal temperature and pressure. First, a substrate is set in contact with particles of CaO-SiO2-based glass soaked in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. Second, the substrate is soaked in another solution highly supersaturated with respect to the apatite. In the present study, the CaO-SiO2-based glass as the nucleating agent was replaced by Na2O-SiO2 glasses, SiO2 glass and SiO2 gel. The induction periods for the apatite nucleation on poly-ethersulfone substrates were ∞, a little longer than 168, 96, 48, 1.5 and 0.5h for SiO2 glass, SiO2 gel, Na2O 10⋅SiO2 90, Na2O 20⋅SiO2 80, Na2O 30⋅SiO2 70 and Na2O 40⋅SiO2 60mol% glasses, respectively, whereas 24h for MgO 4.6⋅CaO 44.7⋅SiO2 34.0⋅P2O5 16.2⋅CaF2 0.5wt% glass G. The short induction period for the glasses with high Na2O contents is attributed to high dissolution rates of sodium and silicate ions from them. The adhesive strengths of the formed apatite layer to the poly (ethylene terephthalate), poly (methyl methacrylate), poly-ethersulfone and polyamide 6 were 5.37, 1.63, 6.80 and 2.91MPa for Na2O 30⋅SiO2 70mol% glass, whereas 3.48, 1.06, 4.40 and 0.63MPa for glass G. It is considered that highly polar carboxyl or sulfinyl groups were formed on the polymer surfaces by the hydrolysis of their ester, amide or sulfonyl group in SBF with its pH considerably increased by the Na+ dissolution from the glass, and that these polar groups formed a fairly strong bond with the apatite. Thus formed apatite-organic polymer composites are expected to be useful as the bone-repairing as well as soft tissue-repairing materials.

The segmental orientations in a uniaxially stretched, fully entangled linear and crosslinked polystyrene (PS) melt containing a small amount (3% by weight) of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were studied as a function of the molecular weight of PPO, M n,2 , by means of IR dichroism spectroscopy. Segments of PPO molecules are oriented by two different mechanisms. one is related to the entanglement interaction between PPO and PS, and accordingly PPo chains longer than a critical length (about 10 4 in molecular weight) are relevant to this mechanism. The other mechanism is related to the intyeraction of PPO and PS at a segmental level, and hence it is relevant to both long and short PPO chains

The thermoreversible gelation of aqueous O-(2,3-dihydrorypropyl)cellulose solutions induced by addition of borax was studied. The sol-gel transition thresholds were determined as a function of borax concentration, polymer molecular weight and concentration, and temperature. On the basis of 11 B-NMR analyses, the number of cross-links L per chain was determined at each point ofthe sol-gel phase diagrams. At a constant temperature, the plot of L(M w /M n ) vs C:C * gave a master phase diagram independent of polymer samples, where C * is the overlap concentration

A series of cellobiose octaalkanoates, Cel-II-n (n is the carbon number of the alkyl chain), with n = 7–14 were prepared and their mesogenic properties examined by differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction. All of these compounds form enantiotropic discotic columnar phases, in which the columns are built up by a regular stacking of the cellobiose moieties and are packed in a two dimensional lattice. Homologues with n = 9–14 form the Dho phase only whilst the compound with n = 7 forms the Dro phase. The n = 8 compound forms the Dho phase at higher temperatures and the Dro phase at lower temperatures. Structural parameters obtained from X-ray diffraction studies are presented for both phases.

The complexation behavior of solutions of borax and O-(2,3-dihydroxypropyl)cellulose with a number-average degree of polymerization of about 20 was studied by 11 B-NMR spectroscopy. The equilibrium constants of the (ion/diol) 1:1 monocomplexation, K 1 , and the 1:2 dicomplexation, K 2 , were determined as a function of temperature. A comparison of these results with those obtained for a low-mass model system containing 1,2-propanediol (PG) instead of DHPC has revealed that (i) as in the PG system the complexation in the DHPC system proceeds by the formation of α,β-diol/borate five-membered rings, (ii) both K 1 and K 2 are appreciably larger in the polymer system than in the PG system, and (iii) these differences in both K 1 and K 2 are entropic in origin and are not related to the enthalpy

Mono- and Multilayer Langmuir-Blodgett Films of Cellulose Tri- n -alkyl Esters Studied by Transmission Electron Microscopy

This paper deals with the preparation of two series of chito-oligosaccharide derivatives, chitobiose octaalkanoates, and chitotriose undecaalkanoates, in which the amino- and hydroxyl groups were blocked with alkyl pendants of differing lengths via an ester linkage. By differential scanning calorimetry(DSC) and optical microscopic observations, these compounds were found to exhibit an enantiotropic mesophase at temperatures ranging from ca. 50 °C to ca. 200 °C. The texture of the mesophases were similar to those of the discotic columnar liquid crystals formed by the cellobiose and cellotriose equivalents. However, the amido group in the chito-derivatives seems to stabilize the mesophase to an appreciable extent, bringing about higher temperatures and a longer temperature span of the mesophase than those of the cello-equivalents.

On the basis of the Di Marzio-type lattice model and the freely-jointed-chain model with a statistical distribution of segment length, there were obtained analytical equations that describe the segmental orientations in a weakly deformed system containing two polymers of arbitrary length and arbitrary flexibility. The equations include several new predictions: for example, when a cross-linked polymer 1 swollen by an un-cross-linked polymer (diluent) 2 is deformed by a stretch, the excluded-volume or packing effect brings about an excess orientation of segment 1 over that which would be observed in the absence of the volume effect

An attempt was made to prepare highly dielectric polymers from O-(2,3-dihydroxypropyl)-cellulose (DHPC)1 by cyanoethylation, nitrobenzoylation, cyanobenzoylation, and trifluoroacetylation. To accomplish this, DHPC samples with different molar substitution (MS) were prepared by homogeneous dihyroxypropylation of cellulose with glycidol in a 10 wt.-% LiCl/DMA solvent system. Among the sample derivatives, all of which are soluble in various organic solvents, the cyanoethylated derivatives with high MS values have dielectric constants higher than 30 at room temperature and 1 kHz. These derivatives also form cholesteric liquid-crystalline (LC) phases in a wide temperature range, but the dielectric constant is independent of the phase structure. The results are discussed in terms of the structural difference among the sample polymers.

A novel polyhydroxy polymer, o-(2, 3-dihydroxypropyl) cellulose (DHPC) was synthesized by reaction of cellulose with 2, 3-epoxy-1-propanol (glycidol). The reaction was carried out in both homogeneous and heterogeneous media, which resulted in two types of DHPCs, coded DH and HDH, respectively. They were compared with each other with respect to structural and physicochemical properties, such as relation between molar substitution-degree of substitution, substituent distribution within anhydroglucose unit, water solubility, aqueous solution viscosity, surface activation effect and thermal and dielectric properties of cyanoethyl DHPCs. Significant differences between the two types of DHPCs were observed in all these properties, which were discussed in terms of the difference in the substituent distribution along the cellulose chain.

The effects of orientation-dependent interactions on the segmental orientation in weakly deformed polymers were examined on the basis of lattice theories and gas-of-rods theories. Both the freely jointed chain and the wormlike chain wre considered as polymer models. It was shown in a somewhat general fashion that the orientation-dependent excluded-volume effect or packing effect could give rise to a considerable amount of excess orientation over that predicted in the absence of such an effect.

Cellulose tri-n-alkanoates, fully substituted ester-type derivatives of cellulose, having acyl groups with n carbon atoms (3 form a novel thermotropic mesophase, characterized by a low birefringence and an extremely high viscosity compared with those of cholesteric mesophases of ether-type derivatives. Photomicroscopic, differential scanning calorimetry, and X-ray diffraction studies indicate that the mesophase formed by the cellulose tri-n-alkanoates is of a hexagonal columnar type in which two polymer chains are included in one hexagonal lattice. Two possible packing structures, resembling direct and inverse hexagonal phases of amphiphilic molecular systems, are proposed and discussed in relation to the chemical structure of the polymer.

An attempt was made to render wool fibers shrinkproof without causing any damage to the hydrophobic nature of the scale surface. To this end, wool fibers were treated with a water soluble multifunctional epoxide, i.e., glycerol polyglycidyl ether (GPE) in concentrated salt solutions, where the prominence of scale edges was depressed. The role of GPE is not to chemically modify the fiber surface, but to crosslink the cuticular cells to prevent their edges from prominence in aqueous media. Excellent shrink resistance can be imparted to wool by applying GPE in saturated NaCl solution in the presence of a reductive agent such as Na2S2O5, while the hydrophobic nature of the surface remains unchanged.

A photografting technique to produce functional groups of silanol able to induce apatite nucleation was attempted on polyethylene substrate for biomimetic formation of bone-mineral-like apatite layer on its surface. The polyethylene surface was subjected to vapor-phase photografting of vinyltrimethoxysilane and subsequently to hydrolysis. The photografting formed methoxysilyl groups on the polyethylene substrate, which was changed into silanol groups successively by the hydrolysis in a hydrochloric solution. The polyethylene modified in this way formed a dense and homogeneous bone-mineral-like apatite layer in a solution with ion concentrations 1.5 times that of human blood plasma. This result indicates that the biomimetic process in combination with a polymeric grafting technique might provide a homogeneous bone-mineral-like apatite coating even on polymer fibers to be woven into an apatite-polymer composite with three-dimensional structure analogous to that of natural bone.

A dense, uniform, and highly biologically active bone-like apatite layer can be formed in arbitrary thickness on any kind and shape of solid substrate surface by the following biomimetic method at ordinary temperature and pressure: First, a substrate is set in contact with particles of bioactive CaOSiO2-based glass soaked in a simulated body fluid (SBF) with inorganic ion concentrations nearly equal to those of human blood plasma so that a number of apatite nuclei are formed on the substrate. Second, the substrate is soaked in another solution with ion concentrations 1.5 times those of SBF (1.5SBF) so that the apatite nuclei grow in situ. In the present study, organic polymer substrates were treated with glow-discharge in O2 gas atmosphere, then subjected to the above-mentioned biomimetic process. The induction periods for the apatite nucleation on all the examined organic polymers were reduced from 24 to 6 h, with glow-discharge treatment. The adhesive strengths of the formed apatite layer to the substrates increased from about 4 to 10 MPa for poly(ethylene terephthalate) and poly-ether sulfone, and from 1 ∼ 2 to 6 ∼ 7 MPa even for poly(methyl methacrylate), polyamide 6 and polyethylene. It is supposed that highly polar groups such as carbonyl, ester, hydroxyl, and carboxyl ones formed by glow-discharge treatment increased the affinity of a silicate ion with the substrates to decrease the induction period, and also increased the affinity of the apatite with the substrate to increase the adhesive strength. The apatite-organic polymer composites thus obtained are expected to be useful as bone-repairing materials as well as soft tissue-repairing materials. © 1995 John Wiley & Sons, Inc.

A dense, uniform and highly biologically active bone-like apatite layer can be formed in arbitrary thickness on any kind and shape of solid substrate surface by the following biomimetic method at ordinary temperature and pressure. First, a substrate is set in contact with particles of bioactive CaO SiO2 based glass soaked in a simulated body fluid (SBF) with inorganic ion concentrations nearly equal to those of human blood plasma. Second, the substrate is soaked in another solution with ion concentrations 1.5 times those of SBF (1.5 SBF). In the present study, organic polymer substrates treated with 5 M NaOH solution were subjected to the above mentioned biomimetic process. The induction periods for the apatite nucleation on polyethyleneterephthalate (PET), polymethylmethacrylate (PMMA), polyamide 6 (PA6), and polyethersulfone (PESF) substrates were reduced from 24 to 12 h with the NaOH treatment. The adhesive strength of the formed apatite layer were increased from 3.5 to 8.6 MPa, from 1.1 to 3.4 MPa, and from 0.6 to 5.3 MPa with the NaOH treatment, for PET, PMMA, and PA 6, respectively. It was assumed that highly polar groups, such as carboxyl and sulfinyl ones formed by the hydrolysis of an ester group on PET and PMMA and of an amide group on PA 6, or of a sulfonyl group on PESF with the NaOH treatment, attached a large number of hydrated silica dissolved from the glass particles, to accelerate the apatite nucleation, and also to form a strong bond with the apatite. The apatite-organic polymer composites thus obtained are expected to be useful as bone-repairing as well as soft tissue-repairing materials.

Gegenstand unserer Untersuchungen war die Konfiguration von Polymethylmethacrylat (PMMA), das aus Methylmethacrylat mit Butylmagnesiumchlorid in Toluol bei −50°C einmal in Abwesenheit (Blank-Polymerisation) und einmal in Gegenwart von vorgelegtem isotaktischem PMMA (Replica-Polymerisation) dargestellt wurde. Es zeigte sich, das bei der Blank-Polymerisation eine Beziehung besteht zwischen dem Monomer-Umsatz und der Konfiguration der erhaltenen Polymerisate: die bei niedrigen Umsatzen (

The salt exclusion of electrolytes and polyelectrolytes in aqueous GPC was investigated theoretically and experimentally, in order to elucidate the feasibility of GPC as a technique for measuring the Donnan salt exclusion parameter, Γ¯, of polyelectrolytes. Three simple salts different in the valency of the anion, i.e., sodium chloride, sodium sulfate and naphthalene-1,3,6-trisulfonic acid trisodium salt, were eluted with aqueous NaNO3 solution on a Sephadex G-10 gel column. The experimental results were analyzed in terms of the Donnan equilibrium established on the gel, and the Γ¯ value of these simple salts was evaluated. It was found that the Γ¯ value from GPC was in good agreement with the theoretical value of 1/2 for an ideal case, showing that the colligative properties of electrolytes and polyelectrolytes such as Γ¯ can be accurately investigated by means of GPC. GPC experiments on the Donnan salt exclusion were further carried out for the heparin-NaCl system by using a Sephadex G-25 gel column. From the experimental data, the Γ¯ value of heparin was estimated.

The conformation and conformational change of wool keratin S- carboxymethylated low-sulphur proteins (SCMKA), which are α-helical fibrous proteins, have been investigated in aqueous solution by means of c.d. Comparisons of various methods proposed for c.d. analysis of protein secondary structure are made using least-squares curve-fitting of the observed c.d. spectra of SCMKA with a linear combination of the corresponding reference spectra of secondary structures. It has been found that (i) the most satisfactory results are obtained with the method13 which takes into account the β-turn contribution: (ii) SCMKA is 52–54% α-helical in water and has little β-form, (iii) the addition of n-propanol produces, even at higher concentrations of n-propanol, little chnage in spectra with respect to helical character in water; (iv) SCMKA undergoes a thermally-induced conformational transition from α-helix to random coil around 50 C; and (v) S- aminoethylated low-sulphur proteins with positively charged protecting groups are /_~50% α-helical in water, which is similar to SCMKA, showing that the protecting groups introduced in the low-sulphur proteins are little effect upon their conformation in water

The binding of Cu(II) by keratin proteins extracted from wool in aqueous solution has been investigated by gel filtration and equilibrium dialysis in order to compare the binding data obtained by different methods. The gel filtration binding experiments were carried out on a Sephadex G-25 gel column using 0.05 M acetate buffer as eluent in a pH range of 4.5—6.5. The elution profiles of the Cu(II)–keratin complexes were classical at equilibrium Cu(II)–concentrations from 1 to 25 ppm in the range of pH from 4.5 to 5.5. It was found that if the elution profile is classical, reliable binding data can be obtained by gel filtration with a simple technique. On the other hand, at a higher pH of 6.5, anomalous elution profiles were observed; in addition to the classical peaks, a ghost peak with respect to the Cu(II)–concentration appeared. Different mechanisms proposed for the appearance of the ghost peak by other authors were tested but failed to explain the present data. However, it was experimentally proved that the gel filtration data agreed with those of equilibrium dialysis if the Cu(II) exhibiting the ghost peak was independent of the binding by protein.

Conformation of high-glycine (HG) proteins, a non-helical protein group derived from reduced and S-carboxymethylated wool keratin, has been investigated by circular dichroism and x-ray diffraction measurements on their cast films. It was found that these proteins are able to form a β-structure in the films cast from formic acid solution, as had been in the case of the high-sulfur (high-S) proteins which are considered to originate from the matrix between the microfibrils. The results were compared with those on the high-S proteins and discussed in terms of the known primary structure of a component protein from HG protein group.

Sorption behavior of Hg2+ by the kerateine gel of thiol-type, which was prepared from wool keratin, was investigated. The behavior was discussed in relation to (i) the amphoteric nature, (ii) the chemical modification of side-chain polar groups, and (iii) the heat denaturation of kerateine gels. It was found that the apparent isoelectric point of the kerateine gel was closely related to the pH at which the Hg2+ uptake showed the minimum. The Hg2+ uptakes by modified kerateine gels in acid media depended on their modification history. The results indicated that in acid media, the dominant binding modes of Hg2+ consist in chemosorption by the thiol as well as amino groups in the kerateine gel and in chelation of Hg2+ through these groups. On the other hand, in neutral and alkaline media, very high Hg2+ uptakes were observed for all types of kerateine gels independent of their modification history. Such high Hg2+ uptakes could be explained in terms of the cooperative interactions between electron negative atoms incorporated in the kerateine gel, namely, sulphur, nitrogen, and oxygen rather than the ionization effect of the acidic groups present. The swelling volume of the heat-denatured kerateine gels decreased considerably with increasing the treatment temperature, and a good relation was found between the rate of Hg2+ uptake and swelling volume of the gel: the rate of Hg2+ uptake decreased with decrease in the swelling volume.

Sorption behavior of heavy metal ions by various kerateine gels, whose thiol groups were substituted with different groups, were investigated. For this purpose, the thiol groups of kerateine gels were modified by (i) functional residues with chelate-forming or ion-binding nature, (ii) residues with large group moments, and (iii) non-specific alkyl groups. In acid media, the sorption behavior of Hg2+ by these kerateine gels depended strongly on the substituent introduced, although introduction of any substituent could cause no appreciable increase in the uptake. The results were discussed in relation to the chemical structure of kerateine gels. On the other hand, prominent increases in the Hg2+ uptake were observed for all types of kerateine gels independent of their substituent, when the pH of medium goes from neutral to alkaline. The sorption isotherms of Hg2+ observed at pH 9.0 for S-alkyl kerateine gels were almost the same as that for the thiol-type gel. A series of experiments on Hg2+ desorption from the gel showed that the sorption characteristics of S-substituted kerateine gels were more advantageous than that of the thiol-type gel from the standpoint of recovering Hg2+ once sorbed by the kerateine gel. In addition, it was found that the sorption behavior of some metal ions, i. e., Cd2+, Pb2+, and Cu2+, varied to some extent with the substituents introduced, although all types of kerateine gels exhibited predominantly higher uptakes for Hg2+ than those for these metal ions.

The hypochromic effect in the UV spectra of polystyrene and styrene copolymers in solution was investigated in detail. For this purpose, isotactic and syndiotactic-rich polystyrenes as well as their dimer model compounds, 2,4-diphenylpentanes, and styrene-methyl methacrylate copolymers were prepared. UV absorption measurements were carried out in dioxane and tetrahydrofuran at various temperatures. The extinction coefficients of phenyl rings depended not only on the solvent and the temperature but also on the microstructure of the polymers. A discontinuous temperature dependence of the extinction coefficients was observed between 40 and 50°C for homopolystyrenes as well as their dimer model compounds. It was suggested that this might be explained in terms of the rotation of phenyl rings. On the other hand, the hypochromicity in binary copolymers appeared to depend strongly on the sequential arrangement of monomers (the chain architecture and the chemical composition of copolymers). The measured average extinction coefficients were well interpreted by a simple treatment by using triad probability proposed by Harwood. The results were discussed in relation to the UV spectrometer which is being used as an auxiliary detector in gel-permeation chromatography and microcolumn chromatography.