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Comparison of the dielectric relaxation (DR) behaviors of two polar rod-like low-mass molecules (LMs), cyanobiphenyl (CB) and 5-phenyl-2,3′-bipyridine (PBP), in antiplasticized polycarbonate (PC) revealed that rotations around the short and long axes of the LMs appeared from 60 to 125 °C (β region) and from −150 to −50 °C (γ region), respectively. The cooperativity between the local dynamics in PC, measured by dynamic mechanical analysis, and the rotation of the LMs around the short axis was examined based on the relaxation times and activation energies for the LMs (CB and PBP) and PC. The dynamic cooperativity involved the antiplasticization of PC. In contrast, the rotation of the LM (PBP) around its long axis was independent of the local motion in PC, resulting in no contribution to the antiplasticization phenomenon. Adding rod-like low-mass molecules (LMs) increases the elastic modulus of polycarbonate (PC). The anisotropy of the rotational dynamics of rod-like LMs in PC was investigated by dielectric relaxation and dynamic mechanical analysis. Two rotations of the LM around the short and long axes were separately observed at 80 °C and −100 °C, respectively. The rotation of the LM around the short axis was cooperative with the local dynamics of PC and. In contrast, the rotational motion around the long axis was independent of PC motions.

We have investigated the relation between the polymer and low-mass molecule (LM) dynamics in antiplasticized polycarbonate (PC). Antiplasticization results in enhancement of the Young’s modulus of polymeric materials by adding LMs. Comparison of the dynamic mechanical properties and dielectric relaxation behavior suggests that the LMs are immobile below room temperature (~ 25 ºC) and mobile above room temperature. The LM dynamics shows a similar trend to the local chain motion of PC, indicating the dynamical relation between the two components. Additionally, we investigated the effect of the LM size on antiplasticization and the local chain motion of PC by using alkyl cyano-biphenyl with various carbon numbers and 4-pentyl-4′-cyanoterphenyl. The LM size does not affect the degree of modulus enhancement of PC at the room temperature. However, mechanical relaxation of the local chain motion of PC shows wider temperature dependence for shorter LM size. The activation energy of molecular motion decreases with decreasing LM size, indicating that restriction of the local chain motion of PC and the LMs becomes weaker for smaller LM size.

Cross-linked poly(ethyl acrylate-co-methyl methacrylate) (P(EA-MMA)) nanoparticles were prepared by soap-free emulsion polymerization. Size of the isolated nanoparticles in various organic solvents was largely swollen when the solubility parameter of the solvent was similar to that for P(EA-MMA). Well-ordered colloidal crystal assembly film of the P(EA-MMA) nanoparticle was prepared by drying the as-prepared aqueous suspension. The transparent and colorless film exhibited structural color when it was swollen in the organic solvent. Wavelength of the structural color revealed linear relationship with the size of the isolated nanoparticle in the same solvent. This solvent-responsive color-changing behavior explained that the solvent swelling of the nanoparticle increased the repeating distance of the colloidal crystal and the wavelength of the reflected light from the ordered structure. These results suggest that the structural color of the swollen film can be tuned by the solvent quality for P(EA-MMA).

In this study, flexible transparent hybrid films with low thermal expansion coefficient were prepared by combination of alumina fillers and polymerizable/non-polymerizable surface modifiers with carboxyl group. Four types of alumina fillers with different shape and size were used in this study, and could modify with surface modifiers containing carboxyl groups by electrostatic interaction and disperse homogeneously in resulting hybrid films regardless of the shape and size. So the hybrid films obtained showed high transmittance around 90%T, and it was considered, from transmission electron microscopic analysis, alumina fillers were dispersed at near original filler size, without aggregation. Moreover, thermal mechanical analysis cleared that the use of pillar or fiber type filler is more effective to reduce CTE compared with plate type fillers, especially CTE of hybrid film prepared with fiber type filler was drastically decreased to 17 ppm/K, while the influence by the difference of filler shape/size was not observed on tensile properties, surface hardness. By use of fiber type alumina filler and combination of polymerizable surface modifier and non-polymerizable surface modifier which seems to interact with matrix, for optimizing of the crosslink density, it was possible to reduce CTE, while the good mechanical properties was kept. Finally, hybrid film indicating low CTE value as 19 ppm/K, high flexibility (windable against 0.4 mm radius steel bar), and good tensile properties and surface hardness which were equal to or higher than those of matrix could prepared.

This study deals with control of the molecular weight and molecular weight distribution of poly(vinyl acetate) by iodine-transfer radical polymerization and reversible addition-fragmentation transfer (RAFT) emulsion polymerizations as the first example. Emulsion polymerization using ethyl iodoacetate as the chain transfer agent more closely approximated the theoretical molecular weights than did the free radical polymerization. Although 1H NMR spectra indicated that the peaks of α- and ω-terminal groups were observed, the molecular weight distributions show a relatively broad range (Mw/Mn = 2.2–4.0). On the other hand, RAFT polymerizations revealed that the dithiocarbamate 7 is an excellent candidate to control the polymer molecular weight (Mn = 9.1 × 103, Mw/Mn = 1.48), more so than xanthate 1 (Mn = 10.0 × 103, Mw/Mn = 1.89) under same condition, with accompanied stable emulsions produced. In the Mn versus conversion plot, Mn increased linearly as a function of conversion. We also performed seed-emulsion polymerization using poly(nonamethylene L-tartrate) as the chiral polyester seed to fabricate emulsions with core-shell structures. The control of polymer molecular weight and emulsion stability, as well as stereoregularity, is also discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Polypeptide hydrogels were prepared by cross-linking of hydrophobically-modified poly[ N 5 -(2-hydroxyethyl) l -glutamine] having alkyl side chains –C n H 2 n +1 . Chain length of the alkyl group was n = 8, 16, and 18, and their mole fractions in the polypeptide were varied in the range of 0.05–0.16. Shape memory ability of the prepared polypeptide hydrogels was investigated. After deformation at 60 °C, the hydrogel was cooled in order to fix the temporary deformed shape. It was found that crystallization of the alkyl side chains did not occur, and the fixation ability of the hydrogel at 0 °C was low. In the subsequent heating process, the deformed temporary shape spontaneously recovered to the original shape gradually with increasing temperature, in other words, the shape recovery ratio varied with depending on the recovery temperature. From these observations, it was proposed that the shape fixation of the polypeptide hydrogel was achieved by strong segregation of the hydrophobic alkyl chains at low temperature, and the shape recovery of the deformed hydrogel was accompanied by the gradual decrease of the segregation strength with the temperature increase.

Uniaxially oriented liquid crystalline poly(γ-benzyl l-glutamate) (PBLG) gel was prepared by cross-linking the lyotropic liquid crystalline PBLG solution in magnetic field, and PBLG was converted to poly[N5-(2-hydroxyethyl) l-glutamine] (PHEG) by side-chain aminolysis reaction. The prepared PHEG gel retained the liquid crystallinity after the conversion from PBLG to PHEG when immersed in α-helix-forming solvent such as ethylene glycol. By the addition of water into the immersion solvent, conformational transition of PHEG from α-helix to random coil was occurred, and the optical anisotropy of the gel was disappeared. With this helix-to-coil transition of PHEG, the gel was swollen in the direction perpendicular to the orientational axis of PHEG, and was shrunk in the parallel direction. As the result, the gel in cylindrical shape in ethylene glycol, in which α-helical PHEG is oriented along the cylindrical axis, changed to more isotropic shape in water. This anisotropic shape change of the gel was described...

The aim of this study was the preparation of novel water repellent UV curable materials using acrylic modified melamine (AM) and poly-dimethylsiloxane (PDMS). UV curable acrylic melamines containing silicone segments (SiAMs) were synthesized by condensation of methylolmelamine, 2-hydroxyethyl acrylate, and carbinol-modified PDMS. The SiAM films with a 0.3 wt% PDMS segment that were cured by UV irradiation had higher transparency than that of a blended sample. Examination with a scanning electron microscope revealed that the blend sample has cohesion of the silicone segments, while such a phenomenon was not observed in the composite samples (SiAMs). From these results, it was confirmed that aggregation of the silicone segments was prevented by introducing the silicone segments into the acrylic melamine. By introducing 0.3 wt% of PDMS segments into AM, good water-shedding properties were confirmed, while several of the most attractive features of AM, such as hardness, adhesion, and refractive index, were maintained.

Thermoresponsive phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) (P(CVE-MA)) in mixed solvent of propyl acetate (PrAc) and n-alkane has been investigated. At a proper solvent composition of PrAc/n-octane, the polymer solution was transparent at lower temperature, and became turbid with heating, which suggest that this polymer solution exhibits lower critical solution temperature (LCST) type phase behavior. Controllability of the cloud point of the polymer solution was studied by light scattering technique. At the fixed polymer concentration of 1 mass%, the cloud point value changed from 76 °C to 31 °C with increasing the n-octane content from 6 to 16 mass% in the mixed solvent, with excellent linear relationship. The cloud point curve plotted against polymer concentration shifted to higher temperature with decreasing molecular weight of P(CVE-MA). The cloud point curve also shifted to higher temperature when the chain length of the added n-alkane became longer, and this result was explained by n-alkane's polarity and molecular size.

Shape memory behavior of polymer blends consisting of thermoplastic polyurethane (PU) and crystalline poly(oxyethylene) (POE) have been investigated. PU is in a rubbery state at room temperature and has an ability to recover from a deformed temporary shape to a permanent shape by entropic elasticity, and POE has a role to fix the temporary shape by crystallization and solidification of the system. As a result, excellent shape memory properties can be obtained by blending elastic PU and crystalline POE. With increasing POE content in the blend, the shape fixity ratio below crystallization temperature was increased to almost 100%, but shape recovery above melting temperature occurred more slowly. These experimental results were reasonably described by viscoelasticity and the phase separated morphology of the PU/POE blend. The effect of changing molecular weight of POE on the shape memory behavior was not remarkable. The shape recovery behavior was found to be expressed by using a simple mechanical viscoelastic model.

In this study, high oxygen permeable transparent hybrid copolymers were prepared with hydrophilic monomer such as 2-hydroxyethylmethacrylate (HEMA) or N,N-dimethylacrylamide (DMAA) and mono- or difunctional silicone macro-monomer introduced methacryl groups. In HEMA-based hybrid copolymers, difunctional silicone macro-monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker were required in order to prepare transparent hybrid materials, while high transparent DMAA-based hybrid copolymers could be prepared without EGDMA cross-linker. The polymerization kinetics investigation revealed that this difference between HEMA and DMAA in preparation condition to transparent hybrid material originated to monomer reactivity in copolymerization and DMAA showed high reactivity compared with HEMA. Moreover, DMAA-based hybrid copolymers indicated high water content and high oxygen permeability as against HEMA-based hybrid copolymers because of its low cross-linking density.

Comb-like copolymer of N-phenyl maleimide and n-octadecyl vinyl ether was synthesized by conventional free radical solution polymerization. The molecular weight and molecular weight distribution were measured by GPC. The chemical composition of copolymer was characterized by FT-IR, 1H NMR and 13C NMR, and the results indicated that the obtained copolymer contained much more content of N-phenyl maleimide rather than equal molar ratio of monomer unit. The comb-like copolymer can exhibit upper critical solution temperature thermoresponsive phase behavior reversibly in N,N-dimethylformamide and some proper alcohols such as 1-butanol, 1-hexanol, etc. The effect of polymer concentration and co-solvent on thermoresponsive behavior of polymer solution was investigated, and the cloud point of polymer solution can be tuned conveniently. The high resolution 1H NMR method was used to comprehend the reversible thermoresponsive behavior in molecular level, and the results revealed that as temperature decreased the pendent long alkyl side chain aggregated and phase separation occurred at cloud point temperature; however, the mobility of main polymer chain decreased at lower temperature.

In this study, transparent poly(methylmethacrylate) (PMMA)-silicone hybrid materials, P(MMA-co-SigUMAx), were prepared with methylmethacrylate (MMA) and multifunctional silicone macromonomer introduced methacryl groups. The transmittance of hybrid materials improved with increase of methacryl groups of silicone macromonomer and reached around 90% T. Atomic force microscopic analysis, scanning electron microscope examinations, and copolymerization kinetics estimation by proton nuclear magnetic resonance revealed that the silicone macromonomer randomly incorporated in the copolymer with MMA by the increase of methacryl groups and suppresses the aggregation of the silicone segment. The hybrid materials introduced over 10 wt % of silicone component had water-shedding surface and the water contact angle was elevated from 65 to 95°. Though the mechanical properties of hybrid materials were lowered by introduction of flexible silicone component, thermal property such as 5 wt % weight loss temperature were improved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Small amount of impurities or contaminations in recycled plastic have a possibility to influence on mechanical properties of product. In this study, miscibility and mechanical properties of melt-blended high-impact polystyrene (HIPS) and poly(α-olefin) (PO)-based grease have been investigated. We have focused attention on the molecular weight (Mw) of PO, and the range of Mw for PO in the used greases was 690-8,500. Changes of glass transition temperature were observed for polystyrene and polybutadiene phases in the HIPS/grease blends, that indicated small amount of PO was solubilized into HIPS. When Mw of PO was higher than 5,000, insoluble excess PO acted as lubricant, and sample preparation was difficult since slipping between the polymer and chamber wall or screw occurred during melt blending. By this limitation in solubility of HIPS/grease, depression of mechanical properties such as flexural modulus and strength for the obtained blends was not remarkable. On the other hand, blends with high grease content could be obtained for PO with low Mw because of its good solubility with HIPS, as the result, their flexural properties were highly deteriorated than the original HIPS. Therefore, the grease containing high molecular weight PO has a smaller influence on the mechanical properties of HIPS/grease because of the limitation in solubility. Results of chemical stress crack tests for HIPS/grease were also explained by the miscibility of PO with HIPS.

Lower critical solution temperature behavior of poly(2-chloroethyl vinyl ether- alt -maleic anhydride) in organic media

The aim of this study was to prepare transparent nanohybrid films with low coefficient of thermal expansion (low CTE), which consist of acryl resin and nanosized clay. The hybrid films with different clay contents were prepared by UV curing of tricyclodecane dimethanol diacrylate (TCDDMDA) including nanosized clay. All obtained films were transparent similar to pure poly(TCDDMDA). In addition, the film containing 40 wt.% of clay showed a low CTE of 10 ppm/K in 150–200 °C, which is similar to that of inorganic materials such as glass. The significant property improvement is related to shape effect and orientation of clay in polymer matrix. Wide-angle X-ray diffraction measurement was carried out to investigate orientation of nanosized clay in polymer matrix. From this measurement, it was confirmed that the clay platelets were oriented parallel with film surface with increasing clay content, and orientation coefficient of the clay in polymer matrix reached to f = 0.65 for the hybrid film containing 40 wt.% of clay. Though, in comparison with the matrix, the flexibility of the hybrid film evaluated by the wind roll test with steel bar was lowered by increase of clay content, the hybrid film containing 40 wt.% of clay could be rewound with steel bar 10 mm across, and its flexibility was retained.

This paper describes a shape memory behavior of graft copolymers poly(methyl methacrylate)-graft-poly(ethylene glycol) (PMMA-g-PEG). In shape memory test, the sample was deformed from its original shape to a temporary shape above glass transition temperature (Tg), cooled below Tg to fix the temporary shape, and subsequently heated above Tg for spontaneous recovery to the original shape. By grafting PEG onto PMMA backbone, shape memory ability was drastically enhanced than PMMA homopolymer. The shape recovery ratio was decreased with the increase in the shape deformation temperature. With considering a good miscibility of backbone and side chain in PMMA-g-PEG, this shape memory ability may be related to a physically cross-linked network structure by chain entanglement of the comb-like graft copolymer. Stress relaxation measurements were investigated in order to confirm the effect of the graft chains on the shape memory behavior.

In this study, two kinds of amphiphilic copolypeptide, C12-poly(N-hydroxyethyl L-glutamine-co-L-tryptophan) (C12-EGT-T) and C12-poly(L-glutamic acid-co-L-tryptophan) (C12-GAT-T) were prepared. By using the mixture of these amphiphilic copolypeptides, pH response of aggregate formation, critical aggregate concentration, the sizes of the aggregates and sustained-release behavior of model substances were investigated. The mixture of the amphiphilic copolypeptides formed aggregates in aqueous medium and showed the ability to uptake model substances such as pyrene and 5-fluorouracil into their hydrophobic moiety. Moreover, pH response was observed in the sustained-release behavior of model substances and the pH region where these properties changed was from pH 7.4 to pH 4.5 in the mixture of C12-EGT-T/C12-GAT-T at 50/50 (mol/mol). These results could be explained by dissociation of trifluoroacetic-acid-treated tryptophan residues in the hydrophilic moieties and destabilization of the aggregates by electrostatic repulsion.

The aim of this study was to prepare transparent polystyrene (PSt) hybrid materials containing silicone macromonomer. Silicone urethane methacrylate (SiUMA) was synthesized by the reaction between the hydroxyl end groups of a silicone macromonomer and the isocyanate group of 2-methacryloyloxyethyl isocyanate (MOI), and copolymers with different weight proportions were prepared by copolymerization of styrene (St), SiUMA and ethyleneglycol dimethacrylate (EGDMA). Though the prepared P(St-co-SiUMA) copolymers which had not introduced EGDMA were opaque, the prepared P(St-co-SiUMA-co-EGDMA) copolymers were transparent, similarly to pure PSt. DSC and 1H-NMR measurements were carried out to investigate the factors in this transparency in detail. From these measurement results, it was confirmed that the reactivity of the copolymerization had a significant influence on the transparency of the product. In addition, the contact angle of P(St-co-SiUMA-co-EGDMA) with 10 wt % SiUMA was greater than 90°, which was a 10° improvement compared to pure PSt. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Poly(methylmethacrylate) (PMMA) shows high strength and transparency but is a flammable material. In this study, the surface of aluminum hydroxide was modified with methacrylate containing phosphoric acid moieties before dispersion in MMA, and organic–inorganic nano-hybrid materials were obtained by bulk polymerization in the presence of the surface-modified aluminum hydroxide. The resulting hybrid materials retained the high transparency of PMMA, with transparency values similar to that of pure PMMA. Moreover, the flame resistance of the hybrid materials was improved in comparison with that of pure PMMA, with depression of the horizontal burning rate becoming a maximum at an inorganic content of 3 wt%. These results suggest that the use of aluminum hydroxide surface-modified with phosphoric acid groups is an efficient method for obtaining good performance fire-resistant polymer materials.

PMMA is used as the most popular dental resin and show high strength and transparency, but is weak against an impact. Although introduction of rubber domain into a matrix polymer has been widely investigated to improve the impact resistance, strength and surface hardness of materials are decreased by rubber element. Therefore, in this study, the core-shell composite nanoparticles containing silica particles in rubber domain were prepared by emulsion polymerization with methyl methacrylate (MMA) and ethyl acrylate. These particles were added to MMA and bulk polymerization was carried out to obtain test specimen. The physical properties including impact resistance were evaluated by three-point bending test, falling ball impact test and Vicker's hardness test. The impact resistance of test specimen was improved in comparison with the test specimen prepared with core-shell particles without silica particle. Moreover, deterioration in mechanical properties was depressed by addition of silica particle to rubber element.

In this study, interpenetrating polymer networks (IPNs) and IPN composite materials were prepared by in situ polymerization of urethane dimethacrylate (UDMA) and bisphenol-A diglycidyl ether epoxy resin (DGEBA) with or without silica nanoparticles. Dynamic mechanical analysis (DMA), three-point bending test, thermogravimetric analysis (TGA) and visible spectrometry were performed to evaluate the physical properties of the resulting IPNs and IPN composite materials. The IPNs showed high transparency and higher elastic modulus and strength than that of each homopolymer at ratio of UDMA/ DGEBA is 70/30. The IPN composites maintained high transparency in spite of the addition of silica nanoparticles. Moreover, elastic modulus and surface hardness of the IPN composites increased with increasing silica content.

In this study, poly(methylmethacrylate) (PMMA)-based hybrid materials were prepared from reactive silica nanoparticles. These nanoparticles were obtained by the reaction of 2-(methacryloyloxy)ethyl isocyanate with colloidal silica dispersed in ethyl acetate, and they were copolymerized in various ratios with methyl methacrylate. Dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and visible spectrometry were performed to evaluate the physical properties of the resulting hybrid materials. The PMMA–silica hybrid copolymers maintained high transparency, and their storage elastic modulus and surface hardness increased with increasing silica content. Moreover, in comparison with PMMA, the hybrid copolymers had greater heat resistance and lower volume contraction.

The phase behavior and crystallization of graft copolymers consisting of poly(n-hexyl methacrylate) (PHMA) as an amorphous main chain and poly(ethylene glycol) (PEG) as crystallizable side chains (HMAx with 15 ≤ x ≤ 73, where x represents the weight percentage of PEG) were investigated. Small-angle X-ray scattering profiles measured above the melting temperature of PEG suggested that a microdomain structure with segregated PHMA and PEG domains was formed in HMA40 and HMA46. This phase behavior was qualitatively described by a calculated phase diagram based on the mean-field theory. Because of the segregation of PEG into microdomains, the crystallization temperature of the PEG side chains in HMAx was higher than that in poly(methyl acrylate)-graft-poly(ethylene glycol) having a similar value of x, which was considered to be in a disordered state above the melting temperature. In HMAx with x ≤ 40, PEG crystallization was strongly restricted, probably because the PEG microdomains were isolated in the PHMA matrix. As a result, the growth of PEG spherulite was not observed because the PEG crystallization occurred after vitrification of the PHMA segregated domains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 129–137, 2007

In this study, glucose derivatives as novel binders for fiber board, 2-(methacryloyloxy)ethyl carbamate glucose (MOCG), was prepared by reaction of 2-(methacryloyloxy)ethyl isocyanate (MOI) and OH group of glucose. MOCGs which controlled the substitution degree were also prepared by changing the molar ratio of glucose and MOI. The MOCGs were polymerized and physical properties of MOCG homopolymers were evaluated. High substituted MOCG homopolyer showed excellent mechanical property and thermal stability. On the other hand, physical properties of low substituted MOCG homopolymer was lowered by the aggregation of the glucose unit.

In this study, glucose derivatives as novel binders for fiber board were prepared with isocyanate compounds, 2-hydroxyethyl methacrylate (HEMA) and glucose. 2-(methacryloyloxy)ethyl isocyanate (MOI), Tolylene 2,4- diisocyanate (TDI) and isophorone diisocyanate (IPDI) were used to prepare the glucose derivatives. When TDI and IPDI were used for preparation of glucose derivative, by-products such as glucose-diisocyanate-glucose and HEMAdiisocyanate-HEMA were produced. The glucose derivatives were polymerized and physical properties of the homopolymers were evaluated. The homopolymers show excellent mechanical property and thermal stability.

In this study, amphiphilic block co-polypeptide consisting of hydrophilic poly(N-hydroxyethyl l -glutamine) (PHEG) and hydrophobic poly( l -tryptophan) (poly(Trp)), PHEG-block-poly(Trp)-T, was prepared by aminolysis of poly(γ-benzyl l -glutamate)-block-poly(Trp) with 2-amino-1-ethanol and subsequent treatment with trifluoroacetic acid (TFA). By using the block co-polypeptide, aggregate formation and sustained-release behaviour of model substances were investigated. The block co-polypeptide formed aggregates in aqueous medium and showed the ability to uptake hydrophobic substances into their hydrophobic moiety. The block co-polypeptide exhibited pH-response, the critical aggregate concentration of PHEG-block-poly(Trp)-T and the sizes of the aggregates depended on pH and decreased at pH 2.0. Moreover, fluorescence studies indicated a loose aggregate structure at pH 2.0 and the release rate of the model substances from the polypeptide aggregates was higher at pH 2.0 than at pH 5.0. These results could be explained by dissociation of Trp residues in the hydrophobic cores of the aggregates.

Dodecyl and dodecanoyl groups (C12) are attached at the chain ends of poly[ N 5 -(2-hydroxyethyl) l -glutamine] (PHEG), and association behavior of this both-ends hydrophobically modified water soluble polypeptide (C12–PHEG–C12) has been investigated by means of light scattering measurements. Water/ethylene glycol (EG) mixed solvents were used as selective solvent for PHEG block, and PHEG changed its structure from random-coil state to α-helix with increasing EG content in the mixed solvent ( W EG ). When W EG is less than 0.5, flower-like micelle with C12 associated core and PHEG corona in loop conformation was suggested to be formed. Increase of W EG from 0.5 to 0.6 induced drastic increase of association number and size of the associate, in which many C12 associated cores may be connected by PHEG in bridge conformation. This structure change of associate is considered to be driven by the increase of helix content of PHEG with W EG , which enhances the possibility to form bridge conformation because of its rigidity. Solution preparation method, i.e. order of addition of solvent, was found to influence the structure of associate, although its effect on the helix content of PHEG was negligible.

Structure analysis of associated micelles formed by polypeptide-based diblock copolymer PEG-b- PHEG, consisting of poly(ethylene glycol) (PEG) and poly(N 5 -(2-hydroxyethyl) L-glutamine) (PHEG), in dilute solu- tion has been investigated. Cyclohexanol/water mixed solvent was used as selective solvent for PEG-b-PHEG, in which PHEG forms associated domains. Circular dichrorism measurements revealed that PHEG block changes its con- formation from � -helix state to random coil state with increase of water content in the mixed solvent from 2.3 to 12.1 wt %. Apparent molecular weight and radius of gyration of associated micelles were derived by light scattering measurements, and most plausible structure of the micelle was evaluated. When the water content is small and helix content of PHEG is almost 100%, a cylindrical micelle with large association number was suggested, and a vesicle-like hollow cylindrical micelle with large diameter was proposed. With the increase of water content and decrease of helix content, association number of the micelle decreased and a core-corona type cylindrical micelle with densely packed PHEG core was plausible. These structure changes of the micelles were interpreted by possible chain packing of � -hel- ical and randomly-coiled PHEG and curvature of PHEG core domain. The obtained results indicate that the conforma- tion and packing manner of the core-forming chain strongly influence the structure of the diblock copolymer micelles. (DOI 10.1295/polymj.37.404)

Para-linked aromatic poly(amic n-dodecyl ester) (PA-12), in which long n-alkyl side chains are attached on rodlike aromatic polyamide, was prepared by polycondensation of 2,5-bis(1-dodecyloxycarbonyl)terephthaloyl chloride and 1,4-diaminobenzene. In as-cast PA-12 film, formation of layered structure with alternating main-chain-segregated and side-chain-segregated layers is suggested by X-ray diffraction measurement. PA-12 is a precursor of rodlike aromatic polyimide, poly(1,4-phenylene pyromellitimide) (PPPI). Solid-state thermal imidization and base-catalyzed chemical imidization of PA-12 film has been investigated. Although the layered structure of PA-12 was destroyed during the imidization reaction, the obtained PPPI exhibited lower density than densely packed PPPI. This result may indicate that the side chain-segregated domain was transformed to a cavity surrounded by PPPI after the imidization reaction. Chemical imidization in pyridine/toluene mixture and subsequent heating at 200 °C was the optimum condition to obtain low density PPPI.

In this study, organic-inorganic hybrid monomer, poly silicic acid urethane methacrylate (PSUMA), was prepared by reaction of poly silicic acid extracted from sodium silicate aqueous solution with THF and 2-(methacryloyloxy)ethyl isocyanate. The PSUMA was copolymerized with methyl methacrylate to obtain hybrid copolymers. The material properties such as mechanical properties, thermal properties, Vickers hardness, transparency and so on were evaluated. The PMMA-PSUMA hybrid copolymers kept high transparency and showed higher elastic modulus and Vickers hardness than those of raw PMMA. Moreover, in comparison with PMMA, the hybrid copolymers had greater heat-resistance and lower volume contraction.

In this study, amphiphilic graft copolypeptides containing L-tryptophan (Trp) were prepared by aminolysis reaction of poly(γ-benzyl L-glutamate)-graft-poly(Trp) with 2-amino-1-ethanol and then treated with trifluoroacetic acid (TFA). Graft copolypeptide hydrogel membranes treated with TFA were also obtained by same method as the graft copolypeptide in the presence of crosslinking agent. By using these graft copolypeptides and hydrogel membranes, aggregation behaviour and sustained-release of hydrophobic substance were investigated. In aqueous medium, graft copolypeptides formed aggregates 90 nm in diameter and exhibited the ability to uptake hydrophobic substances into their hydrophobic moiety. TFA-treated graft copolypeptide showed a pH response; the diameter and uptake ability of the graft copolypeptide were decreased below pH 2.0. This pH response is due to the dissociation of the indole ring of Trp treated with TFA in this pH region. The pH response of drug release from hydrogel membrane treated with TFA was also observed. The hydrophobic drug, testosterone, was released continuously at pH 2.0, whereas the release of testosterone was depressed at pH 5.0. These results can be explained by aggregation and dissociation of Trp residues in the graft copolypeptide. Copyright © 2004 Society of Chemical Industry

Carbon black (CB)-filled composites of polyethylene (PE), polypropylene (PP), and PP/PE blend with weight composition of 40/60 have been prepared by twin screw extruder, and their electrical resistivities have been investigated. In order to improve the surface properties of CB, γ-aminopropyl trimethoxysilane (APS) was used for the surface treatment of CB. The surface treatment of CB by APS was found to effectively decrease percolation threshold, φc, i.e., the electrical resistivity showed drastic decrease when the CB content was larger than φ c. Temperature dependence of APS-treated CB/PP/PE composites exhibited almost constant electrical resistivity (~106 Ωcm) in the range of 25-130°C, and it was increased drastically to ~1012Ωcm above the melting temperature of PE, resulting high positive temperature coefficient (PTC) intensity (ca. 106). This high resistivity was maintained even at the higher temperature than 150°C, and only weak negative temperature coefficient (NTC) behavior was observed. The surface treatment of CB by APS is effective to obtain CB/PP/PE composites having excellent thermal electrical property as a switching material.

Poly(ethylene terephthalate) (PET) / poly(ethylene naphthalate) (PEN) blends with 50/50 composition have been prepared by melt-mixing at the temperatures above 280°C and subsequent heating at 280°C before hot-press molding. Progress of transesterification reaction and formation of PET-PEN random copolymers during these melt-blending processes have been confirmed by 1H-NMR measurement. Dynamic viscoelasticity, DSC thermograms, and SEM images for the PET/PEN blends with shorter heating time at 280°C suggested that the blend sample was in an immiscible state when the transesterification level (T) was less than 5%. With the increase of the heating time, the sample changed to miscible state with T > 5 % and exhibited transparency. The phase-separated morphology was fine and the size of the phase-separated domain was several hundred nanometer when T ≈ 5%. Flexural test for the blend samples revealed that the PET/PEN blends exhibited the maximum flexural strength when T ≈ 5 %. Increase in the melt-mixing temperature was found to accelerate the transesterification reaction, and to shorten the processing time to obtain the miscible PET/PEN blend.

Graft copolymers consisting of amorphous main chain, poly(methyl methacrylate) (PMMA), or poly(methyl acrylate) (PMAc), and crystalline side chains, poly(ethylene glycol) (PEG), have been prepared by copolymerization of PEG macromonomers with methyl methacrylate or methyl acrylate (MMAx or MACx, respectively). Because of the compatibility of PMMA/PEG and PMAc/PEG, from small-angle X-ray scattering results, the main and side chains in graft copolymers were suggested to be homogeneous in the molten state. Differential scanning calorimetry (DSC) cooling scans revealed that PEG side chains for graft copolymers with large PEG fractions were crystallized when the sample was cooled, with a cooling rate of 10 °C/min. The spherulite pattern observed by a polarized optical microscope suggested the growth of PEG crystalline lamellae. Crystallization of PEG in MMAx was more restrained than in MACx. From these results, we have concluded that the crystallization behavior of the grafted side chains is strongly influenced by the glass transition of a homogeneously molten sample as well as dilution of the crystallizable chains. Domain spacings for isothermally crystallized graft copolymers were described by interdigitating chain packing in crystalline–amorphous lamellar structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 79–86, 2005

(E,E)-Methyl sorbate (MS) and (E,E)-ethyl sorbate (ES), i.e., methyl 2,4-hexadienoate and ethyl 2,4-hexadienoate, underwent anionic polymerization in toluene at −60 to 0 °C in the presence of organoaluminum Lewis acids. The NMR, wide-angle X-ray diffraction (WAXD), and semiempirical molecular orbital calculation demonstrated that 1,4-trans-threo-disyndiotactc polymerization occurred (tritactic polymerization). Coordination of methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD) (MAD/t-BuLi = 3) played three important roles, stabilization of the propagating anion, the activation of the monomer, and dissociation of tert-butyllithium (t-BuLi) aggregated in toluene to give polymers with relatively narrow molecular weight distribution (Mw/Mn = 1.3) using t-BuLi−(−)-menthyl ethyl ether (MEE) complex as the initiator. Hydrogenations of poly(MS) and poly(ES) with p-toluenesulfonylhydrazide (TSH) produced head-to-head (H−H) poly(propylene-alt-methyl acrylate) and poly(propylene-alt-ethyl acrylate), respec...

Association behavior and physical gelation mechanism of ABA triblock copolymer dissolved in B-selective solvent have been studied systematically from dilute to moderately concentrated solutions. Static and dynamic light scattering and nuclear magnetic resonance measurements for dilute solutions of poly(methyl methacrylate)-block-poly(tert-butyl acrylate)-block-poly(methyl methacrylate) (PMMA – Pt BuA – PMMA) in 1-butanol (Pt BuA selective solvent) indicated that PMMA– Pt BuA – PMMA chains are molecularly dissolved above 50 8C. With decreasing temperature, the triblock copolymers form associated micelles consisting PMMA associated core and Pt BuA shell. Linear dynamic viscoelastic measurements for solutions with moderate concentration (3.9– 12.0 wt%) revealed that the system was viscous sol state at 60 8C. Drastic increase of shear storage modulus ðG 0 Þ occurred with decreasing temperature, and at 25 8C, G 0 showed rubbery plateau with weak frequency dependency, means the formation of elastic physical gel. The consistency between the temperature for micelle formation and that at the increase in G 0 indicates that the physical gelation is owing to the network formation as the result of the association of PMMA chains and the bridging Pt BuA chains connecting the PMMA cores. Master curves for the dynamic moduli were derived by time – temperature superposition along the frequency axis. Just above sol –gel transition concentration ðCgelÞ; the master curves suggest the existence of fairy amount of aggregate that is not incorporated in the macroscopic network. With the increase in polymer concentration, the master curves become to reveal Maxwell-type viscoelasticity with narrow relaxation time distribution, suggesting the formation of transient network with easily generation and destruction of crosslinks. Concentration dependency of the plateau modulus is stronger than the theoretically expected, means the macroscopic transient network grows with polymer concentration by increasing the fraction of elastically effective bridging Pt BuA chain above Cgel: q 2003 Elsevier Ltd. All rights reserved.

The rheological properties of micellar aqueous solutions of hydrophobically modified ethylene glycol oligomer, poly(ethylene glycol) monododecyl ether (C12E25), have been studied over a wide range of concentration and temperature. The micellar solution of C12E25 exhibits a sol-gel transition accompanied by a disorder-to-order transition of micelle particles. The following conclusions were made: (1)The sol solution behaves like an ordinary viscous liquid of Newtonian flow, presenting no sign of any change in associations. (2) Under shear deformation, the gel exhibits a yield point around the strain of a few per cent, followed by a plastic flow with further deformation. The plastic flow exhibits a strong non-Newtonian flow. (3) As the sear rate increases, the sol-gel transition temperature, observed by steady-flow viscosity, becomes lower with a reduced sharpness of transition. (4) The long-range structural order of the lattice in the gel, destroyed by the plastic flow, is suggested to substantially recover in 10-100s.

Aggregation behavior of hydrophobically modified ethyleneglycol oligomer, poly(ethylene glycol) monododecyl ether (C12E25), in aqueous solution has been studied in wide ranges of concentration and temperature by means of light scattering, X-ray scattering, and linear-viscoelastic measurements. C12E25 forms stable micelles in dilute solution. It is found that the micellar solution exhibits the sol–gel transition accompanied with disorder-to-order structural transition as increasing concentration at lower temperatures, or with decreasing temperature at higher concentrations. The transition concentration is located around 30 wt% irrespective of temperature, while the transition temperature is about 56 °C independent of concentration. In the gel region, the micellar particles form a long-range order structure of body-centered cubic lattice.

We have investigated the morphology and packing manner of graft copolymers consisting of rigid-rod-like poly(γ-benzyl L-glutamate) (PBLG) main chains and grafted diblock copolymers of amorphous poly(propylene glycol) (PPG) and crystalline poly(ethylene glycol) (PEG). The results of differential scanning calorimetry and wide-angle X-ray scattering measurements for graft copolymers with higher side-chain volume fractions suggest that the rodlike main chains and crystallized PEG chains exist in segregated domains. Small-angle X-ray scattering profiles for these samples show diffraction intensity maxima accompanied by higher order peaks, the positions of which suggest the formation of an ordered layered structure. From these observations, the graft copolymers are estimated to form repeated layered structure consisting of segregated PBLG, PPG, and PEG layers. A proposed model for molecular packing of the graft copolymers is consistent with the experimental observation that the repeating distance for the layered structure decreases with an increase in the volume fraction of side chains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1904–1912, 2002

A simple square-gradient theory (SGT) for the interfacial tension of homopolymer-A/homopolymer-B blends with A-B diblock copolymer additives near the critical solution temperature, T c , has been proposed to describe the experimental finding that, as the temperature changes away from T c , the interfacial tension γ increases, and then decreases, exhibiting a maximum. Dynamic mean-field calculations (DMF) of a self-consistent field treatment are also performed to describe it and are compared with those of the proposed SGT. Both of SGT and DMF reasonably describe the γ-maximum behavior and the additive-concentration dependence of the location of γ-maximum in γ-T relation. Agreements of SGT with DMF results are quite satisfactory, although SGT, in general, gives thinner adsorbed layers of block copolymers than those evaluated by DMF.

The effects of low-molecular-weight additives on the interfacial behavior of polymer blends have been studied experimentally and theoretically. The measured interfacial tension near the critical solution temperature T c for poly(dimethylsiloxane)/poly(tetramethyldisiloxanylethylene) as a function of temperature is merely shifted by the addition of oligo(dimethylsiloxane) corresponding to the decrease of T c , giving only a subtle adsorption effect in interfacial behavior. Theoretical calculations have also been carried out for polymer/polymer/additive ternary systems using the square-gradient theory (SGT) and the dynamic mean-field (DMF) calculation. The experimental results are quite consistent with theoretical predictions. Further theoretical calculations demonstrate that higher molecular weights and less miscibility with matrix polymers are most effective for a large adsorption of additives in the interface, leading to a large reduction of interfacial tension. SGT and DMF are found to predict almost the same interfacial tension and composition profiles in ternary polymeric systems.

Crystal structure and molecular packing analysis for crystalline and mesomorphic poly(diethylsiloxane) (PDES) have been studied by wide-angle X-Ray diffraction measurements using uniaxially-oriented PDES sample without crosslinking process. Well-oriented fiber diffraction pattern measured at 0°C, which corresponds to the β2 polymorph, can be satisfactorily indexed by monoclinic unit cell with c (fiber axis)=5.02A. Only four independent reflections can be observed for mesomorphic PDES at 26°C, but the orientational direction of the PDES specimen has been maintained after the crystalline-mesophase transition. Molecular-packing manner of crystalline β2-PDES has been estimated with assuming planar-Si-O-backbone with alternating cis-trans conformation.

Aggregation behavior of poly(N,N-diethylacrylamide) (PDEA) in dilute aqueous solution has been studied by using the static and dynamic light scattering. It has been demonstrated that PDEA is not molecularly dissolved in water but forms molecular aggregates below the cloud point in one phase region. The association number of aggregates is of the order of 100, and the aggregate is suggested to be like a swollen micro-gel. The aggregation does not come from difficulty of dissolving a frozen structure in solid state, but the aggregates are also formed in solution starting from aggregation-free state by changing the solvent quality. The detailed aggregate size and structure depend on the dissolution process of the solid sample in making the solution. Once the aggregate is formed, it is stable, and does not change its association number and dimension for a long time. But, the association number may change with temperature and depends on thermal history.