Showing papers in "Polymer Bulletin in 2005"

Chitosan- metal complexes as antimicrobial agent: Synthesis, characterization and Structure-activity study

Abstract: Chitosan (CS) metal complexes with bivalent metal ions, including Cu(II), Zn(II), Fe(II) were prepared, and characterized by FT-IR, XRD, AAS and elemental analysis. The crystalline and structural properties of chitosan-metal complexes were different from those of chitosan, and the -NH2, -OH groups in chitosan molecule were considered as the dominating reactive sites. In vitro antimicrobial activities of the obtained chitosan-metal complexes, which were found to be much better than free chitosan and metal salts, were examined against two gram-positive bacteria (S. aureus and S. epidermidis), two gram-negative bacteria (E. coli and P. aeruginosa) and two fungi (C. albicans and C. parapsilosis). Results indicatd that the inhibitory effects of chitosan-metal complexes were dependent on the property of metal ions, the molecular weight and degree of deacetylation of chitosan and environmental pH values. Electro microscopy confirmed that the exposure of S. auresus to the chitosan-Cu(II) complex resulted in the disruption of cell envelop. Based on the discussion upon the antimicrobial mechanism of chitosan-metal complexes and their molecular structures, the structure-activity correlation for the antimicrobial activities was elucidated. All the results show that chitosan-metal complexes are a promising candidate for novel antimicrobial agents that can be used in cosmetic, food, textile et al.

On the Stability of Polyproline-I and II Structures of Proline Oligopeptides

Abstract: Proline oligopeptides composed of 13, 6 and 4 Pro residues were synthesized by solid-phase procedure. The circular dichroism spectra showed that the proline oligopeptides form the polyproline-II helix in water and in trifluoroethnol. However, it was shown that the oligopeptide composed of 13 Pro residues remarkably presents conformational transition from the polyproline-II to the polyproline-I helix in methanol and 1-propanol. This result is the first spectrum evidence that proline oligopeptides can form the polyproline-I helix in pure aliphatic alcohol such as methanol and 1-propanol. It was also shown that the propensity forming polyproline-I helix is more favorable in 1-propanol than in methanol, and also that the longer the chain-length is, the greater the stability of the polyproline-I helix is. Such a chain-length dependency of the conformational stability is also supported by the theoretical calculation using molecular mechanics.

Sulfonation of Polyethersulfone by Chlorosulfonic Acid

Abstract: Modification of polyethersulfone (PES) by sulfonation with chlorosulfonic acid as sulfonating agent and concentrated sulfuric acid as solvent was carried out. Factors affecting the sulfonation reaction were studied, and reaction conditions for the preparation of sulfonated PES (SPES) with different degrees of sulfonation were determined. The presence of sulfonic acid groups in SPES was confirmed by FTIR and NMR spectroscopy. Thermal analysis of the SPES samples revealed higher glass transition temperatures and lower decomposition temperatures with respect to the PES.

Polyaniline / carbon nanotube composites: starting with phenylamino functionalized carbon nanotubes

Abstract: Composites of carbon a nanotube with polymers are a developing and interesting area of research. The dispersion of the nanotube in polymer matrices is an important factor while making its nanocomposites. Even though in-situ polymerization approach offers a better approach for synthesizing homogeneous polymer nanotube composites, the dispersion of the nanotubes in the monomer solution is a problem. In this article we report a new chemical method for dispersing nanotubes in monomer and the preparation of uniform tubular composite of polyaniline (PANI) and multiwalled carbon nanotube (MWNT). For this the oxidized multiwalled nanotube (o-MWNT) was functionalized with p-phenylenediamine, which gave phenylamine functional groups on the surface. This functionalization helped to disperse the nanotubes in acidic solution. The in-situ polymerization of aniline in the presence of these well dispersed nanotubes gave a new tubular composite of carbon nanotube having an ordered uniform encapsulation of doped polyaniline. The phenylamine functional groups on the surface were grown into polyaniline chain so that the composite contains polyaniline functionalized CNT and they were no more an “impurity” in the final nanocomposite. The microscopic and structural properties of this composite were compared with that of a composite prepared under identical condition using o-MWNT.

Swelling behavior of chitosan/pectin polyelectrolyte complex membranes. Effect of thermal cross-linking

Abstract: Membranes of the polyelectrolyte complex between chitosan and pectin were prepared by precipitating the complex from a mixture of both polysaccharides It was shown that the swelling kinetics of these membranes follows a Fickean behavior The membranes were heated at 120 °C in order to convert the –NH3+-OOC- salt bonds into amide bonds The thermally treated membranes were stable in strongly acid and basic media The extent of amide bond formation was followed by FTIR spectroscopy It was found that as the reaction time increased, both the absorbance ratio A1744/A1082 and the maximum swelling of the membrane decreased The surface morphology of the membranes did not vary appreciably with the thermal treatment

Physical and Gas Transport Properties of Novel Hyperbranched Polyimide – Silica Hybrid Membranes

Abstract: Physical and gas transport properties of novel hyperbranched polyimide – silica hybrid membranes were investigated Hyperbranched polyamic acid as a precursor was prepared by polycondensation of a triamine monomer, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), and a dianhydride monomer, 4,4’-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA), and subsequently modified the end groups by 3-aminopropyltrimethoxysilane (APTrMOS) The hyperbranched polyimide – silica hybrid membranes were prepared using the polyamic acid, water, and tetramethoxysilane (TMOS) via a sol-gel technique 5 % weight-loss temperature and glass transition temperature of the hyperbranched polyimide – silica hybrid membranes determined by TG-DTA measurement considerably increased with increasing silica content, indicating effective cross-linking at polymer – silica interface mediated by APTrMOS moiety CO2, O2, and N2 permeability coefficients of the hybrid membranes increased with increasing silica content It was pointed out that the increased gas permeabilities are mainly attributed to increase in the gas solubilities On the contrary, CH4 permeability of the hybrid membranes decreased with increasing silica content because of decrease in the CH4 diffusivity and, as a result, CO2/CH4 selectivity of the hybrid membranes remarkably increased It was concluded that the 6FDA-TAPOB hyperbranched polyimide – silica hybrid membranes have high thermal stability and excellent gas selectivity, and are expected to apply to a high-performance gas separation membrane

Poly(vinyl acetate) and Poly(vinyl propionate) Star Polymers via Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization

Abstract: Poly(vinyl acetate) and poly(vinyl propionate) star polymers with four arms were produced via reversible addition fragmentation chain transfer (RAFT) polymerization, employing a tetra-functional xanthate as the RAFT agent, in which the stabilizing groups are linked to the core. These novel star-like RAFT agents induced living/controlled behavior in both the vinyl acetate polymerization at 60 °C and in the vinyl propionate polymerization at 90 °C, respectively, leading to star polymers with minimum polydispersities of 1.2 and maximum apparent number average molecular weights of about 50,000 g·mol-1. The microstructure of the star polymers was confirmed by electrospray ionization mass spectrometry.

Fungicidal and Insecticidal Activity of O-Acyl Chitosan Derivatives

Abstract: A series of O-(acyl) chitosan (OAC) derivatives with a degree of substitution (DS) between 002 and 028 were synthesized by reaction of alkanoic acid derivatives with chitosan in the presence of H2SO4 as a catalyst The reaction was performed at 80 °C for 4 h with different mol ratios of alkanoic acids to chitosan The synthesized compounds were analyzed by 1H- and 13C-NMR spectroscopy A high DS was obtained with O-(butyroyl) chitosan (DS 028) at a mol ratio of (1:5) chitosan to butyric acid Their fungicidal activity against the grey mould Botrytis cinerea (Leotiales: Sclerotiniaceae) and the rice leaf blast pathogen Pyricularia grisea (Teleomorph: Magnaportha grisea) has been evaluated O-(decanoyl) chitosan at mol ratio of 1:2 (chitosan to decanoic acid) was the most active compound against B cinerea (EC50=102 gl-1) and O-(hexanoyl) chitosan displayed the highest activity against P grisea (EC50=111 gl-1) It has been mentioned that some derivatives also repressed spore formation at rather high concentrations (10, 20 and 50 gl-1) The insecticidal activity has been screened at 5 gkg-1 artificial diet against the larvae of the cotton leafworm Spodoptera littoralis (Lepidoptera: Noctuidae) The results revealed that all of the synthesized derivatives showed high inhibition of growth of the larvae of S littoralis compared to chitosan (7% growth inhibition) and the most active one was O-(decanoyl) chitosan (64% growth inhibition) after 5 days of feeding on treated artificial diet

Nanofibers from recycle waste expanded polystyrene using natural solvent

Abstract: A new recycling technique has been developed. In this method, EPS (expanded polystyrene), generally called Styrofoam, is dissolved with natural solvent, d-limonene and electrospun. This method can economically produce the nanofibers. The electrospinning process produces a nonwoven mat of long polymer fibers with diameters in the range of 10–500 nm and high surface areas per unit mass. PS (Polystyrene) polymer dissolved in different solvents such as THF (Tetrahydrofuran), DMF (Dimethylformaide), and DMAc (Dimethylacetamide) etc. may all be electrospun into nanofibers. These solvents cause environmental problem and difficulty of process handling. Natural solvent, d-limonene is used for dissolving PS. PS nanofibers are produced with PS solution using d-Limonene. This paper describes the use of polystyrene (PS) nanofibers electrospun from recycled EPS solution dissolved in d-limonene. The electrospun polystyrene nanofiber diameters vary from 300 to 900 nm, with an average diameter of about 700 nm.

Rheology, Morphology and Estimation of Interfacial Tension of LDPE/EVA and HDPE/EVA Blends

Abstract: Rheological characteristics and morphology of low-density polyethylene (LDPE) /ethylene vinyl acetate copolymer (EVA) and high-density polyethylene (HDPE)/EVA blends were compared. Morphological examinations clearly reveal a two-phase morphology in which the LDPE/EVA blends have smaller dispersed domain size than HDPE/EVA Furthermore, LDPE/EVA shows a finely interconnected morphology at 50wt% of EVA while HDPE/EVA exhibits a coarse co-continuous morphology at the same composition. The morphological observations can be attributed to the lower viscosity ratio and lower interfacial tension in the LDPE/EVA system. The Palierne model also successfully fits to the experimental data giving higher values for interfacial tension of HDPE/EVA system as compared to LDPE/EVA.

Synthesis and Properties of Sepiolite/poly (acrylic acid-co-acrylamide) Nanocomposites

Abstract: Novel hydrogel nanocomposites, based on sepiolite, acrylic acid (AA), acrylamide (AM), and N,N’-methylenebisacrylamide (MBA), were synthesized by solution copolymerization. The structure, morphology and liquid absorbency of these composites were investigated through FTIR, SEM and the like. The influences of sepiolite, crosslinker content, initiator dosage, neutralization degree of AA and molar ratio of AA/AM on the distilled water absorbency (Q w ), physiological saline solution absorbency (Q p ) were discussed in detail. Results showed that needleshaped sepiolite dispersed in nanoscale, and the grafting of AA and/or AM on the sepiolite surface occurred. Compared with the sepiolite-free hydrogel, sepiolite contributed to liquid absorbency, and at its weight content of 15.0%, Q w and Q p were enhanced as high as 11.6% and 14.5%, respectively.

Surface modification of atmospheric plasma activated BOPP by immobilizing chitosan

Abstract: Chitosan was immobilized onto plasma activated biaxially oriented polypropylene (BOPP) films aimed at producing antimicrobially active barrier film for food packaging applications. 1% chitosan dissolved into 0.1 M acetic acid was mixed with 0.1% glutaraldehyde (cross-linking agent) and applied onto N2-plasma + NH3 activated BOPP film. Amount of immobilized chitosan was 1.8 g/m2. Films had strong antimicrobial activity against both Bacillus subtilis and Escherichia coli and they reduced the oxygen transmission rate (OTR) measured in dry conditions from 1500 down to 27 cm3/(m2·24 h). Migration tests for determining the total amounts of substances migrating into food simulants (3% acetic acid, 95% ethanol and iso-octane) indicated, that chitosan coating was permanently immobilized onto BOPP without any leaching (total migration < 2 mg/dm2), thus it met the requirements stipulated in Directive 2002/72/EC relating to plastic materials and articles intended to come into contact with foodstuffs. The results suggest that chitosan treated BOPP films may be exploited in various food packaging applications requiring high oxygen barrier and/or antimicrobially active packaging materials.

Swelling and Thermal Characteristics of Genipin Crosslinked Chitosan and Poly(vinyl pyrrolidone) Hydrogels

Abstract: Chitosan / poly(vinyl pyrrolidone) (PVP) were used to prepare semi-interpenetrating polymeric networks. The hydrogels were crosslinked using genipin, a non-toxic cross-linking agent extracted from the fruits of Gardenia jasminoides Ellis. Swelling properties of these hydrogels were studied in media of different pH’s and temperatures. States of water in the swollen hydrogels at 25°C and pH 7 were determined using Differential Scanning Calorimetry (DSC). The swelling behaviour of the hydrogels was found to be dependent on the temperature and the pH of the swelling medium. The total water content in the hydrogels was found to increase with increasing PVP content.

Porous poly-L-lactic acid scaffold reinforced by chitin fibers

Abstract: In this study, we reinforced the porous poly-L-lactic acid (PLLA) scaffold by chitin fibers. To enhance the strength of the scaffold further, we launched the treatment linking PLLA and chitin fibers by Dicyclohexylcarbodimide (DCC). The structures of the composites with and without link treatment were characterized by Scanning Electron Microscopy (SEM) and porosity. The chemical characteristics of the chitin fibers with and without link treatment were evaluated by Fourier-transformed infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The mechanical strength was measured by compressive tests. The results suggest that after linked with PLLA successfully, the chitin fibers can reinforce the scaffold much more effectively. The linked scaffold, with the compressive strength 4 times than PLLA, also has better structure and pore size than the scaffold without link treatment. So it is a kind of very potential appropriate scaffold for tissue engineering.

Novel Nafion/Hydroxyapatite composite membrane with high crystallinity and low methanol crossover for DMFCs

Abstract: Novel Nafion/Hydroxyapatite (HA) composite membrane with high crystallinity was fabricated to suppress methanol crossover for direct methanol fuel cell (DMFC) applications. In this study, water and methanol diffusivity were evaluated through water-methanol sorption/desorption test and methanol permeation experiments. It was shown that the water-methanol diffusivity and methanol crossover for the composite membranes decrease as HA increases. Structural variation was investigated with wide-angle x-ray. As a result, it was found that the crystallinity of composite membranes increases with HA whereas water uptake content decreases gradually. Methanol permeability using a diffusion cell reduced in the composite membranes, suggesting that high crystallinity and low water uptake of composite membrane result in the suppression of methanol crossover due to the incorporation of HA into Nafion structure.

Homogeneous hydroxyethylation of cellulose in NaOH/urea aqueous solution

Abstract: The 6 wt.% NaOH/4 wt.% urea aqueous solution was proved to be an aqueous non-derivatizing solvent for cellulose by 13C NMR. O-(2-hydroxyethyl)cellulose (HEC) was prepared by a totally homogeneous hydroxyethylation of cellulose using this new solvent for the first time, and the distribution of substituents within anhydroglucose units (AGU) was examined by 13C NMR. It was found that the relative reactivity of the hydroxyl groups within AGU and the new hydroxyl group was in the order C-x > C-6 > C-2 > C-3, an analogous functionalization pattern as HEC obtained by the heterogeneous slurry process. The ethylene oxide efficiency in this homogeneous etherification reaction was 20 – 30%.

Synthesis and characterization of polyurethane/epoxy interpenetrating network nanocomposites with organoclays

Abstract: Novel nanocomposites with varying contents of organophilic montmorillonite (oMMT) were prepared by intercalating oMMT to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP). The PU/EP networks and the oMMT modified PU/EP IPNs nanocomposites were studied with Fourier transform infrared spectrometry, scanning electronic microscopy, transmission electronic microscopy, wide-angle X-ray diffraction, water absorption and tensile test. The results show that oMMT and the IPNs of polyurethane and epoxy resin exhibit synergistic effect on the phase structure and morphology of the IPNs nanocomposites. The addition of oMMT to the PU/EP IPNs matrix provides two fold benefits to the properties of the IPNs nanocomposites. oMMT has not a distinct effect on chemical structure of PU/EP IPNs but promotes the compatibility and phase structure of the IPNs, and the ‘forced compatibility’ of PU and EP in interpenetrating process improves the dispersion degree of oMMT. Both the mechanical properties and water resistance of the PU/EP IPNs nanocomposites are superior to those of the pure PU/EP IPNs.

Adsorption of hexavalent chromium from aqueous solutions using 4-vinyl pyridine grafted poly(ethylene terephthalate) fibers

Abstract: Sorption of hexavalent chromium ions from aqueous solution by 4- vinyl pyridine (4-VP) grafted poly(ethylene terephthalate) (PET) fibers was studied. The Influences of adsorption time, pH of solution and Cr(VI) concentration on the adsorbed amount were investigated. 30 minutes of treatment time was found to be sufficient to reach equilibrium. pH 3.0 was found as the optimum pH value in the process. The maximum adsorption capacity of the material (ks) was found to be 263.16 mg g-1. It was found that the reactive fibers are stable and regenerable by acid or base without losing their activity.

Preparation of methoxy poly(ethyleneglycol)-block-poly(caprolactone) via activated monomer mechanism and examination of micellar characterization

Abstract: The polymerization of e–caprolactone (CL) in the presence of HCl·Et2O via activated monomer mechanism was performed to synthesize diblock copolymers composed of methoxy polyethyleneglycol (MPEG) and poly(e–caprolactone) (PCL). The obtained PCLs had molecular weights close to the theoretical values calculated from the CL to MPEG molar ratios and exibited monomodal GPC curves. We successfully prepared MPEG and PCL diblock copolymers by activated monomer mechanism. The micellar characterization of MPEG-PCL diblock copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AFM and fluorescence techniques. The diblock copolymers formed micelles with a critical micelle concentration (CMC) ranging 2.07×10-2–1.16×10-3 mg/mL depended on the block lengths of diblock copolymers. The diameters of micelles, measured by dynamic light scattering, were 100–250 nm. Most micelles exhibited a spherical shape in AFM.

Optimization of an herbicide release from ethylcellulose microspheres

Abstract: The herbicide 2,4-D was microencapsulated using ethyl cellulose to develop controlled release formulations that protect it from photodegradation and evaporation and to reduce the environment pollution. Ethyl cellulose microspheres loaded with 2,4-D were prepared by the emulsion solvent-evaporation technique. We have obtained the desired microspheres with higher drug entrapment and encapsulation yield by varying certain conditions as stirring speed, polymer-solvent ratio, drug-polymer ratio, pH of continuous phase and organic phase solvent. The shape and size of microspheres were analysed by scanning electron microscopy. The herbicide release was studied at 25 °C and the release data were analysed according to Fick’s Law. The results demonstrate that we can control the release rate by modifying the process parameters.

Pectin-based surperabsorbent hydrogels crosslinked by some chemicals: synthesis and characterization

Abstract: Synthesis of superabsorbent hydrogels from pectin was investigated using three kinds of crosslinkers, CaCl2, ethylene glycol diglycidyl ether (EGE), and glutaraldehyde (GA). Among them, GA was the most suitable to attain high absorbency, reaching ca. 500 g/g in pure water. On the contrary, hydrogels crosslinked by CaCl2 and EGE absorbed much less water, their maximum absorbency was around 200 g/g and 40 g/g, respectively. Absorbency in 0.9% NaCl solution of hydrogel crosslinked by GA was as low as 15 g/g, which indicates absorbency of hydrogels in the present study is sensitive to salt concentration. Biodegradability of pectin-based hydrogels in activated sludge at 25 °C for 18 days was 60–65%.

Preparations and Properties of Waterborne Polyurethane / Nanosilica Composites

Abstract: Aqueous dispersion of polyurethane(PU) ionomers, based on poly(tetramethylene glycol) as soft segment, isophorone diisocyanate as diisocyanate, 1,4-butanediol as chain extender, dimethylol propionic acid as potential ionic center, triethylene tetramine as crosslinker, and triethyl amine as neutralizer, were reinforced with hydrophobic nanosilica to give waterborne PU/nanosilica composites. The reinforcing effects of nanosilica were examined in terms of mechanical, dynamic mechanical, and thermal properties together with water swell and transparency of the dispersion cast films. With the addition of nanosilica to PU, tensile modulus and strength increased, and the rubbery modulus increased in magnitude and extended to higher temperature, and these enhanced mechanical and thermal properties, together with increased swell resistance were obtained without scarifying the transparency of the films.

Synthesis and characterization of diblock and triblock copolymer by enzymatic ring-opening polymerization of ε-caprolactone and ATRP of styrene

Abstract: Diblock and triblock copolymer of e-caprolactone(e-CL) and styrene(St) were obtained by the combination of two different polymerization process, namely enzymatic ring-opening polymerization(ROP) and atom transfer radical polymerization(ATRP) methods. Mono-/di- hydroxyl terminated macromolecules were prepared by enzymatic ROP of e-CL in the presence of Novozyme-435 and methanol/ethylene glycol as biocatalyst and initiator, respectively, and subsequently converted to bromine ended polycaprolactone(PCL) by the esterification of the resulting macromolecules with α-bromopropionyl bromide. The mono- and difunctional macroinitiators were employed in ATRP of styrene using CuCl/2, 2’-bipyridine(bpy) as the catalyst system. The GPC and 1H-NMR analysis indicated a controlled/living radical polymerization which resulted in the formation of block copolymers with narrow polydispersities.

Preparation and Characterization of PS/Multi-Walled Carbon Nanotube Nanocomposites

Abstract: Nanocomposites of polystyrene (PS) with multi-walled carbon nanotubes (MWNT) were produced by co-rotating twin-screw extruder. Characterization of these materials included scanning electron microscopy (SEM), transmission electron microscopy (TEM) and rheology in order to obtain the information on the dispersion of MWNT in the polymeric matrix. It is found that the MWNT dispersed uniformly through the PS matrix showing no significant agglomeration in the various compositions studied. In addition, we also investigated the thermal properties, glass transition temperature and thermal decomposition behavior as a function of the increasing MWNT content.

Pressure Effect on Viscosity for Atactic and Syndiotactic Polystyrene

Abstract: The effect of pressure on viscosity is an important but often overlooked aspect of the flow properties of polymeric materials Generally, an exponential dependence (the so-called Barus equation: η=η0exp(βP)) can be adopted to describe this effect In this work two polymers (an atactic and a syndiotactic Polystyrene) were characterized as far as the effect of pressure on viscosity is concerned by analyzing the non-linearities in the so-called Bagley plots The results obtained show that for both materials the average value of β is in the range 1–3×10-8 Pa-1 No relevant effects of temperature and shear rate were detected in the range analyzed The data obtained were also described by means of a Cross-Vogel model, which reproduces the main features of experimental data

Synthesis of novel poly(pyrazabole)s with electron-withdrawing structure in their main chain

Abstract: Novel organoboron polymers containing pyrazabole and electron withdrawing moiety in the main chain were prepared by Heck-Sonogashira coupling. The coupling reaction between various diyne monomers and pyrazabole derivatives gave the corresponding polymers in good yields. The optical properties of the obtained polymers were investigated by UV-vis absorption and fluorescence spectroscopy. The relation between the electron density on the boron atoms and the optical properties of the corresponding polymers was also studied.

Synthesis and characterization of diblock copolymer by enzymatic ring-opening polymerization and ATRP from a novel bifunctional initiator

Abstract: A new method is reported for synthesizing AB-type diblock copolymer polycaprolactone-block-polystyrene (PCL-b-PSt) from a novel bifunctional initiator 2.2.2-trichloroethanol (TCE) by combining two different polymerization techniques: enzymatic ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Trichloromethyl terminated PCL was prepared by enzymatic ROP of e-caprolactone (e-CL) in the presence of Novozyme-435 and TCE as biocatalyst and initiator, respectively, and subsequently employed in ATRP of styrene (St) using CuCl/2, 2′-bipyridine (bpy) as the catalyst system. The GPC and NMR analysis indicated the formation of the diblock copolymer including the biodegradable PCL block and the well-defined PSt block.

Grazing incidence X-ray diffraction study on surface crystal structure of polyethylene thin films

Abstract: Crystal structure in thin films of melt-crystallized and annealed polyethylene (PE) was examined by grazing incidence X-ray diffraction measurements. Choosing appropriate incident angles of X-rays to the films, surface and bulk molecular aggregation states were successfully extracted. Consequently, it was found that chain packing structure in the surface region was different from that in the bulk one. Based on paracrystalline analysis for the (110) reflection and its higher-order ones of PE orthorhombic crystal, it was clarified that the ordering for the crystalline lattice was lower in the surface region. Also, apparent crystallinity in the surface was lower than the bulk one. These results indicate that disordered crystallites were preferentially formed in the surface region.

Novel Conjugated Polymers Containing [2.2]Paracyclophane and Carbazole Units with Efficient Photoluminescence

Abstract: Novel through-space conjugated polymers based on PPE having [2.2]paracyclophane and N-alkylcarbazole units in the main chain were synthesized by Sonogashira-coupling reaction. All polymers were quite soluble in a variety of organic solvents. Transparent and uniform thin films of the polymers were obtained easily by casting or spin-coating from toluene solution. These polymers possessed good thermal stability. The polymers exhibited strong blue photoluminescence in solution and bluish-green photoluminescence in the solid state.

Preparation and Characterization of New Optically Active Poly(amide imide)s Derived from N,N’-(4,4’-Sulphonediphthaloyl)-bis-(s)-(+)-valine Diacid Chloride and Aromatic Diamines under Microwave Irradiation

Abstract: The present paper is an extension of microwave method describing the synthesis of the new optically active poly(amide-imide)s. The main focus of this work is the design of new effective microwave method for preparing optically active poly(amide-imide)s. Imide-acid (3) was synthesized by the reaction of 3,3’,4,4’-diphenylsulfonetetracarboxylic dianhydride (1) with (s)-(+)-valine (2) in acetic acid. The compound 3 was coverted to diacid chloride 4 by reaction with excess amount of thionyl chloride. Polycondensetion reaction of diacid chloride 4 with several aromatic diamines such as 4,4’-sulfonyldianiline (5a), 4,4’-diaminodiphenyl methane (5b), 4,4’-diaminodiphenylether (5c), p-phenylenediamine (5d), m-phenylenediamine (5e), 2,4-diaminotoluene (5f) and 4,4’-diaminobiphenyl (5g) was carried out in the presence of small amount of o-cresol under microwave irradiation as well as conventional heating method. We obtained a series of optically active poly(amide-imide)s with high yield and inherent viscosity ranging from 0.22-0.35 dL/g. These new polymers were characterized by FT IR, 1H NMR, elemental analyses and specific rotation techniques.