bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of multiblock copolyesters containing poly(dimethylsiloxane) in the soft segments
Authors: El Fray Miroslawa , Altstaedt Volker 
Published: October 2003

AbstractSynthesis and thermal properties of poly(aliphatic/aromatic‐ester) copolymers containing additionally poly(dimethylsiloxane) (PDMS) chains in the soft segments are discussed. A two step method of transesterification and polycondensation from the melt was carried out in a presence of magnesium‐titanate catalyst. An aliphatic dimer fatty acid was used as a component of the soft segments while poly(butylene terephthalate) (PBT) constituted the hard blocks. Effectiveness of the incorporation of PDMS into polymer chain was confirmed by the Soxhlet extraction and infrared spectroscopy of an excess of 1,4‐butane diol destilled off from the polycondensation reaction. Multiblock copolymers showed microphase separation as determined by differential scanning calorimetry. Incorporation of a small amount of PDMS (up to 14.5 wt.‐%) into polymer chain containg low concentration of hard segments of PBT lead to decrease in crystallinity of such copolymers. This may indicate that semicrystalline PBT are dissolved in the amorphous matrix of the soft segments.
Synthesis and properties of segmented copolymers of polyphenylene ether and tetra‐amide units
Authors: Krijgsman Josien , Feijen Jan , Gaymans Reinoud J. 
Published: October 2003

AbstractCopolymers of telechelic poly(2,6‐dimethyl‐1,4‐phenylene ether) segments with terephthalic methyl ester endgroups (PPE‐2T, 3100 g/mol), uniform crystallizable tetra‐amide units based on nylon‐6,T (T6T6T, 13 wt%) and dodecanediol (C12) as an extender were made via a polycondensation reaction. The PPE‐2T/C12/T6T6T copolymers are semi‐crystalline materials with a glass transition temperature (Tg) of 169°C, a melting temperature (Tm) of 268°C and a very high Tg/Tm ratio of 0.82. The modulus is high up to the Tg and the modulus in the rubbery plateau after injection moulding is 10 MPa. The materials are slightly transparent and have good solvent resistance, low water absorption and good processability. With DSC it was calculated that the crystallinity of T6T6T in the copolymer is around 70%. The undercooling (Tm‐Tc) as measured by DSC is 18°C at a cooling rate of 20°C/min. With WAXD it was shown that the tetra‐amide units remain partially organized in the melt.
Synthesis and properties of poly(butylene terephthalate)‐poly(ethylene oxide)‐poly(dimethylsiloxane) block copolymers
Authors: Dahrouch M. , Schmidt A. , Leemans L. , Linssen H. , Götz H. 
Published: October 2003

Abstractchemical structure image
Poly(butylene terephthalate)‐poly(ethylene oxide)‐poly(dimethyl siloxane)‐poly(ethylene oxide) block copolymers, (PBT‐PEO‐PDMS‐PEO)m, are synthesized by polycondensation (PC) of dimethylterephtalate (DMT), 1,4‐butanediol (BDO) and PEO‐PDMS‐PEO. The soft block has been incorporated from 10 to 70 wt‐%; the total molecular weight (MW) of the block‐copolymers amounts to 16000 ‐ 20000 g/mol.One major problem of polyether‐PBT thermoplastic elastomers is their poor thermo‐oxidative stability. Due to the excellent heat stability of PDMS, the resistance of this new thermoplastic elastomer against thermo‐oxidative degradation has been increased 80 %!From differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the PEO‐PDMS‐PEO based COPEs, three phases can be distinguished. Besides the crystalline PBT phase, an amorphous mixed phase of PBT and PEO and an almost pure PDMS phase have been found. Due to the high concentration of the mixed PBT‐PEO phase, the low temperature modulus and the glass transition temperature, Tg, are not dominated by the pure PDMS phase (Tg = −114°C). Depending on the amount of PBT and PEO present, the main glass transition lies in the range of −50°C to 50°C.
Synthesis and characterization of poly(ethylene glycol) methyl ether endcapped poly(ethylene terephthalate)
Authors: Lin Qin , Unal Serkan , Fornof Ann R. , Wei Yuping , Li Huimin , Armentrout R. Scott , Long Timothy E. 
Published: October 2003

AbstractLinear and branched poly(ethylene terephthalate) (PET) copolymers with polyethylene glycol) (PEG) methyl ether (700 or 2000 g/mol) end groups were synthesized using conventional melt polymerization. DSC analysis demonstrated that low levels of PEG end groups accelerated PET crystallization. The incorporated PEG end groups also decreased the crystallization temperature of PET dramatically, and copolymers with a high content of PEG (>17.6 wt%) were able to crystallize at room temperature. Rheological analysis demonstrated that the presence of PEG end groups effectively decreased the melt viscosities and facilitated melt processing. XPS and ATR‐FTIR revealed that the PEG end groups tended to aggregate on the surface, and the surface of compression molded films containing 34.0 wt% PEG were PEG rich (85 wt% PEG). PEG end‐capped PET (34.0 wt% PEG) and PET films were immersed into a fibrinogen solution (0.7 mg/mL BSA) for 72 h to investigate the propensity for protein adhesion. XPS demonstrated that the concentration of nitrogen (1.05%) on the surface of PEG endcapped PET film was statistically lower than PET (7.67%). SEM analysis was consistent with XPS results, and revealed the presence of adsorbed protein on the surface of PET films.
Synthesis and properties of dendritic polymers based on natural amino acids
Authors: Bilibin Alexander , Zorin Ivan , Saratovsky Sergey , Moukhina Irina , Egorova Galina , Girbasova Nina 
Published: October 2003

AbstractDifferent approaches, including polycondensation, polymerization, polymer analog condensation, and ionic binding have been investigated for synthesis of amino acid‐based dendritic polymers. It was shown that a growth of dendrons generation prevents obtaining of products with high polymerization degree in polycondensation and polymerization procedures. In polymer analog condensation a growth of dendrons generation leads to considerable decrease of polymer analog reaction rate as well as substitution degree. Degree of ionic binding depends on a strength of ionogenic groups and dendrns generation.
Synthesis and characterization of hyperbranched aromatic polyamide copolymers prepared from AB2 and AB monomers
Authors: Jikei Mitsutoshi , Fujii Ken , Kakimoto Masa‐aki 
Published: October 2003

AbstractA series of hyperbranched aromatic polyamide copolymers has been prepared and characterized from direct polycondensation of AB2 and AB monomers. Structure of the monomers and the molar ratio of AB2/AB showed strong influence on the properties of resulting copolymers. A small amount of AB2 branching unit improved markedly the solubility of the resulting copolymer. Mark‐Houwink parameters of the copolymers were essentially independent of the mole ratio of the monomers. The physical and mechanical properties of resulting copolymers were influenced not only by the mole ratio of monomers, but also by the structure of the monomers employed.
Hyperbranched polyimides prepared by ideal A2+B3 polymerization, non‐ideal A2+B3 polymerization and AB2 self‐polymerization
Authors: Hao Jianjun , Jikei Mitsutoshi , Kakimoto Masa‐aki 
Published: October 2003

AbstractIn this paper, hyperbranched polyimides having the same repeating unit were synthesized by employing ideal A2+B3 polymerization, non‐ideal A2+B3 polymerization and AB2 self‐polymerization methods. The polymerization behavior, polymer properties were compared for three methods. Hyperbranched polyimides by ideal A2+B3 polymerization, non‐ideal A2+B3 polymerization and AB2 self‐polymerization methods show apparent difference in many physical properties, such as inherent viscosity, glass transition temperature, and film formation behavior etc. The hyperbranched polymers by the non‐ideal A2+B3 polymerization are suitable for smooth, flexible and self‐standing film preparation, which provides useful information for hyperbranched polymers toward self‐standing materials.
Synthesis and characterisation of branched polyarylethers
Authors: Weber Martin , Charoensirisomboon Piyada 
Published: October 2003

AbstractPolyarylethers (Polysulfone: PSU, Polyethersulfone: PES) belong to the group of high performance polymers, having high glass transition temperature as well as high continuous use temperature. As a consequence of their high glass transition temperature, these polymers display high melt viscosity, which limits the number of accessible applications. Since the conventional methods to improve the flow characteristics are limited, the influence of branching by incorporation of the tri‐functional monomer 1,1,1‐Tris‐(4‐hydroxyphenyl)ethane (THPE) on the flow and the mechanical performance of PES was studied.Branching enhances the flow of Polyethersulfone significantly, but has a deleterious effect on the toughness, especially Charpy impact and tensile elongation.
Liquid crystalline properties of unsegmented and segmented polyurethanes synthesised from high aspect ratio mesogenic diols
Authors: Srinivasan Kalathur Sabdham Vangepuram , Padmavathy Tallury 
Published: October 2003

AbstractA series of novel tetrad high aspect ratio mesogenic diol monomers 4‐{[4‐(n‐hydroxyalkoxy)‐phenylimino]‐methyl}‐benzoic acid 4‐{[4‐(n‐hydroxyalkoxy)‐phenylimino]‐methyl}‐phenyl ester were prepared with varying alkoxy spacer length (n=2,4,6,8,10) by reacting 4‐formylbenzoic acid 4‐formylphenyl ester and 4‐(n‐hydroxyalkoxy) anilines. Two series of thermotropic main chain liquid crystalline unsegmented polyurethanes (PUs) were obtained by the polyaddition of the mesogenic diols with hexamethylene diisocyanate (HMDI) and methylene bis(cyclohexylisocyanate) (H12MDI) in dimethylformamide respectively. The effect of the incorporation of a third component namely polyol on the liquid crystalline properties of the polyurethanes was also studied. Linear segmented PUs were synthesised by a two‐step block copolymerisation method. The PUs synthesised were based on six spacer mesogenic diol chain extender, soft segments poly(tetramethylene oxide)glycol (PTMG) (Mn= 650,1000,2000) and polycaprolactone diol (PCL) (Mn=530,1250,2000) of varying molecular weights and different diisocyanates including HMDI, H12MDI and methylene bis(phenylene isocyanate) (MDI). Structural elucidation was carried out by elemental analysis, fourier transform infra red (FT‐IR), nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Inherent viscosity of the unsegmented polymers measured in methanesulphonic acid at 26°C was in the range of 0.13 ‐ 0.65 dL/g while the molecular weights and molecular weight distribution of the segmented polyruethanes was determined using gel permeation chromatography (GPC). Mesomorphic properties were studied by differential scanning calorimetry (DSC) and hot stage polarising optical microscopy and the thermal stability was determined by thermogravimetric(TG)analysis. The monomeric diols and the polyurethanes exhibited nematic texture and good mesophase stability. It was observed that the partial replacement of the mesogenic diol by the polyol of varying molecular weights influenced the phase transitions and the occurrence of mesophase textures. The phase transition temperatures of the investigated polyurethanes showed dependence on the chain length of the soft segment and on the content of the mesogen moiety. A higher content of mesogenic moiety was needed to obtain liquid crystalline property when the soft segment length was increased as observed in the case of PTMG. Grained and threaded textures were observed depending on the molecular weight of the soft segment, the mesogen content and the diisocyanate. The stress‐strain analyses showed that the polymers bused on high molecular weight PTMG soft segment have elastomeric property while the PCL based PUs displayed no elastomeric property.
Designing aromatic polyamides and polyimides for gas separation membranes
Authors: de Abajo Javier , de la Campa José G. , Lozano Angel E. 
Published: October 2003

AbstractAromatic polyamides and polyimides with improved gas permselectivity, can be designed and prepared by systematically changing structural elements that affect these properties. Indeed, a conscientious choosing of the chemical changes may still provide a promising approach to get better and better polymers for selective filtration of gases.The results of this work, in which novel monomers have been used, have confirmed that gas permeability through aromatic polyamides and polyimides much higher than that of conventional polyamides and polyimides can be achieved. It has been done by introducing bulky side groups, using non‐planar monomers, and combining these elements on both monomers: diamines and dianhydrides or diamines and diacids. A theoretical study has also been made to explain the behaviour of some individual polymers, comparing experimental and calculated values of density and free volume.
New reactive polymeric systems for use as waveguide materials in integrated optics
Authors: Dreyer Christian , Schneider Jürgen , Göcks Karin , Beuster Brigitte , Bauer Monika , Keil Norbert , Yao Huihai , Zawadzki Crispin 
Published: October 2003

AbstractCross‐linked polymeric materials are used in a wide range of applications. Special compositions are used in micro‐system technologies and its utilization is extending to integrated optics. We have been working for several years in the field of polymers for optical applications.Highly fluorinated polycyanurate systems have been proven as promising waveguide materials in integrated optics. The refractive index can be adjusted reproducibly in a wide range almost continuously. The layer quality was optimized. Low optical losses of less than 0.3 dB/cm@1550nm were obtained and working optical prototypes were developed. The birefringence had been a major problem, but this was solved by adjusting the coefficient of thermal expansion of substrate and film.We will report in this paper on the polycyanurate ester resins and the new triazine containing polymeric systems.
Low viscous unsaturated polyester resin for monomer free UP‐resins
Authors: Hegemann Günter 
Published: October 2003

AbstractIt was possible to develop comonomer free unsaturated polyester resins for the application in electrical industry. By testing model compounds and mixtures of model compounds it was possible to find the optimised structure of the resin molecule with respect to the position of the copolymerizable double bonds. By choosing the proper composition of the other components of the resin, e.g. the glycols and modifying dicarboxylic acids, it was also possible to manufacture low viscous resins.
New generation of fire retardant polyester resins
Authors: Kicko‐Walczak Ewa 
Published: October 2003

AbstractSmoke evolution [in a smoke chamber (750 x 750 x 1000) ± 5 mm, Polish Standard PN‐91/K‐02501 equivalent to UIC 561‐OR (1991)] was studied in, and the oxygen index flammability test (Polish Standard PN‐76/C‐89020) was carried out for, glass‐reinforced polyester (GRP) laminates obtained with unsaturated polyester (UP) resins containing chlorine and bromine in the chain. In these studies, the effect on these properties of such additives as ZnSnO3 (ZS), ZnSn(OH)6 (ZHS), Al(OH)3 or Mg(OH)2 and Sb2O3 in an amount of up to 30 mass‐% was determined. The most efficient ignition and smoke‐evolution retarder from among the investigated compounds was ZS and ZHS, whereas an essential reduction in smoke evolution was observed also with Sb2O3. GRP laminates with these additives meet the fire‐safety recommendations concerning smoke evolution from materials used in transportation means and in the building industry.
Synthesis, characterization and properties of polycarbonate containing carboxyl side groups
Authors: Zhang Ruifeng , Moore J.A. 
Published: October 2003

AbstractDiphenolic Acid, DPA [bis(4‐hydroxyphenyl)pentanoic acid] can be made from cellulose‐rich waste. The t‐butyl ester was converted to homo‐ and copolycar‐ bonates (with bis‐phenol‐A, BPA). Deblocking the ester yielded polycarbonates with pendent carboxyl groups that exhibit all the properties of polyelectrolytes and retain solubility in aqueous base without degradation for long periods.
New silicon‐containing heterocyclic polyimides
Authors: Schulz Burkhard , Hamciuc Elena , Köpnick Thomas , Kaminorz Yvette , Bruma Maria 
Published: October 2003

AbstractNew aromatic polyimides and polyamide‐imides with phenylquinoxaline rings and dimethylsilane units have been synthesized by solution polycondensation reaction of aromatic diamines containing phenylquinoxaline units with bis(3,4‐dicarboxyphenyl)‐dimethylsilane dianhydride, or with a diacid chloride resulting from the reaction of this dianhydride with p‐aminobenzoic acid. These polymers were easily soluble in organic solvents, such as N‐methylpyrrolidinone and dimethylacetamide, and showed high thermal stability with decomposition temperature being above 440°C and glass transition temperature in the range of 245‐285°C. Very thin coatings were deposited from polymer solutions onto silicon wafers and exhibited smooth, pinhole‐free surface in atomic force microscopy investigations. Some of these polymers showed blue fluorescence in solution and films, with a maximum in the range of 415‐425 nm.
Active polycondensation: from pep tide chemistry to amino acid based biodegradable polymers
Authors: Katsarava Ramaz 
Published: October 2003

AbstractNew polycondensation (PC) methods of polymer synthesis using non‐traditional active derivative of dicarboxylic acids are reviewed. The new PC methods are named by general name “Active Polycondensation” (APC) to tell them from traditional low‐temperature PC. The most of these methods are based on well known in peptide chemistry approaches to the activation of carboxylic groups. In the present paper the syntheses of heterochain polymers of basic classes ‐ polyamides, polyesters, polyurethanes, polyureas, and polybenzazoles by interaction of various active diesters with di‐ and polyfunctional nucleophiles are discussed in brief. Special attention is given to the synthesis of non‐conventional heterochain macromolecular systems, in particular poly(ester amide)s (PEAs), composed of naturally occurring α‐amino acids and other non‐toxic building blocks like fatty diacids and diols ‐ synthetic analogues of naturally occurring amino acid based polymers ‐ peptides and proteins. The synthesis and properties, biodegradation, and some practical applications of PEAs are discussed in brief.
Stereochemistry driven cocrystallisation phenomena in partially cycloaliphatic polyamides
Authors: Koning Cor , Vanhaecht Bert , Willem Rudolph , Biesemans Monique , Goderis Bart , Rimez Bart 
Published: October 2003

AbstractTwo series of isomeric copolyamides were synthesised, viz. polyamides 12.6 for which the adipic acid residues were partially replaced by cis/trans‐1,4‐cyclohexanedicarboxylic acid (1,4‐CHDA), and polyamides 4.14 for which the 1,4‐diaminobutane residues were partially replaced by cis/trans‐1,4‐diaminocyclohexane (1,4‐DACH). A careful DSC and WAXS analysis learned that only the trans isomers of both 1,4‐DACH and 1,4‐CHDA are incorporated into the crystalline phase. During DSC analysis, an intitial high trans content is preserved in the case of the non‐isomerising 1,4‐DACH, whereas the 1,4‐CHDA residues gradually isomerise from a high initial trans content to a significanly lower trans content. Since these cis residues are not incorporated into the crystalline domains, the lower second heating melting points of the 1,4‐CHDA‐based copolyamides in comparison with 1,4‐DACH‐based copolyamides, having similar cycloaliphatic monomer contents, can be understood.
Vinyl monomers containing active hydrogen atoms are a new type of monomer for polycondensation
Authors: Rozenberg Boris A. 
Published: October 2003

AbstractThe latest findings in author's laboratory devoted to the understanding kinetic peculiarities and mechanism of vinyl macromonomers formation by the example of anionic polymerization of 2‐hydroxyethylacrylate (HEA) and 2‐hydroxyethylmethacrylate (HEMA) containing group with mobile hydrogen atoms are discussed. It was shown that polymerization is accompanied by proton‐transfer in each elementary propagation step, which leads to isomerization of the backbone and formation of polyester type macromonomers. Polymerization is accompanied by side transesterification reaction with formation of polyester diacrylates and polyester diols. The peculiarities of polymerization mechanism under the action of alkali metals and its alkoholates were established. Expected applications of the polymerization products are discussed.
Copolyesters based on poly(butylene terephthalate)s containing cyclohexyl groups: synthesis, structure and crystallization
Authors: Sandhya T.E. , Ramesh C. , Sivaram S. 
Published: October 2003

AbstractPoly(butylene terephthalate‐co‐cyclohexylene dimethylene terephthalate) copolymers PBTCT, were synthesized by melt condensation with compositions ranging from 94/08 to 23/77. 13C NMR spectroscopy was used to study the microstructure of the copolyesters and was found to be completely random. The melting temperature, crystallization temperature on cooling, enthalpy of melting and crystallization followed an eutectic behaviour. Thermal and x‐ray diffraction studies indicated that the copolyesters in all composition could crystallize. The XRD studies further indicated that PBT rich copolyesters in the range 75 to 100% BT, crystallized in the PBT lattice while the copolyesters rich in PCT having 38 to 100% CT, crystallized in the PCT lattice.
Atypical polysaccharide physical gels: structure/property relationships
Authors: Clayer Alexandra , Vachoud Laurent , Viton Christophe , Domard Alain 
Published: October 2003

AbstractChitin and chitosan are polysaccharides produced by the biomass. They have the same general chemical structure and constitute the series of linear copolymers of linked β, (1‐>4) glucosamine and N‐actylglucosamine. We studied the possibility of forming physical gels with all the terms of this series, whatever the proportion of the two kinds of residues included in the polymer chains. We show that physical gelation is still possible through a percolating process when certain important conditions are met. Initially the concentration in polymer must be above C*; a critical value of the balance between hydrophobic and hydrophilic interactions must be achieved and gelation must occur simultaneously everywhere in the medium. These conditions were observed in several situations allowing the formation of different kinds of gels at all values of DA. In view of the rare bio‐active properties of chitin and chitosan, these gels were tested for living tissue regeneration and constitute very interesting examples in illustration of our concept of decoys for biological media.
Encapsulation of magnetic self‐assembled systems in thermoreversible gels
Authors: Guenet Jean‐Michel , Poux Sandrine , Lopez Daniel , Thierry Annette , Mathis André , Green Mark M. , Liu Weihong 
Published: October 2003

AbstractWe describe two different ways of encapsulating within the fibrils of thermoreversible polymer gels the filaments of a supermolecular polymer formed by self‐assembly of a bicopper complex. Heterogeneous nucleation is brought about with gels made from isotactic poly(styrene) while compound formation occurs with gels made from poly(hexyl isocyanate). These ways depend upon the interaction between the wings of the supermolecular polymer and the side groups of the polymer. In all cases, the filaments retain their 1‐D structure. Preliminary results from magnetic susceptibility measurements show a striking difference between the pure and the encapsulated supermolecular polymer.