Oxyethylene Chain Research Articles

Self-diffusion study of micelles in poly(oxyethylene)–polydimethylsiloxane diblock copolymer and poly(oxyethylene) alkyl ether systems

Self-diffusion constants of amphiphilic molecules in D 2O solutions of mixed poly(oxyethylene)–polydimethylsiloxane diblock copolymer (POE–PDMS, Si m C 3 EO n ) and poly(oxyethylene) dodecyl ether ( C 12 EO n ) were measured by pulsed-field-gradient NMR method. In the D 2O/Si 25C 3EO 51.6/C 12EO 8 or D 2O/Si 52C 3EO 51.6/C 12EO 8 systems, small and large micelles coexist in a wide range of Si m C 3EO 51.6 fraction in total amphiphiles, whereas such a coexisting phenomenon does not take place in the D 2O/Si 5.8C 3EO 51.6/C 12EO 8 system. The coexisting phenomenon also takes place in the D 2O/Si 25C 3EO 51.6/C 12EO 5 system although the range of mixing fraction is limited. By obtaining each contribution of surfactant and copolymer molecules to the attenuation decay of the echo signal from the proton of the poly(oxyethylene) chain, we could evaluate the composition of the mixed micelles in the D 2O/Si 25C 3EO 51.6/C 12EO 8 system. The copolymer content in the mixed micelle increases proportionally to the copolymer mole fraction in the aqueous solution. From the series of self-diffusion measurements, we can conclude that the miscibility of Si m C 3 EO n and C 12 EO n in aqueous micelles becomes poor and the coexisting phenomenon takes place when the PDMS chain becomes much longer than the dodecyl chain of C 12 EO n or the POE chain of C 12 EO n becomes long. Furthermore it is also revealed that very few silicone copolymer molecules can be incorporated in small surfactant micelles.

Study of the cloud point of an amphiphilic antidepressant drug: Influence of surfactants, polymers, and non-electrolytes

The clouding phenomenon has been studied in an amphiphilic antidepressant drug (amitriptyline, AMT) solution prepared in 10 mM sodium phosphate (SP) buffer in the presence of various additives. The pH variation has also been carried out in the solution containing a fixed amount of the drug (50 mM) and various surfactants (sodium dodecylsulfate, SDS, 5 mM, cetylpyridinium bromide, CPB, 0.5 mM, and t-octylphenoxypolyethoxyethanol, TX-100, 2 mM). Cloud point (CP) was found to decrease with increasing pH with or without surfactants. However, when surfactants were added to 50 mM AMT solutions at fixed pH (6.7), the CP behavior was found to vary according to the ionic nature of the surfactant. Similarly, with polyether type nonionic surfactants (Brij 35, TX-100, Tween 20, Tween 40, Tween 60, Tween 80) the CP was found to increase more distinctly with the surfactant having lower oxyethylene chains (i.e., TX-100). Urea and alkylureas were found to decrease the CP, which was found to be dependent upon the number of methyl groups present in the urea molecules. Contrary to this, thioureas increased the CP slightly. However, the presence of methyl group(s) has similar effect as in alkylureas. The effect of amino acids on CP of AMT solution depended upon their acidic/basic as well as polar/non-polar characteristics. All the sugars caused a decrease in CP. However, the effect of polymers on CP was found to be dependent upon the number of units present in a particular polymer of polyvinylpyrrolidone (PVP) category. The overall behavior can be interpreted in terms of variations in drug-aggregate morphology as well as modifications in the background solvents.

Wormlike Micelles of Pentaoxyethylene Tetradecyl Ether C14E5 and Hexaoxyethylene Hexadecyl Ether C16E6

Micelles of pentaoxyethylene tetradecyl C14E5 and hexaoxyethylene hexadecyl C16E6 ethers in dilute aqueous solutions were characterized by static (SLS) and dynamic light scattering (DLS) experiments at several temperatures T between the LCST and UCST phase boundaries. The SLS results were successfully analyzed with the aid of the thermodynamic theory formulated with wormlike spherocylinder model for SLS of micelle solutions, yielding the molar mass Mw of the micelles as a function of concentration c and the cross-sectional diameter d. The radius of gyration S21/2 of the micelles as a function of Mw was found to be well described by the corresponding theories for the wormlike chain model. Combining the present and previous results for various CiEj (polyoxyethylene alkyl ether) micelles, effects of the hydrophobic (alkyl) i and hydrophilic (oxyethylene) chain length j on the micellar characteristics have been clarified as: (i) The weight-average micellar length Lw becomes larger for larger i and smaller j. (ii) The d values do not significantly vary with the values of i and j. (iii) The stiffness parameter λ−1 decreases with increasing i at fixed j and increases with increasing j at fixed i.

Superabsorbent polymeric materials. XIII. Effect of oxyethylene chain length on water absorbency for the sodium acrylate and poly(ethylene glycol) methyl ether acrylate (PEGMEAn) copolymeric gels

In a previous study, we prepared a series of xerogels based on sodium acrylate (NaA) and 2-hydroxyethyl methacrylate (HEMA, OE = 1) or poly(ethylene glycol) methacrylate (PEGMA, OE = 6) with different oxyethylene (OE) units. The effect of the contents of HEMA and PEGMA in the copolymeric gel on the swelling behavior in deionized water and various saline solutions was studied. Their results showed that the water absorbencies for these two series gels were effectively improved by adding a small amount of HEMA or PEGMA. In this article, a series of novel xerogels based on NaA and hydrophilic monomer poly(ethylene glycol) methyl ether acrylate (PEGMEAn), which was synthesized from acryloyl chloride and poly(ethylene glycol) monomethyl ether with three oxyethylene (OE = 9, 16, 45) chain lengths, were prepared by inverse suspension polymerization. The effects of OE chain length in the copolymeric gel on the water absorption behavior and initial absorption rate for the present xerogels were investigated. Results showed that adding a small amount of PEGMEAn could effectively increase the water absorbency of the gels. In addition, the water absorbency decreased with an increase of the OE chain length in PEGMEAn. The initial absorption rate for the present copolymeric gels increased with increasing OE chain length in PEGMEAn and the content of PEGMEAn in the copolymeric gels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 927–934, 2006

Carbohydrate Rod Conjugates: Ternary Rod−Coil Molecules Forming Complex Liquid Crystal Structures

T-shaped polyphilic triblock molecules, consisting of a rodlike p-terphenyl unit, a hydrophilic and flexible laterally attached oligo(oxyethylene) chain terminated by an 1-acylamino-1-deoxy-D-sorbitol unit, and two end-attached lipophilic alkyl chains, have been synthesized by palladium-catalyzed cross-coupling reactions as the key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by polarized light microscopy, differential scanning calorimetry (DSC), and X-ray scattering. We investigated the mode of self-organization as a function of the length and position of the lateral polar chain and the length of the terminal alkyl chains. Depending on the size of the polar and lipophilic segments, a series of unusual liquid crystalline phases was detected. In three of these phases, the space is divided into three distinct periodic subspaces. In addition to a hexagonal channeled layer phase (ChL(hex)) consisting of layers that are penetrated by polar columns, there are also two honeycomb-like network structures formed by square (Col(squ)/p4mm) or pentagonal cylinders (Col(squ)/p4gm). The cylinder walls consist of the terphenyl units fused by columns of alkyl chains, and the interior contains the polar side chains. In addition, a hexagonal columnar phase was observed in which the polar columns are organized in a continuum of terphenyls and alkyl chains with an organization of the terphenyl cores tangentially around the columns with the long axis perpendicular to the columns. For one compound, a reversal of birefringence was observed, which is explained by a reorientation of the terphenyl cores. The addition of protic solvents induces lamellar phases.

Synthesis and Solubility Properties of Methanofullerenes Containing Primary Ammonium Ion Functionalities

AbstractThe synthesis of novel methanofullerene derivatives bearing a primary ammonium ion functionality is described. They are obtained by a Bingel cyclopropanation reaction on C60 with malonate esters, bearing both a solubilizing poly(oxyethylene) chain and an aliphatic chain ending with a BOC‐protected amine. After removal of the protecting group, a counterion exchange methodology allows for the introduction of a perfluorinated anion, bringing the overall solubility of these derivatives to 98 mg/mL in an organic CH2Cl2 solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Kinetics, mechanism and cloud point measurements in the oxidative degradation of non-ionic Triton X-100 surfactant in acidic permanganate solutions

The polyoxyethylene chain of non-ionic surfactant Triton X-100 [4-(1,1,3,3-tetramethylbutyl) phenyl polyethylene glycol,TX-100] was degraded by permanganate in the presence of HClO4. The oxidative degradation rate and cloud point have been obtained as a function of [surfactant], [permanganate], [HClO4], and temperature. Dependence of the reaction rate on adding inorganic salts (Na4P2O7, NaF and MnCl2) was also examined. The oxidation rate increased with increase in [TX-100] and [H+]. The higher order kinetics with respect to [TX-100] at lower [H+] shifted to lower order at higher [H+]. The cloud point of TX-100 (67°C) shifted to lower temperature (23±0.5°C) after oxidative degradation of the polyoxyethylene chain. Evidence of complex formation between TX-100 and MnO 4 − was obtained spectrophotometrically. Presence of the primary alcoholic (–OH) group in the TX-100 skeleton is responsible for the degradation of oxyethylene chain. Both monomeric and aggregated TX-100 molecules are oxidized by permanganate. A catalytic oxidation mechanism is proposed on the basis of the experimental findings.

Micelles and Gels of Mixed Triblock Copoly(Oxyalkylene)s in Aqueous Solution

The micellization in dilute aqueous solution of a 50/50 wt% mixture of two triblock copolymers, E45B14E45 and E62P39E62, and the gelation of concentrated micellar solutions have been investigated over a range of temperatures. Here E, B, and P denote oxyethylene, oxubutylene, and oxypropylene chain units. Comparison is made with aqueous solutions of the individual copolymers. The results of light scattering measurements are consistent with effectively separate micellization of the two copolymers in the mixture. Hard gel formed when the extent of micellization was high for both copolymers. Because of the relatively high critical micellization temperatures of copolymer E62P39E62, the low-temperature boundary of the hard gel was high for this copolymer and for the mixture. The minimum concentration for hard-gel formation was higher for the mixture than for either of the individual copolymers, as would be expected for packing of two distributions of micelles of different average size.

Synthesis of a novel type of hybrid fluorocarbon ionic surfactants containing polyoxyethlene chain

A novel type of hybrid ionic surfactants containing oxyethylene chain and fluorocarbon chain in one molecule, n-C 8F 17SO 3 −N +(C 2H 5) 3(CH 2CH 2O) n H ( n = 4.0, ∼4.1, 8.7, 13.2, 17.8, 22.3), were prepared. The compounds were achieved from the reaction of polyethylene glycol and perfluorooctanesulfonyl fluoride in the presence of Et 3N. The evaluation of their behavior at the air–water interface has been studied from measurements of surface tension versus variation of concentration, and the properties of the hybrid surfactants are not consistent with the empirical rule observed from the fluorinated nonionic surfactant.

Hexagonal Liquid Crystalline Phases Formed in Ternary Systems of Brij 97−Water−Ionic Liquids

Phase diagrams of two ionic liquids: hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate (bmim-PF(6)) and relatively hydrophilic 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF(4)) in aqueous solutions of Brij 97 were determined at 25 degrees C. Two hexagonal liquid crystalline phases formed in bmim-PF(6)- and bmim-BF(4)-containing ternary systems were investigated by means of small-angle X-ray scattering (SAXS) and rheological techniques, with comparison of composition and temperature effects. From analysis of the SAXS data, bmim-PF(6) is dominantly penetrated between the oxyethylene chains of surfactant molecules, whereas bmim-BF(4) is mainly located in the water layer of hexagonal phases. The strength of the network of hexagonal phase formed in the Brij 97/water/bmim-BF(4) system is appreciably stronger than that of the Brij 97/water/bmim-PF(6) system, indicated by the smaller area of the surfactant molecule at the interface and the higher moduli (G', G' '). Temperature has a converse effect on the lattice parameters of the two hexagonal phases.

Chain-length-dependent conformational transformation and melting behaviour of alkyl/oligo(oxyethylene)/alkyl triblock compounds: α-octyl-ω-octyloxyoligo(oxyethylene)s

The chain-length-dependent conformational transformation and the melting behaviour of triblock compounds alpha-octyl-omega-octyloxyoligo(oxyethylene)s, H(CH2)8(OCH2CH2)mO(CH2)8H (abbreviated as C8EmC8) (m = 1-8), have been studied by infrared spectroscopy and differential scanning calorimetry. The compounds with m = 1-5 assume the all-trans planar form (gamma-form) in the solid state, while those with m = 7 and 8 assume the planar/ helical/planar form with conformational defects in the alkyl chain (beta'-form). Conformational polymorphism was observed for C8E6C8: the gamma-form for the annealed solid and the planar/helical/planar form without conformational defects (beta-form) for the unannealed solid. The conformational transformation from the planar form into the planar/helical/planar form takes place at a length of the oligo(oxyethylene) chain m = 6. This result for C8EmC8 and a similar conformational transformation for C6EmC6 at m = 5 (previous work) demonstrate that the conformation of the CnEmCn triblock compounds in the solid state is determined by intramolecular conformational restoring force in the central oligo(oxyethylene) block, intermolecular dipole-dipole interaction of the C-O bonds and intermolecular packing force in the end alkyl blocks. The melting points of the gamma-form solid of C8EmC8 are much lower than the melting points of n-alkanes with similar molecular masses. The observed thermodynamic quantities show that the planar structure of the oligo(oxyethylene) chain is stabilized by the force of the magnitude that maintains the rotator phase of n-alkanes. For the beta'-form solid of C8EmC8, the alkyl blocks, which are partially noncrystalline, and the oligo(oxyethylene) block melt together at the melting point, unlike the beta-form solid of C6EmC6, for which the melting of the alkyl blocks takes place before the melting of the oligo(oxyethylene) block. The beta-form solid of C8E6C8 (unannealed) melts via the gamma-form solid.

Supramolecular dendrimers: Unusual mesophases of ionic liquid crystals derived from protonation of DAB dendrimers with facial amphiphilic carboxylic acids

Supramolecular liquid crystalline (LC) dendrimers were prepared by self-assembly of first to fifth generation amino terminated DAB dendrimers with facial amphiphilic carboxylic acids. These carboxylic acids are composed of three distinct incompatible segments, a rigid rod-like terphenyl core, two terminal alkyl chains and a polar lateral carboxylate group. The COOH groups were either directly connected to the terphenyl core or via oligo(oxyethylene) chains of different lengths. Depending upon the length of the polyether chain used, the dendrimer generation, the ratio of dendrimer to carboxylic acid or the temperature, a series of six different LC phases were observed. As well as a smectic phase (SmA), two different square columnar phases (Colsqu), a mesophase combining a layer structure with a hexagonal organisation of columns (channelled layer phase, ChLhex) and two additional mesophases (Colhex and M) with unknown structures were found. The square columnar phases are either composed of square cylinders (plane group p4mm) or a regular arrangement of square and triangular cylinders (plane group p4gm). In these dendrimer–carboxylic acid complexes protons are transferred from the COOH groups to the amino groups of the dendrimer, which gives rise to ionic complexes (dendroelectrolyte–amphiphile complexes). This concept allows the tailoring of the mesomorphic properties in a thermodynamically controlled self assembly process. The T-shaped ternary amphiphilic structure of the acid components and the incompatibility of the ionic species formed during the self assembly process are responsible for the formation of unconventional mesophase structures.

Structure and rheology of aqueous micellar solutions and gels formed from an associative poly(oxybutylene)-poly(oxyethylene)-poly(oxybutylene) triblock copolymer.

The structure and shear flow behaviour of aqueous micellar solutions and gels formed by an amphiphilic poly(oxybutylene)-poly(oxyethylene)-poly(oxybutylene) triblock copolymer with a lengthy hydrophilic poly(oxyethylene) block has been investigated by rheology, small angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). SANS revealed that bridging of chains between micelles introduces, in the micellar solution, an attractive long-range component which can be described through a potential of interaction corresponding to sticky soft spheres. The strength of the attractive interaction increases with increasing concentration. Rheology showed that the dependence of the storage modulus with temperature can be explained as a function of the micellar bridging, micellisation and phase morphology. SAXS studies showed that the orientation adopted by the system in the gel phase under shear is similar to that previously observed by us for the gel phase of a poly(oxyethylene)-poly(oxybutylene) diblock copolymer with a long poly(oxyethylene) chain, suggesting that the micellar corona/core length ratio and not the architecture of the block copolymer influences the alignment of the gel phase under shear.

Matrix assisted formation of ferrihydrite nanoparticles in a siloxane/poly(oxyethylene) nanohybrid

Matrix-assisted formation of ferrihydrite, an iron oxide hydroxide analogue of the protein ferritin core, in a sol–gel derived organic–inorganic hybrid is reported. The hybrid network (named di-ureasil) is composed of poly(oxyethylene) chains of different average polymer molecular weights grafted to siloxane domains by means of urea cross-linkages and accommodates ferrihydrite nanoparticles. Magnetic measurements, Fourier transform infrared and nuclear magnetic resonance spectroscopy reveal that controlled modification of the polymer molecular weight allows the fine-tuning of the ability of the hybrid matrix to assist and promote iron coordination at the organic–inorganic interface and subsequent nucleation and growth of the ferrihydrite nanoparticles whose core size (2–4 nm) is tuned by the amount of iron incorporated. The polymer chain length, its arrangement and crystallinity, are key factors in the anchoring and formation of the ferrihydrite particles.

Template Effects of Metal Cations for Controlling the Regioisomer Distribution on the Photodimerization of N,N′‐Linked Bis(anthracenecarboxamides)

AbstractTwo bis(fluorophore) compounds linked by an oxyethylene chain, N,N′‐(4,7,10‐trioxatridecane‐1,13‐diyl)bis(1‐anthracenecarboxamide) (1) and N,N′‐(4,7,10‐trioxatridecane‐1,13‐diyl)bis(2‐anthracenecarboxamide) (2), were synthesized, and the intramolecular photodimerization of the anthracene units was carried out in acetonitrile solution. The photoproduct ratios of the regioisomers derived from 1 and 2 were quantified in the absence and presence of metal cations. Upon photo‐irradiation of 1, three intramolecular photodimers, trans head‐to‐head dimer D1, cis head‐to‐head D2 and cis head‐to‐tail D3, were formed. In the photodimerization of 1, the presence of Ba2+ enhanced the formation of D1, whereas Mg2+ suppressed it. These isomer distributions strongly depended on the structure of the complex induced by the metal cations in the ground state. On the other hand, upon photo‐irradiation of 2, only two photodimers, cis head‐to‐tail dimer D5 and cis head‐to‐head D6, were formed in both the absence and presence of metal cations, and their ratio changed only slightly suggesting that no conformational changes were induced by the complexation with metal cations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Nonionic surfactants adsorption onto activated carbon. Influence of the polar chain length

The adsorption of a nonionic surfactants series characterized by a different length of the hydrophilic tail on an activated carbon has been studied over a wide concentration range. Adsorption isotherms show two steps limited by the critical micelle concentration (c.m.c.) of the surfactants. The adsorption extension depends on the oxyethylenic chain length, in such way that the amount adsorbed decreases with increasing the chain length, although the effect is much lower for the longest polar chains. In the concentration range below the c.m.c. of the surfactants, the molecules are adsorbed by direct interactions with the activated carbon surface, but with different configuration of the polyoxyethylene chain (POE) directed to the aqueous phase. For concentrations above the c.m.c., the adsorption takes place by the interactions between the adsorbed surfactants molecules and differences related to the length of the hydrophilic chain are also found.

The effect of the length of the oxyethylene chain on the conductivity of the polyurethaneurea electrolyte

Polyurethaneureas (PUU), which were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and 3,5-diaminobanzoic acid (DABA), were used as polyelectrolytes in this study. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to monitor the effect of the various kinds of PEG on the changes in morphology of PUU electrolytes corresponding to the concentration of lithium perchlorate (LiClO 4) dopants. The results of DSC and FT-IR indicate the Li + ions coordinate with the soft and hard segments. Additionally, the crystallinity of the PEG soft segment and the ordered hydrogen-bonded urea carbonyl groups decreased with increasing salt concentration. Impedance spectroscopy (IS) measurements show that the PUU electrolyte with the high phase separation degree has the high ionic conductivity. The hard-segment T g and the soft-segment T m influence the conductivity behavior of polyelectrolytes with increasing measurement temperature.

The Application of Ozone in the Decomposition of Aqueous Solutions of Nonionic Surfactants

ABSTRACT Aqueous solutions of nonionic surfactants are decomposed by ozone. In the experiments compounds differing in chemical structure (i.e., the presence of a benzene ring in the molecule, the type of aliphatic chain [linear or branched] and the length of the polyoxyethylene chain) were used. The research was conducted using solutions of Triton, Tergitol, Symperonic, and Brij surfactants produced by Fluka Chemie Ag. The initial concentrations were chosen to be over and below a critical micelle concentration (CMC). Decomposition was analyzed by polarography, spectrophotometry, total organic carbon (TOC) and chemical oxygen demand (COD) value. It was found that the rate and effectiveness of ozonation depended on the chemical structure of surfactant molecule, chain structure (linear or branched), oxyethylene chain lengthening, and a monomeric or micelle form of the surfactant molecule appearing in the solution.

Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units: Influence of characteristic dangling chains on swelling behavior of resulting amphiphilic gels

AbstractNovel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH2C(CH3)CO(OCH2CH2)23OCOC(CH3)CH2, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004

Versatility of potential biomedical use of functional polysuccinates

AbstractPolysuccinates with pendant allyl groups (PSAGE) were synthesized by melt copolymerization of succinic anhydride with allyl glycidyl ether and eventually other glycidyl ethers. It was found that PSAGE could be crosslinked by radical copolymerization with methyl methacrylate. Oxidized PSAGE considered as multifunctional epoxy resin was cured with use of glutaric anhydride to form solid material susceptible to hydrolytic degradation to water‐soluble non‐toxic products. Comb‐like amphiphilic polysuccinates containing both pendant poly(oxyethylene) chains and epoxy groups have been synthesized as well and checked for their solubility in water. Properties of PSAGE‐type polymers suggests their potential use as biomaterials and polymeric drug carries.Please note, in the print publication of D. Theis, T. Schmidt, K.‐F. Arndt, Macromol. Symp. 210 (2004), 465, erroneously the DOI 10.1002/masy.200450651 is repeated. There, the DOI should read: 10.1002/masy.200450652