Peter Friedel

Leibniz-Institut für Polymerforschung Dresden e.V. · Institut Theorie der Polymere

Amyloid β peptide can aggregate into thin β-sheet fibrils or plaques deposited on the extracellular matrix, which is the hallmark of Alzheimer’s disease. Multifunctional macromolecular structures play an important role in inhibiting the aggregate formation of amyloidogenic materials and thus are promising candidates with antiamyloidogenic character...

Application of lipases (preferentially Candida antarctica Lipase B, CALB) for melt polycondensation of aliphatic polyesters by transesterification of activated dicarboxylic acids with diols allows to displace toxic metal and metal oxide catalysts. Immobilization of the enzyme enhances the activity and the temperature range of use. The possibility t...

The phase separation and surface characteristics of poly(propyl methacrylate-b-methyl methacrylate) (PPrMA-b-PMMA) diblock copolymers were studied and compared to strongly phase-separated poly(pentyl methacrylate-b-methyl methacrylate) (PPMA-b-PMMA) block copolymers (BCPs). PPrMA-b-PMMA with varied compositions and molar masses was synthesized by l...

Molar mass and end group number of a hyperbranched polyester are significantly increased by its transformation to a pseudodendrimer. Three generations of pseudodendrimers are obtained from hyperbranched aliphatic polyester core by modification with a protected AB*2 monomer. A sequence of protection and deprotection steps leads to OH‐terminated pseu...

Diblock copolymers (BCP) with poly(methyl methacrylate) and poly(1H,1H,2H,2H-perfluorodecyl methacrylate) (PsfMA) blocks prepared by anionic polymerization in tetrahydrofuran at −78 °C and atom transfer radical polymerization (ATRP) at 60 °C, respectively, with stepwise varied composition over a wide range in the phase diagram are compared with res...

This study investigates the morphology changes in thin diblock copolymer (DiBCP) films occurring in the interaction with modified nanoparticles (NPs). Magnetite (Fe 3 O 4 ) and silica (SiO x ) were prepared and used. Poly(pentyl methacrylate-b-methyl methacrylate) (PPMA-b-PMMA) (70/30 mol mol ⁻¹ , hcp cylinders of the PMMA phase) DiBCP were employe...

Poly(methacrylate)s with semifluorinated side-chains of the general structure -(CH2)n-(CF2)m-F were studied to elucidate the influence of the side-chain structure on the ordering behavior in the solid state and in thin films. The aim was to find correlations between the chemical structure of the polymer, chemical composition near the surface, order...

The Van der Waals equation (VdW-EoS) is a prototype equation of state for realistic systems, because it contains the excluded volume and the particle interactions. Additionally, the simulated annealing (and the similar simulated compressing) approach applies the time dependence on to one of the variables of state to simulate quasi static state chan...

Dendronization of a hyperbranched polyester with different generation dendrons leads to pseudo-dendritic structures. The hyperbranched core is modified by the divergent coupling of protected monomer units to the functional groups. Compared to dendrimers, the synthetic effort is significantly less, but the properties are very close to those of high-...

Die Dendronisierung von hochverzweigten Polyestern mit Dendronen unterschiedlicher Generationen führt zu pseudo-dendritischen Strukturen. Der hochverzweigte Kern wurde durch divergente Kopplung von geschützten Monomereinheiten an die funktionellen Gruppen modifiziert. Verglichen mit Dendrimeren ist der präparative Aufwand hier deutlich geringer; di...

Diblock copolymers (BCPs) show phase separation on mesoscopic length scales and form ordered morphologies in both bulk and thin films, the latter resulting in nanostructured surfaces. Morphologies in thin films are strongly influenced by film parameters, the ratio of film thickness and bulk domain spacing. Laterally structured polymer surfaces may...

Diblock copolymers (BCPs) show phase separation on mesoscopic length scales and form ordered morphologies in both bulk and thin films, the latter resulting in nanostructured surfaces. Morphologies in thin films are strongly influenced by film parameters, the ratio of film thickness and bulk domain spacing. Laterally structured polymer surfaces may serve...

The distribution of hydrophobic nanoparticles deposited on a hydrophilic polymer film is investigated by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy before and after spin-coating a polymer solution on the particle film and drying it at room temperature. Various polymers and solvents are used. To reach...

Semifluorinated (SF) side chain polymers show phase separation between polymer backbone and SF side chains. Due to strong interaction between SF segments the side chains determine the structure behaviour strongly, often resulting in layered structures in which backbones and layers of SF side chains alternate. The interest in this work was directed...

Glycopolymers are promising materials in the field of biomedical applications and in the fabrication of supramolecular structures with specific functions. For tunable design of supramolecular structures, glycopolymer architectures with specific properties (e.g. controlled self-assembly) are needed. Using the concept of dendronized polymers, a serie...

The conversion of 1,3-bis-(6-amino-pyridin-2-yl)-urea (1) with N,N'-carbonyldiimidazole at high temperatures in DMSO yielded a mixture of defined cyclic trimers and tetramers. On the basis of model reactions, exchange reactions were evidenced, which convert the cyclic tetramer into a stable cyclic trimer. Linear even numbered oligomers were obtaine...

The paper compares building and decomposition pathways of two phosphonic acids, amino trimethylene phosphonic acid (ATMP) and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP).The theoretical formation reactions were composed using elementary reactions and compared to reaction routes published in literature. As result, summary reaction pathways for...

SANS measurements in THF-d6 were carried out at the D11 instrument at ILL, Grenoble with two aliphatic aromatic hyper-branched (hb) samples with nearly the same degree of polymerization (DP ≈ 90), containing hydroxyl (OH) and silyl-ether (SY) terminal groups. The choice of a large region of momentum transfer q permitted probing the global shape and...

The introduction of functionalities into block copolymers opens a wide field of possibilities for subsequent reactions, for instance to stabilize the morphology or to create stable hybrids. Methacrylate-based di- and triblock copolymers were synthesized by sequential anionic polymerization. Allyl methacrylate was used to form the third block and as...

Monomers with phosphorus-containing substituents were incorporated into aromatic–aliphatic polyesters to develop polymeric halogen-free flame retardants as additives for poly(butylene terephthalate) (PBT). They were built into the polyester backbone of PBT substituting 1,4-butane diol as monomer by phosphorus-containing aromatic–aliphatic diols. St...

A series of diblock copolymers of n-pentyl methacrylate and methyl methacrylate (PPMA/PMMA BCP) with one or two terminal functional groups was prepared by sequential anionic polymerization of PMA and MMA using an allyl-functionalized initiator and/or and end-capping with allyl bromide. Allyl functional groups were successfully converted into OH gro...

Poster

Simultaneous characterization of the degree of branching and molar mass on a molecular level for hyperbranched polymers is still strongly limited. Therefore model hyperbranched polyesters for development of new chromatographic techniques on the basis of 2,2-bis(hydroxymethyl)propionic acid were synthesized. The two types of OH-functionalities (line...

Diblock copolymers show phase separation on the sub-micrometer scale thus giving rise to specially ordered morphologies both in bulk and thin films. One important question is to find out relationships between bulk morphology (determined mainly by molecular parameters, i.e., the block ratio, molar mass, thermal history), and morphologies in thin fil...

The main objective of the work presented here was focused on the effect of intercalation and organization of dyes in restricted volumes on their nonlinear optical properties. Thus, the nonlinear optically active dye 1,5-di-(4-dimethylaminophenyl)- penta-2,4-dien-3-one (DMABA) was intercalated into the silicate layers of montmorillonite which was pr...

Temperature-resolved scattering measurements (SAXS and WAXS) combined with other methods giving thermal behaviour information (DSC, Broadband Dielectric Spectroscopy) were used to get detailed information about the structural changes induced by increasing flexibility of polyesters with semifluorinated side chains and an alternating backbone of isop...

The multiple application of reductive amination on primary amino groups of first and second generation poly(propyleneimine) dendrimers is used as a one‐pot approach to introduce twice the amount of the oligosaccharide units as surface groups, compared to initially present amino groups in the first and second generation dendrimers. This was proven b...

From naturally formed ammonium hydrogen urate, a common compound in uroliths, X-ray powder diffraction measurements, indexing and force-field-constrained Rietveld refinement including anisotropic characterization of peak width broadening were performed using the BGMN[tm] program. The ammonium hydrogen (acid) urate crystallizes in a triclinic unit c...

The main objective of the presented work was focused on the understanding of the phase behaviour of diblock copolymers consisting of poly(pentyl methacrylate) and poly(methyl methacrylate) blocks (PPMA-b-PMMA) with the aim to obtain nanostructured surfaces. Block copolymers with varied molar masses and block length ratios were synthesized via seque...

Journal article

A series of alternating maleimide (MI) copolymers with fluorinated side chains have been investigated using broadband dielectric spectroscopy. The side chains consist of fluoroalkane (–Cx F2x+1, x=1, 7, 9) end groups connected to the main chain via methylene spacers. The experiments were carried out in a frequency range of 0.1 Hz to 10 MHz and at t...

We studied the bulk and surface properties of maleimide (MI) copolymers based on three different main chains, poly(ethene-alt-maleimide), poly(styrene-alt-maleimide), and poly(octadecene-alt-maleimide), with two different types of side chains (4-(N-perfluoroheptylcarbonyl)aminobutyl and n-dodecyl). By the given alternating substitution pattern of t...

Well-measured contact angles with different solid-liquid systems fall approximately on smooth patterns when plotted versus liquid surface tension. However, there are deviations of 1 degrees -3 degrees , which are outside the error limits. It is the purpose of this paper to elucidate the reasons for such deviations. Two types of liquids were selecte...

Twofold Schultz-Zimm distribution of diblock copolymers. Summary: A modified random phase approximation method with a cumulant expansion for the semi-flexible structure factor of diblock copolymers was exercised to describe the phase separation behavior of semi-flexible and polydisperse diblock copolymers. Scattering curves and spinodal diagrams we...

Broadband dielectric spectroscopy has been used to analyze the molecular dynamics in a set of nine poly(ethene-alt-N-alkylmaleimide)s. The polymers were studied in the frequency range from 0.1 Hz to 10 MHz and at temperatures between 120 and 500 K. The alternating maleimide copolymers possess alkyl side chains varying in length from methyl to octad...

The goal of the work presented here was to synthesize multiblock copolymers based on transesterification polycondensation of end group functionalized PEEK with PSU oligomers in the melt. In the synthesis of PEEK oligomers by nucleophilic aromatic substitution cyclization occured observed by decreasing amount of end groups. The phase behavior of the...

Several series of polyester imides (PEIs) were prepared by melt polycondensation of trimellitimidobenzoic acid and acetylated, substituted hydroquinones as well as by solution polycondensation of corresponding dichlorides with hydroquinones. The influence of either phenyl- or tert-butyl substituents at the hydroquinone unit on the hydrodynamic (dif...

Alkyl-perfluoroalkyl compounds are known to form a microphase-separated structure due to the thermodynamic immiscibility between the fluorinated and the protonuted segments. Many similarities between bulk and surface structures of such polymers were found in the past which can be explained by both microphase separation in the bulk as well as surfac...

The amphiphilic ligand 4,4′-bis-(1-butyl-pentyl)-[2,2′]bipyridinyl-6,6′-diamine (BBPBPDA) was synthesized by the Chichibabin reaction. It formed stable monolayers on the water surface which could be transferred onto solid substrates to construct Langmuir–Blodgett (LB) multilayers. The experimental data obtained by monolayer investigations on the wa...

Flory-Huggins interaction parameters of polymeric systems including polysulfone and aromatic poly(ester imides) were calculated using solubility parameters in order to estimate the tendency of phase separation of the respective block copolymers. The scope of the work was to compare L values based on ' calculated by means of increment tables as well...

Silver salts are dissolved in poly(butyl methacrylate) to derive polymer electrolytes via coordinative interaction between the silver ion and the carbonyl oxygen atom. The dissolved silver ions react subsequently with propylene to form reversible silver/olefin complexes that can be utilized as olefin carriers for facilitated olefin transport. The c...

The condensation reactions of the structurally similar monomers 1,3-phenylenediamine (1a) and 2,6-diaminopyridine (1b) with N,N-carbonyldiimidazole have been compared. Whereas the reaction of 1a resulted in an amino terminated oligomeric polyurea, a mixture of two macrocyclic trimers and one macrocyclic tetramer was obtained in the case of 1b. The...

The structure and dynamics of polyesters composed from a rigid aromatic backbone and oxyalkylperfluoroalkyl side chains have been studied using differential scanning calorimetry, small- and wide-angle X-ray scattering, pressure–volume–temperature measurements and rheology. The system was found to undergo three phase transitions. Starting from lower...

A first generation dendrimer D1 was placed onto defined surfaces to study the excitation energy transfer between D1 as donor molecule and a pyrene containing polymer 213 as acceptor molecule in Langmuir−Blodgett (LB) multilayers. Fluorescence experiments were carried out at several excitation wavelengths (220, 260, 312, and 341 nm). D1 formed a clo...

Materials with low surface energy are very important in applications that require reduced wetting or adhesion. Monolayers of -CF3 containing compounds possess the smallest surface energy known until now that has to promote surface investigations. Perfluoroalkyl compounds were shown to form a microphase-separated structure due to the immiscibility b...

We report bulk and surface properties of maleimide copolymers with two different backbones, poly(propene-alt-N-(n-alkyl)maleimides) (PAlkMI) and poly(styrene-alt-N-(n-alkyl) maleimides) (SAlkMI), with different lengths of n-alkyl side chains (methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and dodecyl). The contact angle and solid surface tensi...

For the modeling of polymer meso-structures, the spinodal points can be obtained by random phase approximations. The necessary number of these spinodal points to describe a phase diagram can significantly be reduced, if the usual sampling-point method is replaced by a Newton iteration, utilizing all the transiently computed data. This has the conse...

The phase separation behaviour of block copolymers of the type (A–B) n (segmented block copolymers, multiblock copolymers) containing segments with different degrees of flexibility was investigated using a stepwise variation of the incorporated blocks A and B. Amorphous/rigid blocks (polysulfone segments) were systematically combined with amorphous...

The reaction of different metasubstituted aromatic diamines with triethylorthoformate (TEOF) was investigated. Whereas the conversion of 1,3-phenylenediamine 1a resulted in an oligomeric polyformamidine, the formation of cyclic trimers was observed when nitrogen-containing aromatic diamines such as 2,6-diaminopyridine 1b, 2,4-diaminopyrimidine 1c,...

A proposal for the solid-state structure of poly(p-phenylene isophthalate) with oxydecylperfluorodecyl side chains is presented, which was calculated by the new Rietveld refinement program BGMN®. A triclinic unit cell with a = 0.575 nm, b = 4.06 nm, c = 2.1 nm, α = 91.2°, β = 85.7°, and γ = 66.1° was obtained using space group symmetry P1¯ (No. 2)...

A proposal for the solid-state structure of poly(p-phenylene isophthalate) with oxydecylperfluorodecyl side chains is presented, which was calculated by the new Rietveld refinement program BGMN®. A triclinic unit cell with a = 0.575 nm, b = 4.06 nm, c = 2.1 nm, α = 91.2°, β = 85.7°, and γ = 66.1° was obtained using space group symmetry P1¯ (No. 2)...

Fully aromatic copolyesters with regular chain structure containing kinked monomer units were investigated by powder diffraction experiments combined with structure modelling. The proposed series of copolyester structures including isophthalic acid was continued with (TPA–HQ–IPA–HQ)n (containing 104 atoms as repeating unit). The monoclinic unit cel...

Structure determination from X-ray powder diffraction data by RIETVELD method has the following optimization criterion usually: best agreement between calculated and measured data reached by variation of structural parameters. XPD RIETVELD refinement of organic solids is very difficult. The lattice positions are structured and contain low scatterin...

The use of BGMN's fundamental parameter approach to describe complicated instrumental profiles is demonstrated. Monte-Carlo raytracing is able to simulate extreme sample geometries: commonly used reflection (but specimen of low attenuation coefficient), transmission and capillary geometry. Advantages and disadvantages of different geometries in ter...

By means of PSU/LCP multiblock copolymers with different molecular weights of the blocks in binary solution cast blends it was shown that the interpenetration of the PSU phase of the block copolymer and the PSU matrix leads to a partial miscibility of the blend, if the molecular weight of the PSU segments of the block copolymer exceeds the entangle...

Multiblock copolymers (MBCPs) consisting of polysulfone (PSU) segments and segments of the liquid crystalline poly(ethyleneterephthalate-co-oxybenzoate) (PET/HBA) form rather complex morphologies. Scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM) investigations of two block copolymers with si...

A new heterocyclic compound, cyclo-tris(2,6-pyridylformamidine), was synthesized as a highly crystalline powder-like substance from which very small whiskers were produced by a sublimation technique. By rotating-crystal and powder diffraction measurements, a set of structural data were obtained which were fitted mathematically to a structural model...

Fully aromatic copolyester with regular chain structure containing kinked monomer units were investigated by powder diffraction experiments combined with structure modelling. Temperature dependent X-ray measurements show the existence of low and high temperature solid state modifications of poly(p-phenylene isophthalate), (IPA-HQ)n. From the X-ray...

Metal complexes of salicylideneamines exhibit very interesting properties and have been well characterized since the late 1920s. Amphiphilic salicylideneamines have been synthesized in order to introduce such complexes in Langmuir−Blodgett multilayers. They do not hydrolyze under the applied experimental conditions and form stable monolayers. On su...

The basic nature of the formamidine group -NH-CH=N-, its high reactivity and its ability to form salts with weak acids are some reasons for the growing interest in form-amidine containing compounds. Recently was found that the reaction of 2,6-diamino-pyridine with triethyl orthoformate resulted in a cyclic structure with three formamidine groups. X...

Aromatic copolyesters with regular chain structure were investigated in order to correlate their primary chemical structure, some molecular characteristics (inherent viscosity, molecular weight) and crystallographic data as well as melting behaviour. A series of copolyesters were synthesized by polycondensation of complex aromatic dicarboxylic acid...

The chemisorption of hydrogen on As stabilized GaAs(001) surfaces is studied both from the experimental and theoretical points of view. The discussion of local densities of valence states and of core level shifts leads us to conclude that both GaH bonds are formed. Agreement between theory and experiment can be found without any need for empirical...

The dynamic progress in the field of nanostructured materials results mainly from the wide range of their opportunities in application. Due to the immiscibility of the chemically different segments in diblock copolymers, micro- and nanophase separation processes give rise to different bulk morphologies. More recently, developments were directed to...

Chemical modification of polymer surfaces is the great challenge nowadays to govern e.g. the biocompatibility, wettability and con- ductivity for tuning the application of polymer surfaces. In this con- text, our approach was to establish different surface functionalities by the exchange between aliphatic and fluorinated side chains with similar si...

Das Projekt wurde im Rahmen des EU NoE NANOFUN-POLY zu- sammen mit Partnern aus Italien, Spanien und Griechenland durchgeführt. Es zielt auf die Entwicklung von nanostrukturierten Oberflächen basierend auf wohl definierten Poly(pentylmeth- acrylat-b-methylmethacrylat)-Diblockcopolymeren (PPMA/PMMA), die mittels anionischer Polymerisation synthetisi...

Materials with low surface energy are very important in applications that require reduced wetting or adhesion. Monolayers of -CF 3 -containing compounds possess the smallest surface energy known until now that has to promote surface investigations. On the other hand, for this understanding it is necessary to investigate the bulk structure and its t...

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