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Fully aliphatic (isocyanurate ring-based) polyester-ether polyurethane (PUR) foams have been developed, and the influence of starch and 2-hydroxyethyl cellulose (HEC) additives on their structure, ...

The formation of amyloid fibrils from certain proteins stays behind a number of pathologies, so-called amyloidoses. Glycosaminoglycans are polysaccharides and are known natural constituents of amyloids in vivo. However, little is known about the effect of other naturally abundant polysaccharides, and even less is known about the effect of chemically modified polysaccharides on the formation of amyloid fibrils. In the case of low-molecular weight compounds, aromatic substances are known to often influence amyloid formation significantly. We investigated the influence of glycogen (GG) and several modifications of GG with cinnamoyl groups, benzoyl groups and phenylacetyl groups. As model systems, hen egg-white lysozyme (HEWL) and amyloid beta peptide (1-42) (Aβ1-42), which is an Alzheimer disease-relevant system, were used. The fluorescence of thioflavin-T (ThT) was used for the rapid detection of fibrils, and the fluorescence results were confirmed by transmission electron microscopy (TEM). Other techniques, such as isothermal titration calorimetry (ITC) and dynamic light scattering (DLS), were employed to determine the interactions between HEWL and the modifications. We achieved similar results with both model systems (HEWL and Aβ1-42). We showed that π-π interactions played an important role in the process of amyloid fibril formation because fundamental changes were observed in this process even with a very small number of groups containing an aromatic ring. It was found that almost all GG modifications accelerated the formation of amyloid fibrils in both model systems, HEWL and Aβ1-42, except for GG-Ph1 (1.6 mol% phenylacetyl groups), which had a retarding effect compared to all other modifications.

We investigated the influence of glycogen (GG), phytoglycogen (PG), mannan (MAN) and cinnamoyl-modified GG (GG-CIN) on amyloid fibril formation. We used hen egg-white lysozyme (HEWL) as a model system and amyloid beta peptide (1-42) (Aβ1-42) as an Alzheimer's disease-relevant system. For brief detection of fibrils was used thioflavin T (ThT) fluorescence assay and the results were confirmed by transmission electron microscopy (TEM). We also deal with the interaction of polysaccharides and HEWL with isothermal titration calorimetry (ITC) and dynamic light scattering (DLS). We found that all polysaccharides accelerated the formation of amyloid fibrils from both HEWL and Aβ1-42. At high but physiologically relevant concentrations of GG, amyloid fibril formation was extremely accelerated for HEWL. Therefore, on the basis of the herein presented in vitro data, we hypothesize, that dietary d-glucose intake may influence amyloid fibril formation not only by influencing regulatory pathways, but also by direct glycogen-amyloid precursor protein molecular interaction, as glycogen levels in tissues are highly dependent on d-glucose intake.

In the after-fire restoration of the buildings belonging to the culture heritage, the use of salvaged scorched wood elements is desirable but often leading to the long-term malodorous, irritating, ...

The paper is focused on investigation of layered double hydroxides (LDH) functionalized with ionic liquid (IL) as novel catalytic/initiating system for ring opening polymerization (ROP) of e-caprolactone. Firstly, the Ca2+/Al3+ LDH nanoparticles were synthesized via a co-precipitation method followed by the anion exchange using phosphonium IL with decanoate anions producing the modified LDH with interlayered IL-anions. Then, the progress of microwave-assisted polymerization in the presence of the modified LDH was studied showing the anionic mechanism of ROP initiated by the water molecules, which were adsorbed on the LDH surface and intercalated in the LDH galleries. The whole polymerization was significantly accelerated by microwave energy, which induced molecular rotations of the intercalated IL-anions leading to LDH delamination and exfoliation into individual nanosheets, which made the catalytic sites (IL-anions) easily accessible for the eCL molecules. The kinetics of microwave-assisted ROP thus showed a 4.6-fold increase of the reaction rate compared to the polymerization performed under conventional heating. Activation enthalpy and entropy were calculated for the microwave-assisted polymerizations initiated by the modified LDH. The use of microwave-active catalytic-initiating LDH nanoparticles enables to synthesize the organometallic catalyst-free PCL or, at higher LDH loadings, the highly-exfoliated PCL/LDH nanocomposites, which are highly desirable for e.g. packaging materials.

This paper shows two ways of efficiency improvement of bio-polyol synthesis to generate more environmental and economic benefits. The application of waste oil in the synthesis of plastic components allows recycling of such municipal waste and is consistent with the principles of Green and Sustainable Chemistry. The economic aspects are associated with analyzing the influence of different catalysts on the time and temperature of ring opening reactions as well as the costs of the catalysts used in this process. This work presents the impact of three types of catalysts, (sulfuric acid, acid diethyl ether complex and tetrafluoroboric acid solution in water) on the ring opening reactions of epoxidized cooking oils and the properties of the final bio-polyols. The application of sulfuric acid in this experiment required a much higher temperature than in the case of the catalysts based on tetrafluoroboric acid and a longer reaction time. The shortest reaction time was achieved using tetrafluoroboric acid diethyl ether complex but the costs of this catalyst limit its possible application. However, similar products were obtained when using a tetrafluoroboric acid solution in water and the costs of this catalyst are acceptable for industrial applications. The properties of the bio-polyols and the tendency for the occurrence of the oligomerization reaction depended on the type of the catalysts used and were confirmed by the means of Fourier transform infrared spectroscopy, gel permeation chromatography, MALDI-TOF as well as by viscosity changes. It was concluded that the type of the catalyst and its concentration have a major impact on the physical and chemical properties of the resultant bio-polyols.

The modified layout of the barrier method called liquid chromatography under limiting conditions of enthalpic interactions is presented. It enables automated quantitative separation of blends of synthetic polymers, for example the single step discrimination of both parent homopolymers from the block copolymers. Moreover, this method enables the estimation of molar mass and molar mass distribution of the block copolymer precursor. Adjacent large sequences of mobile phase of different composition are applied as barriers. They are created by a computer controlled pair of pumping systems in the form of longitudinal profiles along the column. The home synthesized block copolymers polystyrene-block-poly(2-vinylpyridine) served as model examples of the method application. The adsorption retention mechanism was exploited using mesoporous bare silica gel column packing. Series of block copolymers of similar composition can be quickly handled with the method to optimize their synthesis.

Four new bis(tpy) unimers with different linkers between the thieno[3,2-b]thiophene-2,5-diyl central unit and terpyridine-4&prime, yl (tpy) end-groups: no linker (Tt), ethynediyl (TtE), 1,4-phenylene (TtPh) and 2,2&prime, bithophene-5,5&prime, diyl (TtB) are prepared, characterized, and assembled with Fe2+ ions to metallo-supramolecular polymers (Fe-MSPs). The Fe-MSP films prepared by spin-casting on Indium Tin Oxide (ITO) glass are characterized by atomic force microscope (AFM) microscopy, cyclic voltammetry, and UV/vis spectroscopy and studied for their electrochromism and effect of the unimer structure on their electrochromic performance. Of the studied MSPs, Fe-Tt shows the highest optical contrast as well as coloration efficiency (CE = 641 cm2 C&minus, 1) and the fastest optical response. This makes it an excellent candidate for possible use in electrochromic devices.

Polyurethane (PUR) foams are due to their versatility highly demanded not only in traditional applications but also in biotechnological and environmentally-oriented processes in which they can reach the open environment. Therefore, new PUR foams with degradation-on-demand features are highly desirable and their (bio)degradation behavior has to be understood. Herein, we have studied abiotic and microbial degradation of fully aliphatic PUR foam, developed as a biomass carrier for biofiltration. The progress of abiotic hydrolysis shows complete degradation of soft polyol segments and partial cleavage of hard isocyanate-derived segments. Microbial in-vitro degradations showed much higher activity of fungus Fusarium solani than bacterium Pseudomonas sp. Biodegradation of the PUR foam in soil reveals that 77% of the soft segments are mineralized after 6 months reaching the final mineralization of 43%. The results demonstrate that a non-hazardous and sustainable PUR foam can be successfully prepared for applications requiring material bioactivity (biorecycling, etc.).

The aza-Michael reaction is the addition of an amine to an electron deficient C=C double bond. This reaction is also used in the synthesis of precursors of polymeric networks. In this study, we paid attention to the kinetics and mechanism of the aza-Michael addition of cyclohexylamine (CHXA) to diethyl maleate (DEM) performed as a solvent-free, catalyst-free reaction and to concurrent reactions. In situ Raman spectroscopy, NMR spectroscopy and gas chromatography/mass spectrometry have shown the occurrence of three simultaneous reactions: (i) the aza-Michael addition of CHXA to DEM leading to diethyl 2-(cyclohexylamino)succinate, (ii) isomerization of DEM to diethyl fumarate (DEF), and (iii) the aza-Michael addition of CHXA to DEF formed by the reaction (ii). All of these reactions proceed with third order kinetics, first order in DEM or DEF and second order in CHXA. We propose a kinetic model that allows kinetic constants to be estimated. Furthermore, a numerical solution of the set of differential equations confirms the expected kinetic equations of reactions (i) and (ii) and gives values of rate constants comparable to the estimated ones. A DFT mechanistic study illustrates the structure of the reaction intermediates and transition states of all reactions and explains the contribution of the second amine molecule in the reaction mechanism.

Simple organic bases were explored as metal-free initiators for the copolymerization of epoxides with anhydrides. A comprehensive study encompassing the effect of solvent, temperature, concentration and purity of reactants was performed to find optimal conditions for achieving the highest catalytic performance. Detailed MALDI-TOF study elucidated the microstructure of obtained copolymers and confirmed the presence of two types of initiating species derived from organic base and diacid impurity from anhydride. Kinetic studies confirmed controlled manner of the copolymerization and further clarified the mechanism of polymerization. Among all tested initiators, bis(triphenylphosphine iminium)chloride (PPNCl) proved to be the most efficient initiator, which produced highly alternating polyesters with molar masses up to 21 kg mol−1. Crucial role of monomer impurities on achievable molar mass of polyesters was proven. The versatility of PPNCl as an initiator was further demonstrated by the copolymerization of various epoxides and anhydrides producing large scope of polyesters.

In this paper, the medium chain glycerides of coconut oil were used as solvolysis reagents for microwave-enhanced conversion of polycarbonate into recycled polyols. First, triglycerides of coconut oil were transesterified with glycerol to monoglycerides bearing functional hydroxyl groups, which were able to react with carbonate linkages resulting in cleavage of polycarbonate chain. The important accelerating effect of microwave irradiation on kinetics of polycarbonate solvolysis was observed. The developed recycling process produced a mixture of low-molecular weight polyols applicable for synthesis of novel polyurethanes.

Here, we present the synthesis, physicochemical, and preliminary biological characterization of micellar polymer-betulinic acid (BA) conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer carriers, enabling the controlled release of cytotoxic BA derivatives in solid tumors or tumor cells. Various HPMA copolymer conjugates differing in the structure of the spacer between the drug and the carrier were synthesized, all designed for pH-triggered drug release in tumor tissue or tumor cells. The high molecular weight of the micellar conjugates should improve the uptake of the drug in solid tumors due to the Enhanced permeability and retention (EPR) effect. Nevertheless, only the conjugate containing BA with methylated carboxyl groups enabled pH-dependent controlled release in vitro. Moreover, drug release led to the disassembly of the micellar structure, which facilitated elimination of the water-soluble HPMA copolymer carrier from the body by renal filtration. The methylated BA derivative and its polymer conjugate exhibited high cytostatic activity against DLD-1, HT-29, and HeLa carcinoma cell lines and enhanced tumor accumulation in HT-29 xenograft in mice.

In the article we present a unique analytical tool for the characterization of conjugated polymers – SEC-DAD (Size Exclusion Chromatography – Diode Array Detector). The chromatographic separation is performed in a conventional SEC mode which provides narrow molecular-weight fractions of the analyzed polymer. The uniqueness of the SEC-DAD combination comes out with the utilization of DAD for the monitoring the absorption characteristics of particular fractions along the molecular weight distribution. If applied in the characterization of the conjugated polymers, SEC-DAD helps to reveal the dependencies of (i) the extent of conjugation and (ii) covalent and configuration structure of the polymer on the molecular weight.

Water-blown fully aliphatic polyurethane foam was prepared at room temperature from trimer of hexamethylene diisocyanate and poly(diethylene glycol adipate) diol and post cured at 55 °C. In contrast to aromatic-based PUR foam analog, the produced flexible PUR foam exhibited highly porous structure with open cell content of 94% and average cell size of 700 μm. Therefore, it was subsequently tested as biodegradable cellular carrier of microorganisms (fungus Fusarium solani and bacterium Pseudomonas sp.) for biofiltration. Firstly, tests on enzyme activities (lipase, protease and urease) and utilization of PUR foam as the sole carbon and nitrogen source and determination of degradation products were carried out. Fusarium solani shown much higher both enzyme and degradation activities and higher spectrum of degradation products. Finally, the performance of a biofilter packed with the developed cellular carrier was investigated for removal of a mixture of acetone, propionic acid, ethyl acetate, toluene and α-pinene. Proven sorption properties of PUR foam against all pollutants and a high maximum elimination capacity of 218 ± 33 g m−3 h−1 make the new lightweight biofilm PU carrier suitable for this application due to their multi-functionality.

Since their addition to the polymer-architecture portfolio, gradient copolymers have attracted significant attention. Up to now, however, the existence of the intramolecular composition gradient must have been ascertained by sampling during living copolymerization because a reliable method for the detection of the composition gradient in the finalized copolymer had not been established yet. Here we show that MALDI-ToF mass spectrometry not only identifies imperfect, i.e. prematurely terminated copolymers but these copolymers can be used as "time capsules" which provide information on composition evolution and the intramolecular composition gradient.

A graft copolymer of poly(4-methylstyrene-graft-2-vinylpyridine) was prepared by the living “grafting onto” method. Its molecular weight and composition was analyzed by size-exclusion chromatography, liquid chromatography under limiting conditions of desorption, 1H NMR, and light scattering. The results indicated a non-negligibly broad distribution of grafting density. Its conformational behavior was studied by reversed phase liquid chromatography with gradient elution. Targeted studies provided two discrete base-line separated fractions. Their compositions were estimated by pyrolysis gas chromatography. The results suggest that distinct chain conformations (differing in grafting density and interacting differently with stationary phase) exist in studied solutions and can be separated by well-tuned chromatographic techniques. Experimental data were analyzed and interpreted on the basis of theoretical and computer studies of the conformational behavior of graft copolymers in selective solvents.

N-(prop-1-yne-3-yl)-4-(piperidine-1-yl)-1,8-naphthalimide (PNPr), i.e., the monomer with a terminal ethynyl group and 1,8-naphthalimide fluorophore, has been successfully copolymerized with a series of monoethynylarenes into well-soluble high-molecular-weight (Mw up to 210 000) linear polyacetylene-type copolymers containing from 14 to 51 mol% units derived from PNPr. The copolymerization of PNPr with bifunctional 4,4′-diethynylbiphenyl provides polyacetylene-type micro/mesoporous fluorescent network containing 8 mol% PNPr units and exhibiting the Brunauer–Emmett–Teller surface of ≈1000 m2 g−1. The copolymerizations (catalyzed with acetylacetonato(norborna-2,5-diene)rhodium complex, [Rh(nbd)acac]) proceed smoothly despite the fact that the homopolymerization of PNPr fails. The fluorescence of PNPr (emission at ≈ 510 nm) has been retained after the incorporation of PNPr into the copolymers. The fluorescence of the copolymers can be induced by a direct excitation of PNPr units or via an energy transfer mechanism. In the latter case, the comonomeric units with aromatic hydrocarbon fluorophores (e.g., of the biphenyl-type) emitting at 380–400 nm (after irradiation with 300 nm UV radiation) serve as energy donors for fluorescent PNPr acceptors. The difference between the wavelengths of the primary absorbed radiation and the finally emitted radiation is 210 nm.

The spontaneous, catalyst free polymerization of four monomers of the bis(pyridyl)acetylene and bis[(pyridyl)ethynyl]benzene types containing either 2-pyridyl or 4-pyridyl groups via activation with benzyl bromide leads to ionic π-conjugated polyacetylene-type polyelectrolytes (CPEs). All polymers are characterized by means of NMR, IR, UV/vis and photoluminescence spectroscopies, thermogravimetric analysis (TGA) and matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). The position of the pyridyl groups in the monomer influences the degree of quaternization and the extent of conjugation of CPEs. Monomers with 4-pyridyl groups provide CPEs with a low extent of quaternization [N+/(N+ + N) = 0.27–0.34] and high extent of conjugation. On the other hand, the CPEs derived from 2-pyridyl-containing monomers are highly quaternized [N+/(N+ + N) = 0.77–1.00], however, possess lower conjugation of the main chains. The mechanism assuming quaternization and polymerization as competitive reactions is proposed to explain the difference in the extent of quaternization of CPEs. Prepared CPEs i) are well soluble in polar solvents, e.g., water, methanol, dimethyl sulfoxide, and dimethylformamide, ii) exhibit photoluminescence (emission in the violet to yellow region), and iii) possess high thermal stability.

The long-term stability of poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene]vinylene} (MEH-PPV) in solutions exposed to air at daylight and in the dark at room temperature has been studied using the size exclusion chromatography (SEC), UV/vis, fluorescence and IR spectra of aged samples, and comparison of UV/vis spectra of SEC fractions. Solvents currently used in the preparation, analysis and processing of MEH-PPV were used: tetrahydrofuran (THF), chloroform (CHCl3) and chlorobenzene (PhCl). The SEC-DAD data revealed a serious decrease in the delocalization of electrons in MEH-PPV chains, even in the large ones, which proves a deep damage to the structure of the chains prior to their cleavage. The IR spectra of aged samples show that the saturation of main-chain double bonds and the changes in the substitution of phenylene rings are the main chemical structure defects present in chains of aged MEH-PPV. The rate as well as the extent of the overall degradation process is ca ten to fifty times enhanced by the ordinary daylight. The rate of cleavage and the damage to the structure of MEH-PPV molecules are significantly influenced by the choice of the solvent; they increase in the order: PhCl < CHCl3 < THF. PhCl can be recommended as one of the best solvents for MEH-PPV processing from solutions.

A sustainable solvent-free process of the utilization of waste cooking oils has been developed using different types of catalysts. The process offers a tool to create a cleaner technology for the production of bio-components which will be building blocks of the sustainable polymeric materials. Used cooking oils collected from local restaurants have been epoxidized using homogeneous (H2SO4, H3PO4) and heterogeneous (Amberlite IR-120) catalysts. The epoxidation reactions were carried out using “in situ”-formed peroxy acid. The effect of the catalysts on the epoxidation process and the properties of the final products were described. The highest conversion (81%) was achieved for the reaction catalyzed by H2SO4, but the selectivity of this reaction was the lowest (47%). On the other hand, the highest selectivity was obtained for the reaction performed using H3PO4, but the yield of this reaction (26%) was the lowest. In the case of ion-exchange resin (Amberlite IR-120), the conversion of double bonds, selectivity and efficiency were 55, 74 and 40%, respectively. The extent of side reactions depended on the type of used catalyst as it was confirmed by FTIR, GPC, MALDI-TOF as well as by the changes of the product's viscosity. The results should play an important role in the future development of a new approach to the environmentally friendly solvent-free epoxidation process of waste oils.

Complexes [Rh(nbd)(acac)], [Rh(cod)(acac)] and [Rh(cot)(acac)] (nbd = norborna-2,5-diene, cod = cycloocta-1,5-diene, cot = cyclooctatetraene) were investigated as catalysts of polymerization of monosubstituted acetylenes into stereoregular cis-transoid poly(monosubstituted acetylene)s. All complexes (without cocatalyst) are highly active in phenylacetylene (PhA) polymerization in both coordinating (THF) and non-coordinating (CH 2 Cl 2 ) solvents. [Rh(cot)(acac)] prepared in situ by ligand substitution in [Rh(ethylene) 2 (acac)] with cot is efficient in PhA polymerization even in systems with a high cot content. Selection of solvent and cycloolefin ligand of the catalyst allows the control over poly(phenylacetylene) molecular weight ( M w = 3 × 10 4 to 4 × 10 5 ). [Rh(nbd)(acac)] exhibit (moderate) activity also in polymerization of alkylacetylenes (alkyl = n -butyl, tert -butyl, 4-chlorobutyl, cyclopropyl, yields up to 28%, M w up to 7.3 × 10 4 ) and in copolymerization of alkylacetylenes with arylacetylenes. In situ 1 H NMR monitoring of polymerization systems revealed monomer-assisted transformation of [Rh(cycloolefin)(acac)] complexes into precursors of polymerization centres consisting in proton transfer from the monomer to acac ligand of the catalyst under release of acetylacetone. [Rh(cycloolefin)(acac)] catalysts thus differ from the widely used [Rh(nbd)Cl] 2 catalyst which is transformed into active centres precursors only in reaction with cocatalyst or a molecule of coordinating solvent and which is efficient only in presence of a proper cocatalyst and/or coordinating solvent.

Molecular weight (MW) and configurational stabilities of a series of high- cis poly[(2,4-difluorophenyl)acetylene]s (PdFPhA, M w from 2.2 × 10 4 to 9.7 × 10 5 ) exposed to the atmosphere and diffuse daylight are reported. Polymers dissolved in THF- d 8 undergo simultaneous cis -to- trans isomerization and degradation under formation of a bimodal MW distribution. Degradation and isomerization rates are tightly connected and decrease with decreasing MW of the parent PdFPhAs. This finding may be interesting for the functional applications of substituted polyacetylenes. The partly aged PdFPhAs contain two separable fractions: higher-MW high- cis macromolecules containing a low amount of unpaired electrons and lower-MW deeply isomerized cis / trans macromolecules enriched in the unpaired electrons content. The difference in MW of these fractions reflects the various degradation rates of isomerized and high- cis macromolecules. Only a slow degradation without changes in the configurational structure proceeds if PdFPhA is allowed to age in the solid state. The suppression of the cis -to- trans isomerization reflects the suppression of motion of the polymer chains segments in the solid state.

A theoretical analysis of improving the separation power of size exclusion chromatography by decreasing flowrate is conveyed. The variance of the elution curves is larger than expected form estimated dispersity in molecular weight, Mw/Mn. The shape of the elution curves depends strongly on experimental conditions. When the experimental conditions are approaching those to the ideal separation, judged by statistical properties of the curves, both skew and excess kurtosis of the elution curves increase near the exclusion limit in accord with theoretical prediction. In analyses of polystyrene standards by size exclusion chromatography for polymers of molecular weight about thirty thousand and higher, the longitudinal diffusion is not important even at low flow-rates.

High- cis poly(phenylacetylene) (PPhA) has been prepared by polymerization of phenylacetylene with [Rh(COD)acac] catalyst and its molecular weight (MW) and configurational stability studied by SEC, 1 H NMR, UV/vis and IR techniques. PPhA dissolved in THF and THF- d 8 and exposed to the atmosphere and daylight at room temperature was found to undergo simultaneous cis - trans isomerisation and oxidative degradation accompanied by formation of a small amount (∼2 wt. %) of 1,3,5-triphenylbenzene. The extent of 1,3,5-triphenylbenzene formation was at least one order of magnitude lower than the extent of formation of new (shorter) PPhA macromolecules via their scission from the longer ones. Preparative MW-based fractionation revealed that a partly aged PPhA contains both (i) deeply isomerised macromolecules (forming the lower-MW fraction) and (ii) microstructurally unperturbed high- cis macromolecules (forming the higher-MW fraction). A hypothesis is postulated explaining the non-uniform distribution of high- cis and deeply isomerised trans -rich macromolecules along the MW distribution of partly aged PPhA. The hypothesis particularly assumes the acceleration of degradation of PPhA chains by simultaneous cis - trans isomerisation due to which the unpaired electron content is enhanced on the isomerised chains.

3-Ethynylthiophene (3ETh) was polymerized with Rh(I) complexes: [Rh(cod)acac], [Rh(nbd)acac], [Rh(cod)Cl] 2 , and [Rh(nbd)Cl] 2 (cod is η 2 :η 2-cycloocta-1,5-diene and nbd -norborna-2,5-diene), used as homogeneous catalysts and with the last two complexes anchored on mesoporous polybenzimidazole (PBI) beads: [Rh(cod)Cl] 2 /PBI and [Rh(nbd)Cl] 2 /PBI used as heterogeneous catalysts. All tested catalyst systems give high-cis poly(3ETh). In situ NMR study of homogeneous polymerizations induced with [Rh(cod)acac] and [Rh(nbd)acac] complexes has revealed: (i) a transformation of acac ligands into free acetylacetone (Hacac) occurring since the early stage of polymerization, which suggests that this reaction is part of the initiation, (ii) that the initiation is rather slow in both of these polymerization systems, and (iii) a release of cod ligand from [Rh(cod)acac] complex but no release of nbd ligand from [Rh(nbd)acac] complex during the polymerization. The stability of diene ligand binding to Rh-atom in [Rh(diene)acac] catalysts remarkably affects only the molecular weight but not the yield of poly(3ETh). The heterogeneous catalyst systems also provide high-cis poly(3ETh), which is of very low contamination with catalyst residues since a leaching of anchored Rh complexes is negligible. The course of heterogeneous polymerizations is somewhat affected by limitations arising from the diffusion of monomer inside catalyst beads.

International audience; The series of novel symmetric and asymmetric salphen cobalt (III) complexes with different counteranions (trichloroacetate, dinitrophenolate, pentafluorobenzoate and acetate) was synthesized and used as catalysts in copolymerization of CO2 with propylene oxide (PO) and cyclohexene oxide (CHO). Hexacoordinated structure of complexes adducts was found in solid phase. The effect of catalyst structure, temperature, CO2 pressure, catalyst/cocatalyst ratio on overall activity and selectivity was investigated. Synthesized salphen-Co (III) complexes were effective for both PO/CO2 and CHO/CO2 highly alternating copolymerization. Substitution of phenylene framework of salphen ligand by chlorine atom led to decrease of activity in PO/CO2 copolymerization. Complexes with trichloroacetate counteranion were shown to be the most active and selective in PO/CO2 copolymerization leading to poly(propylenecarbonate) with highest molar mass. On contrary, catalytic performance of salphen Co (III) complexes in CHO/CO2 copolymerization was almost independent on ligand structure and counteranion. Excellent selectivity to poly(cyclohexenecarbonate) was achieved even at 0.1 MPa CO2. MALDI-TOF analysis of polycarbonates was used to investigate the initiation step of the copolymerization.

This study reports the first Co2 (CO)8 -catalyzed [2+2+2] polycyclotrimerization by the transformation of internal ethynyl groups of aromatic diyne monomers. The reaction yields polycyclotrimers of polyphenylene-type with either hyperbranched or partly crosslinked architecture. The homopolycyclotrimerization of the monomers with two ethynyl groups per one molecule, namely 1,4-bis(phenylethynyl)benzene, 4,4'-bis(phenylethynyl)biphenyl, and 4-(phenylethynyl)phenylacetylene, gives partly crosslinked, insoluble polyphenylenes. The soluble, hyperbranched polyphenylenes are generated via copolycyclotrimerization of 1,4-bis(phenylethynyl)benzene with 1,2-diphenylacetylene (average number of ethynyl groups per monomer molecule < 2). This one-step polycyclotrimerization path to hyperbranched or partly crosslinked polyphenylenes is an alternative to the synthesis of these polymers by Diels-Alder transformation of substituted cyclopentadienones. All polyphenylenes prepared exhibit photoluminescence with emission maxima ranging from 381 to 495 nm. Polyphenylenes with a less compact packing of segments are microporous (specific surface area up to 159 m2 g-1 ), which is particularly important in the case of soluble polyphenylenes because they can be potentially used to prepare microporous layers.