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In the present paper, we describe the synthesis of poly(N-isopropylacrylamide) microgel particles in water/oil inverse emulsion used as carriers for enzyme encapsulation. Since enzymes can be used in different biotechnological applications, their immobilization on polymer colloidal carriers is of great importance. In this work, laccase from Trametes versicolor and also several peroxidases were immobilized in microgels. The polymerization process occurred via radical initiation in aqueous droplets in the presence of the comonomer vinylimidazole and the cross-linker N′,N′-methylene-bis-acrylamide at room temperature. Non-ionic surfactants were used to stabilize aqueous droplets in heptane. Due to the formation of microgels in aqueous media and the low reaction temperature, this technique allows the encapsulation of enzymes without risk of their denaturation, which can be controlled by variation of reaction parameters. Enzyme-containing microgels obtained by this method were analyzed in detail concerning their particle size, swelling properties, zeta potential, as well as resulting enzyme activity. Our experimental data indicate that the presence of imidazole groups in microgel structure allows increasing enzyme loading without reduction of enzyme activity.

We report synthesis of colloids with polymer core and inorganic shell consisting of silver nanoparticles (AgNPs) which can be used as building blocks for the preparation of conducting composite films. Polymer colloids based on copolymer of styrene and butyl acrylate with variable film formation temperature and functional surface have been prepared by surfactant-free emulsion polymerization. Polymer particles with average size between 140 nm and 220 nm and narrow size distribution were used as templates for deposition of AgNPs by microwave-assisted reduction of silver precursors in aqueous medium. The loading of the AgNPs on the polymer particle surface has been increased up to 60 wt.-%. Obtained hybrid colloids were used for preparation of composite films. The electrical conductivity of the composite films starts to increase if the AgNPs loading on the polymer particle surface is above 20 wt.-%.

For grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11-(pyrrol-3-yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X-ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions.

Microgel–clay composite particles were prepared by one-step surfactant–free precipitation polymerization. Laponite nanoparticles present in the reaction mixture become encapsulated during the microgel formation process. Microgel–clay composites based on poly( N -vinylcaprolactam- co -acetoacetoxyethyl methacrylate) containing different amount of incorporated clay nanoparticles were synthesized. The clay content was varied from 2 wt% to 18 wt%. The extremely high incorporation efficiency of the clay nanoparticles into microgels was detected. The size of the hybrid microgels was decreased from 700 nm to 100 nm by increase of the clay concentration in the reaction mixture. Obtained hybrid microgels exhibit negative surface charge and excellent colloidal stability. Microgel–clay composite particles display temperature-sensitive behaviour in water. The swelling degree of the hybrid microgels decreases with increase of the clay loading. Microgel–clay composite particles exhibit temperature-controlled uptake of the cationic dye, Methylene blue, and can be used as scavenger systems in aqueous media.

Temperature-sensitive poly(glycidol)-b-poly(N-isopropylacrylamide) block copolymers (PGl55PNIPAAmy) were synthesised and their aqueous solutions investigated by different methods including differential scanning calorimetry (DSC), UV-VIS spectroscopy as well as dynamic and static light scattering. The cloud point temperature (T c) depended on the composition of the investigated block copolymers and increased with decreasing length of the PNIPAAm block in PGl55PNIPAAmy copolymers. In contrast, the enthalpy of phase separation of PNIPAAm segments measured by DSC decreased with decreasing length of the PNIPAAm block in the polymer. These findings can be correlated with the behaviour of homo-PNIPAAm with similar molecular weights indicating that the influence of PGl on the local environment and phase separation of PNIPAAm chains is similar to the influence observed for PNIPAAm chains bearing different low molecular weight end group. Using DLS measurement, it was shown that the aggregation process depended on the PGl/PNIPAAm block ratio. If the PGl/PNIPAAm ratio was low, stable core-shell aggregates were formed. In contrast, the tendency to formation of large unstable, loose aggregates was observed for copolymers with high PGl/PNIPAAm ratio.

The properties of amphiphilic polyether macromonomers and their behaviour during homo-polymerisation in water and in water/benzene mixture are reported. Homo-poly(glycidol) macromonomer bearing polymerisable p -vinyl benzyl end groups (PGl55-St) and two block poly(glycidol)- b -poly(glycidyl phenyl ether) macromonomers, containing polymerisable p -vinyl benzyl end groups attached to the hydrophobic (PGl52- b -PGlPhE8-St) or hydrophilic (PGlPhE9- b -PGl54-St) block were used for investigations. DLS measurements showed formation of micelles by all macromonomers, what is the reason for enhanced homo-polymerisation. In water the polymerisation initiated with 4,4′-azobis(4-cyanovaleric acid) was fast, while macromonomer conversion was over 90%. Introduction of benzene to the polymerisation system resulted in formation of swollen (less packed) micelles and to a decrease of the local concentration of double bonds in the micelle core. As a result the decrease of reaction rate followed by longer polymerisation time in case of PGl55-St and PGl52- b -PGlPhE8-St was observed. Nevertheless, their conversion remained high and varied from 95 to 10. In contrast for PGlPhE9- b -PGl54-St increase of polymerisation rate, accompanied by slight increase of conversion was observed for homo-polymerisation in water/benzene mixture.

The problem of delamination of electro-deposited polypyrrole (PPY) layers on several substrates can be avoided by using an adhesion promoting system. A new class of compounds–ω-(pyrrol-3-yl)alkylphosphonic acids have been designed to link polypyrrole layers covalently to metal oxide surfaces. Synthetic routes, which lead to the formation of 3-substituted pyrroles with surface active groups are described. The synthesis and characterization are shown in detail. 1-Phenylsulfonyl pyrrole was utilized as a precursor in the synthesis of 3-substituted pyrroles via Friedel-Crafts acylation reaction. Subsequently, two methods were used to synthesize ω-(pyrrol-3-yl)alkylpho- sphonic acid esters. One starts from the brominated oxoalkyl derivatives by removing the protecting group followed by reduction yielding ω-(pyrrol-3-yl)alkylphosphonic acid esters. This method is suitable for hexyl or longer chain derivatives. The other is the reduction of carbonyl group followed by de-protection, which is successful for short as well as long chain derivatives. Finally, ω-(pyrrol-3-yl)alkylphosphonic acids were obtained by hydrolysis of the ester derivatives.

ω-(Pyrrol-1-ylalkyl)dimethylchlorosilanes with different chain lengths were adsorbed on silicon oxide surface, subsequently, the polypyrrole film was deposited on this modified substrate. The chemical deposition of polypyrrole on the modified surface was investigated by SEM and AFM. The thickness of deposited polypyrrole films on different chain adhesion promoter modified substrates has no big difference except that of the short chain length. The electric properties were investigated by current-potential characterization. The results show that the value of the electrical current does not monotonically depend on the length of the spacer of the adhesive monolayer. The electric property shows that the charge carrier mobility is 1.4×10−4 cm2·V−1·s−1.

Block copolymers of poly(glycidol)-b-poly(4-vinylpyridine) were obtained by ATRP of 4-vinylpyridine initiated by ω-(2-chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pKa value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782–1794, 2009

Preparation of core–shell particles consisting of polystyrene–poly(ethylene glycol) monomethacrylate (PS–PEGMA) core covered with polypyrrole (PPy) shell is described. The thickness of PPy shell, which strongly influences electrical properties of the films prepared from the particles, can be varied by changing pyrrole load, controlling the overall template surface area in the system and by influencing the pyrrole polymerization kinetics in the presence of different oxidants. The type of anions and PPy loading strongly influence the electrical conductivity. Typical value of the resistivity of thin film consisting of core–shell particles was 34 Ωm (PPy oxidized by FeCl 3 , shell thickness 3 nm). Current–voltage dependences of low conductivity samples (thin PPy shell layer) are characteristic of contact-limited currents. The conductivity of the particles changes with humidity, which can be utilized in humidity sensors.

In present article, we demonstrate that aqueous microgels can be used as containers for the in-situ synthesis of hydroxyapatite. The hydroxyapatite nanocrystals (HAp NCs) become integrated into microgels forming hybrid colloids. The HAp NCs loaded in the microgel can be varied over a broad range. The HAp NCs are localized within the microgel corona. The deposition of the inorganic nanocrystals decreases the colloidal stability of the microgels and leads to particle aggregation at high HAp NCs loading. Because of the strong interactions between HAp NCs and polymer chains, the swelling degree of microgels decreases, and temperature-sensitive properties disappear at high loading of the inorganic component. We demonstrate that hybrid colloids can be used as building blocks for the preparation of nanostructured films on solid substrates.

The adsorption and self-organization process as well as the surface reactions of several bifunctional adhesion promoters on different oxide surfaces have been investigated. The aim was to improve the adhesion between metal oxides and different organic coatings. We developed a large number of bifunctional compounds, which are able to adsorb spontaneously on different pre-treated metal (oxide) surfaces. The second group can be designed for grafting different otherwise incompatible layers. Therefore, a special two-step procedure has been developed: (1) adsorption of the designed bifunctional molecules on the substrate and (2) surface reaction of the terminal reactive group with a polymeric top coating or with further monomers resulting in a strongly bond composite. For this purpose substances were chosen having a surface reactive group, an aliphatic spacer and a reactive group for a suitable top layer. Phosphonic acids forming strong bonds with several metal surfaces were chosen as surface-active groups on metal oxide substrates. The termination of these compounds with further reactive groups opened a wide range of possible applications. Functionalities like amino or carboxylic groups allowed reactions with commercial lacquers (e.g., polyurethane) for improving adhesion promotion and corrosion inhibition of the metal substrates. By using polymerizable groups like thiophene and pyrrole an in situ surface polymerization with further monomers is possible directly on the substrate. The adsorbed films of bifunctional phosphonic acids on metal (oxide) substrates were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS), the surface polymerized films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), cyclovoltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results showed that monolayers were formed, which were correctly oriented on the surfaces: the phosphonic acid group was attached to the substrate whereas the terminal group was free standing for further reactions. Surface polymerization with additional monomer was possible either chemically or electrochemically resulting in smooth polymer layers of adjustable thickness. The conducting polymers were found to be p-conductive with a doping level of about 30%. Conductivity measurements revealed a conductivity of about 0.13 S/cm for the best films. Based on this principle two possible applications are given: firstly, a corrosion protecting system for steel, and secondly, a model release system for protecting steel after damage of the coating.

This paper presents the first results of a project aimed at investigating the arrangement of polyelectrolyte layers on unalloyed steel. We studied the structure of double and single polymer layers consisting of cellulose phosphate (HP-PP-C) and polyethyleneimine (PEI). Layers were characterized by variable angle ellipsometry, AFM and XPS. In particular, XPS indicated the incorporation of iron ions into cellulose phosphate layers, but, in contrast, these ions could not be observed in PEI layers. Results indicated that the homogeneity and qualitative corrosion performance of double layers (HP-PP-C/PEI) on unalloyed steel depend on the deposition of cellulose phosphate at the interface with steel.

In the present paper, we describe the preparation of hybrid particles consisting of polymeric core with deposited hydroxyapatite (HAp) nanocrystals. Polystyrene submicron particles modified by β-diketone groups have been used as templates for the growth of HAp. Hybrid particles with HAp nanocrystal content between 7 and 50 wt% have been prepared. Microscopy studies indicate that hybrid particles exhibit “raspberry” morphology, and HAp nanoparticles are not homogeneously distributed on the polymer particle surface. The increase in the HAp content on the polymer particle surface reduces the colloidal stability of the hybrid particles because of the vanishing of the surface charge.

In this article, we report the preparation of a kind of novel crosslinked ultrafine fiber by electrospinning of unsaturated polyester macromonomers (UPM) and subsequent thermal crosslinking. The UPM is prepared via a two-step reaction with poly(2-methyl-1,3-propyleneadipate) diol terminated (PMPA), isophorone-diisocyanate (IPDI) and 2-hydroxyethyl methacrylate (HEMA). Poly(3-hydroxyl-butyrate-co-3-hydroxylvalerate) (PHBV) is chosen to improve the processability of the UPM. UPM/PHBV blend ultrafine fibers are successfully electrospun with a proper mass ratio of UPM to PHBV in dichloromethane solution. The fibers are thermally crosslinked after electrospinning. Measurement results indicate that the average diameter of the fibers is about 1 μm and the crosslinked fibers have good solvent-stability and thermal-stability. This novel fiber has potential applications in filtration and protective coating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 107:2142–2149, 2008

In the last decade there has been a steady increase in the number of publications describing the synthesis, characterization and applications of hybrid particles. Colloidal aqueous microgels form an important subdivision of polymer colloids used for the deposition of different functional materials. Due to their numerous attractive properties, microgel particles have been used as templates for the synthesis, storage and transportation of nanostructured materials. This paper reviews the important developments in the area of composite microgels over the last decade, and is limited to microgel particles operating in aqueous media. The patent literature is not included in the review. Different synthetic approaches as well as some properties and applications of composite microgels are discussed. Copyright © 2006 Society of Chemical Industry

A novel type of submicrometer-sized hybrid microgels containing gold nano-particles (AuNPs) has been tested as catalyst in reduction of 4-nitrophenol in aqueous medium. The influence of microgel concentration, gold content, as well as temperature of reaction medium on kinetics of 4-nitrophenol reduction process has been investigated. The pseudo-first-order kinetics was used to evaluate the catalytic reaction rate. It has been demonstrated that reaction rate of 4-nitrophenol reduction can be accelerated if the concentration of microgel in the reaction system or amount of gold nanoparticles loaded into microgels increases. Increase of reaction temperature resulted in rapid increase of reduction rate. Compared to pure gold nano-particles hybrid microgels at similar conditions reduce the activation energy of reduction process by a factor of 2. This indicates that localization of AuNPs within microgel template prevents their aggregation and therefore high catalytic activity can be preserved independently from reaction conditions. Additionally, polymeric template provides suitable environment for better mass transfer in present system that improves the catalyst efficiency.

Novel temperature- and pH-responsive microgels based on poly(vinylcaprolactam-co-acetoacetoxy methacrylate) (VCL/AAEM) functionalized with vinylimidazole (VIm) has been prepared in aqueous medium using simple batch dispersion polymerization procedure. Obtained microgel particles are characterized by narrow particle size distribution and their hydrodynamic radius can be varied from 200 to 500 nm (pH = 6, T = 20 °C). The T- and pH-sensitivity of obtained particles can be easily tuned by the variation of the Vim content in the copolymer structure. Increase of VIm content in the microgel structure led to increased swelling of the microgels in acidic medium and strong shift of the volume phase transition temperature to higher temperatures. It has been found that sedimentation behavior of obtained microgels is strongly pH-dependent, and this effect can be used for controlled particle separation.

In the present paper composite polymeric particles with polypyrrole (PPy) shell have been examined as reservoirs for uptake of amino acids. The particle morphology can be designed in a way that polypyrrole load on the particle surface as well as the PPy shell thickness can be varied easily by control of the pyrrole polymerization conditions, such as monomer concentration and choice of different oxidants. Three different oxidants have been used for the preparation of PPy outer-layers, namely FeCl3, Na2S2O8, and H3PMo12O40, which give the possibility to incorporate different anions into PPy structure. l - and d -alanine uptake in the presence of obtained particles has been tested as a function of particle concentration and PPy amount on the particle surface. It has been found that composite particles can adsorb quite high amounts of alanine and even show certain enantioselectivity. The uptake efficiency and selectivity depend strongly on the properties of the PPy layer, such as chemical structure (oxidized or overoxidized state) and the nature of the dopant anion.

A series of high clay content Laponite XLS/ polyacrylamide (PAAm) nanocomposite hydrogels (S-M gels) with excellent resilience, low elastic hysteresis, and ultrahigh elongation, have been successfully synthesized. Based on our results, it is concluded that the mechanical properties ofnanocomposite hydrogels probably depend to a great extent on the hydrophilicity and flexibility of the macromolecules. More, over, his found that the transparency during the in-situ polymrization of S-M gels does not change, which is quite different from clay/poly(N-isopropyl-acrylamide) nanocomposite hydrogels.

In this paper we report a study of laccase immobilisation on different kinds of carrier particles. The immobilisation of enzyme on the particle surface with respect to the immobilisation efficiency and the properties of the immobilised enzymes is discussed. The immobilisation of laccase on polystyrene particles bearing reactive beta-diketone groups is characterised by high efficiency, but grafting of the enzyme increases the stability of the colloidal system, which makes the separation/purification procedure difficult. Additionally, the extreme colloidal stability of the immobilisates hinders the application of such particles with immobilised enzymes in some applications where the recycling of the enzyme should be performed. It has been found that hybrid PS-AAEM particles equipped with maghemite show similar immobilisation efficiency to that of their analogues without maghemite and can additionally be manipulated in magnetic fields. The activity of the immobilised laccase is much higher in the pH region 5-7 and the temperature range 50-70 degrees C as compared with that of the free enzyme. Immobilised enzymes also exhibit much better storage stability.

Hybrid microgels functionalized with silver nanoparticles (AgMP) have been prepared and their physico-chemical properties examined. Composite have been obtained by formation of AgNP in presence of poly[vinylcaprolactam-co-(acetoacetoxyethyl methacrylate)] (VCL/AAEM) microgel particles. It has been demonstrated that hybrid particles with different AgNP amounts can be prepared. Hybrid particles are sensitive to temperature and swelling, and collapse processes are reversible. Incorporation of AgNP leads to shrinkage of microgel template due to the partial immobilization of polymer chains on the microgel surface. As a consequence, gradual loss of temperature sensitivity is observed. Hybrid microgels form highly transparent well-organized films on solid substrates, providing homogeneous distribution of AgNP in bulk materials. Presence of AgNP increases considerably the thermal stability of composite films.

In the present paper, we investigate the preparation of polymeric particles based on the biodegradable polyester poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV). A new technique for PHBV particle preparation has been developed. This method utilizes the thermoreversible gelation of PHBV in toluene. Particles have been obtained by the secondary dispersion technique in a three-step procedure: (a) preparation of PHBV solution in toluene; (b) preparation of O/W emulsion by ultrasound followed by the gel formation in toluene/PHBV droplets; and (c) toluene extraction. In the present study we investigated the influence of the stabilizer type and its concentration in the aqueous phase, ultrasound power, and PHBV concentration in toluene on the size and stability of the formed droplets as well as the final PHBV particles. It has been found that PEO/PS block copolymers are the best stabilizers for the present system as compared to conventional tensides such as SDS or CTAB. It has been found that PEO/PS block copolymers allow obtaining PHBV particles with a regular shape and controlled dimensions after toluene extraction. The minimal size of the PHBV particles obtained by this technique was ca. 100 nm. The obtained particles exhibit a relatively broad particle size distribution and the particle shape is strongly affected by the block copolymer composition, ultrasound power and the way of toluene extraction.

Thermosensitive nanogels were prepared from photo-cross-linkable copolymers of N-isopropylacrylamide (NIPAAm) and 2-dimethylmaleinimido ethylacrylamide (DMIAAm). The colloidal nanogels were formed by UV-irradiated solutions of thermosensitive polymers in water at 45 °C. The size of nanogels could be controlled by the concentration of photopolymer solutions, the amount of chromophore DMIAAm in the photopolymer chains, and sodium dodecyl sulfate (SDS) concentrations. Analytical ultracentrifugation could reveal the degree of swelling of the different nanogel preparations, confirming the data from dynamic light scattering. In addition, the quantitative determination of un-cross-linked polymer species was possible. Even the determination of the degree of swelling distribution was reported for a nanogel for the first time. Hydrogel particles could be prepared with low SDS concentration or even in the absence of a surfactant. Therefore, the effects on swelling produced by the addition of alcohols to these nanoge...

In present paper we investigate thermoreversible gelation of biodegradable polyester poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in toluene. Hot PHBV solutions became transparent gels after cooling to room temperature. This physical gelation process was followed by light scattering and viscosity measurements for solutions of different PHBV concentrations. It has been found that gelation temperature increases with increasing polymer concentration in toluene. PHBV films have been prepared by gelation process followed by solvent removal on solid substrates. It has been demonstrated that PHBV concentration in the solution influences the surface morphology of obtained films. Homogeneous PHBV films with increased surface roughness can be obtained by means of developed technique. Hydrolytic degradation studies indicate that surface morphology of obtained PHBV layers changes considerably with degradation time.

The synthesis and polymerization of macromonomers containing a polymerizable styrene head group and a tail of ethylene oxide derivatives of different character were investigated. The synthesis of macromonomers was based on living anionic polymerization of oxiranes. Two monomers were used: 1-ethoxyethyl glycidyl ether (glycidol acetal), which after hydrolysis forms hydrophilic glycidol blocks and glycidyl phenyl ether forming hydrophobic blocks. Polymerizable double bonds were introduced by terminating the living chain with p-(chloromethyl)styrene. The radical polymerization of the macromonomers was carried out in water with addition of a non-polar solvent (benzene) and AIBN as initiator. Core-shell polymers of different character and molar masses were obtained. The conversion of polymerized macromonomers was around 50%. However, the polymerization product could easily be separated from the reaction mixture.

We report on a preparation of hybrid particles with polymeric cores and ZnS shells. Two types of monodisperse sterically stabilized polystyrene particles with hydroxyl-terminated PEG chains (PS/PEGMA) or β-diketone groups (PS/AAEM) on the surface have been prepared and characterized. Formation of ZnS layer on the surface of submicron particles has been studied by SEM and EDX. Deposition of ZnS on the surface of PS/PEGMA particles is not uniform and leads to formation of ‘raspberry’ morphology with rough surface. It has been found that presence of β-diketone groups on the particle surface leads to formation of well-defined ZnS layers. It has been assumed that such effect is due to the complexation of Zn cations by β-diketone groups leading to nucleation and growth of ZnS crystals on the polymer particle surface. Polymeric particles were completely covered with ZnS if the loaded amount of inorganic material was higher then 40 wt%. The thickness of ZnS layer on the particle surface can be easily varied by changing the ZnS load (in present study maximal thickness of the ZnS shell was 70 nm). It has been found that increase of the ultrasound power leads to considerable increase of the ZnS deposition on the particle surface without strong changes of the particle morphology. Hybrid particles have been investigated with XRD technique and their optical properties were studied by UV-spectroscopy. The colloidal stability of obtained particles was studied by separation analyser. Sedimentation experiments indicate that colloidal stability of obtained composite particles depends strongly on loaded ZnS amount and pH value of the aqueous medium. It has been found that highest sedimentation velocities (or maximum of instability) were determined by ZnS loads, which provide complete coverage of the particle surface. Increase of the ZnS layer thickness led to better stability of hybrid particles in aqueous medium.

We report on a preparation of hybrid microgels filled with ZnS inclusions. Temperature-sensitive poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) (VCL/AAEM) microgels have been used as containers for deposition of ZnS by reaction of zinc acetate and thioacetamide under ultrasonic agitation. ZnS was deposited directly into microgels, leading to formation of composite particles which exhibit temperature-sensitive properties, high ZnS contents, and excellent colloidal stability. The influence of ZnS load on microgel size, morphology, swelling−deswelling behavior, and stability is discussed. Hybrid particles contain up to 20 wt % of ZnS, and particle stability decreases with increase of inorganic filler content. Detailed microscopy investigations confirm incorporation of ZnS nanoparticles into microgel network. The possibility of self-assembly of hybrid particles on different surfaces was studied. It has been found that microgels filled with ZnS can form organized particle arrays after water evapora...

Novel well-defined block copolymers composed of polystyrene, poly(2-vinylpyridine), poly(ethylene oxide), or poly(tert-butyl methacrylate) as the first block and poly-(N,N-dialkylacrylamide) (PDA1AAm) as the second block were synthesized by ligated anionic polymerization. The latter was carried out in tetrahydrofuran (THF) initiated by 1,1-diphenyloligostyryllithium in the presence of ZnEt 2 and LiCl. At first the role of the additives LiCI and ZnEt 2 on the mode of the anionic homopolymerization of N,N-dialkyl-acrylamide was investigated. Polymerization in the presence of ZnEt 2 resulted in syndiotactic polymers with narrow molecular weight distribution only. In the presence of both additives, the reaction mixture became heterogeneous with a high degree of isotacticity of the polymers. Despite the fact that the polymerizations were performed in heterogeneous phase, the DAlAAm monomers were polymerized in a quantitative yield. The efficiency of the first block of active sites was always higher than 0.71. Preliminary studies using dynamic light scattering of aqueous hydrochloric acid solutions of poly [(2-vinylpyridine)-block-(N,N-diethylacryl-amide)] block copolymers at different temperatures and at pH 2 showed that above 45 °C, micelle-like aggregates were formed. The heating and cooling cycles were reversible but showed hysteresis, which was obviously due to the isotactic structure of the poly(N,N-diethylacrylamide) block.

This paper describes synthesis and characterization of two thiophene-based azomethines designed to optimize solubility, self-assembly, and charge carrier mobility. We found that incorporation of azomethine and amide moieties in the α,ω-position, and hexyl chains in the β-position of the quaterthiophene, considerably improves the self-assembly properties without suppression of solubility. Self-assembly of azomethine oligomers with (QT-amide) and without amide moieties (QT-aniline) were monitored by UV−vis, XRD, and AFM. Although no changes in the UV−vis spectrum of QT-aniline is observed upon addition of hexane to the solution in THF, the addition of hexane to QT-amide solution induces a red shift of λmax and appearance of fine structure believed to be vibronic in nature. The concentration dependence of the solvatochromism gives strong support for the intermolecular origin of this effect and clearly indicates that the planarization of the oligomer backbone is forced by the aggregation. Although, no clear s...

Stable polypyrrole dispersions were prepared by chemical oxidative polymerization of pyrrole in an aqueous medium containing different anionic salts - sodium benzoate, potassium hydrogen phthalate and sodium hydrogen succinate. Results of the elemental analysis and FT-IR spectroscopy confirmed that the anionic salts are incorporated in the conducting polymers and functioned as the dopants. The retardation of pyrrole polymerization was observed when a certain amount of the salt was used as dopant. SEM images of polypyrrole dispersions indicate large spherical particles (150-180nm). The conductivity of polypyrrole composites has also been investigated.

ω-(Pyrrol-1-yl alkyl) dimethylchlorosilanes with different chain length were synthesized and characterized with IR, NMR and elemental analysis. The growth of self-assembled monolayers of ω-(pyrrol-1-yl alkyl) dimethylchlorosilanes on oxide surfaces has been investigated. The order gradually improved with adsorption time and highly ordered SAMs were obtained for nearly 2 days adsorption time. Characterization of the films has been performed with contact angle measurements, ellipsometry, SPR and grazing incident FTIR. The chemical deposition of polypyrrole on the modified surface was investigated. The thickness of polypyrrole layer was influenced by the concentration of monomer, the deposition time, and the ratio of monomer to oxidant.

Behaviour of temperature-sensitive core–shell VCL/AAEM microgels has been studied in binary alcohol/water mixtures. Amount of alcohol in binary mixture influences strongly the swelling and thermo-sensitive properties of microgels. Alcohol induces swelling of VCL-rich microgel shell leading to larger dimensions of microgel particles and larger surface area. Under these conditions pyrrole polymerization was carried out, and the influence of pyrrole concentration, oxidant nature and temperature on morphology and properties of composite particles was investigated. Contrary to the polymerization in water medium, this selective swelling method gives possibility to increase three times loaded polypyrrole amount and maintain the stability of the colloidal system. It was found that in case when persulfate was applied as oxidant it is possible to vary effectively the particle size of composite microgels by changing the ethanol concentration in water. Contrary, when FeCl3 was used as oxidant formation of secondary particles was detected leading to dispersions with bimodal particle size distribution. The conductivity of the composite particles was much higher if polypyrrole synthesis was carried out in pure water.

In the present paper, polymeric microgels have been prepared by surfactant-free emulsion co-polymerization of acetoacetoxyethyl methacrylate (AAEM) and N-vinylcaprolactam (VCL) in water with water-soluble azo-initiator 2,2′-azobis(2-methylpropioamidine) dihydrochloride (AMPA). It was found that the particle diameter decreased gradually when higher amounts of AAEM were used in monomer mixture. Obtained microgels possess lower critical solution temperature (LCST) in water solutions, so rapid decrease of the particle size was observed at elevated temperatures. As was found using simultaneous static and dynamic light scattering, microgels undergo soft sphere–hard sphere transition during heating.

In a previous paper [Polymer (2003) in press DOI: 10.1016/j.polymer.2003.09.037] polymeric temperature-sensitive microgels were prepared by surfactant-free emulsion co-polymerization of N-vinylcaprolactam (VCL) and acetoacetoxyethyl methacrylate (AAEM). In the present work, VCL/AAEM microgels were used as a template for oxidative polymerization of pyrrole (Py). It was found that pyrrole polymerization takes place directly in microgel structure leading to composite particles. Influence of microgel structure and amount of incorporated polypyrrole (PPy) on particle properties is discussed. Obtained stable composite microgels show similar thermal sensitivity as VCL/AAEM particles with fully reversible collapse-swelling properties.

Solvent-induced aggregation of regioregular head-to-tail poly(3-alkylthiophene)s (PATs) have been studied by means of AFM and UV−vis spectroscopy. In hexane, which is a good solvent for alkyl side chains but poor for polythiophene backbones, PAT molecules undergo ordered main-chain collapse driven by solvophobic interaction. Well-pronounced concentration-independent red shift of λmax and good resolved fine vibronic structure in the electronic absorption spectra observed upon addition of hexane indicate that planarization occurs on the single-molecule level. A helical conformation of the man chain of PATs with 12 thiophene rings per each helical turn has been proposed. At the higher concentration of PATs the collapsed molecules undergo unexpected one-dimensional aggregation. Length of the particles varies from several nanometers to several hundreds nanometers and can be easily adjusted by the solvent composition or concentration of PATs.

Several concepts have been developed for the improvement of adhesion promotion and corrosion inhibition of reactive metal surfaces, like aluminum. The aim of these studies was to replace the present technical procedure for pretreatment of aluminum surfaces with chromium acid. Therefore, the adsorption and organization process of mono- and bifunctional alkyl phosphonic acids and mono alkyl phosphoric acid esters has been investigated. The properties of the adsorbed SAM's were confirmed by industrial linked adhesion and corrosion tests. By functionalization of the terminal position with thiophene, molecules are prepared which can graft conducting polythiophene layers via surface polymerisation on silicon/metal substrates. Also polymeric nano-particles with phosphoric acid groups form thin and smooth well-packed films on aluminum surfaces. Stable core-shell polypyrrole (PPy) dispersions were prepared by using polystyrene (PST) or poly (styrene-co-butyl acrylate) (PST-co-BuA) as the core, and polypyrrole as the shell.

Cellulose as natural and non-toxic material is very interesting for biological applications. Its poor solubility in organic solvents can be improved by introduction of long alkyl chains. Phosphate-substituted cellulose derivatives form ultra-thin layers on several metal surfaces [1, 2]. The layers were applied on the surfaces via dip coating from dilute solutions and characterised by contact angle measurements. Initial corrosion tests were performed. These polymers were applied as adhesion promoters for steel-, titanium- and hydroxy apatite surfaces. Medical implants were pre-treated by UV irradiation, coated with the cellulose derivatives and activated by hot water treatment. The adhesion of the implants surpassed that of conventionally used PMMA systems.

A new class of compounds, ω-(thiophen-3-yl) alkyl phosphonic acids, was used to link conductive polythiophene layers and several metal oxide substrates. In general, the adhesion between polythiophene films and metal substrates is insufficient for technical and microelectronic applications. The use of adhesion promoters between the substrate and the polymer enables the formation of a strongly bonded composite. Adhesive compounds were synthesized which contained a phosphonic acid group attached to the substrate and a thienyl group for surface polymerization with thiophene monomers. The properties of these created adhesion promoters were characterized on several substrates by contact angle measurements and IR investigations. First successful attempts were made to obtain a structured polymer surface via micro-contact printing.

Tert-butylacrylate was polymerized by potassium tert-butoxide in THF and toluene in the presence of 10% (by volume) of ethylene oxide. Polymers with good yields and reasonably narrow MWD (Mw/Mn∼2) were obtained. Microtacticity of the polymers is strongly solvent-dependent, the content of isotactic triads being ∼70% in toluene and ∼40% in THF. Upon using ethylene oxide as part of the solvent, diblock-copolymers of polyethylene oxide with poly-tert-butylacrylate with controlled molecular weight characteristics of the polyethylene oxide block were synthesized. The possibility of diethylvinylphosphonate polymerization on the living chain ends of poly-tert-butylacrylate was checked. At the 10% content of ethylene oxide in the reaction medium, diblock-copolymers of poly-tert-butylacrylate and polydiethylvinylphosphonate were obtained and theIR compositions were determined. Triblock-copolymers polyethylene oxide-poly-tert-butylacrylate-polydiethylvinylphosphonate with low polymerization degree of the second and ...

Polythiophene layers have been grafted onto silicon, iron, platinum and titanium for applications as organic semi-conducting films on solid surfaces. In general, the adhesion between the polymer films and substrates is insufficient for technical and microelectronic applications. The use of adhesion promoters between substrate and polymer and enables the formation of a strongly bonded composite. The polymers were synthesized by chemical or electrochemical surface polymerization.

In this work the emulsion polymerisation of styrene was carried out in presence of the inisurfs (reactive surfactants). The reaction kinetics was followed by dilatometric and calorimetric measurements. The influence of the inisurf concentration in reaction mixture as well as the reaction temperature on the particle properties were studied. Resulting particles were characterised with FFFF-MALLS and PCS. Viscosity measurements indicate the formation of particle flocks in the solution at certain inisurf concentration in reaction mixture.

The adsorption and organisation process of reactive microgels has been investigated on technical aluminium. The aim was to replace the present chromating procedure on reactive metals like aluminium because this process was been considered as an ecological problem. By means of a two-step emulsion polymerization with phosphate substituted monomer we have obtained polymeric nano-particles with phosphate groups on the surface. The core is synthesized by copolymerization from styrene (St) and butyl acrylate (BuA). The results of several analytical methods like contact angle SEM or TEM measurements showed, that these microgels were able to adsorb spontaneously onto the substrate surface and subsequently a structured molecular order was formed. The properties of the adsorbed microgel layers were confirmed by industrial linked adhesion and corrosion tests.

In recent works the self-assembly process has been investigated to replace the present chromating procedure on reactive metals like aluminium and the improve the lacquer adhesion and corrosion inhibition. These self-assembling layers were formed of small bifunctional organic molecules with phosphate or phosphonic acid groups attached to the metal substrate. The idea of this work was to apply these results and techniques to cellulose derivatives on implant metals. The formation of ultra-thin layers of phosphorylated cellulose derivatives has been reported previously. These ultrathin layers were built on metal substrates like aluminium, titanium or steel for adhesion promotion and corrosion inhibition. Hydroxypropyl-2-phosphatepropyl cellulose was synthesised for adhesion on hydrophilic metallic surface. Hydroxypropyl-2-cinnamoylpropylester cellulose was prepared in order to crosslink the adsorbed layers. The layers were formed on metal surfaces via dip coating from dilute solutions and characterised by means of contact angle measurements, SEM investigations and FT-IR spectroscopy. Initial corrosion tests were performed.

The polymer peroxide surfactants obtained by copolymerization of a perox- ide monomer with maleic anhydride were either physically or chemically sorbed on the dispersed-phase surfaces, for example, on mineral fillers and latex particles. Subse- quent initiation of graft copolymerization from the surface resulted in the formation of interfacial compatibilizing polymer layers in water emulsions and dispersed-filled polyethylene. The morphology of the resulting filled polymer was characterized by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1228 - 1239, 2000

A series of temperature and pH sensitive polymers which contain both temperature and pH sensitive components were synthesised by copolymerization of N-isopropylacrylamide (NIP AAm) and acrylamide derivatives containing a spacer and a sensitive headgroup. The cloud point and heat of transition (ΔH PT ) of aqueous solutions of polymers with various compositions were measured by means of DSC. The observed cloud points and ΔH PT values strongly depend on the polymer composition and the pH value. The irradiation of dimethylmaleinimide groups (DMIAAm) bearing copolymers with UV light resulted in crosslinking of the polymers. The prepared thin layers showed fast temperature dependent swelling with transition temperatures similar to the uncrosslinked polymers.

The self-assembly process has been investigated for the replacement of the present chromating procedure on reactive metals like aluminium and to improve the lacquer adhesion and corrosion inhibition. It will be shown, that self-assembled layers can affect adhesion and corrosion inhibition on aluminium and its alloys. For self-assembly molecules (SAMs) substances are required which are able to react spontaneously on the surface for which terminated alkyl-phosphonic and phosphoric acid monoalkyl esters have been synthesised. The best anchor groups for aluminium were ascertained by pH-dependent flotation tests, dynamic contact angle measurements and corrosion tests. Grazing angle Fourier transform infrared spectroscopy (FTIR), angle dependent X-ray photoelectron spectroscopy (XPS) and Auger measurements show the existence and orientation of these new molecular structures. Model surface reactions with isocyanates demonstrate the binding capability to the lacquer.

The adsorption and self-organisation process of alkyl-phosphonic acids and phosphoric acid monoalkyl esters on technical aluminium surfaces have been investigated by different surface sensible techniques: Grazing angle FT-IR- spectroscopy, angle dependent XPS and Auger- spectroscopy. The aim of these studies was to replace the present technical procedure for pretreatment of aluminum surfaces with chromate acid in order to improve the corrosion inhibition and the coating adhesion. The ability for self-assembly is given by substances which have a surface reactive group and a long-aliphatic or aromatic spacer and a supramolecular order is built-up between these spacers. The results show that these molecules are able to adsorb spontaneously onto the aluminum surface and subsequently a structured molecular order is formed. These effects were confirmed by industrial linked adhesion and corrosion tests.