The application of copper‐catalyzed azide/alkyne cycloaddition to monomers containing a ferrocene unit leads to polyferrocenes with ferrocene in the backbone. Catalyst performance and kinetic studies of a model system comprising 1,1'‐bis(azidoethyl)ferrocene and propargyl ether revealed the usage of CuI and DBU as the catalyst in DMF at 50 °C as efficient reaction conditions for the synthesis. The resulting polymers display molecular weight‐averages up to $\overline {M} _{{\rm n}} $ = 10 000 and $\overline {M} _{{\rm w}} $ = 33 000. The polyaddition of monomers both containing ferrocene units led to polyferrocenes with $\overline {M} _{{\rm n}} $ between 4 000 and 11 000 ($\overline {M} _{{\rm w}} $ up to 78 000). The present study thus provides a pathway to polyferrocenes based on modular ligation chemistry.
The concept of Hansen solubility parameters (HSP) is applied to organic semiconductors in order to determine and predict their solubility behavior, which is essential for the design of functional and environmentally friendly ink formulations for organic photovoltaics. Two different conjugated polymers, one semicrystalline and one dominantly amorphous, and one fullerene derivative are selected as prototype candidates to evaluate the applicability of the HSP concept for organic semiconductors. The method for determining the solubility parameters is described and the quality of the HSP fits as well as their suitability for designing of organic electronic inks are discussed in detail.
Photoreorientation of a stripe pattern consisting of an MPS structure in a Langmuir‐Blodgett monolayer by irradiation with linearly polarized light is achieved for the first time using a PDMS/poly(methacrylate) diblock copolymer with a liquid crystalline azobenzene‐containing side chain. The stripe MPS pattern in the trans azobenzene state is diminished by photoisomerization to the cis form upon UV light irradiation. By the erasure of the MPS structure, the anisotropic photo‐oriented stripe pattern is generated upon irradiation with linearly polarized visible light, the orientation of the stripe pattern being orthogonal to the electric vector of the light.
PE/MMT nanocomposites were prepared through in situ polymerization using a nickel diimine catalyst supported on commercially available MMTs such as Cloisite Na+, Cloisite 30B, and Cloisite 93A. XRD patterns revealed that the layers of Cloisite 30B and Cloisite 93A were intercalated after treatment with TMA and the nickel diimine complex. The catalyst supported on Cloisite 30B showed high yields without additional activator and produced nanocomposites with high melting and decomposition temperatures. The thermal properties and crystallinity could be controlled by varying the clay content in the nanocomposite. The morphologies of the resulting particles and the dispersion of the MMT layers in the polymer matrix were characterized by SEM and TEM.
PHA‐based nano‐biocomposites have been prepared by melt intercalation. Two main PHAs, poly(hydroxybutyrate) and poly(hydroxybutyrate‐co‐hydroxyvalerate) have been studied. Structural characterizations were conducted by advanced techniques like SAXS and TEM. A recent method has determined the degree of clay intercalation and dispersion using solid‐state NMR. Well intercalated small tactoids (3–10 layers) homogeneously dispersed into the polymer are obtained when good PHA–clay affinity exists, i.e., with organo‐modified MMT. In the case of non‐modified MMT, microcomposites are evidenced. Crystallization, mechanical, and thermal properties have been correlated to the materials structures.
Platinum(II) polyyne polymers containing thiophene‐acceptor‐thiophene units are synthesized, and their main chain alkynes are functionalized by the formal cycloaddition–retro‐electrocyclization reaction with tetracyanoethylene (TCNE). The polymer energy levels are significantly decreased by the TCNE addition. Bulk‐heterojunction solar cells are fabricated using the TCNE‐adducted platinum(II) polyyne polymers. The use of these polymers as p‐type semiconductors in combination with n‐type fullerene derivatives indicates that the p‐type semiconducting ability decreases by approximately five to ten times after the TCNE addition. On the contrary, when the TCNE‐adducted polymers are employed as a substitute for the fullerene derivatives, the all‐polymer solar cells are initially fabricated.
Spontaneous deposition of fluorescein isothiocyanate labeled dextran (FITC‐dextran) in covalently assembled poly(glycidyl methylacrylate) (PGMA)/poly(allylamine hydrochloride) (PAH) microcapsules was studied and its mechanism was proposed. Incubation of the microcapsules in the FITC‐dextran solution resulted in strong fluorescence emission from the capsule interiors. The deposition was found to be molecular weight ( ) dependent and the number of capsules filled with FITC‐dextran was increased along with the of FITC‐dextran. Furthermore, the correlation between the deposited substances and the charged species in the capsules was explored quantitatively through UV–Vis and fluorescence spectroscopy.
Segmented block copolymers comprised of flexible PEO segments and monodisperse crystallizable bisestertetraamide segments have been synthesized. The influence of the terephthalic units in the soft phase on the transitions and the thermal mechanical and elastic properties are studied. The presence of terephthalic units in the copolymer increases the glass transition temperature of the soft phase by ≈5 °C. The low‐temperature flexibility of the copolymers is improved because of the lower crystallinity and melting temperature of PEO. With the use of terephthalic‐extended PEO segments, segmented block copolymers with low moduli (G' < 15 MPa) and good elastic properties could be obtained.
Blends of a random poly(propylene) copolymer with different types of polyethylene were used to develop a sample independent statistic mathematical model which describes the quality of phase separation of polymer blends obtained by CRYSTAF. By coupling the abstract model with experimental data, process parameters influencing the non‐equilibrium CRYSTAF separation process can be determined. It could be shown that the stirring speed applied during the fractionation process strongly influences the resolution of the derived CRYSTAF profile and thus the quality of fractionation. Nonlinear optimization of the models' response function leads to optimized run parameters for the CRYSTAF process which results in CRYSTAF profiles of high resolution and thus to a high quality in fractionation.
Polyolefins have grown faster in recent years than many other polymers. The production of poly(propylene) increased rapidly when it was possible to optimize the isotacticity of the polymer chain. New fields for future polymer sciences are the defined short and long chain branched polyolefins, block copolymers by chain shuttling, living and emulsion polymerization, and polyolefin nanocomposite materials. These research fields will create polymers with new and specific properties and applications in the near future. Compared to the formation of polymers in nature, the possibilities are today very limited for the synthetic chemistry. Especially, there are great deficits in tailoring the microstructure of copolymers with two or more monomers in a well defined way. It will be a great challenge to solve this problem but then it opens up exciting advantages.
A series of well‐defined poly(methyl methacrylate)‐block‐poly(butyl acrylate) 3‐arm star block copolymers have been synthesized by ATRP. The incorporation of polar hard segment of PMMA was made possible with the aid of halogen exchange technique. Phase‐separated morphology of cylindrical PMMA domains hexagonally arranged in the pBA matrix was observed by small angle X‐ray scattering in all studied materials. The mechanical and thermal properties of the PBA–PMMA 3‐arm star block copolymers have been thoroughly characterized and their thermoplastic elastomer behavior was studied. It was found that the tensile properties of these materials are comparable with those of their linear ABA type block copolymer counterparts with similar compositions.
A compressed exponential function (CEF) is shown to be represented by a distribution of Gaussian functions. The properties and characteristics of the distribution are detailed and discussed, and are illustrated with reference to the change in the NMR spectroscopy proton Hahn echo relaxation response that takes place in a composite material (prepared by melt compounding a mixture of graphite nanoparticles and pyromellitic anhydride modified polypropylene carbonate (PPC)) during aging at 90 °C. The results show that both the width and the average value of the spin‐spin relaxation rate distribution decrease during aging, suggesting that the molecular motion becomes less constrained and less heterogeneous.
Preparation of discrete PPPI microspheres was examined using the crystallization of oligomers during isothermal polymerization of PMDA and p‐phenylene diisocyanate, and that of pyromellitic dithioanhydride and PPDA in poor solvents. In contrast to PPPI microspheres with smooth surfaces that were previously prepared by phase‐separation during the polymerization of PPDA and PMDA, the microspheres obtained here consisted of flake‐like lamellae with rugged surfaces. The diameters of the microspheres ranged from 0.5 to 6.7 µm. They exhibited excellent thermal stability depending on the monomers. These results provide a new preparative procedure of the PPPI microsphere with a rugged surface.
A series of pyrrolidine‐, piperidine‐, and imidazoline‐based dithiocarbamate CTAs have been synthesized and utilized to control the polymerization of vinyl monomers. The controlling ability of the CTAs depends on the presence of both activating and re‐initiating groups and the monomer used. Pyrrolidine‐ and piperidine‐based CTAs proved reasonably good for controlling vinyl acetate polymerizations. The living nature of the vinyl acetate polymerizations was studied by kinetics and chain extension reactions. Interestingly the vinyl acetate polymers synthesized using these pyrrolidine and piperidine based CTAs were almost colorless when precipitated and, therefore, were interesting considering the industrial applications of these polymers.
Parallel atom transfer radical polymerization (ATRP) of styrene and t‐butyl acrylate (t‐BA) was investigated. A series of ATRP polymerizations were carried out in parallel with varying targeted molecular weight ( ) and showed excellent reproducibility of , polydispersity, and conversion. In addition, polymerizations were done to determine the effect of inhibitor on styrene polymerization, yielding similar results. In synthesizing a library of polymers having varying using ATRP, polymers having lower reach their target values earlier and the others continue to react under heating, resulting in peak broadening for the low polymers. Reinitiation experiments indicated that termination reactions were taking place resulting in “dead” polymer chains which were unable to reinitiate polymerization.
Living free‐radical copolymerization of the inimer 4‐vinylbenzyl N,N‐diethyldithiocarbamate with maleic anhydride in the presence of methyl methacrylate produces highly branched poly(methyl methacrylate) star polymers. Subsequently, mikto‐arm stars can be synthesized by condensation of poly(ethylene glycol methyl ether) monosodium alkoxide with functional maleic anhydride sites in the hyperbranched core. The solution properties of these mikto‐arm star copolymers are discussed.
Introducing well‐defined polymeric side chains to bisterpyridine coordination polymers enables the synthesis of materials with tailor‐made optical and mechanical properties. The polymers are introduced either by a copper‐catalyzed azide–alkyne cycloaddition (grafting‐onto) or an atom transfer radical polymerization (polymerization‐from) method. The resulting metallopolymers exhibit improved solubility in common organic solvents and can, therefore, be inkjet‐printed from chlorinated benzene solutions. The photophysical properties of the so‐produced homogeneous films are investigated and a proof‐of‐principle polymer light‐emitting device can be constructed.
Two‐dimensional chromatographic methods were developed using LC‐CC in the first and SEC in the second dimension. These methods were applied for the investigation of PS‐b‐PI diblock copolymers synthesized by different approaches: sequential living anionic polymerization and coupling of living precursor blocks. The first dimension separates according to the individual block length of PS or PI blocks, whereas the second dimension separates with respect to the total molar masses of components. 2D‐LC analysis provides information on the purity of the reaction products, the presence of by‐products, the chemical compositions and the molar masses of all product components. The accuracy and selectivity of 2D‐LC is discussed.
Two kinds of amino‐functionized, triphenylamine and fluorene based copolymers, PFT‐N and PTFF‐N, were synthesized by palladium‐catalyzed Suzuki coupling reaction. The corresponding quaternized polyelectrolytes PFT‐NBr and PTFF‐NBr were obtained through post‐polymerization. The quenching behaviors of PFT‐NBr and PTFF‐NBr in methanol were investigated by the titration of Fe(CN). All of these polymers were investigated as emitting layer in multilayer PLEDs. Devices' performance together with electrochemical properties of these polymers indicate that both of the hole and the electron injection capabilities of them were improved due to the simultaneous introduction of the triphenylamine segment and the aminoalkyl (ammonium) group.
Reductively degradable multiblock polymers for gene and drug delivery were synthesised by oxidative polycondensation of poly(ethylene glycol)‐cysteine derivatives containing ester or urethane bonds. Hydrolysis of the polymers at pH = 5.5, 7.4 and 8.0 and reductive degradation with glutathione and dithiothreitol were studied. The hydrolysis rate of polymer esters increased with increase in pH; the hydrolysis of polymer urethanes was negligible. Chemical substitution of the pendant COOH or NH2 groups significantly affected the rate of the polymer degradation. Surface modification of poly(L ‐lysine)‐DNA complexes with PEG‐cystine multiblocks led to the formation of reductively degradable nanoparticles.
