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.
CNT‐induced formation of transcrystals of γ‐PP are reported. Formation of these transcrystals occurred when PP was infiltrated into nanotube aerogel fibers to form polymer nanocomposites. The PP morphology and microstructure with particular focus on the interfacial region of the CNTs were investigated by means of SEM, DSC and WAXD. The transcrystalline supramolecular microstructures were observed around the individual nanotubes during quiescent melting crystallization. Microstructural analysis showed that γ‐form transcrystals of PP dominate the overall interfacial structure. The content of γ‐form transcrystals increased with increase in nanotube loading. The mechanical properties and electrical conductivities of the nanocomposites have been evaluated.
Herein we explore the possibility to control the fabrication of non‐equilibrium nano‐patterns of spin‐coated organic‐inorganic hybrid materials based on diblock copolymers and metal nanoparticles in thin films. It is demonstrated that the type of solvent and the initial solution concentration, among other factors, can serve as tools to direct the morphology of spin‐coated thin films. The driving forces leading to the pattern formation are reviewed with respect to these parameters—type of solvents and polymer concentration. As a result well‐defined surface patterns of functional hybrid materials are obtained. Moreover, the same tools used to direct the pattern formation can be applied to gain control over the particle size and size distribution.
Two kinds of the totally alkyl‐substituted ladder π‐conjugated compounds, the totally hexyl‐substituted silicon‐bridged stilbene trimer 1 and the totally propyl‐substituted silicon‐ and carbon‐bridged distyrylbenzene 2 , were synthesized. X‐ray crystallography revealed that both compounds adopt the all‐parallel‐aligned packing structures through the interpenetration of the alkyl chains with those of the neighboring molecules. The effect of this packing structure on the photophysical properties was investigated. The fluorescence quantum yield measurements showed that both compounds maintained their high quantum yields (ΦF) even in the crystalline state (ΦF = 0.64 for 1 ; 0.63 for 2 ), suggesting the potential effect of the all‐parallel alignment for attaining the intense emission in the solid state.
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.
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.
Isotactic poly(methyl methacrylate) and syndiotactic poly(methyl methacrylate) form a stereocomplex using an inkjet system. As compared with conventional methods such as simply mixing solutions or dipping substrates with a layer‐by‐layer (LbL) approach, a much smaller amount of polymer chains (9.0 × 107) can theoretically associate with each other, and the process is quicker. Glass and polystyrene substrates are compared as substrates, suggesting different morphologies due to the solvent interactions during the rapid evaporation. The stereocomplex structure is confirmed by infrared spectroscopy and X‐ray diffraction.
Well‐defined diblock poly(L ‐lactide)‐block‐poly(dimethylamino‐2‐ethyl methacrylate) (PLLA‐b‐PDMAEMA) copolymers were synthesized by combining ROP of LLA and ATRP of DMAEMA, from a dual‐initiator 2‐hydroxylethyl 2‐bromoisobutyrate. The molecular characterization of these diblock copolymers was performed using 1H NMR, FT‐IR, and GPC‐MALLS analysis. The responsive behavior of these diblock copolymers in aqueous solutions at different pH and temperatures were investigated using DLS. Results show that both higher pH and temperature result in a higher degree of neutralization, weaker hydrogen bonding, and micellar aggregation. As observed by TEM, changes in micellar morphology are in accordance with DLS results.
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.
Self‐assembling dendrons sterically disfavor the cisoid conformation through which 6π‐electrocyclization proceeds in cis‐polyarylacetylenes. Through the same mechanism, selected self‐organizable dendronized helical cis‐polyphenylacetylenes (cis‐PPAs) undergo an unprecedented thermally induced cisoid‐to‐transoid conformational isomerism in bulk. The motion of helix (un)winding can be converted to unidirectional motion in self‐organizable dendronized cis‐PPAs. By eliminating 6π‐electrocyclization, nanomechanical actuators capable of lifting a US dime have been prepared from self‐organizable dendronized cis‐PPAs.
The influence of magnesium acetate on the non‐solvent‐induced phase separation (NIPS) process of amphiphilic polystyrene‐block‐poly(4‐vinylpyridine)s to gain integral‐asymmetric membranes is investigated. Highly uniform pores over the large areas of the membrane can be achieved, and the average pore diameter is adjusted by varying the total molar mass of the block copolymers used. These stimuli‐responsive membranes, which are solution cast in the absence or the presence of small amounts of magnesium acetate, are directly compared, showing a remarkable effect on the pore structures and their openness. Minor salt addition is considered to influence the polarity of the solvents used in a positive manner such that the NIPS process can be improved significantly.
Well‐defined sulfonated block copolymers were prepared by direct thermolysis with block copolymers of n‐butyl acrylate (nBA) and neopentyl styrene sulfonated (NSS), which were synthesized by Cu‐based living radical polymerization ( <1.20). A simple thermal process for 10 min at 150 °C completely deprotected the neopentyl groups in the poly(NSS) block segment to give fully sulfonated polystyrene backbone. SAXS profile of the block copolymer with 47 wt.‐% of poly(NSS) showed lamella structure, which appeared more clearly with long ranged order after sulfonation of the block copolymer.
It is demonstrated that the mechanical properties of the resulting polymers can be enhanced by adding a coupling agent to a hybrid thiol/ene/cationic system. The coupling agent was a hybrid monomer with methacrylic and epoxycyclohexyl groups linked by a tetramethyldisiloxane moiety. The methacrylic group of the coupling agent reacted in a first stage with the components of the thiol/ene system obtaining a polymer functionalized with epoxycyclohexyl groups. This polymer could react further with the epoxy monomer of the cationic system to form a copolymer. The viscoelastic properties of the obtained polymers were compared by DMA, finding an increment in the storage modulus of the polymers with the coupling agent, ranging from 18 to 67%.
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.
Novel fullerene‐ and polyhedral oligomeric silsesquioxane‐ (POSS) double end‐capped poly(ε‐caprolactone) (PCL) were successfully synthesized. The crystallization behavior of the fullerene‐ and POSS‐ double end‐capped PCL and the effect of aggregation of the POSS and fullerene moieties on the crystallization of PCL were thoroughly studied. The aggregation of the fullerene moieties has much larger confinement effect on the crystallization of PCL than that of POSS. The successful incorporation of two nano‐sized objects, that is, fullerene and POSS, into the PCL matrix may introduce their merits, so that PCL can attain multi‐functional properties.
We report the large scale preparation of nanostructured polyaniline‐Pd nanoparticles composites (designated as PANI(NS)‐PdNPs) through a “seed” induced bulk polymerization. Initially, a small quantity of PANI(NS)‐PdNPs was formed inside the cavities of MCM‐41 and used as the “seed” for the bulk preparation of PANI(NS)‐PdNPs composite. For a comparative purpose a PANI‐PdNPs composite was also prepared in the absence of the seed. FESEM image of PANI(NS)‐PdNPs composite (bulk) shows nanofibrillar morphology. Further, transmission electron microscopy reveals the presence of spherical Pd nanoparticles. PANI(NS)‐PdNPs composite (bulk) showed a good catalytic activity towards reduction of 4‐nitrophenol.
Ag‐nanoparticle‐containing hydrogels were successfully prepared by in situ reduction of silver nitrate in the presence of citrate molecules as stabilizing agent during photoinduced copolymerization of AAm and BAAm. Swelling‐deswelling behavior and thermal properties of the synthesized hydrogels were investigated. The interior morphology of the gels exhibit continuity, which is a common feature for hydrogel networks. Antimicrobial activities of the hydrogels were also investigated against pathogenic E. coli O157:H7, S. aureus, and non‐pathogenic E. coli K‐12, which are model microorganisms for testing bactericidal properties. The hydrogels containing well‐dispersed Ag NPs showed significant antibacterial activity.
A newly developed method for the determination of the radical reactivity ratios is presented. Two main equations are used and the parameters can be calculated from the ordinate and the slope of the linearization plots. Both equations yield identical values when applied to synthetic data which conforms to the ideal situation of no error in the input data. As experimental data are always subject to some kind of error, a sensitivity analysis was carried out which took into account a relatively pronounced error in the monomer reactivity ratios. It turned out that the new linearization method may even be indicative of the quality of the input data under favorable conditions.
Alkynyldextrans with a DS in the range 0.1–1.67 have been prepared as reactive intermediates for further polymer‐analogous functionalisation. DS and substituent distribution were determined by GLC and GLCMS after hydrolysis and acetylation, or methanolysis and trimethylsilylation. Reactivity was in the order O‐2 > O‐4 ≥ O‐3 with pronounced differences in the distinct patterns for propargyl ethers and its higher homologous. A large deviation from a random substituent distribution was observed. Propargyldextrans were not stable during long‐time storage in the solid state, while terminal pentynyl and hexynyl ethers are. Pentynyldextrans showed structure formation of various geometries. They bound silver efficiently, yielding silver nanoparticles by reduction.
Various linear and branched oligoglycidol macromonomers are prepared using anionic ring opening polymerization of the monomers ethoxyethyl glycidyl ether (EEGE) and glycidol. Starting with 4‐vinyl benzyl alcohol (VBA), allyl glycol or N‐(2‐hydroxyethyl) methacryl amide (HEMAm) oligoglycidol macromomonomers with three to six repeating units are obtained in good yields and characterized with NMR, SEC, DSC and TGA. These macromonomers are versatile tools and can be used as prepolymers for the synthesis of reactive amphiphilic copolymers. The successful conversion of the macromonomers to copolymers via radical polymerization is demonstrated.
