Siloxane Segments Research Articles

Polyimide-Based Electrolyte Modified with Siloxane Segments for Proton Transportation

not Available.

Effect of Bridging Groups on Sulfonated Poly(imide-Siloxane) for Application in Proton Exchange Membrane

A series of six-membered sulfonated poly(imide-siloxane)s (SPIs) was synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), aminopropyl-terminated polydimethylsiloxane (PDMS) 2,2-benzidinedisulfonic acid (BDSA), as the sulfonation target diamine groups, and various nonsulfonated diamine monomers behaving as bridging groups. The structure-property relationship of SPI-SXx membranes is discussed in detail according to the chemical structure of the various nonsulfonated diamines of the SPI-SXx membranes from the viewpoints of proton conductivity, ion exchange capacity (IEC), and membrane properties (water uptake and membrane swelling) at equal PDMS content SPI-SXx. The PDMS was introduced to enhance the proton conductivity and water uptake attributed from the high flexibility of the siloxane segments. The conductivity and water uptake of angled SPI-SXm and oxydianiline-based SPI-SX membranes (SPI-SXO) are greater than those prepared from diaminodiphenylmethane-based SPI-SX membranes (SPI-SXD) at a given IEC. These differences resulted from the increased number of entanglements of the SPI-SXx membrane. The SPI-SXD showed almost isotropically dimensional changes with the increase in water uptake, and the volume were slightly smaller than those estimated from the additivity rule. Free volume in the SPI-SXx increased with the increase in bulky irregular packing in nonsulfonated segments, which augmented the water uptake and, in turn, the conductivity of the polymer. With the increase in temperature, conductivity increased more rapidly in SPI-SXx than in Nafion 117. Microscopic analyses revealed that these smaller (<10 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. The new sulfonated poly(imide-siloxane)s have proved to be a possible candidate as the polymer electrolyte membrane for polymer electrolyte fuel cells (PEFCs) and direct methanol fuel cells (DMFCs).

Fluorinated siloxane-containing waterborne polyurethaneureas with excellent hemocompatibility, waterproof and mechanical properties

Two series of polyurethaneurea (PUU) aqueous dispersions consisting of fluorinated siloxane segments were prepared from a high-molecular-weight ( M n = 8361) α,ω-dihydroxypoly[(3,3,3-trifluoropropyl)methylsiloxane] (PTFPMS), dimethylolpropionic acid, isophorone diisocyanate and ethylenediamine, with poly (tetramethylene oxide) and polycarbonate polyols as soft segments, respectively. These anionic aqueous dispersions were stable at the ambient temperature for more than 6 months, with particle sizes ranging from 45 to 98 nm. Both series of PUU films showed the excellent waterproof properties, i.e. the decrease in water absorption and surface energy upon the incorporation of PTFPMS segments. The phase mixing increased in the fluorinated siloxane-containing polyether-based PUUs and the phase separation increased first then decreased in the fluorinated siloxane-containing polycarbonate-based PUUs, with increasing PTFPMS content. All the PTFPMS-modified PUU films showed excellent mechanical properties. The polycarbonate-based PUU film consisting of 5 wt.% PTFPMS had a tensile strength of 60.7 MPa and a breaking elongation of 632%, owing to the increase in the ordered hydrogen bonding degree and the microphase-separation degree between the hard and soft segments in the system. In vitro hemolysis and dynamic clotting time measurements indicated that the thromboresistance was enhanced markedly with increasing PTFPMS content for both series of PUUs, which could be ascribed to the synergistic effect between the carboxylate groups and the PTFPMS segments migrating onto the surfaces of the films.

Selective encapsulation-release and photodegradation characteristics of organic dyes by cross-linked fluoroalkyl end-capped oligomeric nanocomposites possessing aromatic siloxane segments as core units

Cross-linked fluoroalkyl end-capped oligomeric nanocomposites possessing aromatic siloxane segments as core units [RF-oligomer/Ar-SiO2] exhibited an encapsulation ability toward organic dyes such as methylene blue (MB), rhodamine B (RB), 4-hydroxyazobenzene-4′-sulfonic acid sodium salt, and methyl orange (MO). In these organic dyes, MB and RB are effectively encapsulated into these nanocomposites in aqueous solutions. RF-oligomer/Ar-SiO2 nanocomposite-encapsulated organic dyes were found to exhibit a controlled releasing characteristic toward these encapsulated dyes, and encapsulated MB was not released into water; however, this encapsulated dye was smoothly released into acetone under similar conditions. Interestingly, RF-oligomer/Ar-SiO2 nanocomposites possessing biphenylene segments as core units were able to exhibit not a photostable characteristic but extremely higher photodegradation ability toward MO under UV light irradiation.

Preparation and applications of novel cross‐linked fluoroalkyl end‐capped oligomeric nanocomposites possessing aromatic siloxane segments as core units

AbstractFluoroalkyl end‐capped N,N‐dimethylacrylamide oligomer and N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer were reacted with phenylene‐ and biphenylene‐bridged ethoxysilanes under alkaline conditions to yield cross‐linked fluoroalkyl end‐capped oligomeric composites possessing aromatic siloxane segments as core units. These isolated fluorinated composite powders were found to be nanometer size‐controlled fine particles with a good dispersibility and stability in water and organic solvents. Nitrogen adsorption–desorption isotherms confirmed the presence of micropores in these nanocomposites; the micropore size estimated by the HK method was 0.7–0.8 nm. Interestingly, fluorinated nanocomposites possessing a higher micropore volume ratio were found to exhibit a selective encapsulation ability of fullerene into their composite cores. These fluorinated nanocomposites were also applied to the surface modification of poly(methyl methacrylate) film, resulting in a good oleophobicity imparted by fluorine on the surface. In addition, fluorescence emission was visibly observed only from the modified PMMA film surface treated with fluorinated nanocomposites possessing biphenylene units when irradiated by light. Copyright © 2009 John Wiley & Sons, Ltd.

Effect of matrix chemical structure on the thermo‐oxidative stability of addition cure poly(imide siloxane) composites

AbstractA series of addition cure poly(imide siloxane) resins were synthesized, incorporating various concentrations of α, ω‐bis(3‐aminopropyl) poly(dimethyl‐diphenylsiloxanes), and α, ω‐bis(p‐aminophenyl) poly(dimethylsiloxane) into the formulated imide oligomer. Both carbon and glass fiber textile laminates were fabricated using amic acid and polymerization of monomer reactants (PMR) approaches. The cured composite laminates were subjected to an accelerated thermo‐oxidative aging environment of 400°C for 100 h in air. Physical, thermal, and mechanical properties were evaluated to determine the structure‐oxidative stability interrelationships. In general, composite mechanical properties were found to increase with increasing siloxane concentration in the matrix. Composite thermo‐oxidative durability (measured via mass loss and mechanical property retention after oxidative aging) was improved through incorporation of diphenyl and diphenyl‐dimethyl siloxane segments into the imide oligomer backbone up to ∼35% by weight aminosiloxane. Oxidative stability was found to be mostly dependent on the degree of phenyl substitution on the silicon atoms in the siloxane blocks, as compared to the moiety attaching the amine groups to the siloxane block. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

Fabricating superhydrophobic surfaces by molecular accumulation of polysiloxane on the wool textile finishing

In the present study, a novel and simple method of obtaining superhydrophobic surface through the migration of organic siloxane segments in the acrylate side chains to the outmost layer and forming the nano-protuberance on the micro-roughness wool fabrics was described. The chemical compositions and morphologies of the untreated/treated fabrics were characterized by the scanning electron microscopy and X-ray photoelectric energy spectroscopy. Meanwhile, the surface hydrophobicity was evaluated by the static contact angle measurement. The scanning electron microscopy photographs showed that the fiber surfaces of the treated fabrics were obviously granulated, and a wax film covered on the fibers could be observed. X-ray photoelectron spectroscopy analyses and static contact angle measurement further testified that the component of the wax was almost siloxane and that the surfaces of the treated fabrics had superhydrophobic property. The above results indicated that this method could be extended to prepare superhydrophobic surfaces by migrating the low-surface-energy matter and fabricating the nanoscale roughness on the micro-roughness material surfaces.

Synthesis and study of new radial organic/inorganic hybrid epoxides

AbstractA new approach to the synthesis of reactive organic/inorganic hybrid molecules was developed. Alternating hydrocarbon and siloxane segments were introduced into the arms of radial oligomers using hydrosilation chemistry. Cycloaliphatic and glycidyl epoxy‐terminal systems with bisphenol A‐based aromatic hydrocarbon cores and siloxane units derived from 1,1,3,3‐tetramethyldisiloxane were synthesized and fully characterized (molecules 7 and 6, respectively). The cationic UV and thermal curing behavior of these two new radial hybrid epoxies was investigated using photo‐ and thermal‐ differential scanning calorimetry. Hybrid cycloaliphatic epoxy 7 exhibited good UV curing kinetics and photopolymerized to high conversion. The glycidyl analog 6 exhibited poor UV curing kinetics, but was readily cured using 2‐ethyl‐4‐methylimidazole as a nucleophilic curing agent. Both hybrid epoxysiloxanes exhibited extensive thermal cationic cure. The physical properties of cured films of the two new radial epoxysiloxanes were studied and compared with various commercially available hydrocarbon and siloxane benchmark materials. The cured systems exhibited lower moisture uptake and better thermal stability than most hydrocarbon epoxies examined. Several visually compatible blends of the new hybrid molecules with common hydrocarbon resins were identified, and in general organic compatibility was found to be intermediate among selected siloxane‐containing benchmarks. Molecules 6 and 7 represent progress towards the goal of synthesizing highly functional organic/inorganic hybrid molecules which combine the best attributes of both hydrocarbon epoxides and siloxane materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis and characterization of polyimide‐polysiloxane segmented copolymers for fuel cell applications

AbstractSulfonated polyimides exhibit high strength, good film‐forming ability, chemical resistance, and, in their hydrated state, relatively high proton conductivity. Here we report the one‐pot synthesis of sulfonated polyimide‐polysiloxane segmented copolymers through the reaction of a dianhydride with a mixture of three diamines: a nonionic aromatic diamine (4,4′‐oxydianiline), a sulfonated diamine (4,4′‐diamino‐2,2′‐biphenyldisulfonic acid), and a telechelic diamino polysiloxane. Copolymer compositions were evaluated using 1H NMR and size‐exclusion chromatography. The presence of ion‐containing diamines in the reaction mixture inhibited stoichiometric incorporation of hydrophobic siloxane segments. Siloxane segments were found to lower the thermal stability of the polyimide host. Copolymers with and without siloxane segments were cast into free‐standing films. Equilibrium water sorption studies of cast films show that, for the compositions studied here, the presence of siloxane segments does not interfere with water swelling, suggesting that a microphase‐segregated morphology may exist. TEM and SAXS analyses show evidence of phase‐segregation in sulfonated polyimides and reveal that siloxane segments strongly affect ionic clustering. However, proton conductivity only changes slightly when polysiloxane segments are incorporated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3747–3758, 2007

Preparation of poly(IPDI‐PTMO‐siloxanes) and influence of siloxane structure on reactivity and mechanical properties

AbstractSiloxane‐modified polyurethanes were prepared through isophorone diisocyanates (IPDI), poly(tetramethylene oxide) (PTMO), and siloxanes. IPDI served as the hard segment in the structure. Both PTMO and siloxanes were diols and served as the soft segments. In addition, different chemical structures of siloxanes were used, in which siloxane chains would remain in the main chain of polyurethanes (PU) or become the side chain of PU. First, the reactivities of PTMO and siloxanes to react with IPDI in bulk system were studied through DSC, in which the reaction heat was related to their reactivities. Copolymerization of IPDI, PTMO, and siloxanes in bulk were also studied. The results showed that hydrophobicity and steric hindrance of siloxane diols led to their low reactivities. Next, a series of siloxane‐modified PU in toluene solvent were synthesized, and the conversion of NCO groups was determined by the method of chemical titration. In the synthesis of PU copolymers in a solution polymerization, because of low reactivity of siloxanes, a two‐step procedure was adopted. The siloxane diol was first reacted with IPDI in toluene to form NCO‐terminated prepolymer. Then PTMO was added to form final PUcopolymers. The addition of side‐chain siloxanes resulted in PU copolymers with higher molecular weight than main‐chain siloxanes. Both main‐chain and side‐chain siloxanes increased the elongation at break and tensile strength of final PU copolymers. The microphase‐separation of siloxane segments was observed by SEM, which was the main cause for the improved mechanical properties. POLYM. ENG. SCI., 47:625–632, 2007. © 2007 Society of Plastics Engineers.

Synthesis and characterization of imide ring and siloxane-containing cycloaliphatic epoxy resins

A novel imide ring and siloxane-containing cycloaliphatic epoxy compound 1,3-bis[3-(4,5-epoxy-1,2,3,6-tetrahydrophthalimido)propyl]tetramethyldisiloxane (BISE) was synthesized from 1,3-bis(3-aminopropyl)tetramethyldisiloxane and tetrahydrophthalic anhydride by a two-step procedure, which was then thermally cured with alicyclic anhydrides hexahydro-4-methylphthalic anhydride (HMPA) and hexahydrophthalic anhydride (HHPA), respectively. As comparison, a commercial available cycloaliphatic epoxy 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (ERL-4221) cured with the same curing agents was also investigated. The experimental results indicated that the BISE gave the exothermic starting temperature higher than ERL-4221 no mater what kind of curing agents applied, implying the reactivity of the former is lower than the latter. The fully cured BISE epoxy resins have good thermal stability with thermal decomposition temperature at 5% weight loss of 346–348 °C in nitrogen, although they gave the relatively low glass transition temperatures due to the presence of flexible propyl and siloxane segments in the epoxy backbone. The BISE epoxy resins exhibited good mechanical and dielectric properties as well as low water absorption. The improved dielectric properties and the reduced water absorption of BISE epoxy resins are attributed to the low polarity as well as the hydrophobic nature of siloxane segment in the epoxy backbone.

Poly(imide siloxane) and carbon nanotube mixed matrix membranes for gas separation

Recent theoretical work by Sholl and coworkers has predicted that carbon nanotubes, if used as membranes, have the flux/selectivity properties that far exceed those of any other known inorganic or organic material. To verify this prediction, we have fabricated nano-composite membranes consisting of single-walled carbon nanotubes embedded in a poly(imide siloxane) copolymer and evaluated their transport properties. While the siloxane segment enhanced the interfacial contact, the polyimide component imparted mechanical integrity. A poly(imide siloxane) was synthesized using an aromatic dianhydride, an aromatic diamine and amine-terminated PDMS for the siloxane block. The weight percent of PDMS was determined to be 41 using 1H-NMR. Permeability measurements of He showed drops in permeability with the addition on close-ended CNTs. This large drop in permeability of He suggests that the copolymer adhered well to the CNTs and that the prepared CNT MMMs were defect free. However, the permeability of O 2, N 2 and CH 4 increased in proportion to the amount of open-ended CNTs in the polymer matrix. This suggests that CNTs offer an attractive additive for universally enhancing the gas permeability of polymers.

Studies on the effect of structural parameters on the properties of polysiloxaneurethane dispersions and coatings

The results of studies on the effect of introducing double bonds and siloxane segments to the polyurethaneurea chain on the properties of polyurethane and polyurethane-acrylic/styrene dispersions and coatings are presented. In order to investigate that effect a 23 factorial experiment was designed and conducted. Several properties of dispersions, coatings and films were determined, including,inter alia, particle size, stability, and MFFT (minimum film-forming temperatures) of dispersions, hardness, resistance to water and solvents, adhesion of coatings and mechanical properties, and the glass-transition temperature (Tg) of films. Properties of coatings and films subjected to additional curing were also investigated. Analysing the results of the factorial experiment helped to better understand the mutual effect of several factors on the properties of the investigated materials. ESCA (electron spectroscopy for chemical analysis) and DCA (dynamic contact angle) studies of the surface properties of the coatings were also carried out.

Poly(silarylene–siloxane)polyimides from allyl‐terminated oligoimides and hydride‐functional silarylene–siloxanes via hydrosilylation polymerization

AbstractThis research was focused on the design and execution of new synthetic routes to low‐temperature‐curable poly(silarylene–siloxane)polyimides. The synthesis of individual oligoimide and silarylene–siloxane blocks was followed by hydrosilylation polymerization to produce crosslinked copolymers. The silarylene–siloxane and polyimide blocks were structurally characterized by IR and 1H NMR spectroscopy and size exclusion chromatography. The high‐temperature resistance of the copolymers was evaluated through the measurement of heat distortion temperatures (THD's) via thermomechanical analysis and by the determination of the weight loss at elevated temperatures via thermogravimetric analysis. Glass‐transition temperatures (Tg's) of the silarylene–siloxane segments were measured by differential scanning calorimetry. Hydrosilylation curing was conducted at 60 °C in the presence of chloroplatinic acid (H2PtCl6). The copolymers displayed both high‐temperature resistance and low‐temperature flexibility. We observed Tg of the silarylene–siloxane segment as low as −77 °C and THD of the polyimide segment as high as 323 °C. The influence of various oligoimide molecular weights on the properties of copolymers containing the same silarylene–siloxane was examined. The effect of various silarylene–siloxane molecular weights on the properties of copolymers containing the same oligoimide was also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4922–4932, 2005

Preparation and characterization of polysiloxane‐modified epoxy resin aqueous dispersions and their films

AbstractPolysiloxane‐modified epoxy resin aqueous dispersions were prepared by the reaction of amino‐polysiloxane (APS) with a graft epoxy resin that was synthesized with a diglycidyl ether of bisphenol A type epoxy resin and styrene/acrylic acid. The measurements of the epoxy values and FTIR spectra confirmed that this reaction really took place. The modified aqueous dispersion exhibits high viscosity, small particle size, and nearly the same surface tension as the unmodified one. Therefore, this indicates that the siloxane segments could be encapsulated into graft epoxy resin particles during the water dispersion process. For APS‐modified films, the thermal stability and water resistance are remarkably enhanced. Furthermore, lowering of the hardness and surface tension for these films was also observed and the surface composition was measured by X‐ray photoelectron spectroscopy. The experimental data indicate that the siloxane segments easily migrate onto the surface during the film formation process and finally enrich on the surface of the APS‐modified film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 880–885, 2005

Synthesis of a novel siloxane-containing diamine for increasing flexibility of epoxy resins

A new siloxane-containing curing agent (ETSO–DDM) was synthesized from epoxy-terminated siloxane oligomer (ETSO) and 4,4′-diaminodiphenyl methane (DDM) with a hot-melt method. And its structure was characterized by means of FT-IR, 1H NMR, and 13C NMR spectra. The thermal stabilities and the mechanical behaviors of diglycidylether of bisphenol A (DGEBA) epoxy resins cured with ETSO–DDM were examined. The thermal stability factors, such as the initial decomposition temperature (IDT), temperature of maximum rate of degradation ( T max), and decomposition activation energy ( E t), of the DGEBA/ETSO–DDM systems were increased with increasing the ETSO content up to 5 wt% ETSO. The mechanical properties were increased and the internal stress of the cured epoxy resins was decreased as the ETSO content increased. This could be interpreted in terms of the introduction of soft siloxane segment into the epoxy network, which can be attributed to the increasing of the flexibility or decreasing of the internal stress in the DGEBA/ETSO–DDM systems.

Determination of oligomeric chain length distributions at surfaces using ToF-SIMS: segregation effects and polymer properties

While many XPS and SIMS studies of polymers have detected and quantified segregation of low surface energy blocks or components in copolymers and polymer blends [D. Briggs, in: D.R. Clarke, S. Suresh, I.M. Ward (Eds.), Surface Analysis of Polymers by XPS and Static SIMS, Cambridge University Press, Cambridge, 1998 (Chapter 5).], this paper reports ToF-SIMS studies of direct measurement of the segment length distribution at the surface of siloxane copolymers. These data allow insight into the segregation of particular portions of the oligomeric distribution; specifically, in this study, longer PDMS oligomers segregated at the expense of shorter PDMS chains. We have reported XPS analysis of competitive segregation effects for short PDMS chains [Macromolecules 35 (13) (2002) 5256]. In this study, a series of poly(ureaurethane)–poly(dimethylsiloxane) (PUU–PDMS) copolymers have been synthesized containing varying ratios of G-3 and G-9 (G- X describes the average segment length of the PDMS added), while maintaining a constant overall siloxane weight percentage (10, 30, and 60%). These copolymers were utilized as model systems to study the preferential segregation of certain siloxane segment lengths to the surface over others. ToF-SIMS analysis of PUU–PDMS copolymers has yielded high-mass range copolymer fragmentation patterns containing intact PDMS segments. For the first time, this information is utilized to determine PDMS segment length distributions at the copolymer surface as compared to the bulk. The results show that longer siloxane segment lengths are preferentially segregating to the surface over shorter chain lengths. These results also show the importance of ToF-SIMS and mass spectrometry in the development of new materials containing low molecular weight amino-propyl-terminated siloxanes.

Effect of polydimethylsiloxane macrodiol molecular weight on properties and morphology of polyurethane and polyurethaneurea

AbstractTwo series of polyurethanes and polyurethaneureas were prepared using a two‐step bulk‐solution polymerization procedure. Each series consisted of three polymers based on three molecular weights of α,ω‐bis(6‐hydroxyethoxypropyl) polydimethylsiloxane (PDMS): 940, 1913, and 2955. The soft segment in all cases was an 80:20 mixture of PDMS and poly(hexamethylene oxide) (MW 700), and the hard segment was based on 4,4′‐methylenediphenyl diisocyanate and mixed chain extenders (40 wt %). In the polyurethane (PU) series the chain extender was a 60:40 (mol) mixture of BDO and 1,3‐bis(4‐hydroxybutyl)1,1,3,3‐tetramethyldisiloxane (BHTD), whereas in the polyurethaneurea (PUU) series it was a 60:40 (mol) mixture of BHTD and 1,2‐ethylenediamine. The polymerization was carried out by preparing a prepolymer using a bulk polymerization procedure followed by chain extension in a solution of N,N‐dimethylacetamide. Polymers were characterized by size‐exclusion chromatography, tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA). The number‐average molecular weights of the polymers in the PU series were in the range of 114,300–124,500, whereas they were in the 78,400–103,300 range for the PUU series. Polymers with good clarity and mechanical properties were obtained with PDMS‐940 and PDMS‐1913, but those obtained from PDMS‐2955, despite having good tensile strength, had a low percentage of elongation, high modulus, and poor clarity. DSC and DMTA results indicated that regardless of the PDMS molecular weight, the siloxane segments existed as a highly phase‐separated state. This poor compatibility was consistent with the low solubility of PDMS compared to that of the hard‐segment‐forming components. The polymers in the polyurethane series exhibited multiple melting endotherms, attributed to the melting of ordered domains from different hard segments. The combined heats of fusion were similar for the materials in the PU series. In contrast, the polymers in the PUU series showed a hard‐segment order that was significantly less defined, with the heat of fusion approximately a third to a half that of the materials in the polyurethane series. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1565–1573, 2003

Unique block molecules based on glycerol skeleton as C‐3 building blocks for liquid crystals formation by self‐assembly and their future potential for the “nano‐chemistry”

AbstractStudies on design of liquid crystalline block molecules with non‐conventional mesophase morphoplogies have been proposed by Tschierske and co‐workers. These block molecules have a rigid core, a lateral substituent, and an alkyl chain segmenting blocks from each other. Related to this, diglyceryl alkyl ethers found by us have glycerol as a rigid core, a lateral substituent, and an alkyl chain similar to the Tschierske design. These two cases are compared with each other with regard to the relationship between the molecular structure and the liquid crystalline morphologies and other properties. Recently, new soft materials suitable for liquid crystals exhibiting self‐assembly of phase‐segregated structures have been designed. Typical examples of such “block” molecules containing glycerol having a C‐3 building block include: (i) undecyl‐glycerylether‐ modified siloxane derivatives with a siloxane segment as the rigid core and alkyl chains with 2, 3‐dihydroxypropoxy group as a hydrophilic group at a lateral or terminal position of the siloxane segment; (ii) novel hyper branched dendrimers forming the basis of polyglycerol nanocapsules with a core‐shell molecular architecture; (iii) carbon nanotubes based on cyclodextrins (CDs); (iv) polymerizable amphiphilic diacetylene‐containing phospholipids suitable for construction of functional nanocomposites. This is done by self‐assembly and polymerization of diacetylene creating a “block molecular structure” with a polyacetylene chain as a rigid core segment, the lipid headgroups as the hydrophilic segment, and terminal flexible alkyl chains. On the basis of these results, future potential of block molecules as a soft building material for liquid crystalline structures was discussed.

Chelate polymers. III. New polyazomethines of 5,5′‐methylene‐bissalicylaldehyde with siloxane diamines and their divalent metal complexes

AbstractNovel polymeric azomethines of 5,5′‐methylene‐bissalicylaldehyde with two siloxane diamines {H2N(CH2)3(CH3)2SiO[(CH3)2SiO]mSi(CH3)2(CH2)3NH2, where m = 0 or 6.5} were obtained. Their structures were confirmed by elemental and spectral [IR, ultraviolet–visible (UV–vis), and 1H NMR] analysis. The obtained polyazomethines were converted into the chelates of some divalent metals (copper, cobalt, and nickel). The resulting complexes were characterized by electronic and IR spectral measurements, elemental analysis, and thermal studies. From IR and UV–vis studies, the phenolic oxygen and imine nitrogen of the ligand were found to be the coordination sites. The thermogravimetric data indicated that the chelates were less stable than the corresponding ligands and that the thermostability depended on the siloxane segment length and the nature of the metal. Both the macromolecular ligands and the parts of the resultant chelates were soluble in common organic solvents, such as CHCl3, CH2Cl2, dimethylformamide, and dimethyl sulfoxide. The surface compositions of the ligands and some chelates were examined by X‐ray photoelectron spectroscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3169–3179, 2003