Synthesis and characterization of side‐chain liquid‐crystalline poly(ethyleneimine)s with cyanobiphenyl groups

A series of polyethyleneimine‐based side‐chain liquid‐crystalline polymers substituted with different ratios of cyanobiphenyl as pendent mesogenic groups has been synthesized in which the spacer length varies between two and six methylene units. The structures of the synthesized polymers are confirmed by infrared and ¹H nuclear magnetic resonance spectroscopy. The thermal properties of these polymers have been investigated using differential scanning calorimetry, polarized optical microscopy and X‐ray diffraction. The results indicate that the thermal behaviour of the polymers is strongly dependent on the degree of substitution. Polymers containing more than 69% of mesogenic groups exhibit nematic‐type thermotropic liquid‐crystalline behaviour with schlieren textures. Below this limit, the polymers are amorphous. Polymers with a higher degree of substitution present the crystalline states. The phase transition temperatures increase and the mesomorphic temperature ranges widen with increasing degree of substitution. The clearing temperatures decrease as the spacer length increases. An odd–even effect in the clearing temperatures is observed and the odd members display the higher values.     

Synthesis and characterization of organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) side chains

In this work, we reported the synthesis of a dodecahydroxyl-functionalized macrocyclic oligomeric silsesquioxane (MOSS). The novel 24-membered hydroxyl-functionalized MOSS was employed as a macroinitiator for the ring-opening polymerization of ε-caprolactone (CL) and the organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) (PCL) side chains were successfully synthesized. The organic–inorganic macrocyclic molecular brushes were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The results of wide angle X-ray diffraction (XRD) indicate that the architecture of the organic–inorganic macrocyclic molecular brushes did not alter the structure of PCL crystals. Differential scanning calorimetry (DSC) shows that the architecture of organic–inorganic macrocyclic molecular brushes significantly affected the rearrangement of PCL crystals. Compared to linear PCL, the organic–inorganic macrocyclic molecular brushes possessed the improved thermal stability in terms of the temperatures at the maximum of degradation rate and the yields of degradation residues.     

Synthesis and characterization of calixarene-based poly(ε-caprolactone) stars catalyzed by yttrium complex

Two calixarene derivatives (2a, 2b) have been synthesized and used as macro-initiators to prepare star-shaped poly(ε-caprolactone)s (SPCLs) via controlled ringopening polymerization of ε-caprolactone in the presence of yttrium tris(2,6-di-tert-butyl-4-methylphenolate) [Y(DBMP)₃]. The molecular weight of SPCLs was characterized by end group ¹H-NMR analyses and size-exclusion chromatography (SEC). The results indicate that SPCLs based on a calix[4]arene derivative (2a) are well-defined four-arm star polymers with reasonably narrow molecular weight distributions in the given molecular weight range, while SPCLs based on a calix[6]arene derivative (2b) are star polymers with not so defined structures. Differential scanning calorimetry (DSC) analyses suggest that the maximal melting point, the crystallization temperature and the degree of crystallinity of SPCLs increases with the increasing molecular weight and are lower than those of the liner poly(ε-caprolactone) (LPCL) counterpart. Furthermore, polarized optical microscopy (POM) indicates that SPCL exhibits irregular spherulites with poor morphology and slower crystallization rate, whereas LPCL shows fast crystallization rate and good spherulitic morphology. __________ Translated from Acta Polymerica Sinica, 2007, 10: 967–973 [译自:高分子学报]     

Synthesis of functionalized α-zirconium phosphate modified with intumescent flame retardant and its application in poly(lactic acid)

A novel functionalized α-zirconium phosphate (F-ZrP) modified with intumescent flame retardant was synthesized by co-precipitation method and characterized. Poly (lactic acid) (PLA)/F-ZrP nanocomposites were prepared by melt blending method. The thermal stability and combustion behavior of PLA/F-ZrP nanocomposites were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL-94), scanning electronic microscopy (SEM), and cone calorimeter test (CCT). The results showed that the addition of flame retardant F-ZrP slightly affect PLA's thermal stability, but significantly improve the flame retardancy of PLA composites. In comparison with neat PLA, the LOI value of PLA/F-ZrP was increased from 19.0 to 26.5, and the UL-94 rating was enhanced to V-0 as the loading of F-ZrP at 10%. SEM results suggested the introduction of F-ZrP in the PLA system can form compact intumescent char layer during burning. All these results showed that the F-ZrP performed good flame retardancy for PLA.     

Extraction and complexation of copper(II) with para-tert-butylbenzhydrazide and its N′,N′-dimethyl derivative

The extraction of copper(II) with the para-tert-butylbenzoic acid hydrazide and related N??,N??-dimethyl derivative was studied. The composition and structure of the extracted complexes were determined, the mechanism of extraction of copper(II) in different media was suggested, the extraction constant was calculated. The copper(II) complex compounds with these reagents were isolated.     

High temperature pyrolysis of poly(phenylene vinylene)s with poly(ε-caprolactone) or polystyrene side chains

Journal of Thermal Analysis and Calorimetry - High temperature pyrolysis studies of poly(phenylene vinylene)s PPVs with lateral substituents poly(ε-caprolactone) (PPV–PCL) or...     

Synthesis of α-tocopherol analogs with unsaturated side chain and their transformation into the corresponding chromans with ω-functionalized side chain

-Tocopherol analogs with double bond-containing side chains were synthesized by condensation of trimethylhydroquinone with optically active (3R/S,4S)-3,4,8-trimethylnona-1,7-dien-3-ol and linalool in the presence of the zeolite-containing Tseokar-10 aluminosilicate. Ozonolysis of these compounds gave the corresponding chromans with -formyl or (after hydride reduction) -hydroxyl groups in the side chain.     

Synthesis and properties of poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) copolyesters

Bio-based poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) (PIFCL) copolyesters were synthesized from 2,5-furandicarboxylic acid, isosorbide and ε-caprolactone. The obtained copolyesters were characterized by ¹H NMR, ¹³C NMR, intrinsic viscosity, GPC, DSC, TGA and tensile testing. The NMR characterization results confirmed the insertion of lactones units into poly(isosorbide 2,5-furandicarboxylate) (PIF) chains. All PIFCL copolyesters were amorphous with T_{D, 5%} higher than 300 °C. The glass transition temperatures of PIFCLs with FDCA molar ratio from 74% to 45% were within the range of 132.1 °C and 72.4 °C. Tensile testing revealed that introduction of ε-caprolactone into PIF chain imparted PIFCL with excellent mechanical performance, typically, PIFCL polyseter with FDCA molar ratio of 45% had a Young's modulus 858 ± 92 MPa, a tensile strength 44 ± 4 MPa and an elongation at break 480 ± 45%.     

Synthesis and structural studies of homooligomers of geminally disubstituted β(2,2)-amino acids with carbohydrate side chain

A new class of geminally disubstituted C-linked carbo-β(2,2)-amino acids (β(2,2)-Caa) were prepared from d-glucose. The structures of homooligomeric di-, tetra-, and hexapeptides prepared from (S)-β(2,2)-Caa were studied with NMR (in CDCl(3)), CD, and Molecular Dynamics calculations. These β(2,2)-peptides have shown the presence of stable 6-membered (6-mr) NH(i)···CO(i) intra-residue H-bonded (C(6)) strands. It was found that the strand structures realized in these systems were additionally stabilized by the electrostatic interaction arising due to the proximity of amide proton (NH(i)) to the oxygen of the preceding methoxy group (O(Me)(i-1)) at the C3 carbon of the carbohydrate ring. The new β(2,2)-Caa residues with additional support to H-bonding considerably expand the domain of foldamers.     

Synthesis of mesoporous γ-alumina by sol–gel process and its characterization and application for sorption of Pu(IV)

Mesoporous γ-alumina samples were prepared by the sol–gel process from the boehmite sol having different template solutions. Copper doped material was also prepared from sol containing template solution along with copper nitrate. Studies were performed to understand the influence of templates on the morphology of the synthesized samples particularly with respect to specific surface area and porosity. Synthesized samples were used to study sorption of Pu(IV) from nitric acid–oxalic acid solutions. Distribution ratios (D) for Pu(IV) were determined using the γ-alumina samples with an objective to employ these for the recovery of Pu.     

Synthesis and characterization of poly(L-lactide-co-ε- caprolactone) copolymers: influence of sequential monomer addition on chain microstructure

A series of copolymers with various compositions were synthesized by one-step and two-step bulk ring-opening polymerizations of L -lactide (LA) and ε-caprolactone (CL) using stannous octoate [Sn(Oct)₂] and 1-hexanol as the initiating system. For the sequential two-step polymerization, a poly(ε-caprolactone) (PCL) prepolymer was polymerized first to a percent conversion of approximately 70% and LA then added in order to produce a copolymer with a chain microstructure different from that obtained from the corresponding one-step reaction. The resulting copolymers were characterized using a combination of nuclear magnetic resonance spectroscopy (¹H- and ¹³C-NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). The average sequence lengths of the lactidyl ( ) and caproyl ( ) units, the degree of randomness (R) and the transesterification coefficient (T_(II)) were calculated from the ¹³C-NMR spectra. The appearance of a signal due to CapLCap sequences was directly attributable to transesterification of lactidyl (LL) units. It was found that both and values from the two-step syntheses were significantly longer than from the corresponding one-step syntheses, leading to different semi-crystalline morphologies and chain microstructures. The copolymers all showed at least some blocky chain structure as a result of the significant difference in monomer reactivity (LA > CL) between LA and CL. Thermal properties including stability depended on both composition and chain microstructure which could be controlled by the method of synthesis. From their DSC curves, the two-step copolymers were seen to be semi-crystalline whereas the one-step copolymers were mainly amorphous. A more blocky microstructure, as obtained from the two-step method, appeared to result in a lower thermal stability. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of a novel perylene diimide derivative and its charge transfer interaction with C_(60)

A novel organic electron acceptor, N,N′-dipyrimidinyl-3,4,9,10-perylene-tetracarboxylic diimide (DMP), was designed and synthesized. The molecular structure was characterized by FTIR spectrum and elemental analysis. By cyclic voltammetry measurements, DMP was found to possess a lower LUMO energy level than N,N′-diphenyl-3,4,9,10-perylene-tetracarboxylic diimide due to the stronger electron-withdrawing pyrimidinyl group than the phenyl group. Fluorescence quenching is observed in a dual-layer film consisting of a DMP layer and a C60 layer and was attributed to the charge transfer at the interface due to the energy level offset between DMP and C60.     

Synthesis of poly(ε-caprolactone) diols and EO-CL block copolymers and their characterization by liquid chromatography and MALDI-TOF-MS

Polymers of ε-caprolactone were synthesized by microwave-assisted polymerization initiated with polyethylene glycols (PEG 200 and PEG 300) and monodisperse diols (mono-, di-, tri-, tetra- and hexaethylene glycol) and tin octoate as catalyst. These polymers were characterized by different chromatographic techniques (SEC, LAC and LCCC) and MALDI-TOF-MS. A comparison with commercially available polycaprolactone diols with molecular weight 530 and 830 showed that the new polymers had a much higher content of triblock structures, while the commercial samples contained considerable amounts of diblocks.     

Synthesis and biodegradation of poly(2-pyrrolidone-co-ε-caprolactone)s

Copolyesteramides of 2-pyrrolidone with ε-caprolactone were synthesized by ring-opening copolymerization. The copolymers were random-like and their melting temperature and heat of fusion were dependent on the polymer composition. Biodegradation by a polyamide 4 (PA4) degrading microorganism showed rapid degradation in the region of amide-rich polymer composition. On the contrary, enzymatic hydrolysis using a lipase resulted in a different tendency, that is, ester-rich copolymers hydrolyzed rapidly. Activated sludge makes copolymers degrade to CO₂ in wide polymer composition ratio. Copolyesteramides are expected to be applied as an environmentally-friendly plastics or bioabsorbable polymers in medical fields.     

Surface grafting of microfibrillated cellulose with poly(ε-caprolactone) - Synthesis and characterization

In cellulose nanocomposites, the surface of the nanocellulosic phase is critical with respect to nanocellulose dispersion, network formation and nanocomposite properties. Microfibrillated cellulose (MFC) has been grafted with poly(ε-caprolactone) (PCL), via ring-opening polymerization (ROP). This changes the surface characteristics of MFC and makes it possible to obtain a stable dispersion of MFC in a nonpolar solvent; it also improves MFC’s compatibility with PCL. The thermal behavior of MFC grafted with different amount of PCL has been investigated using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). From TGA measurements, the fraction of PCL in MFC-PCL samples was estimated to 16%, 19%, and 21%. The crystallization and melting behavior of free PCL and MFC-PCL were studied with DSC, and a significant difference was observed regarding melting points, crystallization temperature, degree of crystallinity, as well as the time required for crystallization.     

Synthesis,characterization and anti-microbial activity of poly(ethylene oxamide- N,N ′-disuccinate) and its polymer metal complexes

Poly(ethylene oxamide-N,N′-disuccinate), abbreviated as (PEODS), has been synthesized by condensation of oxamide-N,N′-disuccinic acid and 1,2-ethylene glycol. Coordination polymers were synthesized by the reaction of (PEODS) with hydrated acetates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The resulting polyester-metal complexes were characterized by elemental analysis, UV-Visible, FT-IR, ¹H-NMR, ESR spectroscopy and magnetic susceptibilities. Thermal behavior of all the synthesized compounds revealed that polymer metal complexes are more stable than the polymeric ligand. In addition all the synthesized polymers were screened for anti-bacterial activity against B. subtelillisr, B. megaterium, S. aureus, E. coli, S. typhi, P.?aeruginosa, S. boydii and for antifungal activity against C. albicans, T. species, A. flavus, A. niger, F. species, M. species, and P. species by agar well diffusion methods. All the polymers showed good anti-bacterial and anti-fungal activity, which increased on coordination with the metal ions.     

Synthesis of a dehydroabietyl derivative bearing a 2-(2'-hydroxyphenyl)benzimidazole unit and its selective Cu²+ chemosensing

A dehydroabietyl derivative 2 bearing a 2-(2'-hydroxyphenyl)benzimidazole unit was synthesized and its sensing behaviors toward metal ions were investigated by UV-Vis and fluorescence spectroscopy methods. In THF solution, compound 2 exhibited excellent selectivity for CuII over miscellaneous other metal ions including CrII, MnII, CoII, NiII, ZnII, CdII, AlIII, MgII, PbII, HgII, NaI, LiI and KI evidenced through the quenching of the fluorescence of the benzimidazole fragment. The reaction between 2 and Cu2+ was found to be stoichiometric with the formation of a 1:1 complex.     

Phase behavior and its viscoelastic response of polylactide/poly(ε-caprolactone) blend

Polylactide (PLA)/polycaprolactone (PCL) blends with various blend ratios were prepared via melt mixing. The morphology, linear and non-linear viscoelastic properties of the blend were studied using scanning electron microscope (SEM) and cone-plate rheometer. Three typical immiscible morphologies, i.e., spherical droplet, fibrous and co-continuous structure can be observed at various compositions. The elasticity ratio was proposed to play an important role together with the viscosity on the phase inversion because PLA/PCL blend presents a high viscosity ratio between two components. Two emulsion models were used to predict the linear viscoelastic properties of the blend with various morphologies. The Palierne model gives better fit compared with the G–M model, but both fail to predict the viscoelastic properties of the co-continuous blend. The viscoelastic behavior of those blends shows different temperature dependence due to their different morphologies. The principle of time–temperature superposition (TTS) is only valid for the co-continuous blend while fails with the rheological data of those blends with discrete spherical and fibrous domain structure. Moreover, although the discrete phase is difficult to be broken up due to the high viscosity ratio of the systems, the change of viscoelastic responses of those blends before and after preshear shows large difference, indicating that different morphologies have different sensitivity to the steady shear flow.     

Melting of poly(ε-caprolactone) studied by step-heating calorimetry

This study demonstrates that the step-heating calorimetry, which is a kind of temperature-modulated differential scanning calorimetry, can provide valuable information on the polymer melting. Time-dependent heat flow due to the melting of lamellar crystallites in a narrow range of thickness can be directly observed, from which thickness distribution of lamellar crystallites and thickness dependence of the melting kinetics are deduced. A sample of poly(ε-caprolactone) was used as a model material of semi-crystalline polymer, which has high crystallinity (0.79) so that no recrystallization and/or reorganization occur during melting in the step-heating scan. It was revealed that superheating dependence of the melting rate coefficient increases with increasing lamellar thickness, which may be attributed to variation of the fold surface roughness with respect to lamellar thickness. Analysis based on the cylindrical nucleation model revealed much lower free energy values of lateral surface than that evaluated from crystallization behavior, suggesting that the nucleus for melting is more stable than that for crystallization.