Bulky Pendant Groups Research Articles

Chain cleavage mechanism of palm kernel oil derived medium-chain-length poly(3-hydroxyalkanoates) during high temperature decomposition

Medium-chain-length poly(3-hydoxyalkanoates) (mcl-PHAs) are natural polyesters having the molecular formula of [∼OCHR–CH 2–COO∼] n, composed of monomers each having 6 to 14 carbon atoms, with relatively bulky alkyl pendant group. They are primarily synthesized by fluorescent pseudomonads under unbalanced nutrient availability as carbon and energy storage compounds. From thermogravimetic analysis, the mcl-PHAs produced from Pseudomonas putida grown on palm kernel oil showed a drastic decomposition at temperature above 195 °C. An increase of HO–CHR∼∼ terminals was observed when the mcl-PHAs were thermally decomposed at 160–180 °C, which was presumably due to the hydrolytic chain cleavage initiated at –COO–CHR∼∼, the main skeletal bonds of the biopolyester. At 190 °C, molecules with RCH≡CH∼∼ were also observed as minor decomposition products from the FTIR and NMR measurements and this could be probably due to the dehydration of HO–CHR∼ groups of hydroxyl acids, producing terminally unsaturated oligomers. These observations were consistent with the detection of three new unsaturated monomers: C 4:1, C 6:1 and C 8:1 in the methanolyzed mcl-PHAs in gas chromatography analysis.

Novel thermal stable organosoluble polyamides and polyimides based on quinoxalin bulky pendent group

A new diamine containing a bulky diphenylquinoxalin pendant, 3,5-diamino-N-(2,3-diphenylquinoxalin-7-yl)benzamide (DQB), was synthesized in four steps through the nucleophilic aromatic substitution of 3,5-dinitrobenzoylchloride with 2,3-diphenylquinoxalin-6-amine and subsequent catalytic reduction. All intermediates and DQB were fully characterized by FTIR, NMR and elemental analysis. A series of polyamides PA(a–e) was synthesized from this diamine by direct polycondensation with various dicarboxylic acids, triphenyl phosphate and pyridine in N-methyl-2-pyrrolidynone (NMP). Three polyimides PI(a–c) were synthesized from this diamine using commercial dianhydrides in two-step polycondensation. Characterization of polymers was accomplished by FTIR, H NMR, elemental analysis, DSC, DMTA, GPC, and TGA. The intrinsic viscosities of PAs ranged from 0.54 to 0.67 dL/g. PAs displayed T g values of 140–298 °C and 10% weight loss of 415–485 °C in N2. The T g values of the PIs varied between 200 and 310 °C, with 10% weight loss above 500 °C in N2. The PAs were soluble in common polar aprotic solvents at room temperature whereas the aromatic PIs were dissolved by heating at 60 °C.

Flexible, low-colored and transparent thin films prepared from new thermo-stable and organo-soluble poly(amide-imide)s

An imide ring-containing diacid, 2,2′-diphenyl-4,4′-bis(N-trimellitoyl)diphenyl ether (PTPE) was synthesized through a three-step pathway starting from 2,2′-diiodo-4,4′-dinitrodiphenyl ether. A series of novel aromatic poly(amide-imide)s having bulky phenyl pendant groups at 2,2′-disubstituted positions were then prepared via a direct phosphorylation polycondensation between PTPE and various aromatic diamines. Chemical structure of the new monomer as well as the resulted polymers was thoroughly confirmed by IR and NMR spectroscopic methods. Intrinsic viscosities [ η] of the polymer solutions at 25 °C were measured by the extrapolation of their viscosity numbers till zero concentration. M w ¯ and M n ¯ values of the resulting polymers were determined using gel-permeation chromatography (GPC). The polymers showed a good film-forming ability, and some characteristics of their thin films including color and flexibility were investigated qualitatively. In addition, the absorption edge values ( λ 0) obtained from their UV curves were determined, and all the resulting poly(amide-imide)s films exhibited high optical transparency. Thermal stability of the polymers using their TGA thermograms was investigated. The T g values of the poly(amide-imide)s obtained from their DSC plots were also quantified. Crystallinity amount of the prepared macromolecules was evaluated using wide-angle X-ray diffraction (XRD). Furthermore, solubility of the samples in a variety of organic solvents including dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), pyridine, tetrahydrofuran (THF), and toluene was tested.

Synthesis and characterization of new polyamides and polyimides containing dioxypyrimidine moiety in the main chain with bulky imidazole pendent group: solubility, thermal and photophysical properties

A new symmetrical diamine monomer containing dioxypyrimidine and two diaryl imidazole bulky pendent group was synthesized by the nucleophilic substitution reaction of 4,6 dihydroxy pyrimidine with the synthesized 2-(2-chloro-5-nitrophenyl)-4,5-diphenyl-1H-imidazole (I). A series of novel fluorescent imidazole-containing polyamides (PAs) with inherent viscosities of 0.52–0.78 dL/g was prepared by direct polycondensation of the diamine with various dicarboxylic acids. These PAs were readily soluble in many organic solvents and could be solution-cast into tough and flexible films. The PAs exhibited glass transition temperatures (Tg)s between 202 and 260 °C, and 10% weight loss temperatures in the range of 345–470 °C in air. In addition, three novel polyimides (PIs) with inherent viscosities of 0.38–0.56 dL/g were prepared by addition reaction of the diamine with commercially available tetracarboxylic dianhydrides and subsequent chemical imidization. The PIs exhibited good solubility in polar solvents such as NMP. These polymers exhibited Tgs in the range of 237–285 °C and their 10% weight-loss temperatures varied from 440 to 520 °C.

Rheological and Morphological Properties of Phosphorus-Containing Polysulfones

Polysulfones with bulky phosphorus pendant groups, obtained by chemical modification of the chloromethylated polysulfones were subjected to rheological, surface tension and atomic force microscopy investigations, to establish the processing/morphology/property relationships of these polymers. The effects of the substitution degrees, of the bulky phosphorus pendant groups bound in different positions, and also of intermolecular and intramolecular interactions, influenced the rheological results. High hydrophobicity, low work of water adhesion and low adhesion to interface, would be advantageous for some applications. Atomic force microscopy showed that increasing of the bulky phosphorus pendant groups influences the pores characteristics and roughness, confirming the poor adhesion.

Morphology and interference color in spherulite of poly(trimethylene terephthalate) copolyester with bulky linking pendent group

A novel phosphorus-containing copolyester (PTTP), poly(trimethylene terephthalate) (PTT) copolyester with a bulky linking pendent group of 9,10-dihydro-10-[2,3-di(hydroxycarbonyl) propyl]-10-phosphaphenanthrene-10-oxide (DDP) was prepared, and its crystallization, crystal morphology and interference color were investigated in this article for the first time. Differential scanning calorimeter (DSC) results showed that with the increase of DDP content, the melting point (T(m)) and crystallization ability of PTTP decreased. WAXD results suggests that the three samples share one crystal structure, however the crystallinity decreases with increasing DDP content. Polarized optical microscope (POM) observation indicated that the samples showed non-banded spherulites at a lower and higher temperature, and banded spherulites at the middle temperature range. From the micrographs obtained from scanning electronic microscopy (SEM) and atomic force microscopy (AFM), ringed patterns with many defects could be found for samples with higher DDP contents, which crystallized at a lower temperature, and a transformation from square-shaped spherulites to circular spherulites was noted for samples with higher DDP contents, which crystallized at a higher temperature. The interference color of the spherulites was also studied and it was shown that with the increase of film thickness or decrease of DDP content, the spherulites became more colorful under POM observation, indicating that the hindering effect and randomness caused by incorporating the DDP monomer with a bulky pendent group into the PTT molecular chain exhibited a negative influence on the molecular mobility and crystallization ability of the copolyester, and led to the formation of the defective band morphology and the less colorful interference color of the PTTP spherulites.

Controlling interpenetration in CuCN coordination polymers by size of the pendant substituents of terpyridine ligands

To systematically investigate the effect of the pendant groups of ligands on the assembly of coordination polymers (e.g, controlling interpenetration), four terpyridine ligands with bulky pendant groups, namely, 4′-(4-tolyl)-4,2′:6′,4′′-terpyridine (L1), 4′-(4-ethylphenyl)-4,2′:6′,4′′-terpyridine (L2), 4′-(4-isopropylphenyl)-4,2′:6′,4′′-terpyridine (L3), and 4′-biphenyl-4,2′:6′,4′′-terpyridine (L4) have been synthesized for comparative purposes. The reactions of CuCN and L1–L4 under the same solvothermal conditions provided four CuCN coordination polymers: [(CuCN)2L1]n (1), [(CuCN)2L2]n (2), [(CuCN)2L3]n (3), and {[(CuCN)3L41.5]·H2O}n) (4), respectively. Single-crystal X-ray analyses reveal that compounds 1–3 are isostructural with the same topological 4-fold interpenetrated 3D CuCN networks, and compound 4 is a non-interpenetrated CuCN network. This success demonstrates that the interpenetration is suppressed by the alteration of the size of the pendant groups of terpyridine ligands.

Synthesis and characterization of new optically active and organosoluble copoly amides containing phthalimide rings as a pendent group

AbstractA series of new optically active and organosoluble copoly aimides 10a–f were synthesized through the direct polycondensation reaction of N‐phthalimido‐L‐aspartic acid 4 with 4,4′‐diamino diphenyl ether 8, 4,4′‐diamino diphenyl sulfone 9 in the presence of adipic acid 5, fumaric acid 6 and terephthalic acid 7 as a second diacid in a medium consisting of N‐methyl‐2‐pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. Phthalimide rings as a bulky pendent group in the polymer chains disturb inter‐ and intrachain interactions and make these PAs readily soluble in polar aprotic solvents such as N,N‐dimethyl acetamide (DMAc), N,N‐dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP) and solvents such as sulfuric acid. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, solubility tests and UV‐vis spectroscopy. Thermal properties of the CoPAs 10d–f were investigated using thermal gravimetric analysis (TGA). Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Characterization of terpolymers containing 1,2,4‐oxadiazolic pendant groups with potential application as workover fluids

AbstractPresence of planar, bulky heterocyclic pendant groups, attached to polymer chains, alters the thermal properties and, once gelled, they modify their rheological properties as well. The authors report generation of stiff gels coming from terpolymers containing 1,2,4‐oxadiazolic pendant groups, obtained by chemical modification of commercial polyacrylonitrile. The gels formed in basic aqueous solutions were compared and the effect of substituents linked to the heterocycles on thermal stability and viscoelastic properties was also analyzed. The structural modifications were followed by FTIR. The potential use of these terpolymers as workover fluids is discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Novel Inherently Flame-Retardant Poly(trimethylene Terephthalate) Copolyester with the Phosphorus-Containing Linking Pendent Group

A novel phosphorus-containing copolyester, poly(trimethylene terephthalate)-co-poly(trimethylene DDP)s (PTTP), was synthesized through esterification and polycondensation of terephthalic acid (TPA), 1,3-propane diol (PDO), and 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP). The analysis of phosphorus content and the test of intrinsic viscosity indicated that DDP was successfully introduced to the poly(trimethylene terephthalate) (PTT) chain. The chemical structure of the resulting copolyesters was further confirmed by 1H NMR and 31P NMR. The thermal behaviors were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and it was shown that the introduction of DDP lowered the melting temperature and crystallization because of its bulky pendent groups and decreased the initial decomposition temperature in the nitrogen atmosphere due to its weak P−C bond. The flame retardant properties of the resulting copolyesters were characteri...

Novel soluble fluorinated poly(ether imide)s with different pendant groups: Synthesis, thermal, dielectric, and optical properties

AbstractThree types of new bis(ether dianhydride) monomers, [4,4′‐(2‐(3′‐methylphenyl)‐1,4‐phenylenedioxy)‐diphthalic anhydride (4a)], [4,4′‐(2‐(3′‐trifluoromethylphenyl)‐1,4‐phenylenedioxy)‐diphthalic anhydride (4b)], and [4,4′‐(2‐(3′,5′‐ditrifluoromethylphenyl)‐1,4‐phenylenedioxy)‐diphthalic anhydride (4c)] were prepared via a multistep reaction sequence. Three series of soluble poly(ether imide)s (PEIs) were prepared from the obtained dianhydrides by a two‐step chemical imidization method. Experimental results indicated that all the PEIs had glass transition temperature in the range of 200–230 °C and the temperature of 5% weight loss in the range of 520–590 °C under nitrogen. The PEIs showed excellent solubility in a variety of organic solvents due to introduction of the bulky pendant groups and were capable of forming tough films. The casting films of PEIs (80–91 μm in thickness) had tensile strengths in the range from 88 to 117 MPa, tensile modulus from 2.14 to 2.47 GPa, and elongation at break from 15 to 27%. The casting films showed UV‐Vis absorption edges at 357–377 nm, low dielectric constants of 2.73–2.82, and water uptakes lower than 0.66 wt %. The spin‐coated films of PEIs presented a minimum birefringence value as low as 0.0122 at 650 nm and low optical absorption at the optical communication wavelengths of 1310 and 1550 nm. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3281–3289, 2010

Synthesis and characterization of optically active polyamides based on 2-(1,3-isoindolinedione-2-yl)glutaric acid by direct polycondensation

Five new optically active polyamides (PAs) 6a–6e were prepared by direct polycondensation reaction of 2-(1,3-isoindolinedione-2-yl)-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a–5e in a medium consisting of triphenyl phosphite (TPP), calcium chloride, pyridine (Py) and N-methyl-2-pyrrolidone (NMP). The polycondensation reaction produced a series of polyamids 6a–6e in quantitative yields with inherent viscosities of 0.26–0.39 dL/g. The resulting polymers were fully characterized by means of 1H-NMR, FT-IR spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis (TGA) and differential thermal gravimetry (DTG). Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP) and sulfuric acid.

Synthesis and Characterization of Soluble Low-κ Poly (aryl ether ketone) Copolymers with Pendent Adamantyl Groups

The aromatic bisphenol monomers containing bulky pendant (adamantyl) groups, 4-(1-adamantyl)-1,3-benzene diol (AdRES) and 4,8-bis(1-adamantyl)-1,5-dihydroxy naphthalene (AdNp) were successfully prepared via the Friedel—Crafts reaction and used to synthesize a series of new poly (aryl ether ketone) copolymers with (3-trifluoromethyl) phenyl hydroquinone or other bisphenols and 4,4′-difluorobenzophenone (DFB) by nucleophilic aromatic substitution polycondensation. All the novel PAEKs were amorphous and their solubility was improved by the introduction of bulky pendant groups, so they were readily soluble in common organic solvents. DSC data showed that Tg values of the resultant copolymers were dramatically increased when adamantane is incorporated into the copolymers as a pendent group and their T g values increased with increasing content of adamantyl groups. According to thermogravimetric analysis, all the polymers showed excellent thermal stabilities. The mechanical properties of the polymers can be controlled by varying the molar ratio of diphenol-containing adamantyl to (3-trifluoromethyl) phenyl hydroquinone. These novel poly (aryl ether ketone) films had low dielectric constants ranged from 2.62 to 2.95 at 1 MHz and low water absorptions of 0.12—0.29%; their dielectric constants decreased with the increasing content of the adamantyl group.

Soluble poly (aryl ether)s containing naphthalene pendant group: synthesis, characterization and electrospinning

Two soluble poly(aryl ether)s were prepared conveniently from bis(4-hydroxy-3,5-dimethylphenyl)naphthylmethane (1) and two activated dihalide monomers including 4,4′-difluorobenzophenone and bis(4-chlorophenyl)sulfone by an aromatic nucleophilic substitution. The bulky naphthyl and tetramethyl pendant groups in the polymer backbone could decrease the packing density and intermolecular interaction of macromolecular chain and make these poly(aryl ether)s show a good solubility. They all could be dissolved in CHCl3, CH2Cl2 and tetrahydrofuran at room temperature with a dissolvability of more than 10 wt%. Furthermore, the poly(aryl ether)s could be electrospun into microfiber (10–15 μm) with nanopores (200–350 nm). The morphologies of these fibers were characterized by scanning electron microscopy. The porous morphology on the fiber surface was also investigated using scanning probe microscope.

Synthesis and characterization of new optically active polyamides containing 2-(4-nitro-1,3-dioxoisoindolin-2-yl)succinic acid and aromatic diamines via direct polycondensation

A new class of optically active polyamides (PAs) (6a-e) having 4-nitro-1,3-dioxoisoindolin-2-yl pendent groups were prepared by direct polycondensation reaction of 2-(4-nitro-1,3-dioxoisoindolin-2-yl) succinic acid (4) with various aromatic diamines in a medium consisting of triphenyl phosphite, calcium chloride, pyridine, and N-methyl-2-pyrrolidone. The resulting new polymers were obtained in high yields with inherent viscosities ranging between 0.32 and 0.48 dL/g, and were characterized by elemental analysis, FT-IR spectroscopy, specific rotation, solubility tests, and thermogravimetric analysis techniques (TGA and DTG). Bulky pendent groups of the polymer chains disturb interchain and intrachain interactions and make these PAs readily soluble in polar organic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), NMP (N-methyl-2-pyrrolidone), and sulfuric acid. 2-(4-nitro-1,3-dioxoisoindolin-2-yl) succinic acid (4) was prepared by reaction of 3-nitrophthalic anhydride (1) and L-aspartic acid (2) in acetic acid solution.

Synthesis and thermal properties of soluble silicon containing phenylated aromatic–aliphatic polyamides

Aromatic polyamides find many applications in diverse and critical areas due to their high thermal stability coupled with high mechanical properties. However most of such aramides are difficult to fabricate because of their limited solubility and high melting temperature. Improvements in processability have been reported by incorporating bulky pendant groups and aliphatic spacer groups. Similarly to improve the solubility of polymers approaches of incorporating silicon in main polymer chain and co-polymerization techniques were useful. We report the synthesis and characterization of a series of phenylated silicon containing aromatic–aliphatic polyamides from a mixture of 2, 5-bis (4-carboxy methylene phenyl)-3, 4-diphenyl thiophene (CMPDT) and bis-(4-carboxy phenyl) dimethyl silane (BCPDS) in various mole proportions, with commercial aromatic diamine. Thus a series of novel co-polyamides having pendant phenyl groups, methylene spacer and silicon moiety was prepared by judicious combination of (CMPDT); BCPDS and aromatic diamine; bis-(4-aminophenyl) ether (ODA), by direct polycondensation using Yamazaki’s phosphorylation method. These high molecular mass polyamides were obtained in high (89–98%) yields and had viscosities in the range of 0.23–0.57 dL/g in DMAc. Polyamides showed improved solubility in polar aprotic solvents, like NMP, DMAc, DMSO and DMF; had high thermal stability; with no mass loss below 335 °C.

Conjugates of Enkephalin Analogs: Synthesis and Discrimination of μ and δ Opioid Receptors Based on Membrane Compartment Concept

A series of conjugated cyclic and linear enkephalin analogs, Tyr-c[D-A 2 bu-Gly-Phe-Asp(NH-X)], where X = methyl, stearyl or PEG 350 , and Tyr-D-Ala-Gly-Phe-Cys(S-X), where X = methyl, octyl, or farnesyl, were synthesized in solution to investigate the receptor selectivity of opioids based on Schwyzer's membrane compartment concepts. 5,6 Cyclizations of the target compounds were achieved in high yields (> 60%) employing BOP, NaHCO 3 in DMF despite the steric hindrance of the bulky pendant groups. In the binding assay, the hydrophobic fatty acyl conjugates retained μ-receptor selectivity. The unsaturated farnesyl conjugate exhibited the increased binding affinity than the saturated stearyl conjugate for both μ-and δ-opioid receptors. The PEG conjugates displayed the δ-receptor selectivity. The low molecular weight PEG 350 conjugate exhibited the increase selectivity than the high molecular weight PEG 5000 conjugate to the δ-receptor. The results of this study support the membrane compartment concepts.

Synthesis and characterization of new cardo poly(bisbenzothiazole-urea)s containing bulky pendant groups

A series of novel rigid poly(bisbenzothiazole-urea)s (PBTUs III) containing bulky pendant groups were synthesized from 2,2-diaminodibenzothiazoles and aromatic diisocyanates conveniently in the mild condition. The inherent viscosity, solubility, thermal stability, morphology, mechanical and photophysical properties of them were investigated and compared in detail. The inherent viscosities were in the range of 0.58–0.73 dL/g. All of the polymers exhibited excellent solubility in various polar organic solvents. They also showed good thermal stability and mechanical properties. The decomposition temperatures at 10% weight loss were in the range of 368–431 °C in nitrogen. All the PBTUs III were amorphous. Tensile strength of PBTUs III showed the range from 85 to 98 MPa. Compared with poly(benzothiazole)s, all the PBTUs III had the larger optical bandgap and lower photoluminescence quantum yields.

Crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties: Synthesis, characterization and properties

A novel phenylethynyl-contained bisphenol monomer, (2,5-dihydroxyphenyl)(4-(2-phenylethynyl)phenyl)methanone (PEBP), has been synthesized and characterized. The resultant monomer was copolymerized with hydroquinone and 4,4′-difluorobenzophenone by means of an aromatic nucleophilic substitution reaction to provide a series of crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties (PE-PAEKs). The solubility of PE-PAEKs tended to be improved with the increase in PEBP content. Wide-angle X-ray diffraction (WAXD) results showed that introduction of bulky pendant groups into molecular chains led to decrease in crystallinity. PE-PAEKs were successfully cured upon heating. Dynamic mechanical analysis (DMA) results indicated that the glass-transition temperature (Tg) of the cured PE-PAEKs was increased. Thermogravimetric analysis (TGA) results implied that the thermal stability of the cured PE-PAEKs was excellent.

Synthesis and properties of novel soluble aromatic polyamides derived from 5-(2-phthalimidyl-3-methyl butanoylamino)isophthalic acid and aromatic diamines

Wholly aromatic polyamides are high-performance and attractive materials, but, due to their low solubility, their applications have been restricted. In this work a new class of wholly aromatic and optically active polyamides ( PAs) having phthalimide and S-valine pendent groups were prepared by the reaction of 5-(2-phthalimidyl-3-methyl butanoylamino)isophthalic acid ( 1) as a diacid monomer with various readily available aromatic diamines. Triphenyl phosphite/pyridine in the presence of calcium chloride and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The resulting novel polymers were obtained in good yields, inherent viscosities ranging between 0.21 and 0.74 dL g −1 and were characterized with elemental analysis, FT-IR, 1H NMR, specific rotation and thermogravimetric analysis techniques. Bulky pendent groups of the polymer chains disturb interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethylacetamide, N,N-dimetheylformamide, dimethyl sulfoxide, NMP and solvents such as sulfuric acid. Thermogravimetric analysis showed that the 10% weight loss temperature in a nitrogen atmosphere were more than 320 °C, which indicates that the resulting PAs have good thermal satiability as well as excellent solubility. In addition because of existence of chiral center and optical activity of these polymers, they have potential to be used as chiral stationary phase in chromatography technique for the separation of racemic mixtures.