New optically active poly(amide-imide)s from N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)bis-l-phenyl alanine and aromatic diamines: synthesis and characterization

In this work, new optically active poly(amide-imide)s (PAIs) having bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic diimide groups were prepared by the reaction of N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)bis-l-phenyl alanine (4) as a diacid monomer with various readily available aromatic diamines. Triphenyl phosphite (TPP)/pyridine (Py) in the presence of calcium chloride (CaCl₂) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The diacid (4) was synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with l-phenyl alanine (2) in acetic acid solution. The resulting new polymers were obtained in good yields, inherent viscosities ranging between 0.29 and 0.48 dLg⁻¹ and were characterized with elemental analysis, FT-IR, ¹H-NMR spectroscopy, specific rotation, and thermal gravimetric analysis (TGA, DTG) techniques. Thermogravimetric analysis indicated that the residual weight percent of polymers at 600 °C was between 53.80 and 56.21%, which show these are moderately thermally stable. 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.     

New photosensitive and optically active organo-soluble poly(amide–imide)s from N,N′-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids and 1,5-bis(4-aminophenyl)penta-1,4-dien-3-one: synthesis and characterization

A new series of N,N′-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a–g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 1 with two equimolars of various amino acids such as L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e, L-2-aminobutyric acid 2f and L-histidine 2g in an acetic acid solution. Also 1,5-bis(4-aminophenyl)penta-1,4-dien-3-one 7 was synthesized by using a two-step reaction. At first 1,5-bis(4-nitrophenyl)penta-1,4-dien-3-one 6 was prepared from the reaction of two equimolars 4-nitrobenzaldehyde 5 and one equimolar acetone 4 in ethanol and NaHCO₃ and dinitro compound 6 was reduced by using Na₂S. Then seven new photosensitive and optically active organo-soluble poly(amide–imide)s (PAIs) 8a–g with good inherent viscosities were synthesized from the direct polycondensation reaction of new N,N′-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a–g with 1,5-bis(4-aminophenyl)penta-1,4-dien-3-one 7 by two different methods such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride (CaCl₂)/pyridine (py) and direct polycondensation in a tosyl chloride (TsCl)/pyridine (py)/N,N-dimethylformamide (DMF) system. The polymerization reactions produced a series of photosensitive and optically active organo-soluble PAIs with high yield and good inherent viscosity. The resulted polymers were fully characterized by means of FTIR and ¹H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests, UV-vis spectroscopy, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and derivative of thermaogravimetric (DTG). These macromolecules exhibited maximum UV-vis absorption at around 370 and 265 nm in a DMF solution.     

Low-dielectric-constant aromatic homopolyimide and copolyimide derived from pyromellitic dianhydride, 4,4′-oxydianiline, 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene,or 1,3-bis(4-aminophenoxy)benzene

Low-dielectric-constant aromatics, homopolyimide and copolyimide, were introduced. Homopolyimides were prepared by pyromellitic dianhydride (PMDA) as an anhydride monomer and 4,4′-oxydianiline (ODA), 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene, or 1,3-bis(4-aminophenoxy)benzene as an amine monomer. The copolyimides were prepared with PMDA as an anhydride monomer, ODA as an amine monomer with the addition of 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene, or 1,3-bis(4-aminophenoxy)benzene as another amine monomer. The polyimides were well characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, thermomechanical analysis, dielectric measurements, and tensile testing. The homopolyimide and copolyimides showed lower dielectric constants than the homopolyimide formed by ODA and PMDA. The results also indicate that the interchain distance, the quantities of phenyl ether, and the position of the substitute are factors that not only affected the thermal performance of polyimide by improving the molecular flexibility but also reduced the dielectric constant of polyimide by increasing the free volume of the molecular chain and decreasing the polarization points per unit volume. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47405.     

Highly refractive and organo-soluble poly(amide imide)s based on 5,5′-thiobis(2-amino-4-methyl-thiazole): Synthesis and characterization

A new thioether-bridged diimide-diacid (DIDA) monomer was synthesized from the condensation of 5,5′-thiobis(2-amino-4-methyl-thiazole) (DA) and trimellitic anhydride at 1 : 2 molar ratio. A series of novel organic-soluble poly(amide imide)s (PAIs) bearing flexible thioether linkages and heteroaromatic thiazole groups were synthesized from DIDA with various commercially available aromatic diamines (1–5) via a direct polycondensation method with triphenyl phosphite and pyridine. The resulting polymers were obtained in high yields and possessed inherent viscosities in the range of 0.47–0.91 dL g^–1. All of the polymers were amorphous in nature, showed good solubility and could be easily dissolved in amide-type polar aprotic solvents (e.g., N-methyl-2-pyrrolidone, dimethyl sulfoxide, and N,N-dimethylacetamide), and even dissolved in less polar solvents (e.g., pyridine and tetrahydrofuran). They showed excellent thermal stability with glass transition temperatures between 233–269°C and 10% weight loss temperatures in excess of 480°C in nitrogen and 450°C in air atmosphere. The flexible structure endowed the PAI films with good optical transparency. The optical transmittances of the PAI films at 450 nm were higher than 80% for the thickness of approximately 10 μm. Moreover, the thiazole moieties and flexible thioether linkages in the molecular chains of the PAIs provided them with high refractive indices of 1.7329–1.7509 and low birefringences of 0.0065–0.0098. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

In vitro degradation assessment of optically active poly(urethane-imide)s based on α-amino acids

The aim of this work is to obtain optically and biologically active poly(urethane-imide)s (PUIs) using N,N’-(pyromellitoyl)-bis-l-tyrosine dimethyl ester (5) as a chiral and biologically active diphenolic monomer. Step-growth polymerization of diol 5 with various aliphatic and aromatic diisocyanates was carried out by gradual heating technique. The resulting PUIs were characterized with FT-IR, and two of them by ¹H-NMR spectroscopy and elemental analysis. Thermogravimetric analysis and differential scanning calorimetry were used to determine the thermal properties of the two representative PUIs. The morphology of polymer was studied by X-ray diffraction analysis. Furthermore, in vitro toxicity and biodegradability behaviors of the obtained PUIs were studied in culture media and soil burial degradation which reveals that the synthesized polymers are biologically active and biodegradable in natural environment.     

Synthesis and characterization of optically active helical poly(α, β-unsaturated ketone) with bulky pendant of binaphthyl

The synthesis and chiroptical properties of a novel optically active helical polymers, poly[(S)-6-acryloyl-2,2′-bisalkoxy-1,1′-binaphthyl] (poly-3), were reported. All the monomers readily underwent anionic polymerization to yield the polymers displaying optical rotations and Cotton effects in the UV–vis absorption region of side groups distinct to monomers (3) and the corresponding model compounds such as (S)-6-propionyl-2,2′-bisalkoxy-1,1′-binaphthyl (4) and (S)-6-heptanoyl-2,2′-bisalkoxy-1,1′-binaphthyl (5), implying the formation of main-chain chirality, most probable helicity. Their helical conformations were quite stable as revealed by the almost unchanged chiroptical properties measured at different temperatures.     

Synthesis and characterization of poly(11-(4′-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether)

Summary Polymers based on 11-(4-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether have been synthesized by living cationic polymerization, photo-initiated cationic polymerization using onium salts and thermal initiated cationic polymerization using onium salts. The polymers have been characterized by size exclusion chromatography, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and polarized light microscopy. Living cationic polymerization resulted in a polymer of low molecular mass M_n3 600, with a uniformity index (D) of 1.2 displaying a focal conic texture indicative of smectic A (s_A) phase with preserved cyanogroup and trans-configuration. Photo-initiation using 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide and diphenyliodonium hexafluorophosphate resulted in an insoluble polymer exhibiting only vague liquid crystalline textures. Initiation with phenothiazine and phenacyltetramethylenesulfonium hexafluoroantimonate also yielded a partly insoluble polymer with a disturbed s_A phase. It is suggested that the monomer and polymer are sensitive towards radicals leading to cross-linking and branching. The thermal initiation on systems with -methylbenzyltetramethylenesulfonium hexafluorophosphate and p-methoxybenzyltetramethylenesulfonium hexafluorophosphate resulted in completely soluble mesomorphic polymers of M_n13 000, D=1.7 and M_n26 000, D=2.8 respectively, in both cases with a preserved cyanogroup and a transconfiguration. Polarized light microscopy revealed a distinct focal conic structure indicative of s_A in both cases.     

Synthesis and characterization of a novel kind of thermotropic liquid crystalline poly(urea-ester)s based on bis(4′-hydroxyphenyl)-tolyene-2,4-diurea

A new diphenol monomer bis(4′-hydroxy-phenyl)-tolyene-2,4-diurea was synthesized by reaction of 2,4-toylene diisocyanate with p-aminophenol in N,N-dimethylformamide (DMF). The product was characterized by elemental analysis (EA), differential scanning calorimetry (DSC), and ¹H-NMR. And a novel kind of liquid crystalline poly(urea-ester)s were obtained by using this monomer. By using a polarizing microscope with hot stage (POM), wide-angle X-ray diffraction (WAXD) and small-angle X-ray diffraction (SAXD) the polymers were proven to be nematic liquid crystal. The result of DSC showed that the effect of the monomer composition on the melting point of poly(urea-ester)s was significant. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 577–583, 2001     

Synthesis and properties of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane

A new kind of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was prepared by the anionic polymerization with a “seed solution” as initiator. The synthesis of monomers N,N′-bis(hydroxydiphenylsilyl)tetraphenylcyclodisilazane (BHPTPC), N,N′-bis(chlorodiphenylsilyl)tetraphenylcyclodisilazane (BCPTPC), and 1,3-dichloro-1,1,3,3-tetraphenyldisilazane (DCTPS) are all reported in this study. The synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was characterized by ¹H–NMR, ²⁹Si–NMR, gel permeation chromatography (GPC), and intrinsic viscosity. The thermal stability of the polysiloxane was studied by isothermal gravimetric analysis (IGA). The results demonstrated that the synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane had excellent thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 929–933, 2001     

The nucleation effect of N,N′-bis(benzoyl) alkyl diacid dihydrazides on crystallization of biodegradable poly(l-lactic acid)

Five N,N??-bis(benzoyl) alkyl diacid dihydrazides were synthesized from benzoyl hydrazine and alkyl diacyl dichloride which were derived from alkyl diacid via acylation. PLLA/N,N??-bis(benzoyl) alkyl diacid dihydrazide samples were prepared by melt blending and hot-press forming process. The nucleation effect of N,N??-bis(benzoyl) alkyl diacid dihydrazide on crystallization of biodegradable poly(l-lactic acid) (PLLA) was investigated using differential scanning calorimetry (DSC) and vicat softening analysis. The results showed that five N,N??-bis(benzoyl) alkyl diacid dihydrazides acted as powerful nucleating agent for PLLA; with incorporation of N,N??-bis(benzoyl) alkyl diacid dihydrazide, the crystallization peak became sharper and shifted to higher temperature as the degree of supercooling decreased at a cooling rate of 1?°C/min from melt. The nucleation activities of five N,N??-bis(benzoyl) alkyl diacid dihydrazides were quantitatively determined. It is shown that N,N??-bis(benzoyl) suberic acid dihydrazide has higher nucleating activity than the other N,N??-bis(benzoyl) alkyl diacid dihydrazides. In the presence of N,N??-bis(benzoyl) alkyl diacid dihydrazide, the melting behavior of PLLA is affected significantly. In addition, the thermal stability of PLLA/0.8?% N,N??-bis(benzoyl) alkyl diacid dihydrazide is tested and reported. Compared to the neat PLLA, the onset degradation temperature of PLLA/0.8?% N,N??-bis(benzoyl) alkyl diacid dihydrazide samples has been decreased significantly.     

Biodegradable elastic photocured polyesters based on adipic acid, 4-hydroxycinnamic acid and poly(ε-caprolactone) diols

A novel series of photocurable biodegradable polyesters (CAC/PCL) were synthesized by a high-temperature solution polycondensation of poly(ε-caprolactone) (PCL) diols varying molecular weight (M_W; 1250, 2000, 3000) and a diacyl chloride of 4,4′-(adipoyldioxy)dicinnamic acid (CAC) as a chain extender derived from adipic acid and 4-hydroxycinnamic acid. The resulting polyesters were photocured by the ultraviolet (UV) light irradiation in order to prepare elastic polyester with enhanced thermal and mechanical properties. The effects of photocuring by the UV light irradiation on the thermal, tensile and hydrolytic properties of the CAC/PCL were examined. DSC indicated that the melting temperatures and the crystallinities are decreased by the photocuring. The tensile properties of the photocured CAC/PCL films depended on the M_W of PCL-diols and photocured time. The CAC/PCL1250 films photocured for 10-60 min exhibited a strength-at-break of 3.1-4.7 MPa and an elongation-at-break of 640-1500%, and recovered very rapidly to the original size from 90 to 300% extension. Enzymatic degradation was performed in the phosphate buffer solution (pH 7.2) with Ps. cepacia lipase at 37 °C and evaluated by the weight loss. Non-photocured CAC/PCL films were degraded very rapidly and the weight loss after 3 h incubation was more than 60%. The weight loss of the photocured films decreased remarkably with increasing the photocuring time due to the increase of cross-linking density, while it increased with increasing the M_W of PCL-diols. The photocured CAC/PCL1250 film is promising as a novel biodegradable elastomer for biomedical applications as well as environmental applications.     

Synthesis and properties of polyimides based on isomeric (4, 4′-methylenediphenoxyl) bis (phthalic anhydride)s (BPFDAs)

Isomeric (4, 4′-methylenediphenoxyl) bis (phthalic anhydride)s (BPFDAs)were synthesized and their structures were determined via IR spectra and ¹H NMR. Polyimides were then prepared from isomeric BPFDAs and aromatic diamines in N, N-Dimethylacetamide (DMAc) via the conventional two-step method. Polyimides based on 3, 3′-BPFDA are soluble in common organic solvents at room temperature, while polyimides based on 4, 4′-BPFDA were only partially soluble in high-boiling-point solvent even upon heating. The 5% weight-loss temperatures (T _5% ) of these polyimides were in the range of 430–500 °C in air. Dynamic mechanical thermal analysis (DMTA) indicated that the glass-transition temperatures of polyimides from 3, 3′-BPFDA are around 10–20 °C higher than those of polyimides from 4, 4′-BPFDA. The wide-angle X-ray diffraction showed that all polyimides are amorphous.     

Synthesis and properties of poly(ester imide) copolymers from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′-bis(trifluoromethyl)benzidine,and 4-aminophenyl-4′-aminobenzoate

A series of poly(ester imide) (PEsI) copolymers were synthesized using 3,3′,4,4′-biphenyltetracarboxylic dianhydride (4,4′-BPDA), 2,2′-bis(trifluoromethyl)benzidine (TFMB), and 4-aminophenyl-4′-aminobenzoate (APAB) as the monomers. Wide-angle x-ray diffraction results revealed that the average interchain distances of these polymers ranged from 4.6 to 5.7 Å, increasing with the increase of TFMB contents. PEsI-0.3 and PEsI-0.4 exhibited a glass transition temperature (T_g) of 445 and 455°C, respectively, while no distinctive T_g was observed for the PEsI copolymers when the APAB content was >50 mol%. The coefficients of thermal expansion (CTE) of these PEsI copolymers ranged from 3.8 to 24.2 ppm K⁻¹, increasing with the increase of TFMB contents. The PEsI copolymers exhibited a modulus of 5.7–7.8 GPa, a tensile strength of 282–332 MPa, and an elongation-at-break of 10.2%–23.3%. Furthermore, these copolymers exhibited a dielectric constant of 2.53–2.76, and a low dissipation factor (D_f) of 0.0026–0.0032 at 10 GHz in dry state. Because of their excellent combined properties, these PEsI copolymers are promising candidates as dielectric substrate materials for the applications in next generation flexible printed circuit boards operating at high frequencies.     

Synthesis of new diacid monomers and poly(amide-imide)s: study of structure–property relationship and applications

Two diimide-diacid monomers 4,4′-bis[4″-(trimellitimido)phenyl isopropylidene-4″′-phenoxy]diphenyl sulfone and 4,4′-bis[4″-(trimellitimido)phenylisopropylidene-4″′-phenoxy] were synthesized. The structures of the monomers were characterized by FT-IR and ¹H-NMR spectroscopy. A series of novel poly(amide-imide)s were prepared from this two diacids and aromatic diamines through phosphorylation reaction. The PAIs were characterized by FT-IR, ¹H-NMR, XRD, TGA, and DSC, solution viscosity, solubility test and electrical properties. Poly(amide-imide)s showed excellent solubility due to the presence of flexible groups and isopropylidene unit in the polymer backbone. They also exhibited good thermal stability and the temperatures at which 10% weight loss occurred in the range 385–465 °C. These PAIs found to have a dielectric constant in the range 3.25–4.20 at 10 kHz and have excellent electrical insulation character and can be used as insulation materials for electrical items operating at elevated temperatures.     

Novel nanocomposites based on reactive organoclay of l-tyrosine and amine end-capped poly(amide–imide): Synthesis and characterization

In the present study, a series of nanocomposite materials were successfully prepared using a poly(amide–imide) (PAI) matrix and novel reactive organoclay as a reinforcing agent. The organoclay was synthesized from Cloisite Na⁺ and protonated form of l-tyrosine amino acid via ion-exchange reaction. It was confirmed by Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetry analysis techniques. An optically active PAI was synthesized via solution polycondensation reaction of N,N′-(pyromellitoyl)-bis-phenylalanine diacid chloride and 4,4′-diaminodiphenylether. Then it was end-capped with amine end groups near the completion of the reaction to interact chemically with organoclay. Organoclay/PAI nanocomposite films containing different amounts of organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The nanostructures and properties of the organoclay/PAI hybrids were investigated using different techniques. Thermogravimetry analysis results indicated that the addition of organoclay into the PAI matrix increased the thermal decomposition temperatures of the resulting hybrid materials. The presence of amino acids as a biodegradable segment in both novel organoclay and optically active PAI, made the resulting nanostructure materials susceptible for biodegradation.     

Synthesis and properties of aromatic polyesters and brominated polyesters derived from α,α′-bis(4-hydroxyphenyl)-1,4(or 1,3)-diisopropylbenzene

The interfacial polycondensation technique was used for the preparation of polyarylates and brominated polyarylates. Polyarylates and brominated polyarylates were prepared by mixing a solution of diacid chloride such as terephthaloyl chloride, isophthaloyl chloride, or their mixture in dichloromethane with an aqueous alkaline solution of ,-bis(4-hydroxyphenyl)-1,4(or 1,3)-diisopropylbenzene or ,-bis(4-hydroxy-3,5-dibromophenyl)-1,4(or 1,3)-diisopropylbenzene using triethylbenzylammonium chloride as the phase transfer agent. Moderate to high molecular weight polyarylates with _inh up to 1.27 dL/g were obtained, and most of them could be cast into tough and flexible films depending on the polymer composition. In general, polymers containing more 1,3-isomer or isophthaloyl chloride moieties gave transparent and flexible films and had lower glass transition temperatures and higher solubility. Although these polymers have two isopropylidene linkages in their repeating units, they still exhibit moderately high thermal stability and show no obvious weight loss before 400 °C. The introduction of bromine on the polymer backbone caused a decrease of inherent viscosity, crystallinity, and thermal stability of the polyarylates, while causing an increase in glass transition temperature and a great enhancement of fire retardancy.     

Novel poly(ε-caprolactone)s bearing amino groups: Synthesis,characterization and biotinylation

A novel functional ε-caprolactone monomer containing protected amino groups, γ-(carbamic acid benzyl ester)-ε-caprolactone (γCABεCL), was successfully synthesized. A series of copolymers [poly(CL-co-CABCL)] were prepared by ring-opening polymerization of ε-caprolactone (CL) and γCABεCL in bulk using tin (II)-2-ethylhexanoate [Sn(Oct)₂] as catalyst. The morphology of the copolymers changed from semi-crystalline to amorphous with increasing γCABεCL monomer content. They were further converted into deprotected copolymers [poly(CL-co-ACL)] with free amino groups by hydrogenolysis in the presence of Pd/C. After deprotection, the free amino groups on the copolymer were further modified with biotin. The monomer and the corresponding copolymers were characterized by ¹H NMR, ¹³C NMR, FT-IR, mass, GPC and DSC analysis. The obtained data have confirmed the desired monomer and copolymer structures.     

Synthesis and characterization of poly(ε-caprolactone)-containing amino acid-based poly(ether ester amide)s

A new family of biodegradable amino acid-based poly(ether ester amide)s (AA-PEEAs) consisting of three building blocks [poly(ε-caprolactone) (PCL), L -phenylalanine (Phe), and aliphatic acid dichloride] were synthesized by a solution polycondensation. Using DMA as the solvent, these PCL-containing Phe-PEEA polymers were obtained with fair to very good yields with weight average molecular weight (M_w) ranging from 6.9 kg/mol to 31.0 kg/mol, depending on the original molecular weight of PCL. The chemical structures of the PCL-containing Phe-PEEA polymers were confirmed by IR and NMR spectra. These PCL-containing Phe-PEEAs had lower T_g than most of the oligoethylene glycol (OEG) based AA-PEEAs due to the more molecular flexibility of the PCL block in the backbones, but had higher T_g than non-amino acid based PEEA. The solubility of the PCL-containing Phe-PEEA polymers in a wide range of common organic solvents, such as THF and chloroform, was significantly improved when comparing with aliphatic diol based poly(ester amide)s and OEG based AA-PEEAs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012