Synthesis and Optical Properties of Thermally and Photochemically Cross-Linkable Diacetylene-Containing Polymers

Quadratic Non-Linear Optical Properties of the poly(2,5-bis(but-2-ynyloxy) Benzoate Containing the 2-(ethyl(4-((4-nitrophenyl)buta-1,3-diynyl)phenyl)amino)ethanol) Chromophore

Excellent quadratic non-linear optical (ONL-2) properties of the poly(2,5-bis(but-2-ynyloxy) benzoate, containing a polar diacetylene as a chromophore, were found. According with the Maker fringes method, oriented polymer films showing an order parameter of ∼0.23 can display outstanding and stable Second Harmonic Generation (SHG) effects under off-resonant conditions (SHG-532 nm). Also, the macroscopic non-linear optical (NLO)-coefficients were evaluated under the rod-like molecular approximation, obtaining: χ_zzz⁽²⁾ and χ_zxx⁽²⁾ in the order of 280 ± 10 and 100 ± 10 pm V^-1, respectively. The mechanical and chemical properties, in addition to the large ONL-2 coefficients exhibited by this polymer, make it a promising organic material in the development of optoelectronic/photonic devices.

Astrochemistry and Astrobiology: Materials Sciencein Wonderland?

Astrochemistry and astrobiology, the fascinating disciplines that strive to unravel the origin of life, have opened unprecedented and unpredicted vistas into exotic compounds as well as extreme or complex reaction conditions of potential relevance for a broad variety of applications. Representative, and so far little explored sources of inspiration include complex organic systems, such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives; hydrogen cyanide (HCN) and formamide (HCONH2) oligomers and polymers, like aminomalononitrile (AMN)-derived species; and exotic processes, such as solid-state photoreactions on mineral surfaces, phosphorylation by minerals, cold ice irradiation and proton bombardment, and thermal transformations in fumaroles. In addition, meteorites and minerals like forsterite, which dominate dust chemistry in the interstellar medium, may open new avenues for the discovery of innovative catalytic processes and unconventional methodologies. The aim of this review was to offer concise and inspiring, rather than comprehensive, examples of astrochemistry-related materials and systems that may be of relevance in areas such as surface functionalization, nanostructures, and hybrid material design, and for innovative technological solutions. The potential of computational methods to predict new properties from spectroscopic data and to assess plausible reaction pathways on both kinetic and thermodynamic grounds has also been highlighted.

Synthesis and properties of (A2+B4)-type hyperbranched polyimides with different terminal groups

To investigate the effect of terminal groups on the properties of hyperbranched polyimides (HBPIs) for potential optical applications, a series of HBPIs bearing different terminal groups have been synthesized through a novel aromatic CF3-containing tetra-amine, 4,4′-di[3,5-di(2-trifluoromethyl-4-aminophenoxy)phenoxy] sulfone, and a long chain dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane, via a two-step polycondensation procedure. The synthesized HBPIs could form flexible and tough polyimide (PI) films, which exhibit good thermal stability with the glass transition temperatures of 191–234°C for differential scanning calorimetry measurement, the 5% weight loss temperatures of 533–610°C, and residual weights of 45.8–58.6% at 800°C under nitrogen atmosphere. The PI films have favorable mechanical properties with tensile strengths of 77–92 MPa, elongation at break of 3.55–7.99%, and initial modulus of 2.05–2.86 GPa. The films also exhibit the good transmittance of higher than 80% at 800 nm. The average refractive indices ( nav) and in-plane/out-of-plane birefringence (Δ n) measured at 632.8 nm are in the range of 1.5539–1.6022 and 0.0065–0.0077, respectively. The good transmittance in the visible region, tunable nav, and low Δ n are very suitable for optical applications.

Thermal properties of diacetylene–containing polymer prepared from propargyl-terminated monomer with pyridine

A novel diacetylene–containing main chain-type polymer, poly[2,6-bis(4-propargyl-oxy-benzoyl)pyridine] (P1), was synthesized via oxidative coupling reaction with a new propargyl-terminated monomer, 2,6-bis(4-propargyl-oxy-benzoyl)pyridine (M1), which was incorporated a substituted pyridine into the molecular chain of model monomer, 4,4′-bis(propargyl-oxy)benzophenone (M0). The structures of the new monomer and the resulting polymer were verified by Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. Differential scanning calorimetry was used to investigate the curing behaviors of M1 and P1. The onset curing temperature of M1 was 199.0°C, and the exothermic enthalpy of M1 was 973.4 J g−1, while the initial curing temperature for polymer P1 reduced by 48°C and the exothermic enthalpy was almost half. Thermogravimetric analysis (TGA) showed the excellent thermal stabilities of M1 and its polymer in argon atmosphere (the decomposition temperatures at 5% weight loss were 446°C for M1 and 370°C for P1 and their char yields at 800°C exceeded 71%). The above TGA data were superior to that of the model monomer (M0) and its polymer (P0) under the same conditions.

Synthesis and properties of hyperbranched polyimides derived from tetra-amine and long-chain aromatic dianhydrides

The synthesized hyperbranched polyimides obtained from a novel tetra-amine have a treelike randomly branched topology with a branch-on-branch structure, which affords a compact, globular molecule.

Synthesis and properties of comb-shaped poly(arylene ether)

A novel comb-shaped fluorinated poly(arylene ether) (cs-FPAE) was prepared from a difluoride monomer, 4-(2,6-difluorobenzoyl)diphenyl ether, with commercial 4,4′-(hexafluoroisopropylidene) diphenol by nucleophilic polycondensation reaction. The number-average molecular weight and polydispersities of cs-FPAE were in the range of 11,000–25,000 and 1.9–2.5, respectively. The refractive index (1.4667–1.5644) and birefringence (0.005–0.02 at 1550 nm wavelength) of spin-coated polymer films were determined using the prism-coupling method.

Aminosilane-functionalization of a nanoporous Y-type zeolite for application in a cellulose acetate based mixed matrix membrane for CO2 separation

The micro-sized nanoporous Y-type zeolites were silylated and incorporated into a homogeneous cellulose acetate membrane which resulted in an improvement in the morphology and CO2/N2 separation properties of the corresponding mixed matrix membranes.

Poly(aryl ether ketone/sulfone)s containing ortho-methyl and pendant trifluoromethyl-substituted phenyl groups: Synthesis and properties

Two novel bisphenols, 1,1-bis(4′-hydroxy-3′,5′-dimethylphenyl)-1-(3′′-trifluoromethylphenyl)-2,2,2-trifluoroethane (4M6FDO) and 1,1-bis(4′-hydroxy-3′,5′-dimethylphenyl)-1-[3′′,5′′-bis(trifluoromethyl)phenyl]-2,2,2-trifluoroethane (4M9FDO), with methyl groups ortho-substituted to the phenol groups, bulky trifluoromethyl-substituted phenyl groups and trifluoromethyl groups in the structure, were synthesized and characterized. The bisphenols were polymerized with 4,4′-difluorobenzophenone and bis(4-fluorophenyl) sulfone, respectively, via a aromatic nucleophilic substitution polycondensation to afford four poly(aryl ether ketone/sulfone)s (PAEKs/PAESs) with the inherent viscosities of 0.32–0.52 dL g−1. The ortho-methyl and pendant trifluoromethyl-substituted phenyl groups endow the polymers with good solubility, the rigidity of the polymer chains increase the glass transition ( Tg) of the polymers to 197–235 °C. Flexible and tough films cast from N,N-dimethylacetamide showed good thermal stability, low dielectric constants of 2.67–2.73 and low water uptakes of 0.21–0.40%. Moreover, the polymers showed good transparency with light transmittance at 450 nm as high as 96% and cutoff wavelength as low as 285 nm. The PAEKs also exhibited low light-absorption at the optocommunication wavelengths of 1310 and 1550 nm.

Special positive birefringence properties of mesogen-jacketed liquid crystalline polymer films for optical compensators

Special positive birefringence optical compensative films were constructed from mesogen-jacketed liquid crystalline polymers. The heterocyclic groups present in the structure easily advance the birefringence properties. The title compounds have positive birefringence values of up to 0.0350.

Synthesis and Characterization of Thioether and Pyridine-Bridged Aromatic Polyimides with High Refractive Indices and High Glass Transition Temperatures

In this study, a novel aromatic diamine containing thioether and pyridine linkages, 2,6-bis[4-(4-aminophenylenesulfanyl)phenyl]-2-phenylpyridine (BASPP), was synthesized and characterized. The BASPP, along with several other sulfur-containing diamines, including 4,4′-( p-phenylenedisulfanyl) dianiline (2SPDA), 4,4′-bis( p-aminophenylsulfanyl)biphenyl (2SBPA), 4,4′-sulfonylbis[( p-phenylenesulfanyl)aniline] (BADPS), and 2,7-bis( p-aminophenylenesulfanyl)thianthrene (APTT) were polymerized with a sulfur-containing dianhydride, 4,4′-thiodiphthalic anhydride (TDPA), via a two-step polycondensation procedure to obtain five polyimides (PI-1 to PI-5). Flexible, tough, and transparent polyimide (PI) films with tensile strengths that ranged from 78.6 to 96.3 MPa were successfully cast from their poly(amic acid) (PAA) precursors. The PI films exhibited good thermal stability with glass transition temperatures ( T g values) as high as 265°C and 5% weight loss temperatures > 505 °C. The high sulfur contents and flexible thioether linkages endowed the PI films with refractive indices ( nav) as high as 1.7166 at 1310 nm and birefringence ( Δn) < 0.01. The PI-4, containing both pyridine and thioether moieties in the main chain, exhibited the best combined properties, including Tg of 265 °C, nav of 1.6966, Δn of 0.0078, and optical transmittance of 88% at 450 nm at the film thickness of 10 µ m.

Cross-linkable bromo-fluorinated poly(arylene ether ketone)s for photonic device applications

A series of novel cross-linkable bromo-fluorinated poly(arylene ether ketone)s have been synthesized and used to fabricate photonic devices. The polymers, prepared by polycondensation reactions of decafluorobenzophenone with mixtures of bisphenols in different ratios, exhibit excellent solubility in common organic solvents and can be easily cast into optical-quality thin films by spin coating. The materials are thermally stable with decomposition temperatures (Td, 5% weight loss) over 450 degrees C and have high glass transition temperatures (Tg) in the range of 164 degrees C-178 degrees C. By controlling the bromine content of the polymers, the refractive index can be precisely controlled over a range as wide as 0.07. The material has excellent design flexibility, low optical loss (0.4-0.6 dB/cm at 1550 nm), a low birefringence (2-3 x 10(-3)), and is suitable for use in wavelength sensitive photonic devices based on arrayed waveguide gratings.

Synthesis of Ethynyl End-Capped Oligo-Aryl Ethers

A series of aryl ether oligomers end-capped with ethynyl groups have been synthesised via a three-step process, i.e. iodination of oligo-aryl ethers, nucleophilic substitution of the iodide group with 2-methyl-3-butyn-2-ol catalysed by Pd/Cu and subsequent deacetonation in KOH/toluene. Effects of reaction temperature and the Pd/Cu catalyst on iodination and the substitution reaction are discussed.