Poly(amideimide)s containing pendant pentadecyl chains: Synthesis and characterization

The effects of long and bulky aromatic pendent groups with flexible linkages on the thermal, mechanical and electrical properties of the polyimides and their nanocomposites with functionalized silica

A novel diamine bis(4-aminophenyl)bis{3,4[(4-(8-quinolyloxymethyl carbonyl)]}methane, containing two long/bulky aromatic pendent chains was synthesized by incorporating aromatic and hetero aromatic groups with flexible linkages. Flexible, stretchable, thermally stable and processable polyimides were prepared by reacting this newly synthesized diamine with commercial tetracarboxylic acid dianhydrides like 3,3',4,4'-benzophenone tetra carboxylic acid dianhydride (BTDA) and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic Anhydride (BPADA). Nanocomposites of polyimides were prepared using aromatic amine functionalized silica as a filler by solution casting method. The current work investigates the effects of incorporating long/bulky aromatic side chains and flexible linkages on the thermal, mechanical, electrical and optical properties of the polyimides and nanocomposites. The polyimides showed good thermal stability (T 10% = 364 & 388), high flame resistance, low glass transition temperatures (T g = 130 °C & 156 °C), very low dielectric constants (2.5 & 2.8 at 1 MHz) and good optical transparency. The neat polyimides displayed good elongation at break (133-155%) but possessed low tensile strength. The chemically imidized polyimides showed good solubility in low and high boiling solvents. Nanocomposites of polyimides based on aromatic amine functionalized silica exhibited enhanced properties with T 10% values varying between 409-482 °C, T g between 165-280 °C and higher dielectric constants (3-5.7 at 1 MHz).

From the Synthesis of Biobased Cyclic Carbonate to Polyhydroxyurethanes: A Promising Route towards Renewable Non-Isocyanate Polyurethanes

With a global production of around 18 million tons (6th among all polymers) and a wide range of applications, such as rigid and soft foams, elastomers, coatings, and adhesives, polyurethanes (PUs) are a major polymer family. Nevertheless, they present important environmental and health issues. Recently, new and safer PUs, called non-isocyanate polyurethanes (NIPUs), have become a promising alternative to replace conventional PUs. Sustainable routes towards NIPUs are discussed herein from the perspective of green chemistry. The main focus is on the reaction between biobased carbonates and amines, which offers an interesting pathway to renewable polyhydroxyurethanes (PHUs). An overview of different routes for the synthesis of PHUs draws attention to the green synthesis of cyclic carbonate (CC) compounds and the aminolysis reaction. Current state-of-the-art of different biobased building blocks for the synthesis of PHUs focuses on CC compounds. Three classes of compounds are defined according to the feedstock: 1) vegetable fats and oils, 2) starch and sugar resources, and 3) wood derivatives. Finally, biobased PHU properties are discussed.

Cardanol: a green substitute for aromatic oil as a plasticizer in natural rubber

Cardanol grafted natural rubber, prepared at room temperature, is a potential green substitute for carcinogenic aromatic oil plasticized natural rubber.

New organosoluble aromatic poly(esterimide)s containing pendent pentadecyl chains

A new diimide dicarboxylic acid, namely 2,2′-(4-pentadecyl-1,3-phenylene)bis(1,3-dioxoisoindoline-5-carboxylic acid), containing preformed imide rings and pentadecyl chain, was synthesized by the reaction of 4-pentadecylbenzene-1,3-diamine with trimellitic anhydride. A series of new aromatic poly(esterimide)s (PEIs) was synthesized using diphenylchlorophosphate-activated direct polycondensation of 2,2′-(4-pentadecyl-1,3-phenylene)bis(1,3-dioxoisoindoline-5-carboxylic acid), with five commercially available bisphenols, namely 4,4′-isopropylidenediphenol (I), 4,4′-(hexafluoroisopropylidene)diphenol (II), 4,4′-oxydiphenol (III), 4,4′-biphenol (IV), and 4,4′-(9-fluorenylidene)diphenol (V) in the presence of pyridine and lithium chloride. Inherent viscosities of PEIs were in the range 0.54–0.83 dL g−1 in chloroform (CHCl3) at 30 ± 0.1°C. PEIs containing pendent pentadecyl chains were soluble in organic solvents such as CHCl3, m-cresol, N, N-dimethylacetamide, 1-methyl-2-pyrrolidinone, pyridine, and nitrobenzene. Tough, transparent, and flexible films of PEIs could be cast from their CHCl3 solutions. PEIs exhibited glass transition temperature in the range 145–198°C. The temperature at 10% weight loss of PEIs, determined by thermogravimetric analysis under the nitrogen atmosphere, was in the range of 450–470°C indicating good thermal stability.

Synthesis and characterization of new organosoluble aromatic polyamides and polyazomethines containing pendent pentadecyl chains

New aromatic polyamides and polyazomethines containing pendent pentadecyl chains were synthesized by polycondensation of pentadecylbenzene-1,3-diamine with (i) four commercially available aromatic diacids, viz., biphenyl-4,4′dicarboxylic acid, 4,4′-oxybisbenzoic acid, terephthalic acid and isophthalic acid, and (ii) dialdehydes, viz., terephthaldehyde, isophthaldehyde and a 50 : 50 mol% mixture of terephthaldehyde, and isophthaldehyde, respectively. Inherent viscosities of polyamides and polyazomethines were in the range 0.35–0.56 dL g−1 and 0.33–0.38 dL g−1, respectively, indicating the formation of medium molecular weight polymers. The presence of pendent pentadecyl chains in polyamides and polyazomethines led to an improvement in their solubility in organic solvents. Polyamides could be cast into flexible, transparent and tough films from their solution in N, N-dimethylacetamide while polyazomethines could be solution cast into transparent, flexible and stretchable films from their CHCl3 solution. 1H-NMR studies based on amide proton signals and azomethine proton signals indicated the presence of constitutional isomerism in the polyamides and polyazomethines. Wide-angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were amorphous in nature. X-ray diffractograms also displayed sharp reflections in the small angle region (2 θ ≈ 3°) indicating the formation of layered structure arising from packing of flexible pentadecyl chains. The glass transition ( Tg) temperatures of polyamides were in the range 169–215 °C while Tg values for polyazomethines were in the range 16–55 °C. The temperature for the 10% weight loss of polyamides and polyazomethines were in the range 430–460 °C and 425–440 °C, respectively, in a nitrogen atmosphere, which indicated their good thermal stability. Polyazomethines were also characterized by UV-Vis and photoluminescence spectroscopy and optical band gap ( Eg) values, calculated according to the maximum of the UV absorption, were found to be in the range 2.82–3.10 eV.

Silica-containing fluorinated poly(amide-imide) hybrid films

New silica-containing hybrid films were prepared using a fluorinated poly(amide-imide) having hydroxyl groups and tetraethoxysilane, via the sol–gel technique. The polymer was synthesized by solution polycondensation reaction of a mixture of two diamines, 4,4′-diamino-4′′-hydroxy-triphenylmethane and 1,3-bis(4-aminophenoxy)benzene (molar ratio 3/7), with a fluorinated diacid chloride containing imide rings, 2,2-bis[ N-(4-chloroformylphenyl)phthalimidyl]hexafluoroisopropane. To improve the compatibility between the polymer and silica, the pendant hydroxyl groups of the polymer were reacted with 3-(triethoxysilyl)propyl isocyanate. The hybrid films were flexible, tough, and exhibited high thermal stability, having the initial decomposition temperature above 420 °C. The surface morphology of the hybrid films was investigated by scanning electron microscopy. Dynamic mechanical analysis and dielectric spectroscopy revealed subglass transitions, γ and β, and an α relaxation corresponding to the glass transition temperature. Electrical insulating properties were evaluated on the basis of dielectric constant and dielectric loss and their variation with the frequency and temperature. The values of the dielectric constant at 10 kHz and 20 °C were in the range of 3.18–3.48. The influence of the silica content on the polymer properties was examined.