Synthesis and evaluation of properties of novel aromatic poly(ether-imide) with benzazole pendent groups and flexible ether linkages

2011 ◽  
Vol 23 (7) ◽  
pp. 542-554 ◽  
Author(s):  
Hojjat Toiserkani
Keyword(s):  
Weight Loss ◽  
Carboxylic Acids ◽  
Ring Opening ◽  
Polyphosphoric Acid ◽  
Catalytic Reduction ◽  
Amic Acid ◽  
Decomposition Temperature ◽  
Modified Polymers ◽  
Pendent Groups ◽  
Stage Process

Three types of new bis(ether-amine) monomers such as 5-(2-benzimidazole)-1,3-bis(4-aminophenoxy)benzene (3), 5-(2-benzoxazole)-1,3-bis(4-aminophenoxy)benzene (4), and 5-(2-benzothiazole)-1,3-bis(4-aminophenoxy)benzene (5) were prepared in three steps, starting from the reaction of 3,5-dihydroxybenzioc acid with 4-fluronitrobenzene in N, N-dimethylformamide (DMF) solution in the presence of potassium carbonate, followed by catalytic reduction of the intermediate dinitro-carboxylic acids, and subsequent condensation of the resulting diamino-carboxylic acids and 1,2-phenylenediamine, 2-aminophenol or 2-aminothiophenol in polyphosphoric acid (PPA), respectively. Three series of modified poly(ether-imide)s (PEIs) bearing pendent benzimidazole, benzoxazole or benzothiazole groups were prepared from the bis(ether-amine)s with dianhydrides by a conventional two-stage process that included ring-opening polycondensation forming the poly(amic acid)s (PAA) and further thermal or chemical imidization forming poly(ether-imide)s. For comparative purposes, reference poly(ether-imide)s were also prepared by reacting bis(ether-amine) lacking pendent groups namely 1,3-bis(4-aminophenoxy)benzene (6) with the same dianhydrides under similar conditions. The modified polymers were obtained in quantitative yields with inherent viscosities between 0.52 and 0.83 dL g−1. Experimental results indicated that all the PEIs had glass transition temperature between 221 and 283 °C, the decomposition temperature at 10% weight loss between 480 and 572 °C under nitrogen.

Synthesis and characterization of new poly(diketone imide)s derived from 1,4-bis(3,4-dicarboxybenzoyl)benzene dianhydride and various diamines

2020 ◽  
Vol 32 (9) ◽  
pp. 1043-1051
Author(s):  
Lu Kuang ◽  
Wei-Hong Wei ◽  
Xiao-Yan Sang ◽  
Yang Pan ◽  
Cheng Song
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Ring Opening ◽  
Tensile Modulus ◽  
Amic Acid ◽  
Synthesis And Characterization ◽  
Aromatic Diamines ◽  
Thermal Imidization ◽  
Stage Process

1,4-Bis(3,4-dicarboxybenzoyl)benzene dianhydride, an aromatic bis(ketone anhydride) monomer, was synthesized by the Friedel–Crafts reaction of terephthaloyl dichloride and o-xylene, followed by the oxidation of the intermediate tetramethylated compound and cyclodehydration of the resulting tetraacid. A series of new poly(diketone imide)s (PDKIs) were prepared from this dianhydride with various aromatic diamines via a conventional two-stage process that included ring-opening polyaddition to form the poly(amic acid)s followed by thermal or chemical imidization. Most of the PDKIs through chemical imidization were soluble in aprotic amide solvents, such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, m-cresol, and so on. The resulting PDKIs had good thermal property with the glass transition temperature of 203–275°C, the temperature at 5% weight loss of 500–539°C, and the residue of 51–60% at 800°C in nitrogen. Additionally, strong and flexible PDKI films obtained by thermal imidization exhibited outstanding mechanical property with the tensile strength of 88.8–158.5 MPa, tensile modulus of 1.9–3.5 GPa, and elongation at breakage of 7–21%.

Synthesis of 1,4-Bis(3-amino-5-trifluoromethylphenoxy)Benzene and Properties of the Polyimide Film Therefrom

2012 ◽  
Vol 581-582 ◽  
pp. 297-300
Author(s):  
Yun Hua Lu ◽  
Bing Wang ◽  
Guo Yong Xiao ◽  
Zhi Zhi Hu
Keyword(s):  
Catalytic Reduction ◽  
Visible Region ◽  
Optical Transmittance ◽  
Polyimide Film ◽  
Amic Acid ◽  
Decomposition Temperature ◽  
Structure And Properties ◽  
Thermal Decomposition Temperature ◽  
Fluorinated Polyimides ◽  
Thermal Imidization

Firstly, 1,4-bis(3-nitro-5-trifluoromethylphenoxy)benzene(I) was synthesized through the nucleophilic substitution reaction of 3,5-dinitrobenzotrifluoride and 1,4-dihydroxybenzene in the presence of potassium carbonate. Then, the diamine monomer 1,4-bis(3-amino-5-trifluoromethylphenoxy)benzene (II) was obtained through the catalytic reduction with hydrazine and Pd/C. These fluorinated polyimides (PI) were synthesized from the fluorinated diamine II with four kinds of dianhydrides, including pyromellitic dianhydride (PMDA), 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3’,4,4’-oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-benzophenonetetracarboxylicdianhydride (BTDA) respectively, via thermal imidization of poly(amic acid) (PAA). The structure and properties of these obtained fluorinated PIs were characterized. These experimental results showed that these fluorinated PI films exhibited excellent optical transmittance in the visible region and thermal resistance. The PI derived from ODPA showed the best optical transparency with the transmittance higher than 85.38 % at 450 nm. These PIs also exhibited good thermal properties with 5 wt% thermal decomposition temperature above 533 °C.

scholarly journals Performance Evaluation of Cellulose Nanofiber with Residual Hemicellulose as a Nanofiller in Polypropylene-Based Nanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1064
Author(s):  
Mohd Nor Faiz Norrrahim ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Mohd Ali Hassan ◽  
Nor Azowa Ibrahim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Weight Loss ◽  
Tensile Strength ◽  
Performance Evaluation ◽  
Flexural Strength ◽  
Decomposition Temperature ◽  
Cellulose Nanofiber ◽  
Hemicellulose Removal ◽  
Reinforcement Material

Residual hemicellulose could enhance cellulose nanofiber (CNF) processing as it impedes the agglomeration of the nanocellulose fibrils and contributes to complete nanofibrillation within a shorter period of time. Its effect on CNF performance as a reinforcement material is unclear, and hence this study seeks to evaluate the performance of CNF in the presence of amorphous hemicellulose as a reinforcement material in a polypropylene (PP) nanocomposite. Two types of CNF were prepared: SHS-CNF, which contained about 11% hemicellulose, and KOH-CNF, with complete hemicellulose removal. Mechanical properties of the PP/SHS-CNF and PP/KOH-CNF showed an almost similar increment in tensile strength (31% and 32%) and flexural strength (28% and 29%) when 3 wt.% of CNF was incorporated in PP, indicating that hemicellulose in SHS-CNF did not affect the mechanical properties of the PP nanocomposite. The crystallinity of both PP/SHS-CNF and PP/KOH-CNF nanocomposites showed an almost similar value at 55–56%. A slight decrement in thermal stability was seen, whereby the decomposition temperature at 10% weight loss (Td10%) of PP/SHS-CNF was 6 °C lower at 381 °C compared to 387 °C for PP/KOH-CNF, which can be explained by the degradation of thermally unstable hemicellulose. The results from this study showed that the presence of some portion of hemicellulose in CNF did not affect the CNF properties, suggesting that complete hemicellulose removal may not be necessary for the preparation of CNF to be used as a reinforcement material in nanocomposites. This will lead to less harsh pretreatment for CNF preparation and, hence, a more sustainable nanocomposite can be produced.

Iridium-Catalyzed Anti-Stereoselective Asymmetric Ring-Opening Reactions of Azabenzonorbornadienes with Carboxylic Acids

2017 ◽  
Vol 82 (6) ◽  
pp. 3167-3172 ◽  
Author(s):  
Meina Zhu ◽  
Jingchao Chen ◽  
Xiaobo He ◽  
Cuiping Gu ◽  
Jianbin Xu ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Ring Opening ◽  
Ring Opening Reactions ◽  
Asymmetric Ring Opening

Effects of Molecular Weight of Chitosan on the Biodegradability and Thermal Properties of Polybutylene Succinate/Chitosan Composites

2018 ◽  
Vol 775 ◽  
pp. 26-31
Author(s):  
Sukantika Manatsittipan ◽  
Kamonthip Kuttiyawong ◽  
Kazuo Ito ◽  
Sunan Tiptipakorn
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Thermal Properties ◽  
Water Absorption ◽  
Melting Temperature ◽  
Microbial Degradation ◽  
Decomposition Temperature ◽  
Molecular Weights ◽  
Significant Difference ◽  
Polybutylene Succinate

In this study, the biodegradability and thermal properties the composites of polybutylene succinate (PBS) and chitosan of different molecular weights (Mn = 104,105, and 106 Da) were prepared at chitosan contents of 0-10 wt%. After 10 days of microbial degradation, the results show that the amount of holes from degradation was increased with either decreasing Mn or increasing chitosan contents. However, the size of holes was increased with increasing Mn and chitosan contents. The results from Differential Scanning Calorimeter (DSC) present that the melting temperature (Tm) of PBS was decreased with increasing chitosan contents. Moreover, there was no significant difference between Tm of the composites with different Mn of chitosan. From the TGA thermograms, the decomposition temperature at 10% weight loss (Td10) was decreased with increasing chitosan contents. Moreover, the water absorption of PBS/chitosan composites was increased with increasing Mn and content of chitosan.

scholarly journals Spin-Coated Polysaccharide-Based Multilayered Freestanding Films with Adhesive and Bioactive Moieties

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 840 ◽  
Author(s):  
Joana Moreira ◽  
Ana C. Vale ◽  
Ricardo A. Pires ◽  
Gabriela Botelho ◽  
Rui L. Reis ◽  
...  
Keyword(s):  
Weight Loss ◽  
Coating Layer ◽  
Synergetic Effect ◽  
Layer By Layer ◽  
Negative Effects ◽  
Biological Assays ◽  
Modified Polymers ◽  
Marine Mussels ◽  
Cellular Metabolic Activity ◽  
Adhesive Proteins

Freestanding films based on catechol functionalized chitosan (CHI), hyaluronic acid (HA), and bioglass nanoparticles (BGNPs) were developed by spin-coating layer-by-layer assembly (SA-LbL). The catechol groups of 3,4-dihydroxy-l-phenylalanine (DOPA) present in the marine mussels adhesive proteins (MAPs) are the main factors responsible for their characteristic strong wet adhesion. Then, the produced films were cross-linked with genipin to improve their stability in wet state. Overall, the incorporation of BGNPs resulted in thicker and bioactive films, hydrophilic and rougher surfaces, reduced swelling, higher weight loss, and lower stiffness. The incorporation of catechol groups onto the films showed a significant increase in the films’ adhesion and stiffness, lower swelling, and weight loss. Interestingly, a synergetic effect on the stiffness increase was observed upon the combined incorporation of BGNPs with catechol-modified polymers, given that such films were the stiffest. Regarding the biological assays, the films exhibited no negative effects on cellular viability, adhesion, and proliferation, and the BGNPs seemed to promote higher cellular metabolic activity. These bioactive LbL freestanding films combine enhanced adhesion with improved mechanical properties and could find applications in the biomedical field, such as guided hard tissue regeneration membranes.

Laser Writing of High Purity Gold Lines

1989 ◽  
Vol 158 ◽  
Author(s):  
M. Jubber ◽  
J.I.B. Wilson ◽  
J.L. Davidson ◽  
P. John ◽  
P.G. Roberts
Keyword(s):  
Rectangular Cross Section ◽  
Single Crystal Silicon ◽  
Gold Surface ◽  
Decomposition Temperature ◽  
Silicon Substrates ◽  
Beam Diameter ◽  
Scanning Calorimetry ◽  
Crystal Silicon ◽  
Ion Laser ◽  
Stage Process

ABSTRACTGold tracks have been deposited on thermally oxidised and single crystal silicon, gold and nichrome coated silicon wafers by pyrolytic decomposition of gaseous alkyl (triethyl phosphine) gold(I) complexes using focussed 514 nm radiation from an argon ion laser. The precursors, RAu(I)Et3P, R = CH3, C2H5 are low melting point crystalline solids with relatively high vapour pressures (∼5 mtorr). They are representative of a class of compounds being evaluated for laser deposition of gold. Differential scanning calorimetry, DSC, shows that the thermal decomposition of MeAu(I)Et3P in the solid state is a two-stage process. The decomposition temperature is 63 ± 1°C. Tracks were deposited at laser scan speeds up to 35 μm s−1 with a beam diameter (1/e2) at the focus of ∼12 μm. SIMS, EDX and laser ionisation microprobe analysis, LIMA, were used to determine the chemical composition of the tracks. The purity of >98% is consistent with the measured resistivities (4.2 μΩ cm) at room temperature compared to bulk gold (∼2 μΩ cm). These resistivities were achieved without post deposition annealing. Stylus profilimetry and SEM data showed the lines produced from MeAu(I)Et3P have a virtually rectangular cross-section. Together with the absence of the ubiquitous λ-ripples, this feature suggests that deposition is more rapid on the gold surface than on the SiO2 substrate. Laser power thresholds are lower for silicon substrates coated with thin (5 - 10°A) films of gold or nichrome.

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