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1.
Issei Sato Shihori Takeda Yuki Arai Hideharu Miwa Yu Nagase Nobukatsu Nemoto 《Polymer Bulletin》2007,59(5):607-617
Summary Novel poly(tetramethylsilarylenesiloxane) derivatives, i.e. poly(tetramethyl-2,6-silanthrylenesiloxane) (P1), poly(tetramethyl-9,10-silanthrylenesiloxane) (P2), and poly(tetramethyl-1,8-silphenanthrylenesiloxane) (P3), were synthesized by polycondensation of novel disilanol monomers, i.e. 2,6-bis(dimethylhydroxysilyl)-anthracene (M1), 9,10-bis(dimethylhydroxysilyl)anthracene (M2), and 1,8-bis(dimethylhydroxysilyl)phenanthrene (M3), respectively. P1 and P3 were soluble in common organic solvents, such as benzene, toluene, chloroform, dichloromethane, tetrahydrofuran, etc. whereas P2 was almost insoluble in common organic solvents. It was revealed that P1 and P3 were amorphous and that P2 exhibited the crystallinity, as deduced from differential scanning calorimetry (DSC) and X-ray diffraction measurements.
The glass transition temperatures (Tg’s) of P1 (118 °C) and P3 (100 °C) were much higher than that of poly(tetramethyl-1,4-silphenylenesiloxane). The temperature at 5% weight loss (Td5) of P3 was 500 °C, which was higher than those of P1 and P2, and comparable to that of poly(tetramethyl-1,4-silphenylenesiloxane). It would be speculated that the thermostability of
the series of poly(tetramethyl-silarylenesiloxane) derivatives is dependent on the stability of arylene moieties incorporated. 相似文献
2.
Novel poly(tetramethylsilnaphthylenesiloxane) derivatives were synthesized and characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), and X-ray diffraction analyses. Poly(tetramethylsilnaphthylenesiloxane) derivatives were obtained by condensation polymerization of the corresponding disilanol derivatives, i.e. 1,4-, 1,5-, 2,6-, and 2,7-bis(dimethylhydroxysilyl)naphthalenes, which were prepared by the Grignard reaction using chlorodimethylsilane and the corresponding dibromonaphthalene derivatives followed by the hydrolyses, catalyzed by palladium on charcoal. The obtained poly(tetramethyl-1,5-silnaphthylenesiloxane) was insoluble in common organic solvents; however, the other polymers exhibited the good solubility in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. The introduction of tetramethyl-1,5-silnaphthylenesiloxane units into the resulting polymer was confirmed by 1H NMR spectrum of the copolymer obtained by condensation copolymerization of 1,5-bis(dimethylhydroxysilyl)naphthalene with 1,4-bis(dimethylhydroxysilyl)naphthalene. It was revealed from the DSC and X-ray diffraction measurements that poly(tetramethyl-1,5-silnaphthylenesiloxane) and poly(tetramethyl-2,6-silnaphthylenesiloxane) exhibited the crystallinity; however, poly(tetramethyl-1,4-silnaphthylenesiloxane) and poly(tetramethyl-2,7-silnaphthylenesiloxane) were amorphous. The glass transition temperature (Tg) and the temperature at 5% weight loss (Td5) of poly(tetramethylsilnaphthylenesiloxane) derivatives with dimethylsilyl group at 1-position of the naphthylene moiety were higher than those at 2-position of the naphthylene moiety. The Tg and melting point (Tm) of the present polymers were higher than those of poly(tetramethyl-1,4-silphenylenesiloxane). 相似文献
3.
Poly(tetramethyl-1,6-silpyrenylenesiloxane) derivative with phenyl groups on pyrenylene moieties (P1) was prepared via polycondensation of disilanol monomer, i.e. 1,6-bis(dimethylhydroxysilyl)-3,8-diphenylpyrene (M1). P1 exhibited the very high glass transition temperature (T
g) of 191 °C. The temperature at 5% weight loss (T
d5) of P1 was 482 °C, indicating the relatively good thermostability of P1. P1 exhibited the bathochromic effect in the absorption and fluorescence spectra, indicating the expansion of π-conjugation by
introducing phenyl groups onto pyrene skeleton as well as the σ–π and σ*–π* conjugation between pyrene and silyl moieties.
In addition, P1 exhibited relatively weak excimer emission because of the inhibition of the excimer formation of pyrene skeleton by introduction
of bulky phenyl groups onto pyrene skeleton. The fluorescence quantum yields (ΦFs) of M1 and P1 in chloroform were determined to be 0.46 and 0.37, respectively. It was revealed that M1 and P1 exhibited the higher fluorescence intensity than 1,6-diphenylpyrene, owing to the effect of the introduction of silyl moieties
onto pyrene skeleton. 相似文献
4.
2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene was synthesized by Michael addition reaction using 2,7-dibromofluorene and perfluorohexyl ethyl acrylate as the reactants. 9,9-Bis(perfluorohexylethyl propionate) fluorene copolymers were then synthesized by Suzuki coupling reaction with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)-9,9 -dioctyl fluorene, 2,7-dibromo-9,9-dioctyl fluorene and 2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene as the monomers. The fluorinated fluorene copolymers were characterized and investigated via Fourier infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectroscopy (1HNMR), ultraviolet absorption spectroscopy (UV–vis), cyclic voltammetry (CV) and photoluminance spectroscopy (PL). Because of the long fluorine-containing alkyl side chain, the ultraviolet absorption peak of 9,9-bis(perfluorohexylethyl propionate) fluorene is blue-shifted compared with poly(9,9-dioctylfluorene)(PF8). The LUMO energy level increases and the energy band gap of copolymers widens. Due to the self-assembly of the long fluoroalkyl side chain, the photoluminance spectra of 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers exhibit a new excimer emission peak at 550 nm. The photoluminance stabilities of the copolymers under irradiation and humid conditions are significantly improved due to protective effect from the long fluoroalkyl side chain. After being irradiated under 500 W iodine tungsten lamp or kept under 70% relative humid conditions, the 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers showed much better photoluminance stability than that of poly(9,9-dioctylfluorene) (PF8). These show that introducing long fluoroalkyl side chain into conjugated polymer main chain is a promising strategy to improve environmental stability of devices based on organic conjugated polymers. 相似文献
5.
A polymer having high aromaticity and/or cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether-type epoxy resins are prepared from bisphenol A (DGEBA), 9,9-bis(4-hydroxyphenyl)fluorene (DGEBF), 3,6-dihydroxyspiro-[fluorene-9,9′-xanthane] (DGEFX), 10,10-bis(4-hydroxyphenyl) anthrone (DGEA), and 9,9,10,10-tetrakis(4-hydroxyphenyl)anthracene (TGETA) in order to study structure–thermal stability–flame resistance property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 700°C under a nitrogen atmosphere and the glass transition temperature (Tg) for the uncured resins decrease according to the sequence TGETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are DGEBA < DGEBF < DGEFX < DGEA. A Tg for the TGETA is not obtainable but would be expected to be the highest. The char yields at 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA, and TGETA added to the DGEBA system show increases in the char yield, Tg, and oxygen index with increasing concentration of these novel epoxy resins. 相似文献
6.
Yanli Lei Fudong Ma Yong Tian Qiaoli Niu Hongyu Mi Ismayil Nurulla Wei Shi 《应用聚合物科学杂志》2013,129(4):1763-1772
A kind of fluorene‐based conjugated polymer with tethered thymine (T) groups {poly[(9,9‐dioctyl)‐2,7‐fluorene‐{9,9‐dioctyl‐4–1,2,3‐triazol‐[5‐(hydroxymethyl)tetrahydrofuran‐2‐yl]‐5‐methylpyrimidine‐2,4(1H,3H)‐dione}‐2,7‐fluorene]‐co‐[(9,9‐dioctyl)‐2,7‐fluorene‐4,7‐bis(5‐thiophen‐2‐yl)benzo‐2,1,3‐thiadiazole] ( P‐3 )} was successfully synthesized by a Cu(I)‐catalyzed click reaction between the acetylene‐substituted polymer precursor {poly[(9,9‐dioctyl)‐2,7‐fluorene‐(9,9‐dioctyl‐4‐phenylacetylene fluorene)]‐co‐[(9,9‐dioctyl)‐2,7‐fluorene‐4,7‐bis(5‐thiophen‐2‐yl)benzo‐2,1,3‐thiadiazole]} and 3′‐azido‐3′‐deoxythymidine. The chemical structures of the intermediates and target polymer were verified by Fourier transform infrared spectroscopy and 1H‐NMR analyses. The specific binding with Hg2+ of P‐3 was corroborated by ultraviolet–visible spectroscopy and photoluminescence analyses against other metal ions. The results show that P‐3 possessed selectivity and sensitivity toward Hg2+. Around 77% of photoluminescence intensity of P‐3 was quenched when the concentration of Hg2+ reached 7.7 × 10?4 M and with a detection limit in the range of about 4.8 μM. A comparison experiment suggested that a synergic effect of the tethered T and S atoms interrelated with Hg2+ existed in P‐3 . Most of the fluorescence intensity of P‐3 was recovered upon the addition of iodide anions to the P‐3 /Hg2+ complex; this suggested that P‐3 could be used as a potential reversible optical Hg2+ probe. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
7.
Charles U. Pittman Jr. Gui Zhi Li Ho Souk Cho 《Journal of Inorganic and Organometallic Polymers and Materials》2006,16(1):43-59
Three classes of inorganic–organic hybrid phenolic resin/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized.
Multifunctional dichloromethylsilylethylheptaisobutyl-POSS (POSS-1), trisilanolheptaphenyl-POSS (POSS-2), and poly(phenylsilsesquioxane) uncured POSS (POSS-3) were employed. Nonfunctional POSS-4 (octaisobuty1-POSS) was blended into the uncured phenolic resin and cured under the same conditions used for the other three
nanocomposite classes. Weight ratios of 99/1, 97/3, 95/5 and 90/10 were prepared for the POSS-1, 2 and 4 series and 99/1, 97/3 and 95/5 ratios for the POSS-3 nanocomposites. POSS-1 incorporation into this phenolic resin network increases T
g and broadens the tan
peak (DMTA) range. T
g and E′ values at T>T
g both increase with higher POSS-1 content. In contrast, incorporating 5 wt% of POSS-2 into the phenolic resin network lowers T
g to 193 from 213°C for the neat phenolic resin. All values of E′ for POSS-2 composites were higher, than those of the phenolic control in both glassy and rubbery regions. The T
g values of the 1 and 10% POSS-2 systems were higher. Incorporating 10 wt% of POSS-1 or POSS-2 improved the heat distorsion temperature and moduli (E′=123 and 201 GPa at 265°C, respectively, versus 56 GPa for the pure phenolic resin). Increases in E′ for T>T
g and T<T
g were also observed for all POSS-3 nanocomposites. However, the E′ at T>T
g and the T
g values of the POSS-4 composites were lower than those of the control resin. Octaisobutyl POSS-4 cannot form chemical bonds to the resin and could be extracted from its composites with THF. POSS derivatives were not present
in residues extracted by THF from the phenolic resins containing POSS-1, 2 or 3, because each of these derivatives were chemically bound within the phenolic resin. Subsequent heating cycles produce much
larger increases in T
g and E′ values in the rubbery region for the POSS-1, 2 and 3 composites than for the neat phenolic resin or for the POSS-4 systems.
An erratum to this article can be found at 相似文献
8.
Mousa Ghaemy Bahareh Aghakhani Mehdi Taghavi Seyed Mojtaba Amini Nasab Mojtaba Mohseni 《Reactive and Functional Polymers》2013,73(3):555-563
A new para-linked diether-diamine, 9,9-bis{4-[2-(4,5-diphenylimidazol-2-yl)-4-aminophenoxy] phenyl}fluorene (III), bearing fluorene–bisphenol and two ortho-linked diaryl-substituted imidazole rings were synthesized by the catalytic reduction of the nitro groups of compound (II), 9,9-bis{4-[2-(4,5-diphenylimidazol-2-yl)-4-nitrophenoxy]phenyl}fluorene, by using hydrazine monohydrate in the presence of Pd/C. Compound (II) was synthesized by the nucleophilic chloro displacement reaction of the synthesized 2-(2-chloro-5-nitrophenyl)-4,5-diphenyl-1H-imidazole with 9,9-bis(4-hydroxyphenyl)fluorene in refluxing DMAc in the presence of potassium carbonate. This diamine was condensed directly with aliphatic and aromatic diacids via the Yamazaki–Higashi phosphorylation method in the presence of triphenylphosphite (TPP), pyridine (Py) and halide salt to give high molecular polyamides (PAs). The synthesized PAs were obtained in quantitative yields with inherent viscosities between 0.51 and 0.76 dL g?1. The structures of diamine and PAs were characterized by elemental analysis, FT-IR and NMR spectroscopy, and properties of PAs were investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and UV–visible and fluorescence spectroscopy. The PAs showed good solubility in aprotic and polar organic solvents, with high thermal stability exhibiting the glass transition temperatures (Tgs) and 10% weight loss temperatures (T10%) in the range of 226–330 °C and 400–466 °C in air, respectively, and fluorescence emission with maximum wavelengths (λem) in the range of 417–473 nm with quantum yields (Φf) of 9–35%. Two of these polymers together with compounds (II) and (III) were also screened for antibacterial activity against Gram positive and Gram negative bacteria. 相似文献
9.
《Polymer》2014,55(26):6672-6679
The thermal and optical properties of a novel diphenylcyclopentadithiophene-based poly(tetramethylsilarylenesiloxane) derivative (P1), which was prepared via polycondensation of a novel disilanol monomer, i.e., 2,6-bis(dimethylhydroxysilyl)-4,4-diphenylcyclopentadithiophene (M1), were investigated. P1 exhibited good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane and THF at ambient temperature. The glass transition temperature (Tg) of P1 was determined by differential scanning calorimetry to be 109 °C. No melting temperature (Tm) of P1 was observed, indicating the obtained P1 was an amorphous polymer. The temperature at 5% weight loss (Td5) of P1 was 454 °C, indicating the rather good thermostability of P1. Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing dimethylsilyl substituents onto 4,4-diphenylcyclopentadithiophene skeleton. The fluorescence quantum yields (ΦFs) of M1 and P1 in chloroform were determined to be 0.36 and 0.39, respectively. It was revealed that M1 and P1 exhibited the higher fluorescence intensity than diphenylcyclopentadithiophene owing to the cooperative effects of the introduction of diphenyl groups onto spiro carbon of cyclopentadithiophene as well as dimethylsilyl moieties onto 2- and 6-position of cyclopentadithiophene skeleton. 相似文献
10.
Joel Vargas Araceli Martínez Arlette A. Santiago Mikhail A. Tlenkopatchev 《Polymer Bulletin》2008,61(6):689-697
Summary The synthesis of new N-4-trifluoromethylphenyl-exo-endo-norbornene-5,6-dicarboximide (TFmNDI, 2a) and N-3,5-difluorophenyl-exo-endo-norbornene-5,6-dicarboximide (DFNDI, 2b) was carried out. Polynorbornene dicarboximides, 3a and 3b, were obtained via ring opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV)
dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride
(II), respectively. Tg’s for polymers 3a and 3b were observed at 155 C and 142 C, respectively. Compared to polymer 3b, polymer 3a with the bulky trifluoromethyl group showed the highest glass transition temperature and improved mechanical properties. 相似文献
11.
The direct polycondensations of cubane-1,4-dicarboxylic acid with 1,4-phenylenediamine (2 a), 4,4′-oxydianiline (2 b), 4,4′-sulfonyldianiline (2 c), and 9,9′-bis(4-aminophenyl)florene (2 d) were carried out in N-methyl-2-pyrrolidone/pyridine containing triphenylphosphite and lithium chloride at 110 °C for 9 h. Polyamide 3 a obtained from 2 a was scarcely soluble in organic solvent even during heating, and was soluble only in conc-H2SO4, whereas 3 c and 3 d derived from 2 c and 2 d, respectively, were readily soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethylsulfoxide. After treating polyamide 3 d with the rhodium complex catalyst in NMP, cubane units were quantitatively converted into cyclooctatetraenes.
Received: 3 March 1997/Accepted: 1 April 1997 相似文献
12.
Jang Yong Lee Yoon Jung Kwon Je-Wan Woo Doo Kyung Moon 《Journal of Industrial and Engineering Chemistry》2008,14(6):810-817
A solution processible fluorine–thiophene-based copolymers, namely poly[2,7-bis(4-octyl-2-thienyl)-9,9-dioctylfluorene-co-alt-5,5′-(2,2′-bithiophene)] (P1), poly[2,7-bis(3-octyl-2-thienyl)-9,9-dioctylfluorene-co-alt-5,5′-(2,2′-bithiophene)] (P2), poly[2,7-bis(3,3′-dioctyl-5,5′-bithien-2yl)-9,9′-dioctylfluorene-co-alt-5,5′-(2,2′-bithiophene)] (P3) were synthesized using Suzuki and Stille coupling reaction. The polymers showed weight loss starting around 400 °C indicative of good thermal stability. UV–vis properties and photoluminescence (PL) properties were investigated in toluene. P1, P2 and P3 exhibited the absorption maximum at 450, 428 and 435 nm and their PL spectrum peaked at 587, 559 and 560 nm, respectively. And all polymers, P1, P2 and P3, showed electroluminescence (EL) spectrum peaked at 592, 595 and 607 nm in the range of orange red. The polymers were electrochemically active in oxidation regions. P3 especially showed high oxidation stabilities in 1.17 V vs. Ag/Ag+. And P1 and P3 showed higher crystallinity than P2, because they have a repeated unit of 3,3-dialkyl-quaterthiophene. 相似文献
13.
Two‐dimensional ladder‐type polyfluorenes, which consist of polystyrene as the polymer backbone and polyfluorene as the light emitting component, were prepared through three synthetic pathways A, B, and C. In path A, the precursor polymer IP1 was obtained from the graft reaction of fluorene to units of poly(vinylbenzyl chloride) and then the ladder‐type polymer P1 was prepared by coupling at the 2,7‐position of fluorene with FeCl3 as an oxidizing agent in chloroform. In path B, IP2 was obtained from the graft reaction of lithiated 2,7‐dibromofluorene and units of poly(vinylbenzyl chloride), and then P2 was prepared by the aryl‐coupling of IP2 with a Ni‐catalyst through the reductive polymerization. In path C, 4‐(fluorenylmethyl)styrene was prepared by the reaction of 4‐chloromethylstyrene and lithiated fluorene. Fluorene‐attached syndiotatic polystyrene, IP3, was obtained in the polymerization of 4‐(fluorenylmethyl)styrene with CpTiCl3‐MAO catalyst, and for P3 oxidative coupling was further carried out. The polymers exhibited glass transition temperatures (Tg) of 422°C for P1, 404°C for P2, and 311°C for P3, and no melting endotherms were found. Syndiotaticity contributes the high glass temperature of P3 despite low molecular weight. Thermal decomposition temperatures at 5 wt % loss (Td) of 475°C for P1, 448°C for P2, and 365°C for P3 were observed. The fluorescence peaks of P1, P2, and P3 were observed at 401, 416, and 415 nm, respectively. For the emission spectrum of P3, no shoulder or peak regarding of aggregation of polyfluorene was observed. Syndiotacticity, due to the alternative configuration of fluorene, prevents a large Stoke's shift of the luminescence spectrum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1335–1340, 2005 相似文献
14.
Rupashri K. Kadu 《Polycyclic Aromatic Compounds》2017,37(5):395-406
A mild and efficient synthetic strategy has been developed for the synthesis of polyphenylene substituted dendronized monomers containing fluorene unit, namely 2,7-dibromo-9,9-di(4-(pentaphenylphenyl)benzyl) fluorene 5a and 2,7-dibromo-9,9-di(4-(2,3,4,5-tetraphenylphenyl)benzyl) fluorene 5b. The present synthetic route was found efficient, which avoids the unwanted by-product formation and has fewer column chromatography purification requirements. The synthesized compounds 5a and 5b showed promising optical properties. Moreover, TGA study revealed good thermal stability of the synthesized compounds. 相似文献
15.
A novel poly(tetramethyl-1,3-silphenylenesiloxane) derivative having adamantyl moiety, i.e., poly(tetramethyl-5-adamantyl-1,3-silphenylenesiloxane)
(P1) was synthesized by solution polycondensation of a novel disilanol monomer, i.e., 1-[3,5-(dimethylhydroxysilyl)phenyl]adamantane
(M1). M1 was prepared by the Grignard reaction using chlorodimethylsilane and 1-(3,5-dibromophenyl)adamantane, followed by the hydrolysis
catalyzed by 5% palladium on charcoal. P1 exhibited the good solubility in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, benzene,
and toluene at ambient temperature. P1 was also soluble in hot hexane, diethyl ether, and ethyl acetate. The glass transition temperature (T
g) and temperature at 5% weight loss (T
d5) of P1 were 85 and 517 °C, respectively, and much higher than those of poly(tetramethyl-1,3-silphenylenesiloxane), indicating that
P1 is a new polysiloxane derivative with good solubility as well as good thermostability. 相似文献
16.
Yu Zhou Chaofan Zhong Yan He Lifen Xiao Yuan Liu Hailiang Zhang 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(3):328-334
Abstract A novel ligand, 2,7-bis[2-(2′-Pyridyl)benzimidazole]- 9,9′-dioctylfluorene (BPDOF) and its polymeric complexes with copper(II)
and zinc(II) were successfully synthesized and characterized by 1H NMR, FT-IR, elemental analysis, UV-vis, conductivity measurements and gel permeation chromatography. The UV–vis absorption,
fluorescence spectra, and thermal properties of these complexes were investigated at room temperature. The experimental results
show that polymeric metal complexes BPDOF-Cu(II) and BPDOF-Zn(II) emit purple/green luminescence at 430 and 509 nm in DMF
solution and emit green luminescence at 495 and 527 nm in the solid state. Thermal properties measurement and analysis show
that they have good thermal stabilities.
Graphical Abstract Synthesis route: 2,7-bis[2-(2′-Pyridyl) benzimidazole]- 9,9′-dioctylfluorene (BPDOF) was synthesized using 2-(2′-Pyridyl)benzimidazole
and 2,7-dibromo-9,9′-dioctylfluorene by Ullmann condensation. Polymeric metal complexes of the corresponding were synthesized
with CuCl2 · 2H2O, ZnCl2.
相似文献
17.
Takeshi Nakato Masayuki Tomida Atsushi Kusuno Minako Shibata Toyoji Kakuchi 《Polymer Bulletin》1998,40(6):647-650
Summary
The polycondensations of L-aspartic acid (1) with aromatic aminocarboxylic acid, 4-aminobenzoic acid (2a), 4-aminophenylacetic acid (2b), 4-aminomethylbenzoic acid (2c), 4-(4-aminophenyl)butyric acid (2d), and 4-aminocinnamic acid (2e) were carried out using phosphoric acid as a catalyst. The obtained copolymers consiting of the succinimide and amide units,
poly(succinimide-co-amide) (3), were soluble in DMF and DMSO except for that with 2e. The thermal properties differed with varying the 2 unit in 3, i.e., the Tgs of 3a–c (99 ∼ 138°C) were higher than those of 3d (81 ∼ 1 01°C), the apparent difference in the Tm between 3a–d did not observed, and the Td decreased in the order of 3a, 3c > 3d > 3b.
Received: 24 February 1998/Revised version: 3 April 1998/Accepted: 13 April 1998 相似文献
18.
A polymer with high aromaticity and/or cyclic ring structures chain backbone usually has high heat, thermal, and flame resistance. Two diglycidyl ethers of bisphenols were prepared from 4,4′ isopropylidenediphenol (DGEBA) and 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) for evaluation. Four boroxines—trimethoxyboroxine (TMB), triethoxyboroxine (TEB), triisopropoxyboroxine (TIPB) and triphenoxyboroxine (TPB)—were used as the curing agents. DGEBA and DGEBF cured with various boroxines indicate that the trend for their respective glass transition temperature (Tg's), degradation temperatures (Td's), and gel fractions are TMB-cured epoxy ≈ TEB-cured epoxy < TIPB cured epoxy < TPB cured epoxy. The DGEBF system usually has a higher Tg, Td, gel fraction, oxygen index (OI), and char yield than the related DGEBA system. DGEBF/DGEBA (80/20 mol ratio) shows a synergistic effect in regard to char formation. This effect exists not only in the copolymer system but also in blended homopolymers of the separately cured resins. A modified mechanism for the polymerization of phenyl glycidyl ether (PGE) with TMB has been proposed. 相似文献
19.
By using a new theoretical glass transition temperature (T
g)–composition equation, T
g’s of statistic binary copolymers obtained from MMA, St and AN were investigated in this article. The copolymers were prepared
by bulk copolymerization using azo-bis-isobutyronitrile (AIBN) as initiator. The compositions and T
g’s were determined by NMR and DSC, respectively. The monomer reactivity ratios were obtained by nonlinear fitting with Mayo–Lewis
equation. Excellent fitting results were obtained when relations of T
g’s of MMA–St, MMA–AN, and St–AN copolymers with their compositions were investigated by using a new equation which assumed
additivity of bond stiff energy (Liu et al. J Phys Chem B 112:93–99, 2008). This equation contains mole fractions of triads and T
g’s of corresponding periodic copolymers. Compared with the widely used Johnston equation and Barton equation, the new equation
showed its superiority. Meanwhile, T
g’s of the assumed periodic copolymers that have not been acquired were tentatively predicted which may provide useful information. 相似文献
20.
Two bis(ether anhydride)s, 4,4′-[1,4-phenylenebis(isopropylidene-1,4-phenyleneoxy)]-diphthalic anhydride (IV
a) and 4,4′-[isopropylidenebis(1,4-phenylene)dioxy]diphthalic anhydride (IV
b), were prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 4-nitrophthalonitrile with α,α
′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene (I
a) and 4,4′-isopropylidenediphenol (I
b) in N,N-dimethylformamide (DMF) in the presence of potassium carbonate. The bis(ether anhydride)s IV
a and IV
b were polymerized with various aromatic diamines to obtain two series of poly(ether amic acid)s VI
a–g and VII
a–g with inherent viscosities in the range of 0.30∼0.74 and 0.29∼1.01 dL/g, respectively. The poly(ether amic acid)s were converted
to poly(ether imide)s VIII
a–g and IX
a–g by thermal cyclodehydration. Most of the poly(ether imide)s could afford flexible and tough films, and they showed high solubility
in polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, and m-cresol. The obtained poly(ether imide) films had tensile strengths of 45∼83 MPa, elongations-to-break of 6∼27%, and initial
modulus of 0.6∼1.7 GPa. The Tgs of poly(ether imide)s VIII
a–g and IX
a–g were in the range of 194∼210 and 204∼243 °C, respectively. Thermogravimetric analysis (TG) showed that 10% weight loss temperatures
of all the polymers were above 500 °C in both air and nitrogen atomspheres. 相似文献