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1.
Katsuyuki Tsuda Ken'ichi Tsutsumi Manabu Yaegashi Masahiro Miyajima Takashi Ishizone Akira Hirao Fumiaki Ishii Toyoji Kakuchi 《Polymer Bulletin》1998,40(6):651-658
Summary
The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M1) with styrene (M2) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M
ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r
1= 1.80 and r
2= 0.51 for 1a, r
1= 1.72 and r
2= 0.53 for 1b, and r
1= 3.17 and r
2= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition
of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C.
Received: 28 January 1998/Accepted: 5 March 1998 相似文献
2.
Dipropynylbenzenes with alkyl groups (CH3C ≡ CRC6H2RC≡CCH3,
R=n-C6H13, n-C8H17,
n-C10H21, 1a–c, respectively) were polymerized with Mo(CO)6 to afford
solvent-soluble poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c). The polymers (2a–c) had high molecular weight over 3×104, and gave
free-standing membranes by solution casting method. According to thermogravimetric analysis (TGA), these
poly(p-phenyleneethynylene)s showed high thermal stability (T0
≥380 °C). The densities of membranes of poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c) were 0.936–0.965, and their
fractional free volume (FFV) were relatively large (ca. 0.14–0.15). The oxygen permeability coefficients
(PO2) of membranes of 2a–c were 4.88, 7.06, and 16.6 barrers, respectively. 相似文献
3.
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
4.
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
5.
A. N. Tsvigunov 《Glass and Ceramics》2000,57(3-4):94-97
Data of an x-ray structural study of single crystals of silicon carbide α-SiC(6H) and a new, previously unknown modification γ-SiC with a rhombic lattice are described. The rhombic-lattice parameters are
related to the parametera of the hexagonal and cubic lattices of SiC in the following way:a
r=a
h,b
r=3a
h,c
r=3a
c.
Translated from Steklo i Keramika, No. 3, pp. 19 – 22, March, 2000. 相似文献
6.
Claudia Gerdes Julia Schuppan Arnd-Rüdiger Grimmer Michael Bolte Wolfgang Saak Detlev Haase Thomas Müller 《SILICON》2010,2(4):217-227
The structure and bonding of 7-silanorbornadienes was investigated using X-ray Diffraction (XRD), solid-state NMR spectroscopy
and density functional calculations. The solid state structures of four benzo-7-silanorbornadienes (4a, c, d, e) and of one dibenzo-7-silabenzonorbornadiene (5a) are reported and compared with the results of previous structural investigations. The most prominent features of the molecular
structures of all 7-silanorbornadienes are very long Si-C(bridgehead) bonds (d(SiC) = 190.6–196.8 pm) and very acute CSiC
bond angles α (α(CSiC) = 78.7–83.9°). All newly investigated 7-silanorborndienes show for tetracoordinated silicon nuclei
extremely deshielded 29Si NMR resonances (δ29Si = 65.6–31.6). Solid State NMR investigations for 7-silanorbornadienes anti-4a, b reveal highly anisotropic chemical shift tensors of axial or nearly axial symmetry (4a: δ11 = 161, δ22 = δ33 = −11; 4b: δ11 = 113, δ22 = 14, δ33 = −15). The dominating, strongly deshielding δ11 component is oriented almost perpendicular to the plane spanned by the two bridgehead carbon atoms and the bridging silicon
atom. The DFT calculations suggest that the origin of the strong deshielding is a small energy difference between the frontier
orbitals, which are strongly localized at the silicon atom. In addition the computations reveal that both the long SiC bonds
and the strongly deshielded 29Si NMR chemical shift are direct consequences of the bonding situation in 7-silanorbornadienes which are characterized by
through space interaction of the C=C double bonds and by hyperconjugation between the SiC σ-bonds and the unoccupied orbitals
of the C=C double bonds. 相似文献
7.
Toshikazu Sakaguchi Kota Sanada Chihiro Nakasuji Tamotsu Hashimoto 《Polymer Bulletin》2011,66(9):1177-1189
Dipropynylbenzene with branched alkoxy and alkyl groups [CH3C≡CRC6H2RC≡CCH3, R = 2-methylpropoxy (1a), 3-methylbutoxy (1b), 4-methylpentoxy (1c), cyclohexylmethoxy (1d), 2-ethylhexoxy (1e), 2-octoxy (1f), 2-ethylhexyl (1g), and 2-octyl (1h)] were polymerized with Mo(CO)6 in the presence of 4-(trifluoromethyl)phenyl to afford poly(2,5-di(alkoxy or alkyl)-p-phenyleneethynylene)s (2a–h). Polymer 2a was insoluble in any solvents, but the other polymers (2b–h) were soluble in common organic solvents. The polymers with relatively long side chains (2e–h) had high molecular weight over 1.6 × 104 and gave free-standing membranes by solution-casting method. The densities of membranes of 2e–h were 0.914–0.998, and their fractional-free volume values were relatively large (0.094–0.158). The oxygen permeability coefficients
of membranes of 2e–h were 18.4, 12.7, 4.85, and 19.3 barrers, respectively. It was found that poly(p-phenyleneethynylene) with 2-octyl side groups, which have the branch at the nearest position from main chain, exhibited the
highest gas permeability. 相似文献
8.
A novel acrylic monomer, 4-cyanophenyl acrylate (CPA) was synthesized by reacting 4-cyanophenol dissolved in methyl ethyl
ketone with acryloyl chloride in the presence of triethylamine as a catalyst. Copolymers of CPA with methyl methacrylate (MMA)
at different composition was prepared by free radical solution polymerization at 70 ± 1 °C using benzoyl peroxide as an initiator.
The copolymers were characterized by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. The solubility tests were checked in various polar and non polar solvents. The molecular weight
and polydispersity indices of the copolymers were estimated by using gel permeation chromatography. The glass transition temperature
of the copolymers increases with increases MMA content. The thermal stability of the copolymer increases with increases in
mole fraction of CPA content in the copolymer. The copolymer composition was determined by using 1H-NMR spectra. The monomer reactivity ratios determined by the application of linearization methods such Fineman–Ross (r
1 = 0.535, r
2 = 0. 0.632), Kelen–Tudos (r
1 = 0.422, r
2 = 0.665) and extended Kelen–Tudos methods (r
1 = 0.506, r
2 = 0. 0.695). 相似文献
9.
Six new optically active poly(amide-imide)s were synthesized by poly condensation reaction of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole
(8) with six chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenylphosphite (TPP), calcium chloride (CaCl2), and pyridine. Chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) were obtained by the reaction of bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with two equimolar of l-alanine (2a), l-valine (2b), l-leucine (2c), l-isoleucine (2d), l-phenyl alanine (2e), and l-2-aminobutyric acid (2f) in acetic acid. The poly condensation reaction produced a series of novel poly(amide-imide)s (9a–f) in high yield and with inherent viscosities between 0.30 and 0.52 dL/g. The resulting polymers were characterized by elemental
analysis, viscosity measurement, solubility testing, thermo-gravimetric analysis (TGA), 1H-NMR, and FT-IR techniques. 相似文献
10.
Summary
Methylated (β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers n-butyl acrylate (1), n-hexyl acrylate (2) and cyclohexyl acrylate (3) yielding the corresponding water soluble host/guest complexes 1a–3a. The complexes were copolymerized in water by free radical mechanism and the reactivity ratios were determined by measuring
the monomer consumption by HPLC. The following reactivity ratios were found: copolymerization of 1a and 2a: r1= 1.01 ± 0.01; r2= 1.04 ± 0.01; copolymerization of 3a and 2a: r1= 0.74; r2= 1.28; copolymerization of 3a and 1a: r1= 0.75 ± 0.04; r2= 1.13 ± 0.01. In contrast to that, the copolymerization of the uncomplexed monomers 1–3 in organic medium (DMF/H2O) leads to nearly ideal statistical copolymers in all cases.
Received: 28 November 2000/Accepted: 12 January 2001 相似文献
11.
Eiji Ihara Hironori Nishida Mototaka Fujii Tomomichi Itoh Kenzo Inoue 《Polymer Bulletin》2011,66(1):3-15
Thermally induced polymerization of diazoketones, (E)-1-diazo-3-nonen-2-one 1 and (E)-1-diazo-4-phenyl-3-buten-2-one 2, is described. Heating 1 and 2 in a solvent at 60–100 °C afforded polymers, where all the main chain carbons bear acyl groups derived from the monomers
and the main chain contains ca. 25–35 mol% of azo group. Molecular weight of the resulting polymers increased up to M
n = 8,400 by the addition of benzoquinone to the reaction mixtures. The polymerization was supposed to proceed via radical
propagating chain end and copolymerization of 1 with styrene gave copolymers (M
n = 11,000–15,000) having acylmethylene, azo group, and repeating unit from styrene in their main chains. 相似文献
12.
Zhang Aiqin Shen Yinghua Zhang Xiangying Han Lingcui Wang Zhizhong 《Journal of Polymer Research》2010,17(1):11-17
Acrylamide (AM)/2-(methacryloyloxy)ethyltrimethylammonium chloride (MADQUAT) copolymers were prepared by solution and inverse
microemulsion polymerization using ammonium persulfate ((NH4)2S2O8)/sodium hydrosulfite (NaHSO3) as redox initiator at 30 °C. The comonomer reactivity ratios, determined using the Kelen–Tudos (KT) method, were r
A = 0.30, r
M = 1.31 in solution and r
A = 0.63, r
M = 1.13 in the inverse microemulsion, respectively. The copolymer microstructure was deduced from the run number and the heterogeneity,
based on reactivity ratios. It was found that copolymerization in the inverse microemulsion resulted in close to ideal copolymerization,
giving almost random copolymers; copolymerization in solution resulted in some alternating copolymers. The copolymer compositions
indicated that high-conversion samples obtained from the inverse microemulsion are much more homogeneous in composition compared
with those obtained in solution. It was found that the composition distribution of the copolymer prepared by inverse microemulsion
polymerization remained at approximately the feed ratio. The sequence distribution of the copolymer was predicted by first-order
Markov statistical and Bernoulli statistical models, respectively. The results showed that the sequence distribution of the
copolymer prepared by inverse microemulsion polymerization was
almost random, which led to a wider cationic charge distribution and a microstructure that was coincident with the feed ratio. 相似文献
13.
Asymmetric anionic polymerizations of achiral N-substituted maleimide (RMI) (N-cyclohexyl (CHMI), N-phenyl (PhMI), N-tert-butyl (TBMI)) by n-butyllithium (n-BuLi) or fluorenyllithium (FlLi) complexes of chiral bisoxazoline derivatives in toluene gave optically active polymers ([α]25
435− 2.9° to − 8.2°). The polymers prerared with initiator of n-BuLi – 2,2′-bis(4,4′-isopropyl-,3-oxazoline) showed negative specific rotations (poly(RMI), [α]25
435− 5.8° to − 8.2°) which were greater than those ([α]25
435− 2.9° to − 5.9°) with other chiral 2,2′-bis(4,4′-alkyl-1,3-oxazoline) (alkyl group = iso-butyl and benzyl).
Received: 29 July 1997/Revised: 27 August 1997/Accepted: 1 September 1997 相似文献
14.
While the rheological behavior at the gel point (GP) itself is well known, many questions remain about the approach to the
gel point (from either side). For studying this phenomenon, rheological experiments were performed on crosslinked polydimethylsiloxanes
(PDMS) and characteristic patterns in the relaxation behavior were abstracted into a phenomenological model for the relaxation
time spectrum. The well known power law with slope-n and cutoff at the longest relaxation time λ
max governs the relaxation near the gel point. Beyond the gel point, an additional box-like contribution appears in the spectrum.
The relaxation exponent n decreases with increasing extent of crosslinking. The longest relaxation time λ
max and equilibrium modulus Ge show power-law scaling with the distance from the gel point, |p − pc|. For samples with imbalanced stoichiometric ratios r ≥ 1, the function n (p − pc) is independent of r. Samples with strong crosslinker deficiency (r = 0.5) exhibit a different functional form for n (p − pc) from those with r ≥ 1. The power law relaxation with decreasing n in the terminal zone was found previously for a different
crosslinking system. It seems to be a common pattern for partially crosslinked materials from polymeric precursors.
Received: 11 December 1997/Revised version: 18 December 1997/Accepted: 18 December 1997 相似文献
15.
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
16.
Synthesis of poly(ethyl vinyl ethers) containing two dipolar electronic systems and their properties
Summary
5-Nitro-2-(2′-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2′-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2′-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3-nitro-4-(2′-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 5-nitro-2-(2′-vinyloxyethoxy)benzaldehyde (1) and 3-nitro-4-(2′-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b and 4a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 5-6 having nitrooxybenzylidenemalononitrile and nitrooxycyanocinnamate, which is effective chromophore for second-order nonlinear
optical applications. Polymers 5-6 were soluble in common organic solvents such as acetone and DMSO. T
g
values of the resulting polymer were in the range of 70–81°C. Electrooptic coefficient (r33) of the poled polymer films were in the range of 19–27 pm/V, which was improved by introducing of nitro group. Polymers 5–6 showed a thermal stability up to 300°C in TGA thermograms, which is acceptable for NLO device applications.
Received: 24 November 1998/Revised version: 19 January 1999/Accepted: 29 January 1999 相似文献
17.
This paper reports the development of a high-impact epoxy nanocomposite toughened by the combination of poly(acrylonitrile-co-butadiene-co-styrene) (ABS) as thermoplastic, clay as layered nanofiller, and nano-TiO2 as particulate nanofiller. Response surface methodology (RSM) was applied for optimization and modeling of the impact strength
of epoxy/ABS/clay/TiO2 quaternary nanocomposite. A second-order mathematical model between the response (impact strength) and variables (ABS, clay
and nano-TiO2 contents) was derived. Analysis of variance (ANOVA) showed a high coefficient of determination value (R
2 = 98%). Under optimum conditions, maximum impact strength of 29.2 KJ/m2 with 197% increase compared to neat epoxy was experimentally obtained. Also correlation between morphology and impact strength
of the nanocomposite was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). A dispersion of
exfoliated clay platelets, TiO2 nanoparticles with low agglomeration and ABS nanoparticles was obtained as morphology of the nanocomposite. A new and more
effective method for impact toughening of epoxy was introduced. This study clearly showed that the addition of the combination
of layered and particulate nanofillers along with ABS as thermoplastic has a considerable enhancement effect on impact strength
of epoxy. 相似文献
18.
Summary Propargyl esters (HC≡CCH2OC(=O)R; 1: R = n-C5H11, 2: R = CH3, 3: R = CHBrCH3, 4: R = C6H5, 5: R = C(C6H5)3) were polymerized by using (nbd)Rh+(η6-Ph-B-Ph3) (nbd = 2,5-norbornadiene) to produce poly(1)–poly(5) with molecular weights in the range of Mn = 4,900–40,000. Poly(1), poly(3) and poly(4) were readily soluble in common organic solvents such as toluene, THF and CHCl3, and poly(2) showed similar solubility behavior except that it was insoluble in THF. Poly(5) did not dissolve in any organic solvent. Poly(1) was yellow oil, while poly(2)–poly(5) were yellow solids. Poly(1)–poly(4) exhibited UV-vis absorptions in a range of 300–425 nm, which are attributed to the conjugation of the main chain. All the
polymers were thermally stable up to 150–200 °C. 相似文献
19.
Summary N-Hydroxypyridine-2-thione derivativesIa-c and N-hydroxy-4-methylthiazole-2(3H)-thione derivativesIIa-b act as chain transfer agents in free radical polymerizations of methyl methacrylate (C
x
=0.6–4.3), styrene (C
x
=0.32–3.9), methyl acrylate (C
x
=3.1–20), and vinyl acetate (C
x
=9.7–80) at 60°C. Some retardation occurs with vinyl acetate and methyl acrylate.Ib also has the property of initiating the polymerization of methyl methacrylate photochemically, whileIIb acts as a thermal initiator. The chain transfer constants ofIIb make it particularly suitable for regulating molecular weight in batch polymerizations of methyl methacrylate and styrene. 相似文献
20.
Xiaoqing Liu Bo Chen Kang Zhou Jianping Deng Wantai Yang 《Journal of Polymer Research》2011,18(2):217-224
Five achiral N-propargylamide monomers with various phenyl-based substitutents, [HC ≡ CCH2NHCOR, R for M1: C6H4CH3; M2: C6H4CH2CH3; M3: C6H4(CH2)2CH3; M4: C6H4(CH2)3CH3; M5: C6H4C(CH3)3], were synthesized and polymerized with a rhodium catalyst, (nbd)Rh+B-(C6H5)4 (nbd = 2,5-norbornadiene). The corresponding five homopolymers were obtained in high yields of 90–95% and with moderate molecular
weights (M
n ≥ 10 000). All the polymers possessed high cis contents (≥95%). Poly(1)–poly(3) exhibited UV-vis absorption peaks at approx.
350 nm, which indicates that the three polymers formed helical conformations, while no UV-vis absorption peaks could be observed
in poly(4) and poly(5) in the wavelength range of 320–500 nm, demonstrating that these two polymers could not adopt helical
structures under the examined conditions. To confirm the helical structures formed in poly(1)–poly(3), a chiral monomer, M6,
was utilized to copolymerize with M2, which was used as the representative for M1−M3. M6 was utilized since its polymer could
form stable helices under suited conditions. The resulting copolymers exhibited remarkable CD effects, however, the maximum
wavelength in the copolymers varied remarkably, mainly depending on the composition of the copolymers. It is concluded that
in the formation of ordered helical conformations, the substitutents of varied bulk led to different steric repulsion and
varied synergic effects among the neighboring pendent groups. 相似文献