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1.
Thi Tuyet Mai Dang Sung‐Jin Park Jong‐Won Park Dae‐Sung Chung Chan Eon Park Yun‐Hi Kim Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5277-5284
Poly{2,6‐bis(3‐dodecylthiophen‐2‐yl) benzo[1,2‐b;4,5‐b′]dithiophene} (PTBT) was synthesized, via oxidative polymerization by oxidative agent (FeCl3). The mole ratio of FeCl3 and monomer (3.5:1), and keeping low temperature during the dropping of diluted catalyst were very important for the polymerization without crosslinking. The PTBT was confirmed by 1H NMR, FTIR spectra, and elemental analysis. The PTBT has very good solubility in organic solvents such as chloroform, tetrahydrofuran, etc, and good thermal stability with Tg of 164 °C. The PTBT shows UV‐optical absorption at 406 nm and photoluminescence (PL) spectroscopy at 504 nm in a film. The highest occupied molecular orbital (HOMO) energy of the polymer is ?5.71 eV by measuring cyclic voltammetry (CV). A solution‐processed polymer thin film transistor device shows a mobility of 3 × 10?5 – 8 × 10?5 cm2 V?1 s?1, and an on/off current ratio of 104. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5277–5284, 2007 相似文献
2.
Thermal properties of the silica/poly(2,6-dimethyl-1,4-phenylene oxide) films prepared via emulsion polymerized mixed matrix (EPMM) method are investigated, and the impact of the synthesis protocol on the silica content, compatibility between the organic and inorganic phases, and the thermal stability of these nanocomposites is studied. Two series of films, namely EPMM-1S and EPMM-2S, synthesized in one- and two-step process, respectively, with different combinations of surfactant and compatibilizer were prepared. The polymerization of the silica precursor in the films was confirmed by 29Si nuclear magnetic resonance, and its content was investigated by inductively coupled plasma mass spectroscopy analysis. Thermal properties of the EPMM films were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature (T g) of EPMM films was greater compared to the neat PPO film. However, an increase in T g was not related to the concentration of silica in the film, but rather to the quality of dispersion of synthesized nanoparticles. Despite a lower inorganic loading, EPMM-1S films had a greater T g than EPMM-2S films. On the other hand, both the decomposition temperature and the activation energy for the decomposition were directly related to the silica content in the EPMM films. In general, regardless of the synthesis protocol, the presence of compatibilizer (ethanol) leads to greater inorganic content and improved thermal properties of the EPMM films. 相似文献
3.
Atsushi Sudo Kyohei Nishiyama Mika Morimoto Shinichiro Yamamoto 《Journal of polymer science. Part A, Polymer chemistry》2020,58(14):1973-1981
Dimethacrylates with rigid adamantane-like cores were synthesized from myo-inositol orthoester via a sequence of (a) acylation or silylation of the equatorially oriented hydroxyl group, followed by (b) attachment of methacrylate groups on the axially oriented hydroxyl groups. The radical homopolymerization of these compounds proceeded via cyclopolymerization without crosslinking, as the two axially oriented methacrylate groups were fixed in close proximity with each other. The dimethacrylates underwent radical copolymerization with methyl methacrylate (MMA) to afford the corresponding polymethacrylates, exhibiting high glass transition temperatures (Tg), due to the introduction of the rigid orthoester moieties originating from the monomers and the macrocyclic structures formed via intramolecular cyclization of the two methacrylate groups of the monomers. The polymers obtained by polymerization of the dimethacrylate bearing a silylated hydroxyl group served as precursors of hydroxyl-bearing polymers, which also exhibited high Tg due to the formation of a hydrogen bonding network between the hydroxyl groups. 相似文献
4.
This work reports on the steady state fluorescence (SSF) technique for studying film formation from surfactant‐free, nano‐sized polystyrene (PS) latex particles prepared via emulsion polymerization. The latex films were prepared from pyrene (P)‐labeled PS particles at room temperature and annealed at elevated temperatures in 5, 10, 15, 20 and 30 min time intervals above the glass transition temperature (Tg) of PS. During the annealing processes, the transparency of the film was improved considerably. Monomer and excimer fluorescence intensities, IP and IE respectively, from P were measured after each annealing step to monitor the stages of film formation. Evolution of transparency of the latex films was monitored by using photon transmission intensity, Itr. Void closure and interdiffusion stages were modeled and related activation energies were determined and found to be 10.3 and 50.3 kJ mol−1. Void closure temperatures, Tv, were determined from the minima of Itr value. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
5.
In this paper, the effect of irradiation temperature on sol fraction-dose relationship of tluoropolymers was studied. It was found that the increasing of irradiation temperature can result in the decreasing of βvalue of fluoropolymer, which increases the crosslinking probability of fluoropolymer. The relationship between crosslinking parameter βand irradiation temperature (T_i)of fluoropolymer is established as follows:β=2.2×10~(-3) T_g+4×10~(-4)(T_g-T_i)+0.206.values of some tluoropolymers calculated from the above expression are in agreement with the experimental values. 相似文献
6.
The swelling behaviour of poly(butadiene) gels in four different nematogenic liquid crystalline (LC) solvents has been investigated as a function of temperature (T). Microscopy with crossed polarizers reveals that the nematic to isotropic phase transition temperature of the LC solvents inside the gels (TNI g) is slightly lower than that of the surrounding pure LC solvents (TNI o), but the degrees of depression in TNI g in each system are comparable regardless of the considerable differences in the degrees of equilibrium swelling (Q) at TNI g between the various systems. In general, Q in the isotropic phase is larger than that in the nematic phase, but a unique swelling behaviour of the gel is found in the vicinity of TNI due to the phase transition of the LC solvents. Q remains constant in the temperature range of TNI g ≤ T ≤ TNI o in which the phases of the LCs outside or inside the domain of the gels are different, namely, nematic and isotropic phase, respectively. In addition, a finite abrupt (discontinuous-like) change in Q is observed at around TNI. The gels swollen in the LCs, having an ability to interact with the crosslinking points via hydrogen bonding, show a significant thermal hysteresis for the temperature dependence of Q in the vicinity of TNI, while no discernible thermal hysteresis is observed for the gels in the LCs incapable of forming hydrogen bonds. 相似文献
7.
A poly(acrylamide) was synthesized from N α -Boc-N ? -acrolyl-l-lysylglycine methyl ester via radical polymerization. This polymer typically had Mn ~ 100,000 g/mol, Mw ~ 300,000 g/mol, and a Tg of 93°C. Removal of Boc with TFA and cyclization with DABCO? in DMSO at 65°C afforded a soluble piperazinedione-containing polymer that had a Tg of 157°C and thermal stability up to 300°C. These results demonstrate a viable and efficient synthetic route to piperazinedione-containing polyacrylamides of high molecular weight. Related polymers that incorporate substituted indane moieties could be useful high Tg materials for fabrication of LC and NLO devices. 相似文献
8.
Xiaohui Yu Xiaogang Zhao Changwei Liu Zewei Bai Daming Wang Guodong Dang Hongwei Zhou Chunhai Chen 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):2878-2884
A series of polyimides containing ether and ketone moieties were synthesized from 1,3‐bis(4‐fluorobenzoyl) benzene and several commercially available dianhydrides via a conventional two‐step polymerization. The inherent viscosities of Polyamide acids ranged from 0.46 to 0.73 dL/g. Thermal properties, mechanical properties, and thermalplasticity of the obtained polimide films were investigated by focusing on the chemical structures of their repeat units. These films were amorphous, flexible, and transparent. All films displayed low Tgs (184–225 °C) but also excellent thermal stability, the 5% weight loss temperature was up to 542 °C under nitrogen. The films showed outstanding mechanical properties with the modulus up to 3.0 GPa and the elongation at break in the range of 8–160%. The uniaxial stretching of PI‐a at high temperature was studied owing to its excellent flexibility. The PI‐a had an elongation at break up to 1600% at 245 °C and the uniaxially stretched film exhibited a much higher modulus (3.9 GPa) and strength (240 MPa) than undrawn film. The results indicated that PI‐a can potentially be used to prepare materials such as fiber, ultra‐thin film or ultra‐high modulus film. All the obtained films also demonstrated excellent thermoplasticity (drop of E′ at Tg > 103) which made the polyimides more suitable for melt processing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2878–2884, 2010 相似文献
9.
Core–shell latex particles made of a poly(butyl methacrylate) (PBMA) core and a thin polypyrrole (PPy) shell were synthesized
by two-stage polymerization. In the first stage, PBMA latex particles were synthesized in a semicontinuous process by free-radical
polymerization. PBMA latex particles were labeled either with an energy donor or with an energy acceptor, in two different
syntheses. These particles were used in a second stage as seeds for the synthesis of the core–shell particles. The PPy shell
was polymerized around the PBMA core latex in an oxidative chemical in situ polymerization. Proofs for the success of the
core–shell synthesis were obtained using nonradiative energy transfer (NRET) and atomic force microscopy (AFM). NRET gives
access to the rate of polymer chain migration between adjacent particles in a film annealed at a temperature above the glass-transition
temperature T
g of the particles. Slower chain migration of the PBMA polymer chains was obtained with the PBMA–PPy core–shell particles compared
to rate of the PBMA polymer chain migration found with the pure, uncoated PBMA particles. This result is due to the coating
of PBMA by PPy, which hinders the migration of the PBMA polymer chains between adjacent particles in the film. This observation
has been confirmed by AFM measurements showing that the flattening of the latex film surface is much slower for the core–shell
particles than for the pure PBMA particles. This result can again be explained by the presence of a rigid PPy shell around
the PBMA core. Thus, these two complementary methods have given evidence that real core–shell particles were synthesized and
that the shell seriously hinders film formation of the particles in spite of the fact that it is very thin (thickness close
to 1 nm) compared to the size (750 and 780 nm in diameter) of the PBMA core. Transparency measurements confirm the results
obtained by NRET and AFM. When the films are placed at a temperature higher than the T
g of PBMA, the increase in transparency is faster for films made with the uncoated PBMA particles than for films made with
the coated PBMA particles. This result indicates again that the presence of the rigid PPy layer around the PBMA core reduces
considerably the speed at which the structure of the film is modified when heated above the T
g of PBMA.
Received: 02 September 1999 Accepted: 21 December 1999 相似文献
10.
Poly(imide ether sulphone) as novel high-performance polymer has been obtained by the condensation polymerization of 4,4'-bis(4-fluorophthalimido) diphenyl ether with 4,4'-sulfonyldiphenol via aromatic nucleophilic substitution reaction. Its structure was confirmed by means of FTIR and NMR spectroscopy, elemental analysis. Differential scanning calorimetry and thermal analysis measurements showed that synthesized polymer possessed high glass transition temperature (Tg = 210°C) and good thermal stability with high decomposition temperatures (Td > 480°C). Prepared polymer film showed good light transmittance and mechanical strength. 相似文献
11.
《中国化学快报》2020,31(5):1197-1200
Partially biobased polysilylethers (PSEs) are synthesized via dehydrocoupling polymerization catalyzed by an anionic iridium complex. Different types (AB type or AA and BB type) of monomers are suitable. Levulinic acid (LA) and succinic acid (SA) have been ranked within the top 10 chemicals derived from biomass. BB type monomers (diols) derived from LA and SA have been applied to the synthesis of PSEs. The polymerization reactions employ an air-stable anionic iridium complex bearing a functional bipyridonate ligand as catalyst. Moderate to high yields of polymers with number-average molecular weights (Mn) up to 4.38 × 104 were obtained. A possible catalytic cycle via an Ir-H species is presented. Based on the results of kinetic experiments, apparent activation energy of polymerization in the temperature range of 0–10 °C is about 38.6 kJ/mol. The PSEs synthesized from AA and BB type monomers possess good thermal stability (T5 = 418 °C to 437 °C) and low glass-transition temperature (Tg = −49.6 °C). 相似文献
12.
Isao Kaetsu Hiroshi Okubo Akihiko Ito Koichiro Hayashi 《Journal of polymer science. Part A, Polymer chemistry》1972,10(8):2215-2222
The effect of temperature and conversion on the polymerization rate at higher conversion was investigated with regard to the γ-ray-induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the supercooled phase. The polymerization rate changed from acceleration to depression at various conversions, depending on the polymerization temperature. It was found that Tv at which the viscosity of the system became ca. 103 cpoise influenced the shape of the polymerization time–conversion curve. The experimentally obtained conversion reflection point in the polymerization time–conversion curve agreed with the conversion where the polymerization temperature is the same as the calculated Tv of the system. When the polymerization temperature was lower than Tv of the monomer, no acceleration of the polymerization occurred. When the polymerization temperature was higher than Tv of the polymer, no depression of the polymerization rate was observed. The effect of temperature on the saturated conversion (final conversion) was also examined in terms of Tg of the polymerization system. The experimentally obtained saturated conversion agreed with the conversion where the polymerization temperature is the same as the calculated Tg of the system. 相似文献
13.
Lingqiao Li Zhe Qiang Xi Chen Kailong Jin Muzhou Wang John M. Torkelson 《Journal of polymer science. Part A, Polymer chemistry》2020,58(20):2887-2905
Thermo-cleavable bottlebrush polymers were synthesized by a facile grafting-to method via radical coupling and atom transfer radical polymerization (ATRP) without small-molecule synthesis involved. Bottlebrushes were achieved by coupling backbones of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl), which contain nitroxide radicals, and ATRP-synthesized side chains, which can be halogen-abstracted to generate carbon-centered radicals. Bottlebrushes were prepared using homopolymer or block copolymer side chains. Alkoxyamine covalent bonds resulting from radical coupling are thermo-reversible at high temperature, and grafting density may be tuned by annealing of post-synthesis bottlebrush, with the bottlebrush regime going from loose bottlebrush to dense comb and loose comb. The effects of confinement on the Tg and fragility of films of polystyrene bottlebrush were studied by ellipsometry; comparisons were made to thermally cleaved linear components obtained directly after annealing. Relative to linear polymer, bottlebrush topology reduces bulk fragility and suppresses Tg- and fragility-confinement effects. The correlation between the strengths of the confinement effects is consistent with other film studies of linear and non-linear polymers and supports the notion that fragility is a fundamental property underlying perturbations to Tg. Besides providing a platform for advancing fundamental scientific understanding, our synthetic strategy may afford novel applications of bottlebrushes via incorporated dynamic chemistry. 相似文献
14.
Chengtian Shen Qiujie Zhao Naisong Shan Brian B. Jing Christopher M. Evans 《Journal of polymer science. Part A, Polymer chemistry》2020,58(17):2376-2388
A model system of single-ion conducting network electrolytes with acrylic backbone, ethylene oxide (EO) side chains, tethered fluorinated anions, and mobile Li cations was designed and synthesized to investigate structure–property relationships. By systematically tuning four molecular variables, one at a time, we investigated how crosslinker length, mol% of crosslinker added, Li:EO ratio and side-chain length affect conductivity, Tg, and modulus. Ionic conductivity at 90 °C varied by two orders of magnitude (and by three orders of magnitude at room temperature) depending on the molecular details, while a 70 °C span in glass transition temperature (Tg) was observed. The range of crosslinking, which can be achieved without impacting conductivity was also elucidated, and the modulus of the electrolyte can be increased by a factor of 8, up to 2.4 MPa, without impacting ion transport. Changes in conductivity due to crosslink density and crosslinker length are fully explained in terms of Tg shifts, while comonomer length cannot be accounted for by such a shift. The best performing network exhibited 10−5 S/cm at high temperature, which is comparable to other single-ion conductors reported in the literature, while the modulus is higher due to crosslinking. Adding 10 wt% propylene carbonate further increased this value to 10−4 S/cm. This work provides insights into the structure–property relationships of solid-state polymer electrolytes, which retain conductivity but can potentially help suppress dendrites. 相似文献
15.
Allyl ethers as combined plasticizing and crosslinkable side groups in polycarbonate‐based polymer electrolytes for solid‐state Li batteries
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Jonas Mindemark Laura Imholt José Montero Daniel Brandell 《Journal of polymer science. Part A, Polymer chemistry》2016,54(14):2128-2135
Allyl ether‐functional polycarbonates, synthesized by organocatalytic ring‐opening polymerization of the six‐membered cyclic carbonate monomer 2‐allyloxymethyl‐2‐ethyltrimethylene carbonate, were used to prepare non‐polyether polymer electrolytes. UV‐crosslinking of the allyl side groups provided mechanically stable electrolytes with improved molecular flexibility—Tg below ?20 °C—and higher ionic conductivity—up to 4.3 × 10?7 S/cm at 25 °C and 5.2 × 10?6 S/cm at 60 °C—due to the plasticizing properties of the allyl ether side groups. The electrolyte function was additionally demonstrated in thin‐film Li battery cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2128–2135 相似文献
16.
Kalin Dragnevski Athene Donald Phil Taylor Martin Murray Simon Davies Elizabeth Bone 《Macromolecular Symposia》2009,281(1):119-125
Summary: Environmental scanning electron microscopy (ESEM) was used to study the film formation mechanisms and extent of coalescence of three acrylic latex compositions with different glass transition temperatures (Tg), here defined as standard-low Tg, standard-high Tg (both carboxymethyl cellulose- stabilised) and novel (stabilised with a novel polysaccharide derived from agricultural waste). The ESEM analysis revealed that the microstructure of the standard – low-Tg system consisted of individual particles in dispersion and upon evaporation a continuous film formed, whereas in the case of the standard - high Tg latex particle deformation was not observed, but particle aggregation resulted in the formation of crystal-like structures that have formed via the formation of stacking faults. However, in the case of the novel system the microstructure consisted of individual particles and clusters and during evaporation a discontinuous film formed with voids present within its structure and some of the clusters accumulating on the surface of the specimens. 相似文献
17.
Dimer acid‐based polyamides were synthesized by condensation polymerization in the absence and presence of monofunctional reactants. Acetic acid, oleic acid and propyl amine were used as monofunctional reactants. The influences of the equivalent percentage (E%) and type of monofunctional reactant on the physical properties of dimer acid‐based polyamides such as glass transition temperature (Tg), melting point (Tm), heat of fusion (ΔH), degree of polymerization (DP), number average molecular weight (Mn), and kinematic viscosity were investigated. The molecular weight and viscosity of dimer acid‐based polyamides decreased with the increase in equivalent percentage of monofunctional reactant. Differential scanning calorimetry (DSC) studies showed that acetic acid and propyl amine had higher effect on the thermal properties of polyamides than that of oleic acid. In the case of polyamides prepared in the presence of acetic acid, the values of Tg, Tm, and ΔH of the polyamides increased remarkably with the increase in acetic acid content. On the contrary, propyl amine had a decreasing effect on the values of Tg, Tm, and ΔH of the polyamides. Incorporation of oleic acid into the polymer structure had no significant effect on the values of Tg and Tm of the dimer acid‐based polyamides. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
A new class of linear unsaturated polyphosphate esters based on divanillylidene cyclohexanone possessing liquid crystalline‐cum‐photocrosslinkable properties have been synthesized from 2,6‐bis[n‐hydroxyalkyloxy(vanillylidene)]cyclohexanone [n = 6,8,10] with various alkyl/aryl phosphorodichloridates in chloroform at ambient temperature. The resultant polymers were characterized by intrinsic viscosity, FT‐IR, 1H, 13C, and 31P‐NMR spectroscopy. All the polymers showed anisotropic behavior under hot stage optical polarized microscope (HOPM). The liquid crystalline textures of the polymers became more transparent with increasing spacer length. The thermal behavior of the polymers was studied by thermogravimetric analysis and differential scanning calorimetry. The Tg, Tm, and Ti of the polymers decreased with increasing flexible methylene chain. The photocrosslinking property of the polymer was investigated by UV light/UV spectroscopy; the crosslinking proceeds via 2π‐2π cycloaddition reactions of the divanillylidene exocyclic double bond of the polymer backbone. The pendant alkyloxy containing polymers show faster crosslinking than the pendant phenyloxy containing polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5215–5226, 2004 相似文献
19.
Lidia Jasinska Cor E. Koning 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):2885-2895
Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2‐hydroxyethyl methacrylate, N‐vinyl‐2‐pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n‐butoxide. 2D NMR and MALDI‐Tof‐MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by‐product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their Tg values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2885–2895, 2010 相似文献
20.
Tsutomu Takeichi Masaaki Tanikawa 《Journal of polymer science. Part A, Polymer chemistry》1996,34(11):2205-2211
Crosslinking behavior of internal acetylene units linked para to the aromatic rings was investigated by preparing polyimide from 4,4′-diaminodiphenylacetylene (p-intA) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Polyimide was also prepared from 1,4-phenylenediamine (PDA) and 6FDA for comparison. The polymers were moderately to highly viscous at the stage of polyamide acid. Thermal imidization gave polyimide having acetylene units that are linked para to the aromatic connecting units. Differential scanning calorimetry (DSC) measurement of the polymer revealed that exotherm due to the crosslinking of the acetylene unit appeared at ca. 330°C. After thermal treatment at high temperature such as 350 and 400°C, onset of the exotherm shifted to higher temperature and the amount of the exotherm became smaller. The dynamic mechanical properties of the uncrosslinked polyimide film treated at 250°C had a glass transition temperature (Tg) at 330°C with a considerable drop in the storage modulus at this temperature. After the film was exposed to a higher temperature to induce crosslinking, the Tg was observed to increase to above 400°C and the storage modulus was maintained to higher temperatures. Tensile properties of the polyimide showed that the films had good mechanical properties. © 1996 John Wiley & Sons, Inc. 相似文献