首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
Random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(DBMP)3; Ln = La, Nd, Sm, or Dy] as catalysts, among which La(DBMP)3 showed the highest activity. Poly(2,2‐dimethyltrimethylene carbonate‐co‐ethylene carbonate)s [poly(DTC‐co‐EC)]s with high molecular weights were prepared at room temperature and characterized with 1H‐NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC‐co‐EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X‐ray diffraction. The crystallinity and melting temperatures of the poly(DTC‐co‐EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass‐transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

2.
A hydrophobically modified polyacrylamide (PAM) was synthesized by the copolymerization of acrylamide (Am) and N‐hexadecylacrylamide (hAm) through solution copolymerization in a polar organic solvent. Polymer synthesis was performed in three nonaqueous media, including dimethyl sulfoxide (DMSO), a mixture of DMSO and an anionic surfactant such as sodium dodecyl sulfate, and a mixture of DMSO and an acidic surfactant such as dodecyl benzene sulfonic acid. The obtained copolymer, poly(acrylamide‐co‐N‐hexadecylacrylamide) [poly(Am‐co‐hAm)], was characterized by 1H‐NMR. The physical properties of poly(Am‐co‐hAm)s synthesized in different media were compared with those of PAM and with each other by viscosity measurement, X‐ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. We investigated the ways in which the polymerization medium affected the hydrophobic distribution within the resulting copolymer structure. This aspect, in turn, should have altered the solution properties and the microstructure of the copolymer. For this purpose, we studied the viscometric behavior in diluted solutions, the thermal behavior and thermal stability of the copolymers, and finally, the crystalline structure of the copolymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39939.  相似文献   

3.
A poly(aniline‐co‐pyrrole), using anionic spherical polyelectrolyte brushes (ASPB) as dopant and template, was synthesized by chemical oxidation polymerization. The composites were characterized by scanning electron microscopy (SEM), Fourier‐transform infrared spectrometry (FTIR), X‐ray diffraction (XRD), and electrical studies. The SEM images confirmed that the composites had a spherical‐like structure, with a size of ca. 170 nm. The FTIR spectra showed the intermolecular interaction between poly(aniline‐co‐pyrrole) and ASPB. The XRD analysis revealed that the interplanar distance of the copolymers increased from 0.373 nm to 0.391 nm. The electrical conductivity of the poly(aniline‐co‐pyrrole)/ASPB nanocomposites at room temperature was 8.3 S cm−1, higher than that of the conducting copolymers (2.1 S cm−1). These conductive nanocomposites have nanoparticle size, controllable morphology, and the potential for application in inkjet electronic printing. POLYM. COMPOS., 35:1858–1863, 2014. © 2014 Society of Plastics Engineers  相似文献   

4.
A series of pH‐temperature dual stimuli‐responsive random copolymers poly[N,N‐dimethylaminoethyl methacrylate‐co‐poly(poly(ethylene glycol) methyl ether methacrylate][poly(DMAEMA‐co‐MPEGMA)] were synthesized by free radical polymerization. The supramolecular hydrogel was formed by pseudopolyrotaxane, which was prepared with the host‐guest interactions between α‐cyclodextrin (α‐CD) and poly(ethylene glycol) (PEG) side chains. Fourier transform infrared (FT‐IR), nuclear magnetic resonance (1H NMR), and X‐ray diffraction (XRD) confirmed the structures of the hydrogels. The pH‐temperature dual stimuli responsive properties of the hydrogels were characterized by rheometer. Finally, the controllable drug release behavior of the hydrogel, which was used 5‐fluorouracil (5‐Fu) as the model drug, was investigated at different temperatures and different pH values. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43279.  相似文献   

5.
A low crystallinity, the copolyester poly(ethylene terephthalate‐co‐neopentyl terephthalate‐co‐ethylene isophthalate‐co‐neopentyl isophthalate) (PENIT) was synthesized and applied for laminated tin‐free steel. The structures and thermal properties of the copolyester were characterized by 1H‐NMR, thermogravimetry analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy results show that the crystallization ability of the copolyester decreased obviously. Meanwhile, the peel strength, crystallinity, and water‐vapor permeability of the copolyester film were also measured at varied lamination temperatures. The result confirm that an improvement in the lamination temperature led to an increased ratio of amorphous PENIT to crystalline PENIT and decreased structural orientation, and the decrease in the structural orientation sped up the increase in the rate of water‐vapor permeability. On the basis of the purpose of reducing a detrimental effect on the corrosion resistance caused by water permeation, a reasonable lamination temperature was selected. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42308.  相似文献   

6.
We synthesized a series of poly(acrylonitrile‐co‐allyl glycidyl ether)‐graft‐methoxypoly(ethylene glycol) (PAA‐g‐MPEG) copolymers as novel polymeric solid–solid phase‐change materials by grafting methoxypoly(ethylene glycol) (MPEG) to the main chain of poly(acrylonitrile‐co‐allyl glycidyl ether) (PAA). PAA was the skeleton, and MPEG was a functional side chain, which stored and released heat during its phase‐transition process. Fourier transform infrared spectroscopy and 1H‐NMR spectroscopy analysis were performed to investigate the chemical structures. The crystalline morphology and crystal structures were also measured with polarized optical microscopy and X‐ray diffraction. Moreover, the thermal‐energy‐storage properties, thermal stability, and thermal reliability of the PAA‐g‐MPEG copolymers were characterized by differential scanning calorimetry and thermogravimetric analysis (TGA) methods. These analysis results indicate that the MPEG chains were successfully grafted onto PAA, and we found that the PAA‐g‐MPEG copolymers had typical solid–solid phase‐transition temperatures in the range 11–54 °C and high latent heat enthalpies between 44 and 85 J/g. In addition, the as‐prepared PAA‐g‐MPEG copolymers showed reusability and thermal reliability, as shown by the thermal cycle testing and TGA curves. Therefore, the synthesized PAA‐g‐MPEG copolymers have considerable potential for thermal energy storage. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46641.  相似文献   

7.
The synthesis of novel poly(ether ether ketone ketone)s containing a lateral group via the random copolymerization of 4,4′‐biphenol, tert‐butylhydroquinone and 1,4‐bis(p‐fluorobenzoyl)benzene is described. The copolymers were characterized by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and polarized optical microscopy (POM) observation. The results showed that the thermotropic liquid‐crystalline properties were achieved in the copolymers containing 30 mol% and 50 mol% tert‐butylhydroquinone, which have relatively lower melting temperatures due to the copolymerization effect. Both the crystalline–liquid‐crystalline transition (Tm) and the liquid‐crystalline–isotropic phase transition (Ti) were observable in the DSC thermograms, while the biphenol‐based poly(aryl ether ketone) has only one melting transition. The hydroquinone‐based polymer was shown to be amorphous. Thermogravimetric analysis (TGA) results showed that these copolymers are all high‐temperature resistant with higher glass transition temperature between 147 and 149 °C, and higher decomposition temperature Td in the range 480–520 °C. © 2000 Society of Chemical Industry  相似文献   

8.
Aligned thin films of the liquid‐crystalline polymer poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐co‐bithiophene] were prepared, and the correlation between the optical anisotropy and the structural properties was shown. A series of samples with different thicknesses were prepared via a spin‐casting process on rubbed polyimide surfaces. The alignment of the polymer chains was obtained by a temperature treatment just below the clearing temperature. The degree of alignment was investigated with ultraviolet–visible absorption spectroscopy and in‐plane X‐ray diffraction. Independently, each technique revealed Hermans orientation functions in the range of 0.75–0.8. Surprisingly, a layer‐thickness dependence was not observed. In addition, the X‐ray diffraction pole figure technique revealed that the polymer chains were uniaxially aligned along the rubbing direction. The aligned films were in the nematic state, with the director elongated along the rubbing direction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

9.
Novel aromatic poly(ether ketones) containing bulky lateral groups were synthesized via nucleophilic substitution reactions of 4,4′‐biphenol and (4‐chloro‐3‐trifluoromethyl)phenylhydroquinone (CF‐PH) with 1,4‐bis(p‐fluorobenzoyl)benzene. The copolymers were characterized by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction, and polarized light microscopy observation. Thermotropic liquid‐crystalline behavior was observed in the copolymers containing 40, 50, 60, and 70 mol % CF‐PH. The crystalline–liquid‐crystalline transition [melting temperature (Tm)] and the liquid‐crystalline–isotropic phase transition appeared in the DSC thermograms, whereas the biphenol‐based homopolymer had only a melting transition. The novel poly(aryl ether ketones) had glass‐transition temperatures that ranged from 143 to 151°C and lower Tm's that ranged from 279 to 291°C, due to the copolymerization. The polymers showed high thermal stability, and some exhibited a large range in mesophase stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1347–1350, 2003  相似文献   

10.
Polyaniline (PANI), poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)] were synthesized by chemical oxidative polymerization with ammonium persulfate as an oxidizing reagent in an HCl medium. The viscosities, electrical conductivity, and crystallinity of the resulting polymers (self‐doped forms) were compared with those of the doped and undoped forms. The self‐doped, doped, and undoped forms of these polymers were characterized with infrared spectroscopy, ultraviolet–visible spectroscopy, and a four‐point‐probe conductivity method. X‐ray diffraction characterization revealed the crystalline nature of the polymers. The observed decrease in the conductivity of the copolymer and poly(o‐anisidine) with respect to PANI was attributed to the incorporation of the methoxy moieties into the PANI chain. The homopolymers attained conductivity in the range of 3.97 × 10?3 to 7.8 S/cm after doping with HCl. The conductivity of the undoped forms of the poly[aniline‐co‐(o‐anisidine)] and poly(o‐anisidine) was observed to be lower than 10?5 J/S cm?1. The conductivity of the studied polymer forms decreased by the doping process in the following order: self‐doped → doped → undoped. The conductivity of the studied polymers decreased by the monomer species in the following order: PANI → poly[aniline‐co‐(o‐anisidine)] → poly(o‐anisidine). All the polymer samples were largely amorphous, but with the attachment of the pendant groups of anisidine to the polymer system, the crystallinity region increased. The undoped form of poly[aniline‐co‐(o‐anisidine)] had good solubility in common organic solvents, whereas doped poly[aniline‐co‐(o‐anisidine)] was moderately crystalline and exhibited higher conductivity than the anisidine homopolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006  相似文献   

11.
This works aims at (i) studying the antiadhesive properties and the hemocompatibility of poly[2‐(dimethylamino)ethyl methacrylate]‐co‐poly[(ethylene glycol)methacrylate] [poly(DMAEMA‐co‐PEGMA)] copolymers and (ii) investigating the insulin delivery kinetics through hydrogels at physiological pH. A series of poly(DMAEMA‐co‐PEGMA) hydrogels have been synthesized, and their controlled composition was confirmed by X‐ray photoelectron spectroscopy. Then, antibiofouling properties of hydrogels—fibrinogen, erythrocytes, and thrombocytes adhesion—are correlated to their molecular compositions through their hydrophilic properties. As DMAEMA/PEGMA ratio of 70/30 (D70) offers the best compromise between pH sensitivity and hemocompatibility, it is selected for investigating the kinetic rate of insulin release at physiological pH, and the diffusion coefficient of insulin in gel is found to be 0.64 × 10?7 cm2 s?1. Overall, this study unveils that poly(DMAEMA‐co‐PEGMA) copolymers are promising hemocompatible materials for drug delivery systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42365.  相似文献   

12.
A series of poly(ester imide ketone)s (PEIKs) with varied p‐hydroxybenzoic acid (HBA) molar fraction derived from N,N′‐hexane‐1,6‐diylbis(trimellitimide), 4,4′‐dihydroxybenzophenone, and p‐hydroxybenzoic acid were synthesized by a “step‐feeding” polycondensation method in benzene sulfonyl chloride, dimethylformamide, and pyridine. High field 1H, 13C, and 2D NMR spectroscopy measurements were combined to determine the assignments of hydrogen and carbon atoms in the copolymers. 13C inverse gated decoupling NMR spectra were taken and used as a quantitative method to analyze the chain sequence structures of these copolymers. The liquid crystalline behaviors and thermal properties of the PEIKs were characterized by polarized light microscopy (PLM), wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The NMR studies show that the monomeric unit ratios of the PEIKs are very close to the ratios of the monomers added into the polycondensation process. The analytical results of sequence distribution indicate that the sequence ratios of I‐H, H‐D, and H‐H dias rise with the increase of HBA molar fraction, while that of I‐D decrease. It is worth noting that the sequence ratios of H‐H are always very small among the four sequence ratios although the HBA molar fraction varied from 0 to 50%. It was shown that the copolymers possess a typical nematic thermotropic liquid crystalline character and high thermal stability, which is strongly related with the changes in sequence structure of the molecular chains. This type of liquid crystalline polymers also exhibits excellent fiber‐forming character in the melting state, which would find its potential usages in high performance fiber and fiber modification materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3183–3193, 2007  相似文献   

13.
In the present article, we report the chemical synthesis and characterization of poly(aniline‐co‐fluoroaniline) [poly(An‐FAn)]. The copolymerization of aniline and 2‐fluoroaniline was carried out by chemical method in acidic medium. The characterization of poly(aniline‐co‐fluoroaniline) was done using FTIR, UV‐visible spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrography (SEM), and a four‐points‐probe conductivity method. X‐ray diffraction (XRD) and SEM characterization reveal crystalline nature of doped copolymer compared to undoped copolymer. The observed decrease in the conductivity of the copolymer relative to polyaniline is attributed to the incorporation of the fluoro moieties into the polyaniline chain. The chemically synthesized copolymer shows good solubility in common organic solvents, and is, therefore, technological useful. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1460–1466, 2001  相似文献   

14.
A series of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)s[P(3HB‐co‐4HB)s] sheets with the 4HB contents from about 9 to 34 mol % were prepared via melt molding. Their crystallinity, crystalline structures, thermal and mechanical properties were characterized by differential scanning calorimetry, X‐ray diffraction, thermogravimetric analysis, dynamic mechanical analysis, and tensile test. It was found that the melt temperatures (Tm), glass transition temperatures (Tg), and storage modulus (E′) of all the [P(3HB‐co‐4HB)s] copolymers investigated decreased continuously with increasing the amount of the 4HB; the yield stress and breaking stress nearly decreased with the increase of the 4HB contents while the elongation at the yield and break points increased; and the thermal stability of the P(3HB‐co‐4HB)s improved with increasing 4HB contents. The results suggest that the mechanical properties and crystal lattice parameters of the melt molded sheets are somewhat different from those of the solution cast films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

15.
Poly[aniline‐coN‐(2‐hydroxyethyl) aniline] was synthesized in an aqueous hydrochloric acid medium with a determined feed ratio by chemical oxidative polymerization. This polymer was used as a functional conducting polymer intermediate because of its side‐group reactivity. To synthesize the alkyl‐substituted copolymer, the initial copolymer was reacted with NaH to obtain the N‐ and O‐anionic copolymer after the reaction with octadecyl bromide to prepare the octadecyl‐substituted polymer. The microstructure of the obtained polymers was characterized by Fourier transform infrared spectroscopy, 1H‐NMR, and X‐ray diffraction. The thermal behavior of the polymers was investigated by thermogravimetric analysis and differential scanning calorimetry. The morphology of obtained copolymers was studied by scanning electron microscopy. The cyclic voltammetry investigation showed the electroactivity of poly [aniline‐coN‐(2‐hydroxyethyl) aniline] and N and O‐alkylated poly[aniline‐coN‐(2‐hydroxyethyl) aniline]. The conductivities of the polymers were 5 × 10?5 S/cm for poly[aniline‐coN‐(2‐hydroxyethyl) aniline] and 5 ×10?7 S/cm for the octadecyl‐substituted copolymer. The conductivity measurements were performed with a four‐point probe method. The solubility of the initial copolymer in common organic solvents such as N‐methyl‐2‐pyrrolidone and dimethylformamide was greater than polyaniline. The alkylated copolymer was mainly soluble in nonpolar solvents such as n‐hexane and cyclohexane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

16.
Well defined poly (styrene‐co‐methylstyrene) grafted polyaniline/organo‐modified MgAl layered double hydroxide (LDH) was produced through solution intercalation method. After LDH nanoparticles were modified by the anion exchange reaction of MgAl (Cl) LDH with sodium dodecyl benzene sulfonate, Poly (styrene‐co‐methylstyrene) copolymers were synthesized by “living” free radical polymerization and then brominated with N‐bromosuccinimide. Afterwards, 1,4‐phenylenediamine was linked to brominated copolymers and prepared functionalized copolymer with amine. Poly (St‐co‐MSt)‐g‐PANI, has been synthesized by adding solution of ammonium persulfate and p‐toluenesufonic acid in DMSO solvent. Finally, Poly (styrene‐co‐methylstyrene) grafted‐Polyaniline/LDH nanocomposites were prepared by solution intercalation method. Characterization of these well‐defined nanocomposites included FT‐IR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimeter, transmission electron microscopy, and X‐ray diffraction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.  相似文献   

17.
With D,L ‐lactic acid and Nϵ‐carbobenzoyloxy‐L ‐lysine [Lys(Z)] as the starting monomer material and tin dichloride as the catalyst, the drug carrier material poly(lactic acid‐coNϵ‐carbobenzoyloxy‐L ‐lysine) was synthesized via direct melt polycondensation. The copolymer was systematically characterized with intrinsic viscosity testing, Fourier transform infrared spectroscopy, 1H‐NMR, gel permeation chromatography, differential scanning calorimetry, and X‐ray diffraction. The influences of different feed molar ratios were examined. With increasing molar feed content of Lys(Z), the intrinsic viscosity, weight‐average molecular weight, and polydispersity index (weight‐average molecular weight/number‐average molecular weight) gradually decreased. Because of the introduction of Lys(Z) with a big aromatic ring into the copolymer, the glass‐transition temperature gradually increased with increasing feed charge of Lys(Z), and all of the copolymers were amorphous. The copolymers, with weight‐average molecular weights from 10,500 to 6900 Da, were obtained and could reach the molecular weight level of poly(lactic acid) modified by Lys(Z) via the ring‐opening polymerization of the cyclic intermediates, such as lactide and morpholine‐2,5‐dione. However, a few terminal carboxyl groups might have been deprotected during the polymerization reaction under high temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

18.
The present work investigates the structure properties of copolymers using thermogravimetric analysis, hot stage microscopy, static light scattering, field emission scanning electron microscopy, X‐ray diffraction analysis and a Brookfield viscometer. Poly(potassium 1‐hydroxyacrylate) (PKHA) is a water‐soluble polymer. However, the copolymer of styrene and 2‐isopropyl‐5‐methylene‐1,3‐dioxolan‐4‐one is not water soluble at equal molar ratio because the polystyrene reduces the solubility. The effect of styrene on poly(potassium 1‐hydroxyacrylate‐co‐styrene) copolymer, i.e. poly(KHA‐co‐St), was investigated for the increasing solubility of the copolymer. The solubility was increased at a lower molar ratio of styrene such as 0.4 in the copolymer. It was found that the copolymer was soluble in water when a content ratio of 68/32 mol% of homopolymer was incorporated in poly(KHA68co‐St32) copolymer as determined by NMR analysis. Also the poly(KHA68co‐St32) copolymer was found to be salt tolerant, possessed water absorption capacity and was thermally stable up to 183 °C. Moreover, it is shown that the polystyrene content plays a key role in the thermal stability of the copolymer. © 2017 Society of Chemical Industry  相似文献   

19.
A family of new polymers based on poly(4‐(1‐hydroxyalkyl)styrene), and its copolymers with styrene were synthesized and thoroughly characterized by 1H‐NMR, 13C‐NMR, FTIR, and UV spectroscopies. The chemical modification reactions of polystyrene (PS) was used as a novel method of performing the synthesis of poly(4‐(1‐hydroxyethyl‐co‐styrene)), poly(4‐(1‐hydroxypropyl‐co‐styrene)), poly(4‐(1‐hydroxybutyl‐co‐styrene)), and poly(4‐(1‐hydroxyphenylmethyl‐co‐styrene)). The novelty of this method lies in the incorporation of the desired mol % of the functional groups in polystyrene chain, to obtain random copolymers of desired composition. In preliminary testing/evaluation studies the utility and versatility of the new copolymers, which have the potential to be negative‐tone photoresist materials, were studied. Thus a few photoresist formulations based on poly(styrene‐co‐4‐(1‐hydroxyalkylstyrene)) were developed with 5 wt % of a photoacid generator. These studies suggested that the new copolymers synthesized by a simple and alternate method could have the same potential as a photoresist material when compared with the polymers synthesized by the polymerization of the corresponding functional monomer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1902–1914, 2004  相似文献   

20.
An aliphatic‐aromatic random‐block copolyester of poly(ethylene terephthalate) (PET), and poly(enthylene adipate) (PEA), PET‐co‐PEA, was synthesized via melt polycondensation. The chemical structure of the products were characterized by two kinds of spectroscopic techniques (Fourier transform infrared and 1H‐NMR). The thermal properties of the copolyester were characterized by thermogravimetry analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. It was found that the crystallization ability, melting point, glass transition temperature of the random‐block coplyester decreased apparently. Meanwhile, the tensile strength and hydrolysis performance were measured as well. The result showed that the random‐block copolyesters PET‐co‐PEA displayed excellent properties in elasticity and strength. In addition, the potential degradability was found in hydrolysis measurement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44967.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号