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1.
Sodium N-(4-sulfophenyl) maleimide (SPMI) and its saturated succinimide counterpart were first prepared according to established methods. Hydrolysis experiments on these monomers monitored by 1H-NMR showed that although SPMI monomer was about 15% hydrolyzed in D2O at 23°C in 24 h. Sodium N-(4-sulfophenyl) succinimide, which is similar in structure to the imide units in the copolymers, was only 1% hydrolyzed after 18 days at 23°C and 29% hydrolyzed after 18 days at 60°C. This indicated that the saturated imide rings in the copolymer might be sufficiently stable to hydrolysis for the copolymers to be useful. However, hydrolysis at high pH demonstrated that the imide rings would be rapidly saponified under alkaline conditions, destroying the structural rigidity that the intact rings might have provided in the copolymer chains. Sodium N-(4-sulfophenyl) maleimide (SPMI) was copolymerized with acrylamide in water at 30°C without cleavage of the imide ring. Water-soluble poly [acrylamide-co-sodium-N-(4-sulfophenyl) maleimide] (PAMSM) samples containing from 7.4 to 64 mol % imide were prepared. Photoacoustic FTIR and 13C-NMR spectra were used to confirm the structure of the copolymers obtained. Elemental analysis was used to determine the imide content of the copolymers, and from this composition data reactivity ratios were calculated for the two component monomers.  相似文献   

2.
Sorption isotherms of nonionic dyes with two amino groups (one anthraquinone dye and two azo dyes) on various polymers from water were measured at 40–90°C (Nylon-6 and cellulose film) and at 95°C (polyester microfiber). The isotherms were curved, convex to upward, in the range of low dye concentration Cs in water and almost linear in the range of medium to saturated Cs. The isotherms measured at low temperature (40°C for cellulose, 40–60°C for Nylon-6, and at 95°C for polyester) were satisfactorily described by considering three concurrent modes of sorption. They are Nernst type partitioning and bimodal Langmuir sorption (sorption by the higher affinity sites with a small saturation value and that by the lower affinity sites with a large saturation value). However, for the sorption of the anthraquinone dye and one azo dye by Nylon-6 film at high temperature (80–90°C), the amount of dye sorbed by the high affinity site decreased to negligibly small. Accordingly, the isotherms were expressed well by simple dual-sorption model. © 1995 John Wiley & Sons, Inc.  相似文献   

3.
A thermally stable and transparent copolymer (PAED) composed of N-allylmaleimide, N-(2-ethylhexyl)maleimide, and diisobutylene as the repeating units was produced by radical copolymerization in the presence of an azo initiator in chloroform at 60 °C. The thiol–ene reaction between the allyl groups included in the side chain of PAED and the mercapto groups (SH) included in a random-type SH-modified silsesquioxane (SQ) as the crosslinker provided PAED–SQ hybrid materials upon heating. The reaction process for this thermal curing was monitored from the intensity changes of characteristic peaks by IR spectroscopy as well as the gravimetric determination of the isolated insoluble fractions. The thermal, optical, and mechanical properties of the hybrids were investigated. The onset and maximum decomposition temperatures were 322–369 °C and 399–431 °C, respectively. The weight residue at 800 °C was 16–40 wt%, which depended on the amount of the SQ content in the feed. These organic–inorganic hybrid materials were highly transparent and exhibited refractive index of 1.522–1.524 and Abbe number of 40.0–45.8. The tensile test and dynamic mechanical analyses were also carried out to investigate the mechanical properties and the network structures of the hybrids. The addition of triallylisocyanurate (TAIC) to the curing system efficiently improved the conversion of the allyl and SH, leading to the more dense network structure and the higher strength and hardness of the cured hybrids. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2294–2302  相似文献   

4.
Low Tg copolymers of [11(N‐carbazolyl)undecylmethacrylate] and [2,5‐dimethylphenyl‐[(4‐nitrophenyl)azo]‐phenoxyalkylmethacrylate] have been synthesized and the polarized light‐induced birefringence of thick films (70 μm) has been investigated at a constant deducted temperature relative to Tg (T Tg = 10 °C). The optical properties of these copolymers have been studied in relation to the azo‐dye content and the length of the alkyl spacer between the azo‐dye and the methacrylic backbone. They have been compared with the dispersion of (4‐methoxy‐2,5‐dimethylphenyl)‐(4‐nitrophenyl)diazene (DMNPAA) within a poly[11(N‐carbazolyl)undecyl‐methacrylate] and a poly[N‐vinylcarbazole] (PVK) matrix. The experimental curves have been fitted by biexponentials, so emphasizing the effects of the copolymer structure on the kinetics of the writing process. The photoinduced orientation is more than three orders of magnitude higher in a grafted material compared to the dispersion version. The azo‐dye concentration also has an important role in both the amplitude and the dynamics of the photo‐orientation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 205–213, 2000  相似文献   

5.
Radical copolymerization of N-(alkyl-substituted phenyl)maleimides (RPhMI) with isobutene (IB) was carried out with an initiator in various solvents at 60°C. The copolymerization of N-(2,6-diethylphenyl)maleimide (2,6-DEPhMI) with IB in benzene proceeded readily in a homogeneous system to give an alternating copolymer over a wide range of the comonomer compositions in the feed. Whereas the alternating tendency of the copolymerization of other RPhMI with IB decreased depending on the alkyl substituents of RPhMI in the following order: 2,6-DEPhMI > N-(2,6-dimethylphenyl)maleimide ≥ N-(2-methylphenyl)maleimide >. N-(4-ethylphenyl)maleimide. The copolymerization reactivities were discussed based on the rate constants for the homo-propagations and cross-propagations. Subsequently, the effect of the solvent on the rate and the reactivity ratios was examined. It was revealed that the copolymerization in chloroform proceeded with higher alternating tendency at a higher copolymerization rate than in the copolymerizations in benzene or dioxane. The copolymers of RPhMI with IB showed excellent thermal stability, i.e., high glass transition temperature and initial decomposition temperature over 200 and 350°C, respectively. © 1996 John Wiley & Sons, Inc.  相似文献   

6.
The rate of homopolymerization of maleimide has been measured in dimethylformamide solution at 60°C. in the presence of azobisisobutyronitrile; it has been compared to that of N-n-butylmaleimide. The overall rates of polymerization are equal to Rp = k[M]1.1–1.2 [In]0.8 for maleimide, and Rp = k'[M] [In]0.5 for the N-substituted imide. The difference of behavior has been interpreted on the basis of an intramolecular tautomery of the terminal group of the maleimide growing chain and the formation of a resonance-stabilized succinimidyl radical. The relative ease of polymerization of these monomers and of maleic anhydride has been discussed. In the presence of sodium tert-butoxide at 20°C. in dimethylformamide solutions, maleimide polymerizes with hydrogen isomerization. The percentage of N-substituted isomerized units was evaluated at 70–75% by measurement of the rate of hydrolysis in 0.005N sodium hydroxide and comparison with succinimide and N-butylsuccinimide. N-n-butylmaleimide undergoes ring opening together with anionic polymerization in the presence of sodium tert-butoxide at 20°C. and butyllithium at -40°C. Unlike the radical-initiated polymerization, it was impossible to obtain anionic copolymers of maleimide and N-butylmaleimide with acrylonitrile and methyl methacrylate.  相似文献   

7.
Poly[lithium-N(4-sulfophenyl) maleimide -co- methoxy oligo-(oxyethylene) methacrylates] [P(LiSMOEn)s] with three different oligoether side chains and different salt concentrations were synthesized. The copolyelectrolytes are essentially random in structure, with blocks of methoxy oligo(oxyethylene) meth-acrylate (MOEnM) recurring sporadically in between the salt units of N(4-sulfophenyl) maleimide. They all show two glass transitions in the temperature range of ?100 to 100°C. The first one below ?30°C is assigned to the oligo(oxyethylene) side chain (T g1), while the second one located between 20 and 50°C is attributed to the main chain of the polymer host (T g2). The maximum ionic conductivity of the copolymer electrolytes, 1.6 × 10?7 S cm?1 at 25°C, occurs at lithium salt concentration [Li+]/[EO] = 2.2 mol%. The ionic conductive behavior of the copolyelectrolytes follows the Vogel-Tammann-Fulcher (VTF) equation. Moreover, a special VTF behavior exists in the copolymers with shorter oligoether side chain and higher salt concentration. Sweep voltammetric results indicate that these copolyelectrolytes have a good electrochemical stability window.  相似文献   

8.
Abstract

A series of liquid crystalline polyorganosiloxanes containing both azo dye and cholesteryl groups were synthesized by reacting poly[3- chloroformylpropyl)methylsiloxane-co-dimethylsiloxane] with both cholesterol and 4-(4′-methoxyphenylazo)phenol. The yields were between 73 and 81%. Most of these new polyorganosiloxanes are colored solid products. Their chemical structures were confirmed by IR, 1H NMR, and elemental analysis. Their phase behaviors were also investigated by using differential scanning calorimetry (DSC) and polarizing microscopy. The results show that all these polyorganosiloxanes exhibit liquid crystalline behavior at various temperatures and at any azo dye content. As a result of the orientation of both mesogenic azo dye and cholesteryl groups, smectic phases were formed beginning around 0°C, and cholesteric phases appeared above 60°C.  相似文献   

9.
Copolymerization of maleimide (MI) and ethyl α-(hydroxymethyl)acrylate (EHMA) was performed at 60°C with AIBN as the initiator in THF. The monomer reactivity ratios were determined as r1 (MI) = 0.13 and r2 (EHMA) = 2.20. As the molar fraction of MI in the monomer feed increased, the initial rate of copolymerization decreased. TGA diagrams suggested the crosslinking reaction of the copolymer on heating. DSC and WAXD results suggested the existence of incomplete crystallinity in the copolymer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1291–1299, 1998  相似文献   

10.
The copolymerization of divinylbenzene (DVB) and N‐isopropylacrylamide (NIPAm) with dimethyl 2,2′‐azobisisobutyrate of a concentration as high as 0.50 mol/L proceeded homogeneously without any gelation at 80 °C in N,N‐dimethylformamide, where the concentrations of DVB and NIPAm were 0.15 and 0.50 mol/L. The copolymer yield increased with time and leveled off over 50 min. Although DVB was consumed more rapidly than NIPAm, both comonomers were completely consumed in 50 min. The homogeneous polymerization system at 80 °C involved electron spin resonance‐observable propagating polymer radicals, the total concentration of which increased with time. The resulting copolymer was soluble in tetrahydrofuran, chloroform, acetone, ethyl acetate, acetonitrile, N,N‐dimethylformamide, dimethyl sulfoxide, and methanol, but insoluble in benzene, n‐hexane, and water. The copolymer showed an upper critical solution temperature (50 °C on cooling) in a methanol–water [11:3 (v/v)] mixture. Dimethyl 2,2′‐azobisisobutyrate fragments as high as 37–45 mol % were incorporated as terminal groups in the copolymers through initiation and primary radical termination. The contents of DVB and NIPAm were 10–30 mol % and 30–50 mol %, respectively. The intrinsic viscosity of the copolymer was very low (0.09 dL/g) at 30 °C in tetrahydrofuran despite high weight‐average molecular weight (1.2 × l06 by multi‐angle laser light scattering). These results indicate that the copolymer was of hyperbranched structure. By transmission electron microscopy observation, the individual copolymer molecules were visualized as nanoparticle of 6–20 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1609–1617, 2004  相似文献   

11.
A series of crossslinked organic and organic/inorganic polymers based on maleimide chemistry have been investigated for second‐order non‐linear optical (NLO) materials with excellent thermal stability and low optical loss. Two reactive chromophores (maleimide‐containing azobenzene dye and alkoxysilane‐containing azobenzene dye) were incorporated into a phosphorus‐containing maleimide polymer, respectively. The selection of the phosphorus‐containing maleimide polymer as the polymeric matrices provides enhanced solubility and thermal stability, and excellent optical quality. Moreover, a full interpenetrating network (IPN) was formed through simultaneous addition reaction of the phosphorus‐containing maleimide, and sol‐gel process of alkoxysilane dye (ASD). Atomic force microscopy (AFM) results indicate that the inorganic networks are distributed uniformly throughout the polymer matrices on a nano‐scale. The silica particle sizes are well under 100 nm. Using in situ contact poling, the r33 coefficients of 2.2–17.0 pm/V have been obtained for the optically clear phosphorus‐containing NLO materials. Excellent temporal stability (100°C) and low optical loss (0.99–1.71 dB/cm; 830 nm) were also obtained for these phosphorus‐containing materials. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

12.
Abstract

Coloured ferroelectric liquid-crystalline side chain copolymers containing 5 per cent and 15 per cent of an azo dye were synthesized and characterized by DSC, GPC and optical microscopy. Order parameters, S, of the azo compound exceeding 0·8 were measured in the frozen smectic phase for the 5 per cent copolymer. The copolymers exhibit fast electrooptic switching in the range of a few hundred microseconds to milliseconds in the Sc* phase. Both linear (i.e. electroclinic-like) and ferroelectric switching have been observed. Tilt angles of ~19° and spontaneous polarization of ~300nC cm?2 have been recorded in the Sc* phase.  相似文献   

13.
The polymerization behavior of N-(p-aminobenzoyl)caprolactam was studied. It was found that polymerization could proceed by either elimination of caprolactam or by ring opening. Polymers prepared at temperatures above 200°C showed a greater tendency for ring opening to produce alternating aromatic/aliphatic copolymers than did polymers prepared at lower temperatures. Block copolymers of poly(p-benzamide) and nylon 6 were prepared by a two-stage hydrolytic polymerization process or by anionic polymerization at temperatures > 200°C. Polymer microstructures were determined using 13C-NMR spectroscopy by comparison with homopolymers and model alternating copolymers. The alternating copolymer prepared by condensation of N-(p-aminobenzoyl)-6-caproic acid showed a melting transition at 300–305°C in the DSC and a Tg in subsequent heating cycles of 116–119°C. Copolymers made with the two-stage process were rich in p-benzamide sequences and showed no Tg or Tm below 400°C. Copolymer made with NaH was rich in nylon 6 units, showed a Tm of 175–180°C and a Tg of 80–81°C, and was homogeneous in both the melt and solid.  相似文献   

14.
The new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxy‐ carbonyl)aminobenzenesulfonamide (MPBAS) (M1) is synthesized using sulfadiazine as parent compound. It could be homopolymerized and copolymerized with N‐phenyl maleimide (NPMI) (M2) by radical mechanism using AIBN as initiator at 60 °C in dimethylformamide. The new monomer MPBAS and polymers were identified by IR, element analysis and 1H NMR in detail. The monomer reactivity ratios in copolymerization were determined by YBR method, and r1 (MPBAS) = 2.39 ± 0.05, r2 (NPMI) = 0.33 ± 0.02. In the presence of ammonium formate, benzyloxycarbonyl groups could be broken fluently from MPBAS segments of copolymer by catalytic transfer hydrogenation, and the copolymer with sulfadiazine side groups are recovered. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2548–2554, 2000  相似文献   

15.
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156  相似文献   

16.
A doubly hydrophilic triblock copolymer of poly(N,N‐dimethylamino‐2‐ethyl methacrylate)‐b‐Poly(ethylene glycol)‐b‐poly(N,N‐dimethylamino‐2‐ethylmethacrylate) (PDMAEMA‐b‐PEG‐b‐PDMAEMA) with well‐defined structure and narrow molecular weight distribution (Mw/Mn = 1.21) was synthesized in aqueous medium via atom transfer radical polymerization (ATRP) of N,N‐dimethylamino‐2‐ethylmethacrylate (DMAEMA) initiated by the PEG macroinitiator. The macroinitiator and triblock copolymer were characterized with 1H NMR and gel permeation chromatography (GPC). Fluorescence spectroscopy, dynamic light scattering (DSL), transmittance measurement, and rheological characterization were applied to investigate pH‐ and temperature‐induced micellization in the dilute solution of 1 mg/mL when pH > 13 and gelation in the concentrated solution of 25 wt % at pH = 14 and temperatures beyond 80 °C. The unimer of Rh = 3.7 ± 0.8 nm coexisted with micelle of Rh = 45.6 ± 6.5 nm at pH 14. Phase separation occurred in dilute aqueous solution of the triblock copolymer of 1 mg/mL at about 50 °C. Large aggregates with Rh = 300–450 nm were formed after phase separation, which became even larger as Rh = 750–1000 nm with increasing temperature. The gelation temperature determined by rheology measurement was about 80 °C at pH 14 for the 25 wt % aqueous solution of the triblock copolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5869–5878, 2008  相似文献   

17.
Copolymerization of the acrylonitrile-zinc chloride complex with excess vinyl acetate has been investigated. Alternating 1:1 copolymers of acrylonitrile and vinyl acetate of high molecular weights have been successfully prepared. The alternating structure has been ascertained by means of high-resolution nuclear magnetic resonance spectroscopy. The copolymer is amorphous (Tg = 85°C) and has shown thermal and oxidative stability better than those of polyacrylonitrile. The copolymer is soluble in acetone as well as in more powerful solvents such as dimethylformamide, dimethyl sulfoxide, nitromethane, and N-methylpyrrolidone. The copolymer has been processed into films and fibers from its acetone solutions. Films show tensile properties similar to those of cellulose acetate under ambient conditions; they suffer drastic loss in tensile properties at above 50°C and retain their good tensile properties at subzero temperatures (determined as low as ?40°C). Fibers show tensile properties comparable to those of modacrylic fibers under ambient conditions but suffer marked loss in stiffness at 40°C in water and 60°C in air. The fibers also retain their good properties at subzero temperatures (measured down to ?60°C).  相似文献   

18.
A new atom transfer radical polymerization (ATRP) initiator, namely, 2‐(1‐(2‐azidoethoxy)ethoxy)ethyl 2‐bromo‐2‐methylpropanoate containing both “cleavable” acetal linkage and “clickable” azido group was synthesized. Well‐defined azido‐terminated poly(N‐isopropylacrylamide)s (PNIPAAm‐N3)s with molecular weights and dispersity in the range 11,000–19,000 g mol?1 and 1.20–1.28, respectively, were synthesized employing the initiator by ATRP. Acetal containing PCL‐b‐PNIPAAm block copolymer was obtained by alkyne–azide click reaction of azido‐terminated PNIPAAm‐N3 with propargyl‐terminated PCL. Critical aggregation concentration (CAC) of PCL‐b‐PNIPAAm copolymer in aqueous solution was found to be 8.99 × 10?6 M. Lower critical solution temperature (LCST) of PCL‐b‐PNIPAAm copolymer was found to be 32 °C which was lower than that of the precursor PNIPAAm‐N3 (36.4 °C). The effect of dual stimuli viz . temperature and pH on size and morphology of the assemblies of PCL‐b‐PNIPAAm block copolymer revealed that the copolymer below LCST assembled in spherical micelles which subsequently transformed to unstable vesicles above the LCST. Heating these assemblies above 40 °C led to the precipitation of PCL‐b‐PNIPAAm block copolymer. Whereas, at decreased pH, micelles of PCL‐b‐PNIPAAm copolymer disintegrate due to the cleavage of acetal linkage and precipitation of hydrophobic hydroxyl‐terminated PCL. The encapsulated pyrene release kinetics from the micelles of synthesized PCL‐b‐PNIPAAm copolymer was found to be faster at higher temperature and at lower pH. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1383–1396  相似文献   

19.
Three types of novel N-[4-(N′-substituted aminocarbonyl)phenyl] maleimide (RPhMI: N-substituent (R) = phenyl, cyclohexyl, and cyclododecyl) were synthesized and homopolymerized under several conditions. In the copolymerizations of RPhMI (M1) with styrene (ST; M2) or methyl methacrylate (MMA; M2), monomer reactivity ratios and Alfrey-Price Q, e values were determined. All homopolymers decomposed without softening and melting points. The initial degradation temperatures (Td) of poly(RPhMI)s were over 320°C. The glass transition temperatures (Tg) of RPhMI copolymers were much higher than those of N-phenylmaleimide (PhMI)–ST, PhMI–MMA, N-cyclohexylmaleimide (CHMI)–ST, and CHMI–MMA copolymers. Thermal stability of the terpolymers of RPhMI with ST and acrylonitrile (AN) was higher than that of ST–AN copolymers, i.e., AS resin. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2001–2012, 1998  相似文献   

20.
A novel fluorine-containing polymer, poly[N-(2,3,4,5,6-pentafluorophenyl)maleimide], was prepared by the anionic polymerization of N-(2,3,4,5,6-pentafluorophenyl)maleimide (PFPMI). Anionic polymerization with alkali metal tert-butoxides gave poly(PFPMI) in 14–32% yield. Phenyllithium and sec-butyllithium also afforded poly(PFPMI). No polymer was obtained with a radical initiator such as 2,2′-azoisobutyronitrile. The polymerization took place only via the vinylene group of PFPMI and no appreciable side-reaction occurred. The obtained poly(PFPMI) shows unimodal molecular weight distribution and begins to decompose at 325°C.  相似文献   

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