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1.
A polyimide‐graft‐polystyrene (PI‐g‐PS) copolymer with a polyimide backbone and polystyrene side chains was synthesized by the “grafting from” method using styrene polymerization on a polyimide multicenter macroinitiator via ATRP mechanism. The side chain grafting density z = 0.86 of PI‐g‐PS is rather high for graft‐copolymers synthesized by the ATRP method. Molecular characteristics and solution behavior of PI‐g‐PS were studied in selective solvents using light scattering and viscometry methods. In all solvents, the backbone tends to avoid contact with a poor solvent. To describe the conformation and hydrodynamic properties of PI‐g‐PS macromolecules in thermodynamically good solvents for side chains and PI‐g‐PS, the wormlike spherocylinder model is used. Macromolecules of the studied graft‐copolymer are characterized by high equilibrium rigidities (Kuhn segment length >20 nm). In Θ‐conditions, PI‐g‐PS macromolecules may be modeled by a rigid prolate ellipsoid of revolution with a low asymmetry form and a collapsed backbone as the ellipsoid core. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1539–1546  相似文献   

2.
Surface characteristics of film samples of molecular brushes with a polyimide backbone and PMMA side chains, as well as of films of polyimide constituting the backbone and linear PMMA homopolymers obtained via the selective destruction of the polyimide backbone of these brushes, are investigated for the first time. The surface-energy characteristics of the films of molecular brushes are determined by the structure and conformational state of the PMMA side chains. The conformations of molecular brushes possessing a polyimide backbone well screened by side chains are preserved after the transition from solutions to “dry” copolymer films and are characterized by high stability. The observed surface activity of molecular brushes is due to adhesion interactions with functional groups of the substrate. The difference in surface activities is caused by small-scale conformational changes in the side chains of molecular brushes. A globular core of molecular brushes formed by the polyimide backbone remains practically spherical and probably does not change in volume.  相似文献   

3.
Novel macromolecular brushes with a polyimide backbone and diphilic diblock copolymer side chains consisting of a hydrophilic block of poly(methacrylic acid) adjacent to the backbone and the outer hydrophobic block of poly(methyl methacrylate) are synthesized. The synthesis includes the grafting of poly(tert-butyl methacrylate) to the polyimide chain followed by the polymerization of methyl methacrylate on the graft copolyimide as a branched multicenter macroinitiator. Brushes with diphilic side chains are obtained via the acidic hydrolysis of ester groups in the first block of side chains. The grafting polymerization of methacrylates is performed according to the “grafting from” approach by the method of pseudoliving atom transfer radical polymerization using two methodologies of polymerization activated by either copper- or iron-containing complexes. Conditions providing the controlled regime of the polymerization processes under study are found, and pathways for the targeted regulation of the degree of polymerization of methacrylate blocks and their grafting density are determined. As is shown by dynamic light scattering and transmission electron microscopy, the macromolecules of brushes with diphilic side chains form in ethanol homotypic, obviously spherical, supramolecular micellar structures with hydrodynamic radii in the range from 40 to 120 nm depending on the length and grafting density of the two blocks in diphilic side chains.  相似文献   

4.
Graft copolymers with a polyimide backbone and poly(methyl methacrylate) side chains are investigated in dilute chloroform and ethyl acetate solutions via the methods of molecular hydrodynamics and optics. Copolymer samples are prepared through the “grafting from” method via atom-transfer radical polymerization with a multicenter polyimide macroinitiator. In solutions of copolymers with low degrees of functionalization Z (40%), supermolecular structures are formed as a result of interactions between the polyimide backbones. In samples with Z → 100%, the backbone is well screened by side chains; therefore, molecular solutions are formed in both solvents. The hydrodynamic and conformational behavior of samples with high functionalization degrees changes after the transition from ethyl acetate to chloroform owing to the different thermodynamic qualities of the solvents with respect to the copolymer components. In both solvents, the backbone tends to avoid contact with a poor solvent. This effect is more pronounced in the case of ethyl acetate. Macromolecules of the studied graft copolymers are characterized by high equilibrium rigidities (>40 nm) that are 10 times higher than the corresponding characteristics of aromatic polyimides.  相似文献   

5.
A series of well‐defined double hydrophilic graft copolymers containing poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and poly[poly(ethylene glycol) ethyl ether methacrylate] (PPEGEEMA) side chains were synthesized by the combination of single electron transfer‐living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SET‐LRP of poly(ethylene glycol) methyl ether acrylate macromonomer using CuBr/tris(2‐(dimethylamino)ethyl)amine as catalytic system. The obtained comb copolymer was treated with lithium diisopropylamide and 2‐bromoisobutyryl bromide to give PPEGMEA‐Br macroinitiator. Finally, PPEGMEA‐g‐PPEGEEMA graft copolymers were synthesized by ATRP of poly(ethylene glycol) ethyl ether methacrylate macromonomer using PPEGMEA‐Br macroinitiator via the grafting‐from route. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept narrow (Mw/Mn ≤ 1.20). This kind of double hydrophilic copolymer was found to be stimuli‐responsive to both temperature and ion (0.3 M Cl? and SO). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 647–655, 2010  相似文献   

6.
Copolymerization of acrylic acid and p‐chloromethylstyrene (p‐CMS) in dioxane initiated with α,α′‐azobisisobutyronitrile was carried out to produce macroinitiator P(AA‐co‐CMS) containing PhCH2Cl group at 65°C. Then methyl methacrylate was grafted onto P(AA‐co‐CMS) backbone using PhCH2Cl group as an initiation site and FeCl2/triphenyl phosphine complex as a catalyst. The resulted copolymer (AA‐co‐CMS)‐g‐PMMA with a comb‐like branched structure has a hydrophilic backbone (PAA) and hydrophobic side chains (PMMA). Compositions and structures of macroinitiator and the grafted product of P(AA‐co‐CMS)‐g‐PMMA were determined by 1H‐NMR, infrared (IR), and gel permeation chromatography (GPC). The average graft number, the average length of branch chains, the graft ratio, and the graft efficiency were investigated. The swelling behavior of the comb‐like branched polymer was also investigated. The gradual increase of swelling ratios was accompanied by an increase of pH and temperature. The kinetic exponents indicated that the swelling transport mechanisms transformed from Fickian diffusion to non‐Fickian transport as the decreasing pH. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

7.
A series of well‐defined double hydrophilic double‐grafted copolymers, consisting of polyacrylate backbone, hydrophilic poly(2‐(diethylamino)ethyl methacrylate) and poly(ethylene glycol) side chains, were synthesized by successive atom transfer radical polymerization. The backbone, poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) comb copolymer, was firstly prepared by ATRP of PEGMEA macromonomer via the grafting‐through route followed by reacting with lithium diisopropylamide and 2‐bromopropionyl chloride to give PPEGMEA‐Br macroinitiator of ATRP. Finally, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(2‐(diethylamino)ethyl methacrylate) graft copolymers were synthesized by ATRP of 2‐(diethylamino)ethyl methacrylate using PPEGMEA‐Br macroinitiator via the grafting‐from route. Poly(2‐(diethylamino)ethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections, which is tolerant of both acidic and basic environment. The molecular weights of both backbone and side chains were controllable and the molecular weight distributions kept relatively narrow (Mw/Mn ≤ 1.39). The results of fluorescence spectroscopy, dynamic laser light scattering and transmission electron microscopy showed this double hydrophilic copolymer was stimuli‐responsive to both pH and salinity. It can aggregate to form reversible micelles in basic surroundings which can be conveniently dissociated with the addition of salt at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3142–3153, 2009  相似文献   

8.
A well‐defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting‐through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2‐bromopropionyl chloride. Afterwards, grafting‐from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methacrylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli‐responsive to pH and ionic strength. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4056–4069, 2008  相似文献   

9.
A series of well‐defined double hydrophilic graft copolymers containing poly(poly(ethylene glycol) methyl ether acrylate) (PPEGMEA) backbone and poly(2‐vinylpyridine) (P2VP) side chains were synthesized by successive single electron transfer living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SET‐LRP of poly(ethylene glycol) methyl ether acrylate (PEGMEA) macromonomer using CuBr/tris(2‐(dimethylamino)ethyl)amine as catalytic system. The obtained homopolymer then reacted with lithium diisopropylamide and 2‐chloropropionyl chloride at ?78 °C to afford PPEGMEA‐Cl macroinitiator. poly(poly(ethylene glycol) methyl ether acrylate)‐g‐poly(2‐vinylpyridine) double hydrophilic graft copolymers were finally synthesized by. ATRP of 2‐vinylpyridine initiated by PPEGMEA‐Cl macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as catalytic system via the grafting‐ from strategy. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept relatively narrow (Mw/Mn ≤ 1.40). pH‐Responsive micellization behavior was investigated by 1H NMR, dynamic light scattering, and transmission electron microscopy and this kind of double hydrophilic graft copolymer aggregated to form micelles with P2VP‐core while pH of the aqueous solution was above 5.0. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

10.
A series of well‐defined double hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) backbone and poly(2‐vinylpyridine) side chains, were synthesized by successive single‐electron‐transfer living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as the catalytic system. The obtained diblock copolymer was transformed into the macroinitiator by reacting with 2‐chloropropionyl chloride. Next, grafting‐from strategy was used for the synthesis of poly(N‐isopropylacrylamide)‐b‐[poly(ethyl acrylate)‐g‐poly(2‐vinylpyridine)] double hydrophilic graft copolymer. ATRP of 2‐vinylpyridine was initiated by the macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as the catalytic system. The synthesis of both the backbone and the side chains are controllable. Thermo‐ and pH‐responsive schizophrenic micellization behaviors were investigated by 1H NMR, fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. Unimolecular micelles with PNIPAM‐core formed in acidic environment (pH = 2) with elevated temperature (T ≥ 32 °C), whereas the aggregates turned into spheres with PEA‐g‐P2VP‐core accompanied with the lifting of pH values (pH ≥ 5.3) at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 15–23, 2010  相似文献   

11.
Block copolymers of hyperbranched polyethylene (PE) and linear polystyrene (PS) or poly(methyl methacrylate) (PMMA) were synthesized via atom transfer radical polymerization (ATRP) with hyperbranched PE macroinitiators. The PE macroinitiators were synthesized through a “living” polymerization of ethylene catalyzed with a Pd‐diimine catalyst and end‐capped with 4‐chloromethyl styrene as a chain quenching agent in one step. The macroinitiator and block copolymer samples were characterized by gel permeation chromatography, 1H and 13C NMR, and differential scanning calorimetry. The hyperbranched PE chains had narrow molecular weight distribution and contained a single terminal benzyl chloride per chain. Both hyperbranched PE and linear PS or PMMA blocks had well‐controlled molecular weights. Slow initiation was observed in ATRP because of steric effect of hyperbranched structures, resulting in slightly broad polydispersity index in the block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3024–3032, 2010  相似文献   

12.
A series of well‐defined double‐hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom‐transfer radical polymerization (ATRP). PNIPAM‐b‐PEA backbone was first prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with 2‐chloropropionyl chloride. The final graft copolymers with narrow molecular weight distributions were synthesized by ATRP of 2‐(dimethylamino)ethyl acrylate initiated by the macroinitiator at 40 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system via the grafting‐from strategy. These copolymers were employed to prepare stable colloidal gold nanoparticles with controlled size in aqueous solution without any external reducing agent. The morphology and size of the nanoparticles were affected by the length of PDMAEA side chains, pH value, and the feed ratio of the graft copolymer to HAuCl4. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1811–1824, 2009  相似文献   

13.
The blending between poly(methyl methacrylate) (PMMA) and ferroelectric (vinylidene fluoride‐trifluorethylene) [P(VDF‐TrFE)] copolymer chains has been investigated by Fourier transform infrared (FTIR) spectroscopy over the full range of composition, for the copolymer with 50 mol % of trifluorethylene [TrFE]. The FTIR spectra revealed an absorption band at 1643 cm−1, characteristic of the blend and absent in the individual constituents. We attributed this band to the interaction of the carbonyl group of the PMMA side chains with the disordered helical chains present in the amorphous region of the P(VDF‐TrFE). We investigated the consequences of adding PMMA onto the formation of the all trans conformation of the copolymer chains and we demonstrated that the effects of thermal heating on the spectra are relevant only for the samples where the ferroelectric semicrystalline phase is present. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 34–40, 2000  相似文献   

14.
氯化原位接枝制备CPE-g-MMA接枝共聚物   总被引:4,自引:0,他引:4  
氯化原位接枝制备CPE-g-MMA接枝共聚物;接枝共聚物结构;氯化原位接枝;力学性能  相似文献   

15.
A series of well‐defined centipede‐like copolymers with poly(glycidyl methacrylate) (PGMA) as main chain and poly(L ‐lactide) (PLLA) and polystyrene (PSt) as side chains have been synthesized successfully by combination of ring‐opening polymerization and atom transfer radical polymerization (ATRP). The synthetic process includes three steps. (1) Synthesis of PGMA via ATRP; (2) preparation of macroinitiator with one bromine group and a hydroxyl group at every GMA unit of PGMA; (3) ring‐opening polymerization of LLA and ATRP of St to obtain the asymmetric centipede‐like copolymers. The number–average degrees of polymerization of PGMA backbone, PLLA and PSt side chains were determined by 1H‐NMR spectra, and the molecular weights of the resultant intermediates and centipede‐like copolymers were measured by gel permeation chromatography. The molecular weight distributions were narrow and the molecular weights of both the backbone and the side chains were controllable. The thermal behavior of the centipede‐like copolymers was investigated by differential scanning calorimeter. With the increase of PSt side chain length, the glass transition temperature of PLLA side chains shifted to high temperature, and crystallization ability of PLLA side chains became poor. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5580–5591, 2008  相似文献   

16.
This is the first report concerning the use of vinyl polyperoxide, namely, poly(methyl methacrylate) peroxide (PMMAP), as a thermal initiator for the synthesis of active polymer PMMAP‐PS‐PMMAP by free‐radical polymerization with styrene. The polymerizations have been carried out at different concentrations of macroinitiator PMMAP. The active polymers have been characterized by 1H NMR, DSC, thermogravimetric analysis, and gel permeation chromatography. PMMAP‐PS‐PMMAP is further used as the thermal macroinitiator for the preparation of another block copolymer, PMMA‐b‐PS‐b‐PMMA, by reacting the active polymers with methyl methacrylate. The block copolymers have been synthesized by varying the concentrations of the active polymers. The mechanism of block copolymers has been discussed, which is also supported by thermochemical calculations. Studies on the surface texture and morphology of the block copolymer of polystyrene (PS) and PMMA material have been carried out using scanning electron microscopy. Furthermore, in this article, a blend of the same constituent materials (PS and PMMA) in proportions (v/v) similar to that contained in block copolymers has been formulated, and the morphology and surface textures of these materials were also investigated. A comparative microscopical evaluation between two processing methods was done for a better understanding of the processing route dependence of the microstructures. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 546–554, 2001  相似文献   

17.
The four‐step synthesis of amphiphilic glycopolymers associating dextran as backbone and poly(methyl methacrylate) (PMMA) as grafts is reported, using the “grafting from” strategy. In the first step, the dextran OH functions were partially acetylated. The second step consisted in linking initiator groups by reaction of 2‐bromoisobutyryl bromide (BiBB) with the unprotected OH functions. Third, the atom transfer radical polymerization (ATRP) of methyl methacrylate was carried out in DMSO from the resulting dextran derivative used as a macroinitiator. Finally, the cleavage of the acetate groups led to the expected glycopolymers. Careful attention was given both to the copolymer structure and the control of polymerization. PMMA grafts were analyzed by SEC‐MALLS after their deliberate cleavage from the backbone to evidence a controlled polymerization. Moreover, the mildness of the final deprotection conditions was proved to ensure acetate cleavage without either degrading dextran backbone and PMMA grafts or cleaving grafts from dextran backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7606–7620, 2008  相似文献   

18.
A series of ferrocene‐based well‐defined amphiphilic graft copolymers, consisting of hydrophilic poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and hydrophobic poly(2‐acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains were synthesized by successive single‐electron‐transfer living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by SET‐LRP of PEGMEA macromonomer, and it was then treated with lithium di‐isopropylamide and 2‐bromopropionyl bromide at ?78 °C to give PPEGMEA‐Br macroinitiator. The targeted well‐defined graft copolymers with narrow molecular weight distributions (Mw/Mn ≤ 1.32) were synthesized via ATRP of AEFC initiated by PPEGMEA‐Br macroinitiator, and the molecular weights of the backbone and side chains were both controllable. The electro‐chemical behaviors of graft copolymers were studied by cyclic voltammetry, and it was found that graft copolymers were more difficult to be oxidized, and the reversibility of electrode process became less with raising the content of PAEFC segment. The effects of the preparation method, the length of hydrophobic PAEFC segment, and the initial water content on self‐assembly behavior of PPEGMEA‐g‐PAEFC graft copolymers in aqueous media were investigated by transmission electron microscopy. The morphologies of micelles could transform from cylinders to spheres or rods with changing the preparation condition and the length of side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

19.
To develop new hemopurification systems based on cellulose membrane, we synthesized a graft copolymer of cellulose with poly(2‐methacryloyloxyethyl phosphorylcholine) (MPC) by a metal‐catalyzed atom transfer radical polymerization process in homogeneous media. First, cellulose was dissolved in a DMAc/LiCl solution system, and it reacted with 2‐bromoisobutyloyl bromide to produce macroinitiator (cell‐BiB). Then, MPC was polymerized to the cellulose backbone in a homogeneous DMSO/methanol mixture solution in the presence of cell‐BiB. Characterization with FT‐IR, NMR, and GPC measurements showed that there obtained a graft copolymer of cellulose backbone and poly(MPC) side chains (cell‐PMPC) with well‐defined structure, indicating a controlled/“living” radical polymerization. The proteins adsorption studies showed that cellulose membranes modified by the as‐prepared cell‐PMPC owns good protein adsorption resistance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3306–3313, 2008  相似文献   

20.
A series of novel graft copolymers consisting of perfluorocyclobutyl aryl ether‐based backbone and poly(methyl methacrylate) side chains were synthesized by the combination of thermal [2π + 2π] step‐growth cycloaddition polymerization of aryl bistrifluorovinyl ether monomer and atom transfer radical polymerization (ATRP) of methyl methacrylate. A new aryl bistrifluorovinyl ether monomer, 2‐methyl‐1,4‐bistrifluorovinyloxybenzene, was first synthesized in two steps from commercially available reagents, and this monomer was homopolymerized in diphenyl ether to provide the corresponding perfluorocyclobutyl aryl ether‐based homopolymer with methoxyl end groups. The fluoropolymer was then converted to ATRP macroinitiator by the monobromination of the pendant methyls with N‐bromosuccinimide and benzoyl peroxide. The grafting‐from strategy was finally used to obtain the novel poly(2‐methyl‐1,4‐bistrifluorovinyloxybenzene)‐g‐poly(methyl methacrylate) graft copolymers with relatively narrow molecular weight distributions (Mw/Mn ≤ 1.46) via ATRP of methyl methacrylate at 50 °C in anisole initiated by the Br‐containing macroinitiator using CuBr/dHbpy as catalytic system. These fluorine‐containing graft copolymers can dissolve in most organic solvents. This is the first example of the graft copolymer possessing perfluorocyclobutyl aryl ether‐based backbone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010  相似文献   

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