An X-ray Photoelectron Spectroscopic Study of the Poly-N-vinylpyrrolidone Desorption from the Surface of a Granulated Carbon Sorbent

The surface of a carbon sorbent modified with poly-N-vinylpyrrolidone was studied by X-ray photoelectron spectroscopy (XPS). The modification involves polymerization of N-vinylpyrrolidone on the carbon sorbent surface to form poly-N-vinylpyrrolidone. The elemental composition of the carbon sorbent surface before and after modification was determined by XPS. The electronic state of atoms of the identified elements on the surface was evaluated. The contact of the modified carbon sorbent with normal saline simulating the biological medium leads to partial removal (desorption) of the polymer from the granulated sample.

     

Synthesis and self-organization of amphiphilic poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone-2,2,3,3-tetrafluoropropyl methacrylate) diblock copolymers in solution and bulk

It is shown that the amphiphilic diblock copolymers poly(N-vinylpyrrolidone-2,2,3,3-tetrafluoropropyl methacrylate) can be prepared through the reaction of chain transfer to bis(pentafluorophenyl)germane during the polymerization of N-vinylpyrrolidone and the subsequent postpolymerization of isolated functional polymers in 2,2,3,3-tetrafluoropropyl methacrylate. The dilute-solution behavior and self-organizing ability of functional polymers based on poly(N-vinylpyrrolidone) containing end bis(pentafluorophenyl) groups and of amphiphilic diblock copolymers formed on their basis are studied via the methods of static and dynamic light scattering and viscometry. Surface properties at the interface of the films are estimated through the wetting technique.     

Radical and anionic homopolymerization of maleimide and N-n-butylmaleimide

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 R_p = k[M]^1.1–1.2 [In]^0.8 for maleimide, and R_p = 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.     

Synthesis of 2-Methacryloyl-5-hydroxy-3,3,5-trimethylisoxazolidine and Copolymers Thereof

Previously unknown 2-methacryloyl-5-hydroxy-3,3,5-trimethylisoxazolidine was prepared by the reaction of 5-hydroxy-3,3,5-trimethylisoxazolidine with methacryloyl chloride. Homopolymers of this compound and its copolymers with N-vinylformamide and N-vinylpyrrolidone were obtained by radical polymerization.     

Controlled radical polymerization of N-vinylpyrrolidone and N-vinylsuccinimide under the conditions of reversible chain transfer by the addition-fragmentation mechanism

Regular trends in controlled radical polymerization of N-vinylpyrrolidone and N-vinylsuccinimide by the mechanism of reversible chain transfer in the presence of a series of dithiobenzoates and trithiocarbonates were studied. The possibility of preparing soluble poly-N-vinylsuccinimide in concentrated solutions using benzyl benzodithioate as reversible chain-transfer agent was demonstrated.     

Polymerization of N-(2,3,4,5,6-pentafluorophenyl)-maleimide

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.     

Versatile cobalt(Salen-NEt2) for aqueous cobalt-mediated radical polymerization

Cobalt-mediated radical polymerization (CMRP) has enabled the polymerization of a wide range of monomers with predictable molecular parameters and well-defined compositions and architectures. However, the synthesis of hydrophilic polymers by CMRP directly in the aqueous phase is still challenging. Herein, a handy cobalt complex was developed to perform CMRP of N-vinylpyrrolidone (NVP), 2-hydroxyethyl acrylate (HEA), and N,N-dimethylacrylamide (DMA) with linearly increased molecular weight, low polydispersity values, and smoothly shifted gel permeation chromatography (GPC) traces. The chain extensions of NVP, HEA, and DMA revealed the well chain-end fidelity for the synthesis of block copolymers. Moreover, the poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) (PVP-b-PVAc) amphiphilic block copolymer colloidal solution was achieved directly in aqueous phase by cobalt-mediated radical polymerization-induced self-assembly (CMR-PISA), forming the nanoparticles consisting of a hydrophilic PVP corona and a hydrophobic PVAc core. This new mediator opens the opportunity for the synthesis of various hydrophilic (co)polymers in an environmentally friendly manner.     

Phenolic resins bearing maleimide groups: Synthesis and characterization

Novel phenolic novolac resins, bearing maleimide groups and capable of undergoing curing principally through the addition polymerization of these groups, were synthesized by the polymerization of a mixture of phenol and N‐(4‐hydroxy phenyl)maleimide (HPM) with formaldehyde in the presence of an acid catalyst. The polymerization conditions were optimized to get gel‐free resins. The resins were characterized by chemical, spectral, and thermal analyses. Differential scanning calorimetry and dynamic mechanical analysis revealed an unexpected two‐stage curing for these systems. Although the cure at around 275°C was attributable to the addition polymerization reaction of the maleimide groups, the exotherm at around 150 to 170°C was ascribed to the condensation reaction of the methylol groups formed in minor quantities on the phenyl ring of HPM. Polymerization studies of non‐hydroxy‐functional N‐phenyl maleimides revealed that the phenyl groups of these molecules were activated toward an electrophilic substitution reaction by the protonated methylol intermediates formed by the acid‐catalyzed reaction of phenol and formaldehyde. On a comparative scale, HPM was less reactive than phenol toward formaldehyde. The presence of the phenolic group on N‐phenyl maleimide was not needed for its copolymerization with phenol and formaldehyde. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 641–652, 2000     

Tailoring macromolecular architecture with imidazole functionality: A perspective for controlled polymerization processes

Controlled radical polymerization (CRP) allows for the design and synthesis of functional polymers with tailored composition and unique macromolecular architectures. Synthetic methods that are readily available for controlled radical polymerization include nitroxide-mediated polymerization, reversible addition–fragmentation chain transfer polymerization, and atom transfer radical polymerization. N-Vinyl monomers that are typically amenable to free radical methods are often difficult to synthesize in a controlled manner to high molecular weight due to the lack of resonance stabilization of the propagating radical. However, recent advances in the field of CRP have resulted in successful controlled polymerization of various N-vinyl heterocyclic monomers including N-vinylcarbazole, N-vinylpyrrolidone, N-vinylphthalimide, and N-vinylindole. The incorporation of the imidazole ring into homopolymers and copolymers using conventional free radical polymerization of N-vinylimidazole monomer is particularly widespread and advantageous due to facile functionalization, high thermal stability, and the relevance of the imidazole ring to many biomacromolecules. Copolymers prepared with methyl methacrylate displayed random incorporation according to differential scanning calorimetry and amorphous morphologies according to X-ray scattering. Imidazole- and imidazolium-containing monomers have shown recent success for CRP; however, the controlled polymerization of N-vinylimidazole has remained relatively unexplored. Future efforts focus on the development of tailored imidazole-containing copolymers with well-defined architectures for emerging biomedical, electronic and membrane applications.     

Synthesis and Microbiological Stability of Graft Copolymers of N-Vinylpyrrolidone and Chitosan

The kinetics of homogeneous graft polymerization of N-vinylpyrrolidone on chitosan, initiated by ammonium peroxodisulfate, was studied in relation to the reactant concentrations. The reaction orders with respect to the monomer, initiator, and matrix polymer were determined. The compositional nonuniformity and microbiological stability of the copolymer were evaluated.     

Complexation in Water-Soluble Systems Poly-N-vinylpyrrolidone-Fullerene C60

Complexes of fullerene C_{6 0} with poly-N-vinylpyrrolidone were prepared by various procedures in the presence of additional agents in solution (systems C_{6 0}-poly-N-vinylpyrrolidone and ternary system C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone) and in the solid phase (C_{6 0}-polyvinylpyrrolidone and C_{6 0}-KBr-poly-N-vinylpyrrolidone). Formation of a donor-acceptor bond in the system C_{6 0}-poly-N-vinylpyrrolidone was studied by ¹³C NMR. The conditions under which the ternary complex C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone with fullerene content varied from 1 to 5 wt % can be obtained were found.     

Polymerization of N-(fluoro phenyl) maleimides

Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. These include N-(2-fluoro phenyl), N-(3-fluoro phenyl), N-(4-fluoro phenyl), N-(2,4-difluoro phenyl), N-(2,5-difluoro phenyl), N-(2,3,5,6-tetrafluoro phenyl), and N-(pentafluoro phenyl). The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by AIBN in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N-(fluoro phenyl) maleimide]s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. On the basis of the comparison between the overall activation energy of the thermal degradation of poly[N-(fluoro phenyl) maleimide]s and NMR spectra of their corresponding monomers, it can be concluded that the ¹H shifts due to ethylenic protons are so characteristic in sign and magnitude as to be useful in thermal stability elucidation. Some qualitative explanations were given on the stability of these polymers as affected by the type and size of the substituent. The x-ray diffractograms of all samples show two rather broad peaks indicative of noncrystalline structures. The location of the peaks does not depend upon preparation conditions and temperature. Poly(N-maleimide)s of fluoroanilines have not been hitherto described.     

Effect of fullerene on the radical homo- and copolymerization of N-vinylpyrrolidone and (Di)methacrylates

The effect of fullerene on the kinetics of homopolymerization of N-vinylpyrrolidone and its copolymerization with methyl methacrylate and triethylene glycol dimethacrylate is studied via absorption spectroscopy and isothermal calorimetry. It is shown that the addition of fullerene brings about the inhibition of polymerization. The duration of the induction period becomes shorter when small amounts of methacrylic mono- and bifunctional monomers or a chain-transfer agent are added to N-vinylpyrrolidone. The resulting polymers are characterized by IR and absorption spectroscopy.     

Synthesis of poly(N-vinylpyrrolidone) and N-vinylpyrrolidone-methyl methacrylate copolymers in the presence of C-phenyl-N-tert-butylnitrone

The free-radical polymerization of N-vinylpyrrolidone and its copolymerization with methyl methacrylate have been studied at 60°C in the presence of C-phenyl-N-tert-butylnitrone as a chain-growth regulator. It has been shown that the above additive makes it possible to synthesize poly(N-vinylpyrrolidone) and its copolymers without any gel effect and to control molecular-mass characteristics of homo-and (co)polymers.     

Base-catalyzed polymerization of maleimide and some derivatives and related unsaturated carbonamides

Basic catalysts in dimethylacetamide solution initiated the polymerization of maleimide to yield a low molecular weight polymer which has a copolymer structure. Approximately 75–85% of the recurring units are formed by hydrogen transfer and 15–25% by vinyl polymerization, as shown by hydrolysis, to yield aspartic acid on the one hand and ammonia and polymaleic acid on the other. Several maleimide derivatives have been prepared, but none has given a high molecular weight polymer by basic catalysis. Some unsaturated carbonamides such as p-vinylbenzamide, mono-N-acrylyl-hexamethylenediamine, and mono-N-acrylyl-p-phenylenediamine have been synthesized and polymerized by basic catalysts. Polymers with low molecular weights were obtained, but the complete structures of all these polymers were not established.     

SYNTHESIS AND RADICAL POLYMERIZATION OF BIFUNCTIONAL MALEIMIDES WITH DIFFERENT FUNCTIONAL REACTIVITIES

Three bifunctional N-phenylmaleimide derivatives, N-[4-(2-hydroxy-3-methacryloyloxy propyloxycarbonyl)phenyl]male-imide (GMAPMI, 1), N-(4-methacryloyloxyphenyl) maleimide (MAPMI, 2) and 4-(4-maleimidobenzoyloxy)styrene (MIBOSt, 3) having radically polymerizable maleimide and vinyl groups together have been synthesized and polymerized. Polymerizations of the bifunctional maleimide monomers were carried out using a radical initiator at 55°C and the results were compared with those obtained by self-polymerization in the absence of ini-tors. All of the polymers obtained were insoluble in organic solvents owing to cross-linking between different functional groups. The reactivity for homopolymerization of monomer 3 is higher than that of monomers 1 and 2 because the styryl moiety of monomer 3 has better electron-donor strength than the methacrylate moiety. Under the same conditions, GMAPMI was copolymerized with N-vinyl-2-pyrrolidone and styrene as an electron-donor to give higher conversions by electron-donor/acceptor polymerization in which the maleimide moiety of GMAPMI mainly involved as an electron acceptor.     

Dipole Structure and Electrooptical Properties of Poly-N-vinylpyrrolydone in Nonaqueous Solvents

Electrooptical Kerr effect and dielectric polarization were studied for poly-N-vinylpyrrolidone solutions in chloroform and in mixed chloroform-CCl₄ solvent. The results were compared with those for an analogue of the monomeric unit of poly-N-vinylpyrrolidone, low-molecular-weight compound N-methylpyrrolidone.     

Synthesis of di-and triblock-copolymers of vinylic monomers in the presence of high molecular weight nitroxyl radicals formed in situ from N-tert-butyl-C-phenylnitrone

High molecular weight nitroxyl radicals formed directly in polymerization system (in situ) from N-tert-buiyl-C-phenylnitrone are efficient agents for the chain growth control and allow one to perform synthesis of di- and triblock-copolymers based on a number of vinylic monomers (styrene, methyl methacrylate, N-vinylpyrrolidone, and butyl acrylate) under more mild temperature regimes than their low molecular weight analogs. The macromolecular structures synthesized are characterized by GPC, NMR and IR spectroscopy, and MALDI TOF MS method.     

Quantum-chemical study of the reaction of <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone with maleic anhydride

Energy profiles are calculated for the reaction of the structural isomer of N-vinylpyrrolidone with maleic anhydride in the gas phase. One of the reaction pathways leads to the formation and regeneration of maleic anhydride, acting as an activator of the process of (co)polymerization and dimerization of N-vinylpyrrolidone. According to calculations, the intermediate, isomer of N-vintlpyrrolidone, is a hybride of the singlet biradical and zwitter-ionic form.     

Synthesis of copolymers of N-vinylpyrrolidone and 2-ethylhexyl acrylate by DL-methionine-mediated reversible deactivation radical polymerization and their dispersion behavior in preparation of LiFePO4 battery positive slurry with high solid content

Dispersants play a significant role in the formulation of positive battery slurry. Adding a small amount of dispersant can effectively reduce the viscosity of the slurry, which is beneficial for the production of positive batteries. A series of copolymers of N-vinylpyrrolidone (NVP) and 2-ethylhexyl acrylate (2-EHA) with different molar ratios of NVP to 2-EHA, different polymer molecular weights and different polymer structures are synthesized by dl -methionine-mediated reversible deactivation radical polymerization. The ability of these copolymers to disperse LiFePO₄ battery positive slurry with a high solid content (57.08%) as dispersants has been evaluated. Research shows that when the ratio of NVP to 2-EHA is 20 and the polymer molecular weight is 6000, poly(N-vinylpyrrolidone-ran-2-ethylhexyl acrylate) (NVP-ran-2-EHA) exhibits the strongest dispersing ability to the slurry. This polymer can reduce the viscosity of the slurry by 43.925% and has the longest stabilization time of 3 h, which is better than poly(N-vinylpyrrolidone) (PVP) and poly(N-vinylpyrrolidone)-block-poly(2-ethylhexyl acrylate) (PVP-b-PEHA) with the same molecular weight.