Iodine transfer copolymerization of vinylidene fluoride and α‐trifluoromethacrylic acid in emulsion process without any surfactants

The synthesis of poly(VDF‐co‐TFMA) copolymers (where VDF and TFMA stand for vinylidene fluoride and α‐trifluoromethacrylic acid, respectively) by iodine transfer polymerization without any surfactant is presented. First, the synthesis and the control of the copolymerization of VDF and TFMA were investigated in the presence of two chain transfer agents, 1‐perfluorohexyl iodide (C₆F₁₃I) and 1,4‐diodoperfluorobutane (IC₄F₈I). TFMA monomer was incorporated in the copolymer in good yields. Moreover, the molecular weights of the resulting poly(VDF‐co‐TFMA) copolymers were in good agreement with the theoretical values for feed of TFMA/VDF ratios that ranged from 50/50 to 0/100 mol %, showing that TFMA does not disturb the controlled radical polymerization of VDF. The microstructures of the produced copolymers were characterized by ¹H and ¹⁹F NMR to assess the amount of each comonomer, and the molecular weights and the end‐groups of the copolymers. The results on the control of the copolymerization were compared to those obtained with and without the presences of TFMA and surfactant. The addition of a low amount of TFMA improved the control of the polymerization of VDF without using any surfactant. Also, the size of particles, assessed by light scattering, was smaller than 200 nm. The addition of TFMA in low proportions, that is, 5 to 10 mol %, enabled us to stabilize the particle size and to decrease the size by one order of magnitude. The emulsifying behavior of TFMA (in low amount in the copolymer, that is, <10 mol %) was similar to those achieved when a surfactant was added. Indeed, neither sedimentation nor destabilization was observed after several days. The reactivity ratios for r_TFMA and r_VDF were 0 and 1.6 at 80 °C, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4710–4722, 2009     

Radical copolymerization of 2‐trifluoromethylacrylic monomers. I. Kinetics of their copolymerization with norbornenes and vinyl ethers as studied by in situ 1H NMR analysis

Radical copolymerizations of electron‐deficient 2‐trifluoromethylacrylic (TFMA) monomers and electron‐rich norbornene derivatives and vinyl ethers with azobisisobutyronitrile were investigated by analyzing the kinetics in situ with ¹H NMR. Although none of the monomers underwent radical homopolymerization under normal conditions, they copolymerized readily, producing a copolymer containing 60–70 mol % TFMA. Terpolymerization involving these monomers was also investigated. The rates of copolymerization and kinetic chain lengths were determined in some cases on the basis of the in situ kinetics analysis. These radial copolymerizations of TFMA provide a basis for the preparation of chemical‐amplification resist polymers for emerging 157‐nm lithography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1468–1477, 2004     

The States,Diffusion, and Concentration Distribution of Water in Radiation‐Formed PVA/PVP Hydrogels

Abstract

Hydrogels with various compositions of polyvinyl alcohol (PVA) and poly(1‐vinyl‐2‐ pyrrolidinone) (PVP) were prepared by irradiating mixtures of PVA and PVP in aqueous solutions with gamma‐rays from ⁶⁰Co sources at room temperature. The states of water in the hydrogels were characterized using DSC and NMR T₂ relaxation measurements and the kinetics of water diffusion in the hydrogels were studied by sorption experiments and NMR imaging. The DSC endothermic peaks in the temperature range ?10 to +10°C implied that there are at least two kinds of freezable water present in the matrix. The difference between the total water content and the freezable water content was referred to as bound water, which is not freezable. The weight fraction of water at which only nonfreezable water is present in a hydrogel with F_VP=0.19 has been estimated to be g_H2O/g_Polymer=0.375. From water sorption experiments, it was demonstrated that the early stage of the diffusion of water into the hydrogels was Fickian. A curve‐fit of the early‐stage experimental data to the Fickian model allowed determination of the water diffusion coefficient, which was found to lie between 1.5×10^?11 m² s^?1 and 4.5×10^?11 m² s^?1, depending on the polymer composition, the cross‐link density, and the temperature. It was also found that the energy barrier for diffusion of water molecules into PVA/PVP hydrogels was ≈24 kJ mol^?1. Additionally, the diffusion coefficients determined from NMR imaging of the volumetric swelling of the gels agreed well with the results obtained by the mass sorption method.     

Synthesis and characterization of pyrene bearing amphiphilic miktoarm star polymer and its noncovalent interactions with multiwalled carbon nanotubes

A novel amphiphilic miktoarm star polymer, polystyrene‐poly(ethylene glycol)‐poly(methyl methacrylate), bearing a pyrene group at the end of PS arm (Pyrene‐PS‐PEG‐PMMA) was successfully synthesized via combination of atom transfer radical polymerization and click chemistry. The structure and composition of the amphiphilic miktoarm star polymer were characterized by gel permeation chromatography and ¹H NMR. The functionalization of multiwalled carbon nanotubes (MWCNTs) via “π–π” stacking interactions with pyrene‐PS‐PEG‐PMMA miktoarm star polymer was accomplished and the resulting polymer‐MWCNTs hybrid was analyzed by using ¹H NMR, UV–vis, fluorescence spectroscopy, and thermal gravimetric analysis. The high‐resolution transmission electron microscopy and analytical techniques aforementioned confirmed that the noncovalent functionalization of MWCNT's with the amphiphilic miktoarm star polymer was successfully achieved. The MWCNT/pyrene‐PS‐PEG‐PMMA exhibited significant dispersion stability in common organic solvents such as dimethyl formamide, chloroform, and tetrahydrofuran. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Sorption of methanol/MTBE and diffusion of methanol in 6FDA–ODA polyimide

This article discusses the diffusion and solubility behavior of methanol/methyl tert‐butyl ether (MTBE) in glassy 6FDA–ODA polyimide prepared from hexafluoroisopropylidene 2,2‐bis(phthalic anhydride) (6FDA) and oxydianiline (ODA). The diffusion coefficients and sorption isotherm of methanol vapor in 6FDA–ODA polyimide at various pressures and film thicknesses were obtained with a McBain‐type vapor sorption apparatus. Methanol/MTBE mixed‐liquid sorption isotherms were obtained by head‐space chromatography and compared with a pure methanol sorption isotherm obtained with a quartz spring balance. Methanol sorption isotherms obtained with the two methods were almost identical. Both methanol sorption isotherms obeyed the dual‐mode model at a lower activity, which is typical for glassy polymer behavior. The MTBE was readily sorbed into the polymer in the presence of methanol, but the MTBE sorption isotherm exhibited a highly nonideal behavior. The MTBE sorption levels were a strong function of the methanol sorption level. Methanol diffusion in the polymer was analyzed in terms of the partial immobilization model with model parameters obtained from average diffusion coefficients and the dual‐mode sorption parameters. Simple average diffusion coefficients were obtained from sorption kinetics experiments, whereas the dual‐mode sorption parameters were obtained from equilibrium methanol sorption experiments. An analysis of the mobility and solubility data for methanol indicated that methanol tends to form clusters at higher sorption levels. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2254–2267, 2000     

Hydrophilic domain structure in polymer exchange membranes: Simulations of NMR spin diffusion experiments to address ability for model discrimination

We detail the development of a flexible simulation program (NMR_DIFFSIM) that solves the nuclear magnetic resonance (NMR) spin diffusion equation for arbitrary polymer architectures. The program was used to explore the proton (¹H) NMR spin diffusion behavior predicted for a range of geometrical models describing polymer exchange membranes. These results were also directly compared with the NMR spin diffusion behavior predicted for more complex domain structures obtained from molecular dynamics (MD) simulations. The numerical implementation and capabilities of NMR_DIFFSIM were demonstrated by evaluating the experimental NMR spin diffusion behavior for the hydrophilic domain structure in sulfonated Diels‐Alder Poly(Phenylene) (SDAPP) polymer membranes. The impact of morphology variations as a function of sulfonation and hydration level on the resulting NMR spin diffusion behavior were determined. These simulations allowed us to critically address the ability of NMR spin diffusion to discriminate between different structural models, and to highlight the extremely high fidelity experimental data required to accomplish this. A direct comparison of experimental double‐quantum‐filtered ¹H NMR spin diffusion in SDAPP membranes to the spin diffusion behavior predicted for MD‐proposed morphologies revealed excellent agreement, providing experimental support for the MD structures at low to moderate hydration levels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 62–78     

Phase separation temperatures in the ternary system polystyrene/poly(α-methyl styrene)/cyclopentane

Phase separation temperatures of the ternary system polystyrene (PS) (M_w = 1.67 × 10⁴)/poly(α-methyl styrene) (PαMS) (M_w = 9.0 × 10⁴)/cyclopentane with a blend ratio PS/PαMS = 55/45 have been determined over the polymer concentration range 0.02 ≤ ψ_{PS + PαMS} ≤ 0.52, where ψ _{PS + PαMS} is the segment fraction of polymer in ternary system. Phase separation temperatures for the upper critical separation in the ternary system decrease with increasing ψ _{PS + PαMS} over the range 0.1 ≤ ψ _{PS + PαMS} ≤ 0.52. The vapor—liquid equilibrium in this system with a blend ratio PS/PαMS=50/50 has been determined over the concentration range 0.925 ≤ ψ_{PS + PαMS} < 0.995 and the temperature range 60–100°C by the piezoelectric vapor sorption method. The polymer—polymer interaction parameters χ′₁₂ determined are positive except at 100°C and increase with increasing ψ _{PS + PαMS}. Values of χ′₁₂ extrapolated to zero solvent concentration are positive (0.0–1.3) over the temperature range measured. Phase separation behavior is discussed in terms of phase separation temperature in a ternary system and the polymer–polymer interaction parameter.     

Radical copolymerization of 2‐trifluoromethylacrylic monomers. II. Kinetics,monomer reactivities,and penultimate effect in their copolymerization with norbornenes and vinyl ethers

Radical copolymerizations of electron‐deficient 2‐trifluoromethylacrylic (TFMA) monomers, such as 2‐trifluoromethylacrylic acid and t‐butyl 2‐trifluoromethylacrylate (TBTFMA), with electron‐rich norbornene derivatives and vinyl ethers with 2,2′‐azobisisobutyronitrile as the initiator were investigated in detail through the analysis of the kinetics in situ with ¹H NMR and through the determination of the monomer reactivity ratios. The norbornene derivatives used in this study included bicyclo[2.2.1]hept‐2‐ene (norbornene) and 5‐(2‐trifluoromethyl‐1,1,1‐trifluoro‐2‐hydroxylpropyl)‐2‐norbornene. The vinyl ether monomers were ethyl vinyl ether, t‐butyl vinyl ether, and 3,4‐dihydro‐2‐H‐pyran. Vinylene carbonate was found to copolymerize with TBTFMA. Although none of the monomers underwent radical homopolymerization under normal conditions, they copolymerized readily, producing a copolymer containing 60–70 mol % TFMA. The copolymerization of the TFMA monomer with norbornenes and vinyl ethers deviated from the terminal model and could be described by the penultimate model. The copolymers of TFMA reported in this article were evaluated as chemical amplification resist polymers for the emerging field of 157‐nm lithography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1478–1505, 2004     

Polyimide-epoxy alloys prepared via micro-modification: Water sorption and diffusion

A novel polyimide-epoxy or PI-EP alloys are prepared by the modification of polyamic acid in the concentration range of 1.54×10⁻⁶ to 1.54×10⁻² mol/L. The methanol sorption for these alloys at 24 hrs and at equilibrium conditions are determined and the residual solvent in fully cyclized polyimides were calculated. The presence of the residual solvent is visualized in fully imidized polymer and a structure containing partly imidized amic acid moiety is proposed and their concentration (in percentage) is calculated. The water sorption for these alloys at 24 hrs and at equilibrium conditions and the values of the water diffusion coefficient are determined from absorption isotherms. The PI-EP alloys have shown comparatively lower water sorption and higher diffusion coefficient than the unmodified polyimide. The mechanistic aspects of water sorption and diffusion are discussed.     

Mutual diffusion and thermodynamics in the blends of polystyrene and tetramethylbisphenol-A polycarbonate

A study was made of miscible polymer blends of deuterated polystyrene (d-PS) and tetramethylbisphenol-A polycarbonate (TMPC). The Flory interaction parameter χ was obtained from the relation between mutual and tracer diffusion coefficients, D? and D^*, which were measured by forward recoil spectrometry. The temperature dependence of diffusion at PS weight fractions ω of 0.25 and 0.5, and the composition dependence at temperatures 45°C above the glass transition temperature, T_g, were investigated. A stronger dependence of χ on both temperature (at ω = 0.5) and composition was observed in comparison with other miscible binary polymer blends involving PS. Analysis using the generalized lattice-fluid model of Sanchez and Balazs¹ showed that the incorporation of a significant specific interaction is needed to explain the temperature dependence of χ. The diffusion coefficients obtained in the one-phase region were extrapolated to the two-phase region, and these were compared with the effective diffusion coefficient extracted from phase separation dynamics measured by light scattering.² A significant discrepancy between the extrapolated and effective diffusion coefficients was observed. © 1995 John Wiley & Sons, Inc.     

Silicon surface modification with trialkoxysilyl‐functionalized star‐shaped polymers

The synthesis of trimethoxysilane end‐capped linear polystyrene (PS) and star‐branched PS and subsequent silicon (Si) surface modification with linear and star polymers are described. Trimethoxysilane terminated PS was synthesized using sec‐butyl lithium initiated anionic polymerization of styrene and subsequent end‐capping of the living anions with p‐chloromethylphenyl trimethoxysilane (CMPTMS). ¹H and ²⁹Si NMR spectroscopy confirmed the successful end‐capping of polystyryllithium with the trimethoxysilane functional group. The effect of a molar excess of end‐capper on the efficiency of functionalization was also investigated, and the required excess increased for higher molar mass oligomers. Acid catalyzed hydrolysis and condensation of the trimethoxysilane end‐groups resulted in star‐branched PS, and NMR spectroscopy and SEC analysis were used to characterize the star polymers. This is the first report of core‐functionalized star‐shaped polymers as surface modifiers and the first comparative study showing differences in surface topography between star and linear polymer modified surfaces. Surface‐sensitive techniques such as ellipsometry, contact angle goniometry, and AFM were used to confirm the attachment of star PS, as well as to compare the characteristics of the star and linear PS modified Si surfaces. The polymer film properties were referenced to polymer dimensions in dilute solution, which revealed that linear PS chains were in the intermediate brush regime and the star‐branched PS produced a surface with covalently attached chains in the mushroom regime. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3655–3666, 2005     

NMR spectroscopy and free volume analysis of the effects of copolymer composition on the swelling kinetics and chain dynamics of highly crosslinked copolymers of acrylic acid with PEG‐containing multiacrylates

Novel ionizable polymer networks were prepared from oligo(ethylene glycol) (OEG) multiacrylates and acrylic acid (AA), employing bulk radical photopolymerization techniques. The properties of these materials exhibited a complex dependence on the network structure and composition. Penetrant sorption experiments demonstrated that the crosslinked structure of the copolymers depended very strongly on the AA content as well as the number of ethylene glycol groups. The impact of varying the AA content and the oligo(ethylene glycol) chain length on the polymer chain dynamics was examined using diffusion and ¹³C NMR relaxation studies. The penetrant uptake studies indicated a coupling of Fickian and relaxation‐driven contributions to the swelling behavior. The effect of increasing the AA content on the characteristic chain relaxation time was reversed as the oligo(ethylene glycol) chain length was varied, indicating that chain relaxation is controlled by structural considerations, for shorter oligo(ethylene glycol) chains, and by compositional considerations, for longer oligo(ethylene glycol) chains. Measured compositional effects on solid state ¹³C NMR relaxation times supported these conclusions. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1953–1968, 1999     

Precise molecular weight determination and structure characterization of end-functionalized polymers: An NMR approach <Emphasis Type="Italic">via</Emphasis> combination of one-dimensional and two-dimensional techniques

We present here the application of one-dimensional and two-dimensional NMR techniques to characterize the structure of methoxyl end-functionalized polystyrenes (PS). The peaks in ¹H-NMR spectra corresponding to main-chain, side-chain and chain-end groups are assigned by ¹H-¹H gCOSY, ¹H-¹³C gHSQC and gHMBC spectra. For the first time, the spin-lattice relaxation time (T ₁) of protons of the chain-ends is revealed to be affected more by polymer molecular weight (MW) than by the protons of the main-chains and the side-chains (almost independent from MW). As a result, a much higher delay time (d1) for chain-ends (d1 > 20T ₁) is needed for quantitative NMR measurement when using end-group estimation method to obtain the MW of PS, which is in accordance with the value estimated by GPC. An improved method for the polymer MW determination is established, by combination of different NMR techniques to distinguish the peaks, and a large d1 setting to achieve quantitative NMR analysis.     

Preparation of a sorbent for metal ions based on N-(5-methylimidazol-4-ylmethyl) chitosan with medium degree of substitution

A procedure was developed for preparing a heterocycle-containing chelating amino polymer, N-(5-methylimidazol-4-ylmethyl) chitosan, by polymer-analogous transformations of chitosan in reaction with 4-chloromethyl-5-methylimidazole. The procedure allows synthesis of the polymer with the degree of substitution of up to 0.8, with simultaneous formation of the cross-linked structure. The structure of the polymers prepared was proved by IR and ¹³C NMR spectroscopy. The ability of N-(5-methylimidazol-4-ylmethyl) chitosan with the degree of substitution of 0.54 to sorb Cu²⁺ and Ni²⁺ ions was evaluated. According to the sorption isotherms, the sorption capacity of this derivative exceeds that of the unmodifi ed polymer by a factor of 5.     

Dehydration of aqueous acetonitrile solution by pervaporation using PVA–iron oxide nanocomposite membrane

Pervaporative performances were investigated for dehydration of water–acetonitrile using nanocomposite metal oxide and Pervap^® 2202 membranes. Poly (vinyl alcohol) based nanocomposite metal oxide membranes were prepared through co-precipitation of different amounts of Fe (II) and Fe (III). The freestanding nanocomposite metal oxide membranes were characterized by Transmission electron microscopy and X-ray diffraction. Sorption studies evaluated the extent of interaction and degree of swelling of the membranes. Fe containing PVA polymer matrix showed improved flux and selectivity. In order to observe simultaneous effect of flux and selectivity, pervaporation separation index showed 10 wt.% iron oxide containing membrane is the most amongst all tested. The diffusion coefficients were calculated using pervaporation results and sorption kinetics data. An attempt was made to predict sorption selectivity thermodynamically. PV separation factor was observed to be governed by sorption and/or diffusion phenomena and sorption selectivity was found to be higher than PV separation factor. Prediction of concentration profile in the membrane was also attempted and the results showed that water concentration in the membrane drops down with increase in membrane thickness.     

Synthesis of Ferrocene-based Esters as Burning Rate Catalysts and their Anti-migration Study

Ferrocene-based (Fc-based) burning rate catalysts (BRCs) play an essential role in the solid rocket propellants. However, the migration problem during curing and storage limits their applications. To retard the migration problems of Fc-based BRCs and to increase the burning rate (BR) of AP-based propellants, Fc-based esters compounds (Es-Fcs) were synthesized. The synthesized Es-Fcs were characterized by X-ray diffraction, proton nuclear magnetic resonance (¹H NMR),¹³C NMR and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical behaviors of Es-Fcs were investigated by cyclic voltammetry (CV). The BR catalytic activity of Es-Fcs on thermal decomposition of AP were examined by thermogravimetry (TG). Thermal analysis results showed that these Es-Fcs had good BR catalytic effects on thermal decomposition of AP. It was found that the anti-migration performance of Es-Fcs were better than catocene and Fc.     

Co‐Micellization Investigated by Pulsed Field Gradient‐NMR Spectroscopy

Summary: Pulse field gradient‐NMR (PFG‐NMR) spectroscopy is determined to be a more suitable method for the investigation of self‐association processes in multi‐component (co)polymer systems than light scattering methods. Here the co‐micellization of mixtures of the diblock copolymer polystyrene‐block‐(hydrogenated polyisoprene) (PS‐HPI) and the triblock copolymer polystyrene‐block‐(hydrogenated polybutadiene)‐block‐polystyrene (PS‐HPB‐PS) in decane is investigated by PFG‐NMR spectroscopy and the results compared to those experimentally determined by static (SLS) and dynamic (DLS) light scattering. As expected, diffusion coefficients determined by PFG‐NMR spectroscopy are systematically lower than those from DLS. The PFG‐NMR measurements provided higher values of cequation/tex2gif-stack-1.gif(X)/c_tot than the model calculations, illustrating that the basic assumption used in the calculations, i.e., that the number concentration of co‐micelles in mixed solutions follows the dilution with a triblock copolymer solution, 1 − X, is not fully valid at high X (weight fraction of PS‐HPB) values.

Comparison of PFG‐NMR spectroscopy and SLS (cequation/tex2gif-stack-2.gif/c_tot = equilibrium concentration of free PS‐HPB‐PS over the total concentration of copolymers in solution, X = weight fraction of PS‐HPB).     

Sorption and diffusion of methanol and water in PVDF‐g‐PSSA and Nafion® 117 polymer electrolyte membranes

Sorption and diffusion properties of poly(vinylidene fluoride)‐graft‐poly(styrene sulfonic acid) (PVDF‐g‐PSSA) and Nafion® 117 polymer electrolyte membranes were studied in water/methanol mixtures. The two types of membranes were found to have different sorption properties. The Nafion 117 membrane was found to have a maximum in‐solvent uptake around 0.4 to 0.6 mole fraction of methanol, while the PVDF‐g‐PSSA membranes took up less solvent with increasing methanol concentration. The proton NMR spectra were recorded for membranes immersed in deuterated water/methanol mixtures. The spectra showed that the hydroxyl protons inside the membrane exhibit resonance lines different from the resonance lines of hydroxyl protons in the external solvent. The spectral features of the lines of these internal hydroxyl groups in the membranes were different in the Nafion membrane compared with the PVDF‐g‐PSSA membranes. Diffusion measurements with the pulsed field gradient NMR (PFG‐NMR) method showed that the diffusion coefficient of the internal hydroxyl groups in the solvent immersed Nafion membrane mirrors the changes in the diffusion coefficients of hydroxyl and methyl protons in the external solvent. For the PVDF‐g‐PSSA membranes, a decrease in the diffusion coefficient of the internal hydroxyl protons was seen with increasing methanol concentration. These results indicate that the morphology and chemical structure of the membranes have an effect on their solvent sorption and diffusion characteristics. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3277–3284, 2000     

Synthesis and characterization of a new conjugated polymer: Polytrifluoromethylacetylene

Polytrifluoromethylacetylene (PTFMA) was synthesized from trifluoromethylacetylene (TFMA) using a PdCl₂/DMF catalyst solution or the anionic initiator n-butyl lithium. Although PdCl₂ proved to be an effective catalyst for the polymerization of TFMA, long reaction times and poor yields made characterization of the resultant polymer difficult. The use of n-butyl lithium, on the other hand, resulted in high yields of PTFMA in relatively short reaction times. The results of thermal analysis and the effects of n- and p-type doping on the electrical conductivity of the polymer are discussed.     

Imidazole-containing chitosan derivative: a new synthetic approach and sorption properties

A novel method for the synthesis of a hetaryl-containing chelate amino polymer, namely, N-(4(5)-imidazolylmethyl)chitosan (IMC), with a degree of substitution up to 0.3 was proposed. The “synthesis in gel” approach involves direct substitution of the hydroxyl group in 4(5)-imidazolylmethanol. The structures of these polymers were confirmed by ¹H NMR data. For sorption studies, IMC samples were crosslinked with epichlorohydrin and diglycidyl ethers of ethylene glycol and diethylene glycol. The degrees of swelling and sorption properties of the polymers largely depend on the crosslinking agent and the degree of crosslinking. The sorption capacities of IMC for Au^III, Pt^IV, and Pd^II ions are higher than those of the nonmodified polymer. The extraction of noble metal ions from chloride solutions becomes more selective with increasing degree of crosslinking. The sorption capacity of IMC for Co^II and Ni^II ions is higher than those of chitosan and its known N-heterocyclic derivatives.