Radical Polymerization Of N-vinylpyrrolidone Research Articles

2,6-Bis(1-butyl-1H-1,2,3-triazol-1-yl)pyridine-capped poly(N-vinylpyrrolidone)s: synthesis, complexation with metal ions, and self-assembly behavior

In this contribution, we reported the synthesis of 2,6-bis(1-butyl-1H-1,2,3- triazol-1-yl)pyridine-capped poly(N-vinylpyrrolidone)s (denoted BTP-PVPy). First, a 2,6-bis-(1-butyl-1H-[1,2,3]triazol-4-yl)-pyridin-4-yl]-methanol (BTP-CH2OH) was synthesized. The as-obtained BTP-CH2OH was then employed to react with 4-cyano-4-isopropoxythiocarbonylsulfanyl-4-methyl-butyric acid to obtain a BTP-functionalized xanthate. The latter was used to mediate the radical polymerization of N-vinylpyrrolidone (NVP). It was found that the radical polymerization of NVP was in living/controlled manner in the presence of BTP-functionalized xanthate. By controlling the molar ratios of NVP to the BTP-functionalized xanthate, the BTP-capped PVPy samples were obtained with various lengths of PVPy chains. The BTP-capped PVPy samples displayed the self-assembly behavior in aqueous media. Notably, the self-assembly behavior was significantly influenced with the complexation of BTP end groups with the metal ions [Pt(II), Zn(II), and Eu(III)]. The sizes and morphologies of the self-organized nanoobjects were quite dependent on the coordination behavior of the tridentate ligand (viz. BTP) with the metal ions. In addition, the self-assembled nanoobjects in aqueous suspension displayed different photoluminescent behavior, depending on the types of metal ions.

Poly(methyl methacrylate)-block-poly(N-vinyl pyrrolidone) diblock copolymer: A facile synthesis via sequential radical polymerization mediated by isopropylxanthic disulfide and its nanostructuring polybenzoxazine thermosets

In this contribution, we reported a facile synthesis of poly(methyl methacrylate)-block-poly(N-vinyl pyrrolidone) (PMMA-b-PVPy) diblock copolymers via sequential radical polymerizations mediated by isopropylxanthic disulfide (DIP). It was found that the radical polymerization of N-vinyl pyrrolidone (NVP) mediated by DIP was in a controlled and living manner. In contrast, the polymerization of methyl methacrylate mediated by DIP displayed the behavior of telomerization, affording xanthate-terminated PMMA with a good control of molecular weights while the conversion of monomer was not very high. The xanthate-terminated PMMA can be successfully used as the macromolecular chain transfer agent for the polymerization of NVP via RAFT/MADIX process and thus PMMA-b-PVPy diblock copolymers can be successfully synthesized via sequential radical polymerization mediated by isopropylxanthic disulfide. One of these diblock copolymers was incorporated into polybenzoxazine and the nanostructured thermosets were obtained as evidenced by transmission electron microscopy, small angle X-ray scattering, and dynamic mechanical thermal analysis. The formation of nanostructures in polybenzoxazine thermosets was ascribed to a reaction-induced microphase separation mechanism.

Microstructure and biological activity of sulfonated N-vinylpyrrolidone copolymers

This article deals with the preparation, characterization, and in vitro evaluation of new copolymers based on functionalized N-vinylpyrrolidone bearing pendant sulfonic acid groups statistically or alternately distributed in the macromolecular chains. Statistical copolymers were obtained by free radical polymerization of N-vinylpyrrolidone and sulfonated N-vinylpyrrolidone ( r VP = 1.61; r VPSulf = 0.90) in water, and alternating copolymers were synthesized by free radical polymerization of N-vinylpyrrolidone or sulfonated N-vinylpyrrolidone with methyl maleate in N,N-dimethylformamide followed by hydrolysis of the resulting copolymers. The influence of these new materials on acidic fibroblast growth factor–mediated mitogenesis of fibroblasts demonstrated that sequence distribution (copolymer microstructure) plays a key role in the biological performance of these polymers. Alternating copolymers did not present biological activity, whereas statistical copolymers inhibited acidic fibroblast growth factor activity in a sulfonated N-vinylpyrrolidone dose-dependent manner.

Preparation of polyacrylonitrile nanoparticles via dispersion polymerization of acrylonitrile using a poly(N-vinyl pyrrolidone)-cobalt complex in an aqueous system

Monodisperse spherical polyacrylonitrile (PAN) nanoparticles were successfully prepared for the first time by dispersion polymerization of acrylonitrile (AN) in water using well-defined poly(N-vinyl pyrrolidone) (PVP) that was end-capped by a cobalt(II) acetylacetonate (Co(acac)2) complex (PVP-Co(acac)2) as both a macroinitiator and a colloidal stabilizer. The well-defined PVP-Co(acac)2 (Mn = 14,000 g/mol, PDI = 1.25) was synthesized by the bulk cobalt-mediated radical polymerization of N-vinyl pyrrolidone at 20 °C using 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) as an initiator and Co(acac)2 as a regulating agent. The PVP macroradicals generated at 30 °C by the homolytic cleavage of the C–Co bonds in PVP-Co(acac)2 initiated the dispersion polymerization of AN, as well as successfully stabilized the growing PAN particles. The average diameters of PAN nanoparticles synthesized with 20, 30, 40, and 50 wt% of PVP-Co(acac)2 at 30 °C for 24 h were 263.5, 163.1, 157.3, and 143.5 nm, respectively. The PAN nanoparticles had a slightly crumpled spherical appearance, and the degree of crystallinity of the PAN nanoparticles prepared using 30 wt% of PVP-Co(acac)2 was 31.2%. The mol% of VP units in the PAN nanoparticles was about 6 mol%, and the PVP chains were present on the surface of the PAN nanoparticles as a stabilizing layer. The PVP hairy chains could successfully stabilize very small Ag nanoparticles on the surface of the PAN nanoparticles.

Surface grafting modification of fibrous silicates with polyvinylpyrrolidone and its application in nanocomposites

AbstractChemical surface modification of fibrous silicate with polyvinylpyrrolidone (PVP) or its derivates via grafting‐from and grafting‐to methods was investigated. The grafting‐from method was based on the immobilization of reactive end functional groups of silane coupling agents on silicate surface, followed by chain growth via radical polymerization of N‐vinylpyrrolidone (NVP) to form grafted polymers with different molecular weight. In the grafting‐to method, a novel copolymer PVP‐171 with side functionalized groups and designed molecular weight was synthesized by radical polymerization of NVP and vinyltrimethoxysilane (DB171) and then bonded to the surface of fibrous silicates. Evidences from FTIR, XPS, TGA, and BET test indicate that there are ∼ 68,000 reactive sites per square meters on the surface with the grafted vinyl concentration of 59 mequiv per 100 g of clay. XRD patterns and SEM images demonstrate that grafting modification was bound on the silicate surface and make the surface rough with the increase of graft‐loading quantity. In contrast with grafting‐to approach, grafting‐from approach facilitates the dispersion of silicates in PET composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and optical properties of water-soluble poly(vinylpyrrolidone) - modified fullerene C60

The effect of fullerene on the radical polymerization of N-vinylpyrrolidone with lauroyl peroxide in toluene was investigated kinetically. C60 was found to act both as inhibitor and as retarder because the polymerization rate and the molecular weight of resulting poly(vinylpyrrolidone) is decreasing with the increase of the fullerene concentration (0-6.94 x 10-4 mol l-1). The water-soluble poly(vinylpyrrolidone)-modified fullerene C60 compound was characterized by differential scanning calorimetric, Infrared and Raman spectroscopy, UV absorption and photoluminescence. Based on the results obtained by optical measurements, it is argued that by the covalent attachment of the polymeric radicals to fullerene cage the extended electronic conjugation system of the C60 is broken leading to the appearance of a polyene structure.

Synthesis and characterization of poly(N-vinyl pyrrolidone) initiated by stibonium ylide

1,2,3,4-Tetraphenylcyclopentadiene triphenyl stibonium ylide initiated radical polymerization of N-vinyl pyrrolidone (N-VP) in dioxane, at 60±0.2°C, for 60 min under nitrogen atmosphere has been carried out. The system follows ideal kinetics, i.e., R p ∝ [ylide]0.5 [N-VP]1.0. The values of k 2 p/k t and overall energy of activation have been computed as 0.5 × 10−2 lmol−1s−1 and 33 kJ/mol, respectively. The FT-IR spectrum shows a band at 1692 cm−1 due to the =C=O group of N-vinyl pyrrolidone. The 1H-NMR spectrum shows multiplet at 2.4 δ ppm and a doublet at 3.7 δ ppm due to CH2 protons. The DSC curve shows a glass transition temperature (T g) as 48°C. The presence of six hyperfine lines in the ESR spectrum indicates that the system follows free radical polymerization and the initiation is brought about by phenyl radical.

Architecture of polymeric superstructures: Locking of cubic lattices by graft polymerization from photofunctional core-shell polymer microspheres

It is well known that submicron-size colloidal spheres form a body-centered cubic (BCC) or face-centered cubic (FCC) lattice in an aqueous solution [1–5]. More recently, Asher et al. [6] have developed an approach to permanently lock in the crystalline colloidal array ordering in a hydrogel matrix. We have also constructed polymeric superstructures by free radical polymerization of N-vinylpyrrolidone (VP) monomer as a matrix, after polypyrrole microspheres were arranged on a BCC lattice in VP monomer solution [7]. More recently, we demonstrated that the core-shell polymer microspheres [8] and highly armed star polymers [9] led to hierarchical structure transformation of the cubic lattices. That is to say, these radial branched polymers formed a lattice with a BCC structure near the overlap threshold (C∗). In the bulk of the film, this structure changed to a FCC lattice. After such branched polymers formed a cubic lattice in polymerizable vinyl monomer, the polymeric superstructures were locked permanently into an ordered lattice in a solid matrix by means of free-radical polymerization [10, 11]. This technique is one of the best methods for creating nanoscopic polymeric superstructures composed of three or two phase-separated microdomains. However, the microspheres exhibiting relatively large particle diameter were packed with irregular arrangement in places due to polymerization-induced phase separation. In this communication, we report the architecture of polymeric superstructure films formed by locking of polymer matrix by means of graft polymerization from photofunctional core-shell polymer microspheres. The well-defined polystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) diblock copolymer (SV: Mn = 7.27× 104, P4VP block 26.7 mol%) was prepared by the sequential anionic polymerization technique. The details concerning the synthesis, purification and characterization of diblock copolymers have been given elsewhere [12]. Fig. 1a shows the transmission electron microscopy (TEM) photograph of SV specimen cast from toluene. The dark portions are the P4VP phases selectively stained with OsO4. The morphological structure showed the dispersed P4VP spheres in a PS matrix. Core-shell polymer microspheres (SV-M) were synthesized by crosslinking the segregated chains in P4VP spherical microdomains with 1,4-dibromobutane (DBB) vapor at room temperature. The details concerning the synthesis and the characterization of such microspheres have been given previously [13]. Characteristics of the SV-M microsphere are listed in Table I. The crosslink density of P4VP cores was 30.3 mol%. Fig. 1b shows a TEM photograph of SV-M cast from 1.0 wt% toluene solution. This specimen corresponds to the restructural film from the core-shell microspheres. It is found from this photograph that dark crosslinked P4VP cores (average diameter Dc = 30.2 nm) with a narrow size distribution are dispersed in a PS matrix. It was also mentioned previously from small-angle Xray scattering (SAXS) measurements that P4VP cores were packed with a FCC arrangement in a bulk film [8]. The hydrodynamic diameter (DH = 96.9 nm) of microspheres was determined by means of dynamic light scattering (DLS). The C∗ [14] of the SV-M in benzene was calculated to be 11.9 wt% from the DH and total molecular weight of the microsphere. Photofunctional core-shell microspheres (SV-MP) were prepared as follows. The PS shell of parent

Effect of the type of solvent on radical polymerization of N-vinylpyrrolidone

A dilatometric study was made of the kinetics of polymerization of N-vinylpyrrolidone in various solvents (water, ethanol, 2-pyrrolidone and 2-methylpyrrolidone) using AID as initiator. It was established that in protonic solvents the effective rate constant of polymerization increases in proportion to the reduction in monomer concentration. With 2-methylpyrrolidone this constant remains unchanged over a wide range of concentration. It was found that the reaction is accelerated most markedly with aqueous solutions. It was assumed that hydrogen bonds between monomer and solvent molecules are of decisive kinetic significance.