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    Hydrophilic Polymer Supports for Solid-Phase Synthesis: Hydroxyl-Functional Beads of Poly(vinylpyrrolidone)
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    Abstract:
    Poly(vinylpyrrolidone) (PVP) has solubility properties that make it an attractive material for polymer-assisted synthesis applications; however, the naked polymer lacks reactive groups upon which to do chemistry. Furthermore, large differences in radical reactivity between 1-vinylpyrrolidin-2-one (NVP) and most other monomers lead to compositional drift during copolymerization, further complicating the introduction of functional groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Three monomers introducing hydroxyl-functional groups and a new cross-linker, all derivatives of NVP, were synthesized and used in the preparation of a new type of hydrophilic polymer beads by aqueous suspension polymerization. These lightly cross-linked beads contain hydroxyl groups at a functional loading of 0.21−0.29 mmol/g and swell extensively in a broad range of solvents.
    Keywords:
    N-Vinylpyrrolidone
    Functional Polymers
    Reactivity
    Suspension polymerization
    Poly(vinylpyrrolidone) (PVP) has solubility properties that make it an attractive material for polymer-assisted synthesis applications; however, the naked polymer lacks reactive groups upon which to do chemistry. Furthermore, large differences in radical reactivity between 1-vinylpyrrolidin-2-one (NVP) and most other monomers lead to compositional drift during copolymerization, further complicating the introduction of functional groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Three monomers introducing hydroxyl-functional groups and a new cross-linker, all derivatives of NVP, were synthesized and used in the preparation of a new type of hydrophilic polymer beads by aqueous suspension polymerization. These lightly cross-linked beads contain hydroxyl groups at a functional loading of 0.21−0.29 mmol/g and swell extensively in a broad range of solvents.
    N-Vinylpyrrolidone
    Functional Polymers
    Reactivity
    Suspension polymerization
    Citations (15)
    Abstract Results from an experimental study concerning gel formation with nitroxide‐mediated radical polymerization (NMRP) of styrene (S) and divinylbenzene (DVB) in aqueous suspension are reported. Influence of certain polymerization parameters on the dynamics of network formation was measured, namely the polymerization temperature and initial composition. Soluble polymer formed at different polymerization times was analyzed by size exclusion chromatography (SEC) with refractive index (RI) and multi angle laser light scattering (MALLS) detection. Concentration of pendant double bonds (PDB) was quantified by means of ICl titration and the morphology of the S/DVB particles was inspected by SEM. Incidence of cyclizations was assessed and the improvement of network homogeneity when using NMRP/FRP is discussed. magnified image
    Divinylbenzene
    Suspension polymerization
    Citations (19)
    ABSTRACT A versatile strategy for the preparation of end‐functional polymers and block copolymers by radical exchange reactions is described. For this purpose, first polystyrene with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group (PS‐TEMPO) is prepared by nitroxide‐mediated radical polymerization (NMRP). In the subsequent step, these polymers are heated to 130 °C in the presence of independently prepared TEMPO derivatives bearing hydroxyl, azide and carboxylic acid functionalities, and polymers such as poly(ethylene glycol) (TEMPO‐PEG) and poly(ε‐caprolactone) (TEMPO‐PCL). Due to the simultaneous radical generation and reversible termination of the polymer radical, TEMPO moiety on polystyrene is replaced to form the corresponding end‐functional polymers and block copolymers. The intermediates and final polymers are characterized by 1 H NMR, UV, IR, and GPC measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57 , 2387–2395
    Functional Polymers
    Moiety
    Polystyrene
    Citations (2)
    Part 1 The fundamentals: introduction chemistry and kinetic model of radical vinyl polymerization special characteristics of radical vinyl polymerization special characteristics of radical vinyl polymerization. Part 2 The initiating systems: initiation of vinyl polymerization by organic molecules and nonmetal initiators chemical initiation by metals or metal-containing compounds suspension polymerization redox initiators photoinitiated radical vinyl polymerization vinyl polymerization initiated by high-energy radiation functionalization of polymers living radical polymerization. Part 3 Technical processes of vinyl polymerization: continuous processes of radical vinyl polymerization technical processes for industrial production. Part 4 Parameters: data and structures.
    Suspension polymerization
    Vinyl polymer
    Ionic polymerization
    Cobalt-mediated radical polymerization
    Living free-radical polymerization
    Coordination polymerization
    Chain-growth polymerization
    Citations (123)
    Summary Temperature and pH stimuli‐responsive hydrogel particles were synthesized using inverse‐suspension polymerization in batch stirred reactor. Different water soluble co‐monomers were present in the initial mixture (e.g. N‐isopropylacrylamide and acrylic acid) as well as crosslinkers with different functionalities. Different operating conditions such as polymerization temperature, monomers dilution, neutralization and the initial ratios of co‐monomers and monomers/crosslinker were also tried. Hydrogel particles were produced considering classical free‐radical polymerization (FRP) and also RAFT polymerization. Commercially available RAFT agents 4‐cyano‐4‐phenylcarbonothioylthio‐pentanoic acid (CPA), 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid (DDMAT) and cyanomethyl dodecyl trithiocarbonate (CDT) were alternatively used. Sampling at different polymerization times allowed the study of the kinetics of polymerization through the analysis by SEC of the soluble phase. A tetra‐detector array with simultaneous detection of refractive index, light scattering, intrinsic viscosity and ultra‐violet signals was used in these studies. Usefulness of in‐line FTIR‐ATR monitoring to study the building process of such networks was also assessed. The performance of hydrogel beads was studied through drug delivery tests triggered by changes in the environmental temperature and pH. This research aims to contribute for the elucidation of the connection between the synthesis conditions, molecular architecture and properties/performance of such advanced materials.
    Suspension polymerization
    Chain transfer
    Acrylic acid
    Precipitation polymerization
    Citations (21)
    2-Hydroxyethyl methacrylate(HEMA),N-vinylpyrrolidone(NVP) and N,N′Methylene bisacrylamide(MBA) were co-polymerized via inverse suspension polymerization method,and the crosslinked terpolymer microspheres with size of 100~200 μm were obtained.The effects of various factors,such as disperser kind,agitation rate,ratio of oil phase to water phase and the amount of crosslinking agent,on the formation of the microspheres and the diameter of the microspheres were examined.The chemical structure of the microspheres was characterized by FTIR,and their morphology was observed by scanning electron microscopy.
    Suspension polymerization
    Suspension
    Disperser
    Morphology
    N-Vinylpyrrolidone
    Citations (0)
    Chain transfer
    Suspension polymerization
    Kinetic chain length
    Branching (polymer chemistry)
    Chain-growth polymerization
    Cobalt-mediated radical polymerization
    Bulk polymerization
    Precipitation polymerization
    Ionic polymerization