ATRP Method Research Articles

Elastic polyesters improved by ATRP as reactive epoxy-modifiers of PLA

Block copolymers comprising poly(1,4-butylene adipate) or poly(1,4-butylene adipate-co-terephthalate) middle elastic segment and poly(glycidyl methacrylate-co-n-butyl methacrylate) side chains were obtained using the ARGET ATRP method. These copolymers were characterized by various average molar masses, compositions, numbers of epoxy groups per chain and epoxy equivalent weights and were utilized as reactive modifiers of polylactide (PLA) in extrusion type melt processing at 175 or 190 °C. Contrary to neat PLA processing, when modifiers of lower molar masses were applied then an increase in relative melt viscosity was observed in systems throughout the test run due to reactions of PLA-COOH with epoxy side groups in modifiers. The high molar mass modifiers were not as effective in compensation of the PLA degradation effect. Tensile strength properties of all the obtained compositions extruded in the form of thin strands were measured. Most of the obtained modifiers were able to enhance PLA in elasticity or/and strength. An aliphatic modifier acted as a reactive-internal plasticizer, therefore just slightly worsened the tensile strength but improved the elastic modulus and boosted elongation at break (it was up to 120 times higher than that of PLA). Although aliphatic-aromatic modifiers did not change elongation at break significantly, one of them reinforced and elasticized the PLA based system at once.

Synthesis and Characterization of PNIPAm Core Cross‐Linked Star Polymers and Their Functionalization with Cyclodextrin

Poly(N‐isopropylacrylamide) (PNIPAm) core cross‐linked star (CCS) polymers (s‐(PNIPAm)n) are synthesized by arm‐first ATRP method. The related synthesis conditions are investigated and optimized. By varying cross‐linker N,N‐methylenebisacrylamide (BIS) concentration, PNIPAm CCS polymers with about 47, 86, and 211 arms are synthesized. Then, under ATRP condition, the “living” sites at the core of s‐(PNIPAm)n reacting with a monovinyl β‐cyclodextrin (β‐CD) monomer afford β‐CD functionalized s‐(PNIPAm)n (CDF‐SPNIPAm). The structures of the star polymers are characterized. The results indicate that in CDF‐SPNIPAm, the ratio of β‐CD units to PNIPAm arm numbers could be up to 0.6:1. The fluorescence spectra of star polymer/ANS (8‐­anilino‐1‐naphthalenesulfonic acid ammonium salt hydrate) systems prove that the β‐CD moieties of CDF‐SPNIPAm are available for including guest molecules. By using pH‐sensitive adamantyl (Ada)‐terminated poly(4‐vinylpyridine) (Ada‐P4VP) (synthesized by ATRP strategy) as a model guest macromolecule, the host–guest complexation between β‐CD units of CDF‐SPNIPAm and adamantyl groups of Ada‐P4VP is confirmed via 2D NOESY 1H NMR and DLS measurements. The results indicate that the presence of the Ada‐P4VP arms provides temperature‐responsive star polymers with pH sensitivity. Therefore, the β‐CD‐functionalized star PNIPAm could provide host macromolecular platform for constructing novel miktoarm star polymers. image

Non-covalent functionalization of graphene oxide by pyrene-block copolymers for enhancing physical properties of poly(methyl methacrylate)

Pyrene-functionalized poly(methyl methacrylate)-block-polydimethylsiloxane (Py-PMMA-b-PDMS) copolymers were synthesized via ARGET ATRP method and further used to functionalize GO through the π–π interaction between pyrene and the carbon sheets.

Self-assemblies of the six-armed star triblock ABC copolymer: pH-tunable morphologies and drug release

A well-defined six-armed star triblock copolymer s-(PDEA62-b-PMMA195-b-PPEGMA47)6 was synthesized by the core-first ATRP method. The star triblock copolymer shows pH-tunable self-assembly behavior. Interestingly, the reversible vesicle–micelle transition could be achieved by simply adjusting the surrounding pH.

Ionic liquid-mediated synthesis and self-assembly of poly(ethylene glycol)-block-polystyrene copolymer by ATRP method

Poly(ethylene glycol)-block-polystyrene (PEG-b-PS) was synthesized by the atom transfer radical polymerization of styrene using PEG-Br as the macroinitiator in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]). CuBr and 2,2″-bipyridyl were used as the catalyst and ligand, respectively. The structure, composition, and molecular weight of the PEG-b-PS copolymer were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and gel permeation chromatography. The PEG-b-PS copolymer with a high molecular weight (Mn = 51,000 g mol−1) and relatively low polydispersity index (PDI = 1.35) was formed at 110 °C for 5 h. Self-assembly of this amphiphilic block copolymer in toluene at different concentrations and in dimethylformamide (DMF)/water systems was also examined. Transmission electron microscopy showed that the block copolymer formed different morphologies spontaneously according to the different solvent systems used.

Solution behavior of polyimide‐graft‐polystyrene copolymers in selective solvents

ABSTRACTA 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

Oil absorbency of cellulose/butylmethacrylate graft polymer fibers

Cotton pulp cellulose and butyl methacrylate were used as the main raw materials to synthesize cellulose/butylmethacrylate graft polymer (Cell-g-PBMA) via homogeneous ATRP method, after which the graft polymer was dissolved in N,N-dimethylacetamide to prepare a spinning solution, and the novel oil-absorbent Cell-g-PBMA graft polymer fibers were spun by wet-spinning method. The morphology of the polymer fibers before and after oil absorption was analyzed using a high-powered microscope and scanning electron microscope and the saturated oil absorption rate as well as buoyancy recovery of the fiber products were also studied. The results showed that Cell-g-PBMA polymer fibers had a rough surface and exhibited a void network structure that was specific to oil-absorbent materials. The saturated absorption rates of the Cell-g-PBMA polymer fibers for crude oil, vegetable oil, dichloromethane and diesel were 96.5, 78.7, 38.4, and 27.2 g/g, respectively, which were about 3–6 times that of a commercial polypropylene sorbent. The Cell-g-PBMA fibers also displayed excellent oil/water selectivity and high buoyancy recovery in the clean-up of oil over water. Its excellent oil absorbency demonstrated oil absorbent characteristics of both traditional oil-absorbing materials and synthetic oil-absorbing resins, rendering it an excellent fibrous oil-absorbent material.

Functionalization of polyacrylonitrile nanofiber using ATRP method for boric acid removal from aqueous solution

Poly(glycidyl methacrylate-t-N-methyl-d-glucamine) (P(GMA-t-NMDG)) functionalized polyacrylonitrile (PAN) nanofibers were prepared via electrospinning followed by surface modification. The functionalized PAN nanofiber mat was used for boric acid removal from aqueous solutions. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of vicinal polyalcohol groups on the surface of these nanofibers. Surface morphology of PAN-P(GMA-t-NMDG) nanofiber mat was studied by SEM. The analysis results from inductively coupled plasma mass spectrometry show that the boron adsorption process is pH-dependent with a maximum adsorption removal ratio at a pH value of 6.0–7.0. The as-functionalized PAN-P(GMA-t-NMDG) nanofiber mat is very effective for boric acid removal at extremely low concentrations which may find the potential application for further boric acid removal from the RO permeates. Meanwhile, the PAN-P(GMA-t-NMDG) nanofiber mat also demonstrates outstanding reusability.

Synteza kopolimerow poli(uretanowo-metakrylowych) z zastosowaniem makroinicjatora tetrafenyloetanouretanowego metoda polimeryzacji kontrolowanej ARGET ATRP

Poly(methyl methacrylate)-b-polyurethane-b-poly(methyl methacrylate) tri-block copolymers were synthesized for the first time using ARGET ATRP method. A specially prepared for this purpose tetraphenylethane-urethane macroinitiator (TPE-PUR-TPE) was used as a transitional product reacting with methyl methacrylate (MMA) in the presence of CuBr2 or CuCl2 catalyst and N,N,N',N”,N”-pentamethyldiethylenetriamine (PMDETA) or 2,2'-bipyridine (Bpy) as a complexing agent. It was found that both the molecular weight of the resulting copolymer versus MMA conversion and the value of ln([M]0/[M]) as a function of polymerization time increase linearly. High coefficients of linear correlation for the studied relationships indicate that the formation of tri-block copolymers takes place according to the mechanism of atom transfer radical polymerization. The results of FT-IR, 1H and 13C NMR spectral analyses as well as DSC and TGA thermal studies confirm the expected chemical structure of the synthesized macroinitiator and poly(urethane-methacrylate) copolymers produced with its involvement. Additionaly, the studies of surface properties (roughness, contact angle and SFE) of polymer films prepared from these copolymers indicate, based on the observed increase of hydrophobicity, the presence of block segments derived from PMMA.

Nanoreactors based on self-assembled amphiphilic diblock copolymers for the preparation of ZnO nanoparticles

A self-assembled diblock copolymer containing styrene (S), methyl methacrylate and a certain percentage of hydrophilic segment of poly(methacrylic acid) (i.e., poly(styrene)-block-poly(methyl methacrylate/methacrylic acid) was synthesized via the ATRP method in two steps. This was followed by a partial hydrolysis of the methyl ester linkages of the methyl methacrylate block under acidic conditions. The resultant block copolymer had a narrow molecular weight dispersity (Ð<1.3) and was characterized using FT-IR and Raman spectroscopy as well as size exclusion chromatography. The block copolymer was used as a nanoreactor for inorganic nanoparticles (ZnO). The incorporation of a single source precursor, such as ZnCl2, into the self-assembled copolymer matrix and the conversion into ZnO nanostructures was carried out in the liquid phase using wet chemical processing techniques. We report the synthesis and characterization of nanocomposites with dual characteristics due to the functionalities incorporated into the matrix. The optical properties were determined by UV–Vis and fluorescence, the crystallinity was studied using X-ray diffraction, and the thermal stability and studies of the cyclic voltammetry were obtained by thermogravimetric analyzes and potentiodynamic electrochemical measurements, respectively. The structural, topographical and morphological characterizations of the ZnO composite in relation to the precursor block copolymer were analyzed via scanning electron microscopy, transmission electron microscopy and atomic force microscopy.According to the results, the block copolymer shows good transparency in the visible region (when containing 20, 30 and 50wt.% nanoparticles) and was able to absorb UV irradiation below 350nm, indicating good UV-screening effects. The thermo gravimetric analysis data showed that the block copolymer composite is more thermally stable compared to the pure block copolymer. The self-assembled nanoscale morphology of the diblock copolymer results in the formation of uniformly distributed spherical nano particles within the polymer matrix.

Synthesis of poly(2-acetamidoacrylic acid) and its PEGMA block copolymer via ATRP in water

Controlled polymerization of a captodative monomer, 2-acetamidoacrylic acid (AAA), was studied for the first time in the literature. Salt of the monomer in water was polymerized using ATRP method and influence of several factors, including solvent composition, halogen exchange and additives like pyridine and halide salts were investigated to improve the control. Captodative monomers form very stable radicals favoring the active species over the dormant one. Depolymerization at room temperature under ATRP conditions was determined as the major obstacle in front of the high molecular weight polymers and block copolymer formation. Nevertheless, poly(AAA-b-(AAA-co-PEGMA)) block polymers were prepared through ATRP and possible applications were discussed. As an example, pH responsive nature and ability to coat superparamagnetic iron oxide nanoparticles were demonstrated.

Thermal degradation of two different polymers bearing amide pendant groups prepared by ATRP method

Piperidinocarbonylmethyl methacrylate (PyCMMA) and 1-(piperidinocarbonyl) ethylmethacrylate (PyCEMA) monomers were synthesized. Polymerizations of PyCMMA and PyCEMA were carried out by atom transfer radical polymerization. The structure of monomers and polymers was characterized by 1H-NMR, 13C-NMR, and FT-IR spectroscopies. Characterization of poly(PyCMMA) and poly(PyCEMA) were carried out using differential scanning calorimetry and gel permeation chromatography. The experimental results showed that the reaction exhibited characteristics of controlled polymerization. The thermal degradation behaviors of poly(PyCEMA) and poly(PyCMMA) were studied using thermogravimetry and a single line vacuum system consisting of a degradation tube with a condenser for product collection. The poly(PyCEMA) and poly(PyCMMA) were heated from ambient temperature to 325 and 500 °C, respectively. The products of degradation were collected as a cold ring fraction (CRF). The CRFs of degradation were investigated by means of IR, 1HNMR, and GC-MS. For the degradation of both polymers, the major products of CRFs are piperidinocarbonyl methanol and 1,2-dipiperidino,1-oxo ethane. The GC-MS, IR, and NMR data showed that depolymerization below 325 °C to the corresponding monomer was not prominantin the thermal degradation of poly(PyCMMA). The mode of thermal degradation including formation of the major products was identified.

Modification of poly(glycidyl methacrylate) grafted onto crosslinked PVC with iminopropylene glycol group and use for removing boron from water

Polymer supported core–shell type iminodipropylene glycol functions have been shown to be efficient in chelation with boric acid and can be used for removal of boric acid at ppm levels. Dehydrochlorinated poly(vinyl chloride) (DHPVC) polymeric sorbent was synthesized and graft copolymerization of glycidyl methacrylate(GMA) onto DHPVC was carried out using ATRP method. The epoxy rings in grafted PGMA reacted with excess of ethylenediamine to give an amine containing sorbent. Reaction of the latter with glycidol gives corresponding sorbent with iminopropylene glycol functions.The resulting polymeric sorbent has been demonstrated to be an efficient and regenerable specific sorbent for removal of boron in parts per million (ppm) levels. Kinetics of boron sorption and regeneration of the polymer was investigated.

Structure and Properties of Silk Grafted with N, N-Dimethylaminoethyl Methacrylate via the ARGET ATRP Method

Silk with antibacterial properties was grafted using dimethylaminoethyl methacrylate (DMAEMA) in water by the ATRP method. The structure and properties of silk-grafted-PDMAEMA (Silk-g-PDMAEMA) and quaternized grafted silk (Q-Silk-g-PDMAEMA) were investigated. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the grafting of DMAEMA and the quarternization. Differential scanning calorimetry (DSC) measurements indicate that the thermal stability of Silk-g-PDMAEMA slightly increased compared with the control silk. X-ray diffraction (XRD) curves demonstrate that the crystalline structure of Silk-g-PDMAEMA remained unchanged regardless of the DMAEMA grafting. The Q-Silk-g-PDMAEMA had good antibacterial properties when exposed to both Staphylococcus aureu and Escherichia coli, and had good washing fastness. The breaking strength, whiteness and gas permeability of Silk-g-PDMAEMA slightly decreased, which had no effect on the intrinsic properties of silk fabric.

Synthesis, Characterization and Photophysical Properties of Rhenium Complex-Containing Polymer PS-b-PMAA(PNPh-Re)

Two blcok copolymer PSt-b-PtBMA were synthesized by using ATRP method, in acid conditions, and further hydrolysis into amphiphilic copolymers PSt-b-PMAA; the PS-b-PMAA containing transition metal complex was obtained through PNPh-Re covacent-link to PS-b-PMAA chains, and the corresponding copolymers were charcterized by UV-vis and 1 H NMR.

Structure and Properties of Silk Grafted with 2-Hydroxyethyl Methacrylate by ARGET ATRP

In this work, silk was reacted with 2-bromoisobutyryl bromide to obtain silk macroinitiator for activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). Silk macroinitiator was grafted with 2-hydroxyethyl methacrylate (HEMA) via ARGET ATRP method to produce grafted silk in water aqueous. FT-IR characterization of the modified silk substrate showed that HEMA had been grafted onto the silk surface. Scanning electron microscopy (SEM) photos of the grafted silks showed significant differences from the untreated silk. X-ray diffraction curves demonstrated that the crystalline structure of silk remained unchanged regardless of the HEMA grafting. Differential scanning calorimetry (DSC) curves indicated that the thermal stability of the grafted silk was improved. The whiteness, strength and moisture regain of the grafted silk decreased slightly, but the wrinkle recovery angle of the grafted silk increased distinctly compared with the control sample.

Hydrophobic modification of wood via surface-initiated ARGET ATRP of MMA

To convert the hydrophilic surface of wood into a hydrophobic surface, the present study investigated activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) as a method of grafting methyl methacrylate (MMA) onto the wood surface. The wood treated with 2-bromoisobutyryl bromide and with the subsequently attached MMA via ARGET ATRP under different polymerization times (2h, 4h, 6h, 8h) were examined using scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. All the analyses confirmed that PMMA had been grafted onto the wood surface. Water contact angle measurement proved that the covering layer of PMMA on wood made the surface hydrophobic. Polymerization time had a positive influence on the contact angle value and higher contact angle can be produced with the prolongation of the polymerization time. When the reaction time was extended to 8h, the contact angle of treated wood surface reached 130° in the beginning, and remained at 116° after 60s. The ARGET ATRP method may raise an alteration on the wood surface modification.

Surface zwitterionicalization of poly(vinylidene fluoride) porous membranes by post-reaction of the amphiphilic precursor

A facile method to endow porous membranes with high coverage of zwitterionic components on surface was described. The amphiphilic precursor poly(vinylidene fluoride)- graft- N, N-dimethyl aminoethyl methacrylate (PVDF- g-PDMAEMA) was firstly synthesized via ATRP method and then blended with PVDF to prepare flat membranes. The 3-bromopropionic and 1,3-propane sultone were then used as quaternization agent to transit the PDMAEMA into poly(zwitterions) through an surface reaction by treating membranes under a mild condition. The reaction kinetics was investigated, finding that 1,3-propane sultone was more reactive than the 3-bromopropionic. The X-ray photoelectron spectroscopy (XPS) confirmed that nearly 70% of PDMAEMA had been quaternized in 48 h for the 1,3-propane sultone, while only 62% of PDMAEMA was transited for the 3-bromopropionic in 96 h. The porosity determination indicated that the specific area had decreased obviously after the membranes being modified. Morphology changes were found to be responsible for the decreased water fluxes and increased retentions when zwitterions were formed. The successful modification was confirmed by the nice biocompatibility that no platelets adhesion as well as proteins deposition was observed on modified membranes.

Enhancing the hydrophilic and antifouling properties of polypropylene nonwoven fabric membranes by the grafting of poly(N-vinyl-2-pyrrolidone) via the ATRP method

In this work, the surface characteristics of poly(N-vinyl-2-pyrrolidone) (PNVP)-modified nonwoven fabric (NWF) membranes and the effects of the surface characteristics on the membranes antifouling properties were investigated. Effects of grafting time, grafting temperature, and monomer concentration on the grafting degree of PNVP were systematically investigated. The effect of grafting degree on the surface characteristics was also investigated. Scanning electron microscopy (SEM) was used to characterize the structural and morphological changes on the membrane surface. The water contact angles decreased from 113±1.2° to 52±3°, which means that the hydrophilicity of the modified NWF was enhanced with increasing PNVP grafting degree. The surface free energy was calculated, which showed an increase after modification. Static bovine serum albumin (BSA) adsorption experiments were carried out, which showed a decrease of 82.5%. Permeation experiments of water and supernatant solution of active sludge were carried out to determine the antifouling characteristics against the extracellular polymeric substance. Results demonstrated that the modified NWF had higher permeation fluxes and lower flux loss in comparison with the original NWF. Bacterial adhesion on the membrane surface was largely suppressed after the introduction of PNVP.

Preparation of the Sulfonamide Containing Block Copolymer as Polymeric Sorbent for Removal of Mercury from Aqueous Solutions

A new sulfonamide containing polymeric sorbent for the removal of mercury ions from waste waters was prepared starting from poly(glycidyl methacrylate)-b-poly(ethylene glycol)-b-poly(glycidyl methacrylate) (PGMA- b -PEG- b -PGMA) triblock copolymer prepared by using the ATRP method. Epoxy groups on the block copolymer were functionalized with amino groups. Ammonia-functionalized PGMA- b -PEG- b -PGMA was treated with excess of benzenesulfonyl chloride to obtain a sulfonamide-based polymeric sorbent. The sulfonamide containing the polymeric sorbent with a 3.5 mmol · g−1 total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 3.12 mmol g−1 under non-buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe(II) also were extractable in quantities (0–0.45 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4 M HNO3 without hydrolysis of the sulfonamide groups.