Activator Regeneration Atom Transfer Radical Research Articles

Blue‐light‐induced atom transfer radical polymerization enabled by iron/copper dual catalysis

AbstractPhotoinduced initiators for continuous activator regeneration atom transfer radical polymerization (PICAR ATRP) using sodium pyruvate and blue light (λmax = 456 nm) is reported. Water‐soluble oligo(ethylene oxide) methyl ether methacrylate (OEOMA500) was polymerized under biologically relevant conditions. Polymerizations were conducted with 1000 ppm (with respect to the monomer) concentrations of CuBr2, tris(2‐pyridylmethyl)amine, and 1000 ppm or less FeCl3 as a cocatalyst in water. Well‐defined polymers with up to 90% monomer conversion, high molecular weights (Mn > 190,000), and low dispersity (1.14 < Ð < 1.19) were synthesized in less than 60 min. The polymerization rate and dispersity were tuned by varying the concentration of sodium pyruvate (SP), iron, and supporting halide, as well as light intensity. The Cu/Fe dual catalysis provided oxygen tolerance enabling rapid, well‐controlled, aqueous PICAR ATRP of OEOMA500 without deoxygenation.

Sulfoxide-Containing Polyacrylamides Prepared by PICAR ATRP for Biohybrid Materials.

Water-soluble and biocompatible polymers are of interest in biomedicine as the search for alternatives to PEG-based materials becomes more important. In this work, the synthesis of a new sulfoxide-containing monomer, 2-(methylsulfinyl)ethyl acrylamide (MSEAM), is reported. Well-defined polymers were prepared by photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (PICAR ATRP). The polymerizations were performed in water under biologically relevant conditions in a small volume without degassing the reaction mixture. DNA-PMSEAM and protein-PMSEAM hybrids were also synthesized. The lower critical solution temperature (LCST) of PMSEAM was estimated to be approximately 170 °C by extrapolating the LCST for a series of copolymers with variable content of N-isopropylacrylamide. The cytotoxicity studies showed excellent biocompatibility of PMSEAM, even at concentrations up to 2.5 mg/mL. Furthermore, the MSEAM monomer exhibited relatively lower toxicity than similar (meth)acrylate-based monomers at comparable concentrations.

One-pot synthesis of block copolymer dispersant by ICAR ATRP with ppm copper catalyst and the dispersibility on pigment

The controlled / living polymerization mechanisms have advantages on synthesizing the dispersant with defined structures and compositions, while encountering with individual drawbacks in industrial application. Based on the initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) of oligo(ethylene oxide)methyl ether methacrylate (OEEMA) and glycidyl methacrylate (GMA) monomers, the diblock copolymers POEOMA-b-P(OEOEMA-co-GMA) were prepared. The GMA units were further modified with 3-mercaptopropionic acid (MPA) agent. The polymerization and modification procedure can be readily realized in a one-pot technology with complete monomer conversion (~100%) and high ring-opening efficiency (~100%), as well as low concentration copper catalyst (100 ppm). Using the MPA modified P(OEOEMA-co-GMA) as anchoring block, POEOMA as stabilizing block, the obtained block copolymers can be used as dispersant to disperse and stabilize the pigment yellow 14. The standing experiment, optical microscope (OM) and dynamic light scattering (DLS) measurements reached to a consistent conclusion that the absolute number of carboxyl groups on each chain modulate the dispersibility of the dispersions, rather than the relative content of carboxyl groups. This work provided a feasible one-pot technology to efficient dispersants.

Controlled architecture of polyhedral oligomeric silsesquioxane-functionalized poly(glycidyl methacrylate)/polyester composites using surface-initiated ICAR ATRP Technique for High Flame Retardancy and Smoke Suppression

To impart flame retardancy and smoke suppression properties to polyester fabrics, polyhedral oligomeric silsesquioxane (POSS)-functionalized polyglycidyl methacrylate (PGMA) coatings were synthesized via the initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) and polydopamine chemistry. A well-distributed PGMA layer was observed with a low polydispersity index of 1.22. After 6.25 wt% NH2 POSS grafting, the total amounts of heat and smoke were reduced by 55.00% and 86.89%, respectively. The values of the smoke density for the DOPO-POSS- or NH2-POSS-modified copolyester fabrics were reduced by 51.00% and 57.55% at 4.75 wt% PGMA grafting content. SEM, FTIR, and XPS results of the residual char provided strong evidence that a higher graphitization degree of the char was achieved, which was attributed to the Si–O–C and P–O–C cross-linking formation in the condensed phase upon POSS grafting. The firm graphite char layer prevented the release of internal gas and the entry of external oxygen. Moreover, TG-MS showed that the presence of the POSS layer reduced the amounts of CO and H2O released during the pyrolysis of the fabric. More inert gasses, including NH2 and PH3, were generated through POSS layer decomposition, which in turn slowed the combustion process.

Efficient dispersion of TiO2 in water-based paint formulation using well-defined poly[oligo(ethylene oxide) methyl ether acrylate] synthesized by ICAR ATRP

In this work, a new polymeric dispersants based on poly[oligo(ethylene oxide) methyl ether acrylate] (POEOA) as hydrophilic block and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and dopamine (Dopa) as anchoring molecules, have been synthetized and successfully used as efficient tailor-made polymers for the aqueous dispersion of titanium dioxide (TiO2) particles. The controlled structure of this new class of additives was obtained by initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP). The proposed polymer dispersants were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance analysis (1H NMR). The dispersion efficiency was evaluated by dynamic light scattering (DLS), zeta potential (ζ), rheology and transmission electron microscopy (TEM). The influence of different stabilizing blocks bounded to the same anchoring block on the dispersion efficiency was evaluated in aqueous dispersions of TiO2 using a common water-based paint formulation (satin vinyl paint). Aiming for industrial validation, a satin paint was also formulated with the new dispersants. Higher gloss (up to 39%) and improved pigment dispersion were observed when using the tailor-made polymers, comparing to the use of a standard commercial poly(acrylic acid) (PAA) dispersing agent. The data presented suggest that POEOA-based macrostructures are highly efficient additives for the dispersion of TiO2 in water-based paint formulations.

Improved Self-Assembly of P3HT with Pyrene-Functionalized Methacrylates.

A block copolymer with discotic liquid crystalline behavior was synthesized using Grignard metathesis polymerization (GRIM) and initiators for continuous activator regeneration atom transfer radical polymerization (ICAR-ATRP). A novel discotic liquid crystalline mesogen, 6-(pyren-1-yloxy)hexyl methacrylate (PyMA), comprises a block that is attached to regioregular poly(3-hexylthiophene) (rr-P3HT) generated by GRIM and subjected to end-group modification. Due to the continuous regeneration of Cu+ in the reaction mixture in ICAR-ATRP compared to conventional methods, the synthesis was successfully performed with less catalyst. The purity and yield of the final product are increased by eliminating rigorous post-synthesis purification. Stacked pyrene units have contributed to the enhanced long-range π–π interactions and aligning of the P3HT block as observed in thin-film X-ray diffraction (XRD). Furthermore, field-effect mobilities in the order of 10–2 cm2 V–1 s–1 in bottom-gate, top-contact organic field-effect transistors (OFETs) suggest an enhancement in charge transport due to the discotic electron-rich pyrene units that help mitigate the insulating effect of the methacrylate backbone. The formation of uniform microdomains of P3HT-b-poly(PyMA) observed with tapping mode atomic force microscopy (TMAFM) on the channel regions of OFETs indicates the unique packing of the block copolymer in comparison to pristine P3HT. Thermotropic properties of the novel discotic mesogen in the presence and absence of P3HT were observed with both the poly(3-hexylthiophene)-b-poly(6-(pyren-1-yloxy)hexyl methacrylate) (P3HT-b-poly(PyMA)) block copolymer and poly(6-(pyren-1-yloxy)hexyl methacrylate) (poly(PyMA)) homopolymer using polarized optical microscopy (POM) and differential scanning calorimetry (DSC).

ATRP of MIDA Boronate-Containing Monomers as a Tool for Synthesizing Linear Phenolic and Functionalized Polymers.

Despite numerous novel polymeric materials that have been produced by incorporating boronic acid or ester groups into polymers, it remains a challenge to prepare well-defined boronate-containing polymers due to their inherent instability. Herein, we used N-methyliminodiacetic acid (MIDA) to stabilize the reactive organoboron structure. MIDA boronate-containing polymers were synthesized in a good control by initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP). Oxidation and Suzuki-Miyaura coupling were conducted to prepare linear phenol-containing polymers and aromatic functionalized polymers. Upon comparison of similar polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, of which the chain transfer agent (CTA) end groups cause multiple undesired side reactions, the halogen end groups of polymers prepared by ATRP are nontoxic to metal catalysts and stable during the postmodifications, thus providing a more facile tool for synthesizing various functionalized polymers with great potentials in advanced materials.

The synthesis, characterization of opal-poly(methyl methacrylate) graft polymer based on ICAR-ATRP and its effect on performance of poly (lactic acid)

ABSTRACT In this work, initiators for continuous activator regeneration atom transfer radical polymerization was adopted to synthesize opal-poly(methyl methacrylate) graft polymer (opal-PMMA) with methyl methacrylate as monomer. The optimum reaction conditions obtained from orthogonal experiment were as follows: a ratio between ethyl-2-bromoisobutyrate and 2,2ʹ-azobis(2-methylpropionitrile) of 1.5: 60 (mL: mg), reaction time of 9 h, the ratio between FeCl3·6H2O and triphenyl phosphine of 40: 40 (mg: mg) and reaction temperature of 80 °C. The structure of opal-PMMA was characterized by Fourier transform infrared spectroscopy combined with the water contact angles measurement and X-ray photoelectron spectrometer. Furthermore, poly (lactic acid) (PLA)/opal-PMMA composites were prepared by melt blending at different loading levels of opal-PMMA. In addition, the performance, crystallization, and thermal decomposition kinetics of PLA/opal-PMMA composites were studied. Especially, when 0.3 wt% opal-PMMA was added, the impact strength of PLA/opal-PMMA composites was improved by 192% and its crystallinity increased from 9.01% (PLA0) to 35.55%. Meanwhile, thermal decomposition kinetics indicated that opal-PMMA effectively improved the thermal stability of PLA bulk. Rheological test demonstrated that opal-PMMA enhanced the systematical rigidity of PLA compared with the pristine PLA, which could ascribe to the uniform dispersion of opal-PMMA and more entanglement points with PLA molecular.

Polymer grafting from a metallo‐centered enzyme improves activity in non‐native environments

AbstractMetallo‐centered enzymes have found applications in environmental remediation, green synthesis and sensors. These enzymes destabilize at extreme pH, elevated temperature or high‐organic‐content conditions. For these enzymes to find more widespread adoption and use, stabilization in non‐native conditions is critical. We report the impact of grafting polymers from the surface of laccase, a metalloenzyme with a Cu active site, modified with a polymerization‐initiating species ligated to the protein's lysine residues. Initiators for continuous activator regeneration atom transfer radical polymerization was used to graft a small library of polymers from the protein. The impact of polymer grafting on enzyme activity as a function of pH, temperature or organic solvent was determined. While polymer grafting from laccases was found to increase enzymatic activity, we found that grafting high‐molecular‐weight dimethylaminoethyl methacrylate displayed the greatest enhancement to catalytic activity. The results demonstrate that polymer grafting can improve laccase activity in native and non‐native conditions. © 2020 Society of Industrial Chemistry

Development of ICAR ATRP-Based Polymerization-Induced Self-Assembly and Its Application in the Preparation of Organic-Inorganic Nanoparticles.

The functionalization and application of nano-objects generated using a polymerization induced self-assembly (PISA) procedure is becoming a focus in recent years. In this contribution, using ethanol as solvent, poly(oligo(ethylene oxide) methyl ether methacrylate) (POEOMA) as macro-initiator/stabilizer, and 2-(perfluorohexyl)ethyl methacrylate (PFHEMA) and glycidyl methacrylate (GMA) as comonomers, the initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP)-based PISA is realized. The lower GMA content system tends to form spheres with large diameters and heavy contrast, while the lower PFHEMA content system tends to form the spheres or short worms with small diameters. However, the system with further increased GMA content results in the failed ICAR ATRP PISA procedure with the formation of precipitates by the cross-linking reaction between pendant epoxy groups. Furthermore, using the efficient reaction between the epoxy group on GMA and thiol group on mercapto-succinic acid agent, the carboxyl groups can be introduced into the inner cavity of the nano-objects and used for incorporation with the Fe2+ and Fe3+ ions, and the organic-inorganic nanoparticles Fe3 O4 @POEOMA are finally prepared in the presence of a reductant.

Surface-Initiated Initiators for Continuous Activator Regeneration (SI ICAR) ATRP of MMA from 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) Oxidized Cellulose Nanofibers for the Preparations of PMMA Nanocomposites.

An effective method of oxidation from paper pulps via 2,2,6,6–tetramethylpiperidine–1–oxy (TEMPO) compound to obtain TEMPO-oxidized cellulose nanofibers (TOCNs) was demonstrated. Following by acylation, TOCN having an atom transfer radical polymerization (ATRP) initiating site of bromoisobutyryl moiety (i.e., TOCN–Br) was successfully obtained. Through a facile and practical technique of surface-initiated initiators for continuous activator regeneration atom transfer radical polymerization (SI ICAR ATRP) of methyl methacrylate (MMA) from TOCN–Br, controllable grafting polymer chain lengths (Mn = ca. 10k–30k g/mol) with low polydispersity (PDI < 1.2) can be achieved to afford TOCN–g–Poly(methyl methacrylate) (PMMA) nanomaterials. These modifications were monitored by Fourier-transform infrared spectroscopy (FT–IR), scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), and water contact angle analysis. Eventually, TOCN–g–PMMA/PMMA composites were prepared using the solvent blending method. Compared to the pristine PMMA (Tg = 100 °C; tensile strength (σT) = 17.1 MPa), the composites possessed high transparency with enhanced thermal properties and high tensile strength (Tg = 110 °C and σT = 37.2 MPa in 1 wt% TOCN containing case) that were investigated by ultraviolet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile tests. We demonstrated that minor amounts of TOCN–g–PMMA nanofillers can provide high efficacy in improving the mechanical and thermal properties of PMMA matrix.

ICAR ATRP Polymerization-Induced Self-Assembly Using a Mixture of Macroinitiator/Stabilizer with Different Molecular Weights.

The poly[oligo(ethylene oxide) methyl ether methacrylate]s, POEOMA24 and POEOMA78 with average degree of polymerization (DP) of 24 and 78, respectively, are separately achieved by initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) of OEOMA300 monomer. The mixtures of [POEOMA24 ]0 /[POEOMA78 ]0 = 1/1, 2/1, or 4/1 are employed as macroinitiator/stabilizer to practice the ICAR ATRP polymerization-induced self-assembly (PISA) of benzyl methacrylate (BnMA) at 65 °C. When the obtained dispersions are sequentially cooled to room temperature, diluted into ethanol, and observed by transmission electron microscopy (TEM) measurement, the cases of [POEOMA24 ]0 /[POEOMA78 ]0 = 1/1 or 2/1 and target DPPB n MA = 100 or 200 lead to nanoparticles with irregular sizes, while the cases of [POEOMA24 ]0 /[POEOMA78 ]0 = 4/1 and target DPPB n MA = 300 give the regular ones. When the obtained dispersions at a high temperature (65 °C) are directly diluted into room temperature ethanol and observed by TEM, nanoparticles with light contrast but clear contour can be observed. The results show that the higher content of POEOMA78 tends to improve the solubility of diblock copolymer and thus leads to insufficient stabilization of the nanoparticles. The morphological difference from the room-temperature and 65 °C dispersions help elucidate the intrinsic character of the PISA system.

Multi-functionalization of magnetic graphene by surface-initiated ICAR ATRP mediated by polydopamine chemistry for adsorption and speciation of arsenic

Multi-functionalized magnetic graphene was prepared by surface-initiated initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) mediated by polydopamine chemistry. The obtained multi-functionalized magnetic graphene was used as an adsorbent for application in adsorption and speciation of arsenic. Adsorption kinetics and isotherms of arsenic were investigated by batch adsorption experiments. The adsorbent displayed simultaneous or selective removal ability for As(III) and As(V) within different pH ranges. The adsorption of both As(III) and As(V) agreed well with the Freundlich isotherm model, and they were effectively adsorbed through chelation and electrostatic interaction, respectively. Moreover, the functionalized magnetic graphene was examined as a column packing material for speciation analysis of arsenic using solid phase extraction technique. As(III) and As(V) could be effectively separated through a sequential elution strategy. An alkaline solution was firstly employed to selectively elute As(V), and then an acidic solution was utilized to elute As(III). The developed adsorbent in the present study was successfully applied to the determination of As(III) and As(V) in natural and environmental water samples with satisfactory results.

ICAR ATRP in PEG with Low Concentration of Cu(II) Catalyst: A Versatile Method for Synthesis of Block Copolymer Nanoassemblies under Dispersion Polymerization.

A versatile method for synthesis of block copolymer nanoassemblies via initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) dispersion polymerization in a low molecular weight poly(ethylene glycol) (PEG) is discussed. This ICAR ATRP dispersion polymerization uses a low concentration of CuBr2 catalyst, which is stable under atmospheric conditions and is soluble in most polar solvents and employs a polymerization medium of viscous and nonvolatile PEG. Through this ICAR ATRP dispersion polymerization, various block copolymer nanoassemblies, including poly(ethylene glycol)-block-polystyrene, poly(ethylene glycol)-block-poly(methyl methacrylate), and poly(2-hydroxypropyl methacrylate)-block-poly(methyl methacrylate), have been synthesized. The parameters affecting the size and morphology of the block copolymer nanoassemblies are briefly discussed.

How penultimate monomer unit effects and initiator influence ICAR ATRP of n‐butyl acrylate and methyl methacrylate

The relevance of penultimate monomer unit (PMU) effects and the selection of the correct initiator species under typical reversible deactivation radical copolymerization conditions is illustrated, using matrix‐based kinetic Monte Carlo simulations allowing the visualization of all monomer sequences along individual chains. Initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) is selected as illustrative polymerization technique with n‐butyl acrylate and methyl methacrylate as comonomers, aiming at the synthesis of well‐defined gradient copolymers. Using literature based model parameters, in particular temperature dependent monomer and radical reactivity ratios, it is demonstrated that PMU effects on propagation and ATRP (de)activation cannot be ignored to identify the most suited ICAR ATRP reactants (e.g., tertiary ATRP initiator) and reaction conditions (e.g., feeding rates under fed‐batch conditions). The formulated insights highlight the need for further research on PMU effects on all reaction steps in radical polymerization. © 2017 American Institute of Chemical Engineers AIChE J, 2017

Well-defined functional mesoporous silica/polymer hybrids prepared by an ICAR ATRP technique integrated with bio-inspired polydopamine chemistry for lithium isotope separation.

Mesoporous silica/polymer hybrids with well-preserved mesoporosity were prepared by integrating the initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) technique with the bio-inspired polydopamine (PDA) chemistry. By manipulating the auto-oxidative polymerization of dopamine, uniform PDA layers were deposited on the surfaces and pore walls of ordered mesoporous silicas (OMSs), thereby promoting the immobilization of ATRP initiators. Poly(glycidyl methacrylate) (PGMA) brushes were then grown from the OMSs by using the ICAR ATRP technique. The evolution of the mesoporous silica/polymer hybrids during synthesis, in terms of morphology, structure, surface and porous properties, was detailed. And, parameters influencing the controlled growth of polymer chains in the ICAR ATRP system were studied. Taking advantage of the abundant epoxy groups in the PGMA platform, post-functionalization of the mesoporous silica/polymer hybrids by the covalent attachment of macrocyclic ligands for the adsorptive separation of lithium isotopes was realized. Adsorption behavior of the functionalized hybrids toward lithium ions was fully investigated, highlighting the good selectivity, and effects of temperature, solvent and counter ions. The ability for lithium isotope separation was evaluated. A higher separation factor could be obtained in systems with softer counter anions and lower polarity solvents. More importantly, due to the versatility of the ICAR ATRP technique, combined with the non-surface specific PDA chemistry, the methodology established in this work would provide new opportunities for the preparation of advanced organic-inorganic porous hybrids for broadened applications.

Polymerization-Induced Self-Assembly (PISA) Using ICAR ATRP at Low Catalyst Concentration

Polymerization-induced self-assembly (PISA) was achieved by conducting an initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) at low ppm of copper catalyst concentration. A poly(oligo(ethylene oxide) methyl ether methacrylate)50 (POEOMA50) macroinitiator and stabilizer was synthesized by an aqueous ICAR ATRP using CuIICl2/tris(pyridin-2-ylmethyl)amine (TPMA) complex. Subsequently, the dispersion polymerization of benzyl methacrylate (BnMA) in ethanol was realized with a CuIIBr2/TPMA complex either at room temperature or at 65 °C using V-70 or AIBN as radical initiators, respectively. The effect of catalyst concentration, radical initiators, targeted degree of polymerization (DP) of PBnMA, solids content, and temperature on the molecular characteristics and self-assembly behavior of block copolymers POEOMA–PBnMA was evaluated by gel permeation chromatography (GPC), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Block copolymers asse...

Highly Efficient and Facile Photocatalytic Recycling System Suitable for ICAR ATRP of Hydrophilic Monomers.

Photoinduced initiators for continuous activator regeneration atom transfer radical polymerization (ATRP) of hydrophilic monomers in heptane/ethanol latent-biphasic system for copper catalyst separation and recycling have been realized for the first time at room temperature with different wavelengths of visible light LED (green, blue, purple, and white LED) as external stimulus, using 2-bromophenylacetate as the ATRP initiator and camphorquinone/triethylamine as the photoinitiator. In this system, hybrid catalyst complex (HCc) is synthesized as a novel nonpolar catalyst, which is preferentially dissolved in heptane. The hydrophilic polymers obtained catalyzed by HCc in heptane/ethanol mixture solvent show typical "living" features, for example, the values of Mn,GPC increase linearly with monomer conversion up to quantitative level (>96%) and the molecular weight distributions were kept narrow (Mw /Mn < 1.20) throughout the polymerization process. It should be noted that the excellent controllability of this novel polymerization system can be achieved even after 5 catalyst recycling experiments under LED irradiation.

Synthesis of PBMA-&lt;i&gt;b&lt;/i&gt;-PGMA Block Copolymers via ICAR ATRP and their Application in Polymer/Titanium Dioxide Hybrid Materials

Well-defined functional block copolymers, polybutyl methacrylate-b-polyglycidyl methacrylate (PBMA-b-PGMA), were successfully synthesized via initiators for continuous activator regeneration atom transfer radical polymerization ( ICAR ATRP) with pentamethyldiethylene-triamine (PMDETA) as a ligand and copper bromide (CuBr2 ) as a catalyst with concentration of 500 ppm. The PBMA-b-PGMA grafted with titanium dioxide (TiO2 ) nanoparticles was obtained through the reaction between the epoxide on the PGMA segment and amine group on the surface of modified TiO2 nanoparticles. Results showed that the PBMA-b-PGMA block copolymer with about same length of PBMA and PGMA segment could get highest graft ratio and about 17%wt TiO2 nanoparticles were successfully grafted onto the PBMA-b-PGMA block copolymer. The sizes of the PBMA-b-PGMA grafted nanoparticles were about 74 nm in ethyl acetate. The PBMA-b-PGMA grafted TiO2 nanoparticles showed very good dispensability in organic solvent (e.g. ethyl acetate) and polymer matrix. Polymethyl methacrylate (PMMA) containing 0.5%wt PBMA-b-PGMA grafted TiO2 nanoparticles showed strong absorption at about 300 nm and good transparency in visible region, which was attributed to good dispensability of PBMA-b-PGMA grafted TiO2 nanoparticles in PMMA matrix.

ICAR ATRP of Acrylonitrile under Ambient and High Pressure.

It is well known that well-defined polyacrylonitrile (PAN) with high molecular weight (Mw > 106 g·mol−1) is an excellent precursor for high performance carbon fiber. In this work, a strategy for initiators for a continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) system for acrylonitrile (AN) was firstly established by using CuCl2·2H2O as the catalyst and 2,2′-azobis(2-methylpropionitrile) (AIBN) as the thermal initiator in the presence of ppm level catalyst under ambient and high pressure (5 kbar). The effect of catalyst concentration and polymerization temperature on the polymerization behaviors was investigated. It is important that PAN with ultrahigh viscosity and average molecular weight (Mη = 1,034,500 g·mol−1) could be synthesized within 2 h under high pressure.