ATRP Of Methyl Methacrylate Research Articles

The effect of side chain length on hydrodynamic and conformational characteristics of polyimide-graft-polymethylmethacrylate copolymers in thermodynamically good solutions

Samples of graft-copolymers with polyimide backbones and poly(methyl methacrylate) side chains synthesized by ATRP of methylmethacrylate on polyimide macroinitiator are investigated by 1H NMR, GPC, static and dynamic light scattering, sedimentation, and viscosimetry in chloroform and ethyl acetate solutions. Hydrodynamic and conformational behavior of graft-copolymers is well-described by the wormlike spherocylinder and Porod wormlike chain models. Samples of graft-copolymers have high equilibrium rigidity, the Kuhn segment length grows from 20 to 95 nm with the lengthening of side chains. The equilibrium rigidity and hydrodynamic diameter of the investigated graft-copolymers depend on the molar mass M of side chains as M 0.7.

Active, effective, and “green” iron(iii)/polar solvent catalysts for AGET ATRP of methyl methacrylate with various morphologies of elemental silver as a reducing agent

This article reports the AGET ATRP of MMA, with various morphologies of elemental silver as a reducing agent and an iron(iii)/polar solvent catalyst.

Iron(II) complexes bearing anilido-imine ligands: Synthesis and catalysis on ATRP of methyl methacrylate

Reactions of the ortho-C6H4(NHAr)-(CHNAr) with nBuLi and subsequent addition of FeCl2 afford the anilido-aldimine Fe(II) complexes [(ArNCHC6H4-NAr)Fe]2(μ-Cl)2 (Ar=2,6-Me2C6H3 (1a); Ar=2,6-Et2C6H3 (1b)), and (ArNCHC6H4-NAr)Fe(μ-Cl)2Li(THF)2 (Ar=2,6-iPr2C6H3 (1c)). Similarly, reactions of the 2-(ArNC(H))C6H4-HNC9H6N with nBuLi and FeCl2 give the N,N,N-tridentate iron complexes {[2-(ArNC(H))C6H4-NC9H6N]Fe}2(μ-Cl)2 (Ar=2,6-Me2C6H3 (2a), 2,6-Et2C6H3 (2b), and 2,6-iPr2C6H3 (2c)). The X-ray diffraction analysis reveals that 1a and 1b are dimeric complexes and 1c is hetero-binuclear complex. Fe(II) atoms in these complexes are all in a distorted tetrahedral geometry. Complex 2c was confirmed to be a dimeric complex with the iron atom in a trigonal bipyramidal geometry. Complexes 1a–1c show moderate activities in ATRP of MMA in the presence of benzyl chloride (BnCl). While complexes 2a–2c are inert under the same condition.

Iron-mediated AGET ATRP of styrene and methyl methacrylate using ascorbic acid sodium salt as reducing agent

Atom transfer radical polymerization of styrene (St) and methyl methacrylate (MMA) in bulk and in different solvents using activators generated by electron transfer (AGET ATRP) were investigated in the presence of a limited amount of air using FeCl3·6H2O as the catalyst, ascorbic acid sodium salt (AsAc-Na) as the reducing agent, and a cheap and commercially available tetrabutylammonium bromide (TBABr) as the ligand. It was found that polymerization in THF resulted in shorter induction period than that in bulk and in toluene for AGET ATRP of St, while referring to AGET ATRP of MMA, polymerization in THF showed three advantages compared with that in bulk and toluene: 1) shortening the induction period, 2) enhancing the polymerization rate and 3) having better controllability. The living features of the obtained polymers were verified by chain end analysis and chain-extension experiments.

Effect of Pressure on Activation–Deactivation Equilibrium Constants for ATRP of Methyl Methacrylate

AbstractAtom transfer radical polymerization (ATRP) rate for methyl methacrylate (MMA) in acetonitrile solution has been measured up to 2500 bar. The increase in rate, by up to two orders of magnitude for the CuBr/Me6TREN system, is not compromised by an increase in dispersity. Activation–deactivation equilibrium constants were measured for MMA, KATRP, and for two monomer‐free model systems, KEBiB, and KPMMABr, with Me6TREN, TPMA, PMDETA, and HMTETA being the ligands. KATRP and KEBiB agree within one order of magnitude for Me6TREN and TPMA, but differ by about two orders of magnitude for PMDETA and HMTETA, whereas KATRP and KPMMABr are close to each other for PMDETA and HMTETA. The observations indicate an important role of back‐strain effects in ATRP of MMA.

Synthesis and Solution Properties of Loose Polymer Brushes Having Polyimide Backbone and Methylmethacrylate Side Chains

AbstractSummary: Graft‐copolymers with polyimide backbone and PMMA side chains are synthesized by ATRP of methylmethacrylate on the polyimide macroinitiator. The obtained copolymers, macroinitiator, and cleaved side chains are investigated by 1H NMR, SEC, static and dynamic light scattering, sedimentation, and viscosimetry in solutions. The synthesized copolymer is relatively loose polymer brushes: the average distance between grafted PMMA chains is ∼11 nm (4 repeat units of the backbone). The hydrodynamic and conformational characteristics of graft‐copolymers change on passage from ethylacetate to chloroform due to difference in the thermodynamic quality of the solvents with respect to the copolymer components. The backbone is characterized more extended conformation than individual polyimide macromolecule.

Synthesis of Poly(methyl Methacrylate)-Silica Hybrid Materials through Activators Generated by Electron Transfer

Activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) of methyl methacrylate (MMA) on silica nanoparticles were conducted to create controllable shell on silica surfaces. SiO2–Br, the macroinitiator, was prepared by the reaction of amido groups previously indroduced on silica with 2-bromoisobutyryl bromide, followed by the ATRP of MMA using CuBras the catalyst and ascorbic acid (VC) as the reducing agent in the presence of a limited amount of air. The resulting particles were examined by SEM and TEM. The results indicated that the particles were composed of a silica core and a densely grafted outer poly(methyl methacrylate) (PMMA) layer.

ARGET ATRP of methyl methacrylate with 2-(8-heptadecenyl)-4,5-dihydro-1H-imidazole-1-ethylamine (OLC) as both ligand and reducing agent in the presence of air

Copper(II)-mediated activators regenerated by electron transfer for atom transfer radical polymerization of methyl methacrylate (MMA) was successfully carried out in a limited amount of air in the presence of 2-(8-heptadecenyl)-4,5-dihydro-1H-Imidazole-1-ethylamine as ligand that served not only as ligand but also as reducing agents. Reduction of Cu(II) to Cu(I) by an excess amount of nitrogen-based ligand was followed by UV–visible spectroscopy. The kinetics of the polymerizations and effect of different polymerization conditions are investigated. It is found that the polymerization of MMA can be conducted well even if the amount of Cu(II) is as low as 1 mol% catalyst relative to initiator. The results of the polymerizations demonstrate the features of “living”/controlled free-radical polymerization, such as the number-average molecular weights being close to their corresponding theoretical values and increasing linearly with monomer conversion, and narrow molecular weight distributions. Chain extension of poly(methyl methacrylate)s with MMA was successful and demonstrated well-maintained end-group functionality.

Synthesis of acetophenone formaldehyde resin containing ABA type block copolymers by ATRP

AbstractWell‐defined ABA type block copolymers of acetophenone formaldehyde resin (AFR) and methyl methacrylate (MMA) were synthesized via atom transfer radical polymerization. In the first step, acetophenone formaldehyde resin containing hydroxyl groups was modified with 2‐bromopropionyl bromide. Resulting difunctional macroinitiator was used in the ATRP of MMA using copper bromide (CuBr)/N,N,N′,N″,N″‐pentamethyl‐diethylenetriamine (PMDETA) as the catalyst system at 90°C. The chemical composition and structure of the copolymers were characterized by nuclear magnetic resonance (1H‐NMR) spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, and molecular weight measurement. Gel permeation chromatography (GPC) was used to study the molecular weight distributions of the AFR block copolymers. Mn up to 24,000 associated with narrow molecular weight distributions (PDI < 1.5) were obtained with conversions up to 79%. Coating properties of obtained block copolymers such as adhesion and reflectance values were investigated. They showed good adhesion properties on Plexiglass substrates. Reflectance values increased as the resin content of polymer increased. The thermal properties of all polymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All block copolymers showed higher thermal stability than their precursor AFR resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Magneto-Responsive Organogels Prepared Through Surface-Initiated Atom Transfer Radical Polymerization on Iron Nanoparticles

Iron nanoparticles (Fe(np)) with average diameter 50 nm have been synthesized by addition of NaBH4 to FeCl3 solution then radical initiator, (11-(2-bromo-2-methyl)propionyloxy)undecyltrichlorosilane (1) has been immobilized on to Fe(np). Surface-initiated atom transfer radical polymerization (SI-ATRP) of different monomers such as styrene, methyl methacrylate, methacrylonitrile and N-vinylimidazol have been carried out from initiator-grafted Fe(np) and the amount of grafted polymers was determined by thermogravimetric analysis (TGA). Immobilization of PMMA has been monitored by TGA of samples taken from the reaction mixture after 4, 9 and 21 hours. Activators regenerated by electron transfer (ARGET) ATRP of methyl methacrylate and styrene were conducted from initiator-grafted Fe(np) in the presence of phenol and Na-phenoxide respectively and the yields of immobilized polymers were found lower than those we observed in the case of conventional ATRP. The concentration of Fe(np) (c(m)) in the reaction mixture was found to influence significantly the appearance of products; at higher c(m) values SI-ATRP of styrene resulted in the formation of magneto-responsive gels. Transmission electron microscope investigation of bare Fe(np) and magnetic gel revealed that the particles are well-dispersed in the gel while non-grafted Fe(np) form aggregates. XRD measurements were used to determine the composition of magnetic nanoparticles. It was found that the crystalline phase of Fe(np) is mostly reduced iron and the fraction of iron-oxide (hydroxide) species is below the detection limit of XRD. Immobilized polymers have been degrafted by digestion of Fe(np) in HCl and trifluoroacetic acid and the residual polymeric material were identified by FTIR and 1H-NMR spectroscopy. A plausible mechanism for the formation of magnetic gel was given in which polymer network is built up through interparticle termination reactions and Fe(np) act as functional cross-linkers.

High temperature resistant tailor‐made poly(meth)acrylates bearing adamantyl group via atom transfer radical polymerization

AbstractThis investigation reports preparation of tailor‐made poly(meth)acrylates bearing adamantyl group using atom transfer radical homo and copolymerization via initiator as well as via monomer approach. The ATRP of methyl methacrylate was investigated using different initiators having adamantyl group (like AdMBr or AdBr) as well as conventional EBiB initiator and CuBr as catalyst in combination with PMDETA as ligand. It was observed that the incorporation of the bulky adamantyl group increased the rate of polymerization. The polymerization proceeded through first‐order kinetics and molecular weights increased linearly with conversion, close to the targeted molecular weights. The living nature of the end‐group was confirmed by MALDI‐TOF‐mass spectrometry and chain extension experiment. The homopolymerization of adamantyl methyl acrylate (AdMA) and its copolymerization with MA was successfully carried out using methylbromopropionate (MBrP) as initiator and CuBr/dNbpy as the catalyst. Interestingly, the resultant poly(meth)acrylates bearing the adamantyl group had excellent thermal stability and much better thermal stability than the similar polymers without adamantyl group as evidenced from thermogravimetry analysis (TGA) and isothermal TGA studies. Importantly, incorporation of adamantyl group “adamantly” increases rate of polymerization, thermal stability, and glass transition temperature of the polymers. All the polymers were characterized by NMR, MALDI‐TOF‐MS, DSC, and TGA analysis. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7101–7113, 2008

Structured Hybrid Nanoparticles via Surface‐Initiated ATRP of Methyl Methacrylate from Ordered Mesoporous Silica

AbstractStructured hybrid nanoparticles were synthesized via surface‐initiated atom transfer radical polymerization of MMA from ordered mesoporous silica (OMS) nanoparticles with various morphologies. The design of the OMS particles was adjusted to target either spherical core‐shell or cylindrical morphologies with a mean diameter below 400 nm. The polymer growth via ATRP from the silica surface was well‐controlled as demonstrated by the macromolecular characteristics of the grafted chains. Original hybrid multilayered nanoparticles composed of either a dense silica core or hollow core; an inner OMS shell showing radial orientation of the mesopores and an outer PMMA shell with controlled thickness were successfully prepared.magnified image

Polyallene-based graft copolymer via 6-methyl-1,2-heptadien-4-ol and methyl methacrylate

A series of well-defined graft copolymers with a polyallene-based backbone and poly(methyl methacrylate) side chains were synthesized by the combination of living coordination polymerization of 6-methyl-1,2-heptadien-4-ol and atom transfer radical polymerization of methyl methacrylate. We first prepared poly(alcohol) with polyallene repeating units via 6-methyl-1,2-heptadien-4-ol by living coordination polymerization initiated by [(η3-allyl)NiOCOCF3]2, followed by transforming the pendant hydroxyl groups into halogen-containing ATRP initiation groups. Next, grafting-from route was used for the synthesis of the well-defined graft copolymer with excellent solubility: poly(methyl methacrylate) was grafted to the backbone via ATRP of methyl methacrylate. This kind of graft copolymer is the first example of graft copolymer via allene derivative and methacrylic monomer.

Comb Polymers Prepared by ATRP from Hydroxypropyl Cellulose

Hydroxypropyl cellulose (HPC) was used as a core molecule for controlled grafting of monomers by ATRP, the aim being to produce densely grafted comb polymers. HPC was either allowed to react with an ATRP initiator or the first generation initiator-functionalized 2,2-bis(methylol)propionic acid dendron to create macroinitiators having high degrees of functionality. The macroinitiators were then "grafted from" using ATRP of methyl methacrylate (MMA) or hexadecyl methacrylate. Block copolymers were obtained by chain extending PMMA-grafted HPCs via the ATRP of tert-butyl acrylate. Subsequent selective acidolysis of the tert-butyl ester moieties was performed to form a block of poly(acrylic acid) resulting in amphiphilic block copolymer grafts. The graft copolymers were characterized by 1H NMR and FT-IR spectroscopies, DSC, TGA, rheological measurements, DLS, and tapping mode AFM on samples spin coated upon mica. It was found that the comb (co)polymers were in the nanometer size range and that the dendronization had an interesting effect on the rheological properties.

Single‐Mode Microwave‐Assisted Atom Transfer Radical Polymerization Catalyzed by [RuCl2(p‐cymene)(PCy3)

AbstractIn the atom transfer radical polymerization (ATRP) of methyl methacrylate in the presence of [RuCl2(p‐cymene)(PCy3)] (p‐cymene = 4‐isopropyltoluene, PCy3 = tricyclohexylphosphine), a microwave effect is noted which strikingly depends on both the temperature and the method used (conventional microwave synthesis (CMS, i.e., without simultaneous cooling) or enhanced microwave synthesis (EMS, with simultaneous cooling)). Thus, between 85 and 120 °C under CMS conditions, microwave‐assisted polymerizations take place in a controlled fashion, and at 120 °C the microwave‐assisted polymerization is three times faster than the conventionally heated protocol. However, from 130 °C, microwave irradiation has a deleterious effect and the polymerizations are no longer controlled. Likewise, using the EMS method in the temperature range of 85–120 °C results in uncontrolled processes, as indicated by the unsuccessful resumption of the polymerizations. These failures might be attributed to a significantly high concentration of radical species, which results in enhanced propagation and termination ‐ mostly disproportionation ‐ rates.magnified image

Atom Transfer Radical Polymerization of Methyl Methacrylate with α,α,α′,α′‐Tetrachloroxylene as an Initiator

The homogeneous ATRP of methyl methacrylate (MMA) using α,α,α′,α′‐tetrachloroxylene (TCX)/CuCl/N,N,N′,N″,N″–pentamethyldiethylenetriamine (PMDETA) as the initiating system has been successfully carried out. The kinetic plots showed first order relationship vs. monomer concentration. Well‐controlled polymerizations with low polydispersities (Mw/Mn=1.15−1.25) polymers have been achieved. The molecular weights increased linearly with monomer conversions and were close to the theoretical values, indicating high initiation efficiency. The polymerization rate increased significantly with an increase of TCX concentration. The rate of polymerization was about 0.6 orders with respect to the concentration of initiator. The polymerization rate increased significantly with an increase of CuCl concentration. The dependence of ln kp app on ln ([CuCl]0) indicated a 0.91 order. The apparent activation energy was calculated ΔEapp ≠=43.3 KJ/mol, and the enthalpy of the equilibrium, ΔHeq 0, was estimated to be 21.1 KJ/mol. The structure of obtained PMMA was analyzed by means of 1H NMR spectroscopy. The result proved that the TCX acted as a bifunctional initiator for ATRP of MMA.

A coordinatively unsaturated ruthenium methoxide as a highly effective catalyst for the halogen atom-transfer radical cyclization of N-allyl dichloroacetamides and related reactions

Atom-transfer radical cyclization (ATRC) catalyzed by coordinatively unsaturated ruthenium alkoxides 4 , [(η 5-C 5Me 5)Ru(OR)] 2, is investigated, and ruthenium methoxide 4a (R=Me) is found to exhibit excellent catalytic activity for the cyclization of N-allyl-α,α-dichloroacetamides at ambient temperature. Addition of some amounts of two-electron donor ligands such as pyridine and triphenylphosphine improves the catalyst efficiency to afford the corresponding γ-lactams in high yields. The high catalytic activity of this catalyst system enables to control the diastereoselectivity of this 5- exo cyclization kinetically. The present 4a /pyridine system is also effective for the 4- exo cyclization of N-vinylacetamides to afford the corresponding β-lactams in quantitative yields. The 4a /pyridine system is also active towards the ATRP of methyl methacrylate (MMA) at room temperature to afford the poly(MMA) with narrow molecular weight distributions ( M w/ M n=1.2) at the initial stage.

Synthesis and Characterization of Block Copolymers of P(MMA‐b‐n‐BA‐b‐MMA) via Ambient Temperature ATRP of MMA

A binol ester initiator was used as a bifunctional ATRP initiator in combination with PMDETA/copper bromide catalyst system in DMF to synthesize n‐butyl acrylate macroinitiator at 50°C. The resulting macroinitiator was used for a detailed investigation of the ATRP of methyl methacrylate (MMA) with CuCl/N,N,N′,N′,N″‐pentamethyldiethy‐lenetriamine (PMDETA) catalyst system in anisole at 30°C. Thus, the MMA polymerization is shown to proceed with first order kinetics, with predicted molecular weight and narrow polydispersity indices. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers synthesized.

ATRP of (meth)acrylates initiated with a bifunctional initiator bearing trichloromethyl functional groups and structural analysis of the formed polymer

ATRP of methyl methacrylate (MMA), initiated with 1,3-bis{1-methyl-1-[(2,2,2-trichloroethoxy)carbonylamino]ethyl}benzene as a bifunctional initiator (BI) under CuCl catalysis was studied in the presence of 2,2′-bipyridine (bpy) or hexamethyltriethylenetetramine (HMTETA) ligands, in bulk or in toluene. With the bpy, the polymerization reaches only limited monomer conversions and products have broad MWDs. In contrast, polymerization in the presence of HMTETA is a well-controlled process, affords virtually quantitative conversion, giving PMMAs with narrow MWDs and predictable molecular weights within a range of more than one order of magnitude. NMR analysis of the prepared PMMA proved formation of linear polymers with im-measurable extent of chain branching or β-scission as undesired side reactions. The prepared α,ω-dichloro-PMMAs were used as macroinitiators for ATRP of tert-butyl acrylate ( t-BuA), giving the corresponding triblock copolymers with narrow MWDs and molecular weights controllable in a wide range. Block copolymerizations were performed in dimethyl formamide (DMF) or acetone in the presence of pentamethyldiethylenetriamine (PMDETA) as ligand and could be accelerated by addition of metallic copper.

Atom transfer radical polymerizations of methyl methacrylate catalyzed by EBiB/SnCl2·2H2O(FeCl2·4H2O)/FeCl3·6H2O/MA5-DETA systems

The ATRP of methyl methacrylate (MMA) with the system of FeCl2·4H2O, N,N,N′,N″,N″-penta(methyl acylate)diethylenetriamine (MA5-DETA) and ethyl 2-bromoisobutyrate (EBiB) showed high activity and is not well-controlled. The addition of a certain amount of FeCl3·6H2O as the additive into the above system results in the decrease of the polymerization rate and the improvement of the controllability. When SnCl2·2H2O was added instead of FeCl2·4H2O, a novel catalyst system SnCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA formed shows better controllability, higher catalytic activity and higher initiating efficiencies (more than 90%) in comparison with the system FeCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA. The polydispersities of the polymers kept range from Mw/Mn=1.18–1.26. The real active species in the new system is Fe (II) formed from the reaction of FeCl3·6H2O with the active radical species produced from the reaction of SnCl2·2H2O with EBiB.