Catalytic Chain Transfer Polymerization Research Articles

Controllable Synthesis of New Polymerizable Macrosurfactants via CCTP and RAFT Techniques and Investigation of Their Performance in Emulsion Polymerization

We reported herein the synthesis of poly(methacrylic acid)-b-poly(butyl acrylate) (PMAA-b-PBA) block copolymers (surfmers) and their performance as novel polymerizable macrosurfactants in emulsion polymerization. The surfmers bearing terminal unsaturated carbon-carbon double bonds were first successfully designed and sythesized via catalytic chain transfer polymerization (CCTP) and radical addition-fragmentation polymerization (RAFT) techniques. The structures of surfmers were characterized by Raman spectra, nuclear magnetic resonance ((1)H NMR), and gel permeation chromatography (GPC). The critical micelle concentration of surfmers was determined. Subsequently, the surfmers were used as emulsifier to prepare polyacrylate latexes (PA-surf). The influence of the surfmer concentration as well as PMAA and PBA chain segment ratios of surfmer on their performance in emulsion polymerization was discussed thoroughly. The particle size, amount of coagulum, and stability against electrolyte solutions of the latexes were evaluated. Also, the relations between monomer conversion in emulsion polymerization, polymerization rate, emulsion particle size, surface tension, and reaction time were investigated, which showed some interesting information for the probable mechanism underlying this emulsion polymerization system. Atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared spectra (ATR FT-IR) were performed to investigate the surface morphology and component distribution of the latex films. The results show high efficiency of these surfmers in emulsion polymerization, suggesting that the resultant PMAA-b-PBA block copolymers act not only as the emulsifier but also as the stabilizer of monomer droplets as well as the so-called comonomer.

P71 Vascular endothelial growth factor (VEGF) inhibition and erythropoiesis – a missing link?

Herein, we have designed a novel multilayer system composed of poly(methyl methacrylate) [poly(MMA)] brush, biotin, streptavidin and protein-A on a silicon substrate to attach on anti-immunoglobulin G (anti-IgG). poly(MMA) brush with vinyl end-group was first synthesized by the interface-mediated catalytic chain transfer polymerization. The brush was then modified with cysteamine molecules to generate the polymer chains with amine end-group via a thiol-ene click chemistry. The amine end-groups of poly(MMA) chains were also modified with biotin units to ensure selective connection points for streptavidin molecules. Finally, a multilayer system on the silicon substrate was formed by using streptavidin and protein-A molecules, respectively. This multilayer system was employed to attach anti-IgG molecules in a highly oriented manner and provide anti-IgG molecular functional configuration on the multilayer. High reproducibility of the amount of anti-IgG adsorption and homogeneous anti-IgG adsorption layer on the silicon surface could be provided by this multilayer system. The multilayer system with protein A may be opened the door for designing an efficient immunoassay protein chip.

In situ synthesis of transparent fluorescent ZnS–polymer nanocomposite hybrids through catalytic chain transfer polymerization technique

We report the controllable synthesis of zinc sulfide (ZnS) nanocrystals (NCs)/polymer transparent nanocomposite hybrids in situ based on the catalytic chain transfer polymerization (CCTP) technique. Firstly, a polymeric ligand PMAA [PMAA = poly(acrylic acid)] with controllable low-molecular-weight and a terminal double bond was synthesized through CCTP. Secondly, with the use of this versatile polymeric ligand containing a large number of anchors as the stabilizer, the ZnS NCs were fabricated. Finally, the surface polymeric ligands containing terminal double bonds were copolymerized with methyl methacrylate monomer to form NCs–polymer hybrids through free radical polymerization. The properties of as-prepared ZnS NCs and their nanocomposite hybrids were thoroughly investigated by Fourier transform Raman spectra, Fourier transform infrared spectrum, transmission electron microscope, ultraviolet–visible, photoluminescence, and thermogravimetric analyses measurements. The spectroscopic studies reveal that ZnS–polymer nanocomposite hybrids have good optical properties.

Controllable fabrication of nanocrystal-polymer hybrids via the catalytic chain transfer polymerization process

A facile catalytic chain transfer polymerization (CCTP) technique has been developed to synthesize covalently linked CdS nanocrystal-polymer hybrids with good optical properties. The in situ polymerization of methyl methacrylate (MMA) on the surface of modified CdS nanocrystals (NCs) with diameter of 5 nm via CCTP process yielded CdS-polymethylmethacrylate (PMMA) hybrid nanocomposites; while the incorporation of hydroxyl-coated CdS NCs into poly(methacryloxypropyltrimethoxysilane) (PMPS)-co-PMMA matrices prepared by CCTP afforded CdS-PMPS-co-PMMA hybrid nanocomposites, which were further cross-linked by free radical polymerization to form CdS NC-polymer network. The spectroscopic studies indicate that as-prepared CdS NC-polymer hybrids show good photoluminescence (PL) and the NC-polymer network exhibits highly enhanced PL property with respect to that before cross-linking. Also described are the probable mechanism for the catalytic chain transfer polymerization on the surface of modified nanocrystal and the measurement of chain transfer constants.

Catalytic Chain Transfer (co‐)Polymerization: Unprecedented Polyisoprene CCG and a New Concept to Tune the Composition of a Statistical Copolymer

Borohydrido-halflanthanidocene/dialkylmagnesium combinations are found to be powerful catalytic systems for the chain transfer polymerization of isoprene and its copolymerization with styrene. A behavior close to a lanthanide catalyzed polyisoprene chain growth on magnesium is reported. Transmetalation is further shown to occur in the course of the statistical copolymerization of isoprene and styrene. For the same monomer feed, the amount of styrene inserted in the copolymer can be increased by a factor 3 using 10 equiv. dialkylmagnesium versus 1 in the range of our experimental conditions. Chain transfer in the course of a metal catalyzed statistical copolymerization may thus be viewed as a new and original way for the control of the composition of a copolymer.

Controllable synthesis of nanosilica surface-grafted PMMA macromonomers via catalytic chain transfer polymerization

Catalytic chain transfer polymerization (CCTP) has emerged as an efficacious method to produce low-molecular weight polymers. In this paper, we reported the first controllable synthesis of nanosilica surface-grafted poly(methyl methacrylate) (PMMA) (SI-PMMA) macromonomers by using bis(aqua)bis((difluoroboryl)-dimethylglyoximato)cobalt(II) (CoBF) as a chain transfer catalyst via CCTP. In a typical run, we firstly prepared functionalized nanosilica by using 3-(trimethoxysilyl)propylmethacrylate (MPS) as the coupling agent, allowing naosilica containing unsaturated double bonds in end groups. Subsequently, SI-PMMA macromonomers were prepared by PMMA surface-grafted onto the functionalized nanosilica via CCTP. The as-prepared products were characterized by Fourier transforms infrared (FT-IR) spectrum, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transforms Raman (FT-Raman) spectrum and gel permeation chromatography (GPC). We also investigated the dependence of macromonomers on CoBF concentrations.

Molecular Weight Evolution in the Catalytic Chain Transfer Polymerization of CO2-Expanded Methyl Methacrylate

Molecular weight evolution in catalytic chain transfer polymerization of methyl methacrylate expanded with dense CO2 is reported. Experimental molecular weight and polydispersity index data are presented at 50 °C in the range of conversion from 1 to 25%, and at pressures of 5 and 6 MPa. A cobaloxime complex is used as the chain transfer catalyst. Both molecular weight and polydispersity increase in the range of conversion achieved at conditions below the homogeneous expansion limit. Predici simulations suggest that either irreversible catalyst deactivation or cobalt−carbon bond formation, between the catalyst and the propagating radicals, is the most likely mechanism for the increase in molecular weight with conversion. At conditions above the homogeneous expansion limit, a bimodal molecular weight distribution is observed, indicating two zones of polymerization. These conditions produce relatively high molecular weight macromonomers with broad molecular weight distributions.

Controllable synthesis of quantum dot–polymer networks with enhanced luminescence via the catalytic chain transfer polymerization (CCTP) technique

We report on a new available strategy for fabricating CdS QD–polymer hybrids networks with enhanced photoluminescence (PL). Firstly, we synthesized a series of versatile polymeric ligands for the preparation of nanocrystals by catalytic chain transfer polymerization (CCTP) and radical addition–fragmentation polymerization (RAFT) methods. With these versatile polymeric ligands containing a large number of anchors and double bond functional groups, CdS QD–polymer networks were fabricated by the intramolecular cross-linking interaction between the polymeric ligands on the surfaces of each CdS nanocrystal. The as-prepared QD–polymers herein exhibit stable and highly enhanced PL properties relative to their PL before cross-linking. In addition, by measuring the changes of PL intensity, we found the PL intensity of QD–polymers demonstrated remarkable enhancement after 7 months. Related mechanisms were briefly discussed.

α-Diimine, Diamine, and Diphosphine Iron Catalysts for the Controlled Radical Polymerization of Styrene and Acrylate Monomers

The synthesis and characterization of a family of iron complexes of the type R[N,N]FeX2 (X = halide; R[N,N] = RNCH−CHNR, R = alkyl, aryl) and their application as catalysts for the controlled polymerization of styrenyl and acrylate monomers is described. Polymerizations catalyzed by alkylimine iron complexes give rise to atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate, while those catalyzed by arylimine iron complexes give rise to catalytic chain transfer polymerization. A study of the ketimine series, R,Me[N,N]FeCl2 (where R,Me[N,N] = RNC(Me)−C(Me)NR, R = Cy, Ph, DiPP), showed that electronic factors govern the mechanistic pathway. Controlled polymerizations were also observed for methyl acrylate and p-methoxystyrene monomers. Moderate control over the polymerization of 2-hydroxypropyl methacrylate was achieved in methanolic solution using methyl-α-bromophenylacetate as an initiator. The analogous diamine and diphosphine iron complexes, (Et2NCH2CH2NEt2)FeCl2 and (R2PCH2CH2P...

Nanomorphology control in aqueous coatings

Using catalytic chain transfer polymerisation (CCTP) in emulsion polymerisation results in efficient molecular weight reduction. An additional benefit of polymers prepared with CCTP is that they have a chain terminal unsaturated group that can be used in a subsequent graft copolymerisation to yield comb-shaped polymer chains. By careful optimisation of the polymer parameters, film properties can be optimised to yield coatings with very interesting combinations of properties.

Effect of Bulk Viscosity on the Catalytic Chain Transfer Polymerization of CO2-Expanded Butyl Methacrylate and Styrene

The catalytic chain transfer polymerization of CO2-expanded butyl methacrylate and styrene is reported. Experimentally determined values of the chain transfer constant for CO2-expanded butyl methacrylate are presented at 50 and 60 °C and in the range of pressure from 0.1 to 6 MPa, using a cobaloxime complex as the chain transfer catalyst. Similar data are reported for CO2-expanded styrene at 50 °C. The chain transfer constants for both expanded monomers are significantly higher than those obtained in the bulk monomers. It is demonstrated that a linear relationship exists between the chain transfer rate coefficient and the inverse of viscosity. These results provide significant evidence that the rate-determining step in the chain transfer process is diffusion-controlled.

Free radical polymerization with catalytic chain transfer: Using NMR to probe the strength of the cobalt–carbon bond in small molecule model reactions

AbstractThis work examines cobalt–carbon bond formation between the cobalt (II) macrocycle, (tetrakis(p‐methoxyphenyl)porphyrinato)cobalt (II), (TAP)Co, and a variety of radicals derived from vinyl compounds to facilitate a better understanding of the various factors affecting the cobalt–carbon bond strength in catalytic chain transfer polymerization. The reaction of (TAP)Co with the following vinylic molecules was studied: methacrylonitrile, cyclohexene, methyl methacrylate, styrene, methyl acrylate, vinyl acetate, vinyl benzoate, methyl crotonate, cis‐2‐pentenenitrile, and ethyl α‐hydroxymethacrylate. Different concentrations of each vinylic compound were added to (TAP)Co and 2,2′‐azobis(isobutyronitrile) in CDCl3 at 60 °C. The ratio of Co(III) to Co(II) and the nature of the radical bound to the cobalt macrocycle were determined via nuclear magnetic resonance measurements. Several factors are shown to affect the reaction of the radical and the cobalt (II) species (and hence the strength of the cobalt–carbon bond in the resulting compound). These factors are as follows: the number of pathways by which a radical may be derived from the vinyl compound; the variety of radicals that can be produced from the vinylic molecule; the stability of the radical(s) generated; and the relative propagation rate of the vinyl compound. A discussion on the relevance of this study to the behavior of different monomers in catalytic chain transfer reactions is included. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6171–6189, 2006

Catalytic chain transfer polymerisation of CO 2-expanded methyl methacrylate

The catalytic chain transfer polymerisation of methyl methacrylate expanded with dense CO 2 is reported. Experimental values of the chain transfer constant ( C s) are presented at 50 °C and in the range of pressure from 0.1 to 6 MPa, using a cobaloxime complex as the chain transfer catalyst. The effect of small quantities of poly(methyl methacrylate) on the volumetric expansion of the monomer with CO 2 is considered. Experimental data are presented on the pressure limit for homogeneous expansion as a function of the molecular weight of the polymer. It is shown that the values of C s in CO 2-expanded methyl methacrylate are significantly higher than that in bulk monomer. This effect is mainly attributed to the enhancement of the chain transfer rate coefficient, arising from the reduction in the viscosity of the medium, and is consistent with a diffusion-controlled rate-determining step in the chain transfer process.

Dispersion Catalytic Chain Transfer Polymerizations of Methyl Methacrylate in Supercritical Carbon Dioxide

This paper describes a successful dispersion catalytic chain transfer polymerization (CCTP) of methyl methacrylate (MMA) in the presence of a transition-metal catalyst (tetraphenylcobaltoxime boron fluoride, COPhBF (I)) in supercritical carbon dioxide (scCO2) using poly(dimethylsiloxane) monomethacrylate (PDMS-ma) macromonomer as a stabilizer. The final product is a dry, fine powder with controlled molecular weight and a narrow molecular weight distribution. It was found that the dispersion polymerization could reduce the activity of CCT catalyst, which can lead to facile and controlled preparation of high molecular weight vinyl-terminated macromonomers.

New Thiolate−Cobalt(II) Complexes for Catalytic Chain Transfer Polymerization of Methyl Methacrylate

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTNew Thiolate−Cobalt(II) Complexes for Catalytic Chain Transfer Polymerization of Methyl MethacrylateWenxin Wang, Philip A. Stenson, Armando Marin-Becerra, Jonathan McMaster, Martin Schröder, Derek J. Irvine, David Freeman, and Steven M. HowdleView Author Information School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, U.K., and Uniqema R&D Department, The Wilton Research Centre, Wilton, Redcar, TS10 4RF, U.K. Cite this: Macromolecules 2004, 37, 18, 6667–6669Publication Date (Web):August 12, 2004Publication History Received15 April 2004Revised20 July 2004Published online12 August 2004Published inissue 1 September 2004https://doi.org/10.1021/ma049267zCopyright © 2004 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views478Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (46 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Catalysts,Organic compounds,Polymerization,Polymers,Radical polymerization Get e-Alerts

Synthesis of Macromonomers via Catalytic Chain Transfer (CCT) Polymerization and their Characterization via NMR Spectroscopy and Electrospray Ionization Mass Spectrometry (ESI‐MS)

AbstractSummary: Macromonomers consisting of a butyl acrylate (BA) tail and α‐methyl styrene (AMS) or benzyl methacrylate (BzMA) unsaturated termini were synthesized via catalytic chain transfer (CCT) polymerization employing the low spin bis(difluoroboryl)dimethylglyoximato cobalt (II) (COBF) complex. The structures of the generated macromonomers were characterized via 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry (ESI‐MS). A variety of low molecular weight ($\overline M _{\rm n}$ < 4 000 g · mol−1) BA/AMS and BA/BzMA macromonomers were generated by varying the reaction conditions. The generated BA/AMS macromonomers are shown to be terminated by an AMS moiety while consisting of n units of BA plus 1 to 3 units of AMS. The structures of the synthesized BA/BzMA macromonomers give a more complex mixture. Apart from BzMA terminated macromonomer chains consisting of n units of BA plus 1 to 3 units of BzMA, pure BA macromonomers were also generated.Possible structure of BA/AMS macromonomers with various length of the BA tail and a different number of AMS units.magnified imagePossible structure of BA/AMS macromonomers with various length of the BA tail and a different number of AMS units.

High‐conversion catalytic chain transfer polymerization of methyl methacrylate

AbstractIn this work the effects of conversion on the apparent catalyst activity in the catalytic chain transfer polymerization of methyl methacrylate are reported. Several mechanisms are discussed that may explain the experimental observations. The discussion is supported with computer simulations using Predici software. It is shown that the experimental decrease in weight average molecular weight with conversion is smaller than the decrease obtained in simulations. The most likely cause for this discrepancy is slow catalyst deactivation. The half‐life of CoBF under the reported conditions was determined to be about 10 h. Furthermore, the effect of acetic acid (HAc) and benzoyl peroxide (BPO) on the evolution of the molecular weight distribution is investigated. Both HAc and BPO enhance catalyst deactivation. For HAc, catalyst deactivation scales with the square root of its concentration. BPO‐ enhanced deactivation depends linearly on its concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1375–1388, 2004

Catalytic Chain Transfer Copolymerization of Methyl Methacrylate and Butyl Acrylate

AbstractIn this work it is shown that catalytic chain transfer is a very efficient way of controlling molecular weight in the copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The experimental data are compared to a previously developed model based on copolymerization kinetics and the mechanisms for catalytic chain transfer and for cobalt‐mediated living radical polymerization that can describe the observed transfer constants. Secondly, it is shown that the presence of a catalytic chain transfer agent does not affect the reactivity ratios within the concentration range studied. Finally, the effect of conversion and therewith composition drift on the catalytic chain transfer polymerization of MMA and BA is investigated and it is shown that under the conditions employed in the experiments a certain degree of macromer copolymerization is present at high partial conversions of MMA.Evolution of MWD with conversion for the CCT copolymerization of MMA and BA in toluene at 60 °C, [AIBN] = 6 × 10−3 mol · L−1.magnified imageEvolution of MWD with conversion for the CCT copolymerization of MMA and BA in toluene at 60 °C, [AIBN] = 6 × 10−3 mol · L−1.

Solvent Effects, Diffusion Control and Mechanistic Aspects of Catalytic Chain Transfer Polymerization

AbstractIn the catalytic chain transfer polymerization of methyl methacrylate, butyl methacrylate and 2‐ethylhexyl methacrylate in toluene, it was found that the chain transfer constants (CT) were independent of solvent concentration and therefore of solution viscosity, and did not differ from the bulk polymerization values. For a diffusion controlled system, theoretical calculations predict an increase in CT when the solution viscosity is lowered. This points at a non‐diffusion controlled catalytic chain transfer step. These results were obtained when the solvent was thoroughly purified using a Grubbs‐type set‐up, whereas a large reduction in CT was found in unpurified solvent. Similar results were obtained for butyl acetate. Therefore it is concluded that the decrease of CT in non‐purified solvents is not related to the solvent itself, but to solvent impurities. Further we found that methyl methacrylate ended radicals do not covalently bind to the cobalt complex, in contrast to styrene and acrylate ended radicals.Chain transfer constant for the CCT polymerization of 2‐ethylhexyl methacrylate in toluene, and predictions for diffusion controlled systems.magnified imageChain transfer constant for the CCT polymerization of 2‐ethylhexyl methacrylate in toluene, and predictions for diffusion controlled systems.

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

AbstractDuring the 1950's the discoveries of Ziegler's organometallic catalyst systems and Natta's stereoselective olefin polymerization set the stage for extraordinary progress in polymer science and technology. Today advanced catalyst systems are available for catalytic carbon carbon bond formation by means of polyinsertion, metathesis, coupling reactions, and controlled radical polymerization. Modern catalytic olefin polymerization processes and polyolefins are environmentally friendly and meet the demands of a sustainable development. The architectures of homo‐ and copolymers based upon olefin, cycloolefin, diene, styrene and arene feed stocks are tailored as a function of single site catalysts' ligand frameworks. Polymer properties are varied over a very wide range, e.g., liquid/solid, rigid/soft, crystalline/amorphous/rubbery, permeable/impermeable, opaque/transparent, moldable/thermosetting, insulating/conducting. Advanced polymerization reaction engineering, copolymerization processes, reactor granule and reactor blend technologies, tailor‐made single site catalysts, catalyst blends and tandem catalysis improve property profiles, stability, morphology, and melt processing. Tuned cycloolefin polymers are new functional materials for electronic applications. Catalytic chain transfer (CCT) and atom transfer polymerization (ATRP) produce a variety of new functional polymers, reactive oligomers, and block copolymers. Aqueous polyolefin emulsions are obtained when catalytic olefin polymerization is performed in nanodroplets of catalyst miniemulsions. The scope of catalytic polymerization and post polymerization catalysis is progressing well beyond the frontiers of commodity polyolefin manufacturing. Advanced catalytic processes produce polar polymers such as polyethers, polyketones, polyesters, polycarbonates, polyamides, polyaramids, and polyimides. The new phosgene free polycarbonate syntheses are based upon the palladium catalyzed oxidative carbonylation. This overview highlights history, recent progress and modern trends in catalytic polymerization and catalytic polymer modification illustrated by selected examples. Ziegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).magnified imageZiegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).