Comparison of surface confined ATRP and SET‐LRP syntheses for a series of amino (meth)acrylate polymer brushes on silicon substrates

A series of poly(amino (meth)acrylate) brushes, poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA), poly(2‐(diethylamino)ethyl methacrylate) (PDEAEMA), poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA), poly(2‐(tert‐butylamino)ethyl methacrylate) (PTBAEMA), has been synthesized via surface‐confined controlled/living radical polymerizations using surface‐confined initiator from silane self‐assembled monolayers (SAMs) on silicon (Si) wafer substrates. Chemical methods and efficacies for two types of living radical polymerization, atom transfer radical (ATRP) and single electron transfer (SET‐LRP), are described and contrasted for the surface confined polymerization of poly(amino (meth)acrylate)s. Effects of solvent, catalyst/ligand system, and temperature on polymerization success were examined. Chemical compositions after each reaction step were characterized with FTIR spectroscopy, contact angle goniometry, and X‐ray photoelectron spectroscopy while the SAM and polymer brush thicknesses were measured with spectroscopic ellipsometry. For the first time, this study demonstrates successful surface‐confined polymerization of a series of poly(amine (meth)acrylate) brushes from Si‐SAM substrates using a copper metal electron donor catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6552–6560, 2009     

PMMA colloid particles armored by clay layers with PDMAEMA polymer brushes

Poly[2‐(dimethylamino) ethyl methacrylate] (PDMAEMA) brushes on the surfaces of clay layers were prepared by in situ free‐radical polymerization. Poly (methyl methacrylate) (PMMA) colloid particles stabilized and initiated by clay layers with PDMAEMA polymer brushes were prepared by Pickering emulsion polymerization. Transmission electron microscopy was used to characterize the structure and morphology of the colloid particles. The X‐ray diffraction (XRD) results indicated that the intercalated structures of the clay layers were almost destroyed in Pickering emulsion polymerization, and clay layers with exfoliated structures were created. The surface of the colloid particles was analyzed by using X‐ray photoelectron spectroscopy (XPS). The XPS results provide direct evidence that the clay layers with PDMAEMA chains cover the PMMA colloid particles. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2632–2639, 2008     

Surface‐initiated atom transfer radical polymerization grafting of poly(2,2,2‐trifluoroethyl methacrylate) from flat silicon wafer surfaces

Poly(2,2,2‐trifluoroethyl methacrylate) (PTFEMA), a partially fluorinated polymer, was directly grafted from silicon wafer surfaces by a surface‐initiated atom‐transfer radical polymerization (ATRP). The polymer layer thickness increased linearly with monomer conversion and molecular weight of free polymers in solution. The thickness was mainly determined by the experimental conditions such as activator/deactivator ratio, monomer/catalyst ratio, and monomer concentration. PTFEMA layers of more than 100‐nm thick were obtained. The grafted PTFEMA chains were “living” and allowed the extension of a second block of PMMA. X‐ray photoelectron spectroscopy study showed that the chemical compositions at the surfaces agreed well with their theoretical values. A novel surface‐attachable difunctional initiator was also synthesized and applied to the grafting of PTFEMA. The grafting density was doubled using this difunctional initiator, from 0.48 to 0.86 chains/nm². © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1252–1262, 2006     

Grafting of montmorillonite nano‐clay with butyl acrylate and methyl methacrylate by atom transfer radical polymerization: Blends with poly(BuA‐co‐MMA)

11‐(2‐Bromo‐2‐methyl)propionyl‐oxy‐undecyl trichlorosilane atom transfer radical polymerization (ATRP) initiator was covalently attached on montmorillonite clay platelets via silylation reactions. The initiator clay was used to polymerize butyl acrylate (BuA) and methyl methacrylate (MMA) on the clay surface. Polymerization was performed in bulk monomer solution or in DMSO. Polymer modified clay was mixed with a poly(BuA‐co‐MMA) matrix. Small angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) showed that clay modified in DMSO gave exfoliated composites when mixed with the matrix copolymer. Mechanical properties of the composites were studied by dynamic mechanical thermal analysis (DMTA). The results showed that the mechanical properties were improved as a function of clay content, as well with an increasing homogeneity of the nanocomposite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3086–3097, 2009     

Synthesis of well‐defined polymer brushes on the surface of zinc antimonate nanoparticles through surface‐initiated atom transfer radical polymerization

Zinc antimonate nanoparticles consisting of antimony and zinc oxide were surface modified in a methanol solvent medium using triethoxysilane‐based atom transfer radical polymerization (ATRP) initiating group (i.e.,) 6‐(2‐bromo‐2‐methyl) propionyloxy hexyl triethoxysilane. Successful grafting of ATRP initiator on the surface of nanoparticles was confirmed by thermogravimetric analysis that shows a significant weight loss at around 250–410 °C. Grafting of ATRP initiator onto the surface was further corroborated using Fourier transform Infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS). The surface‐initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator‐fixed zinc antimonate nanoparticles in the presence of a sacrificial (free) initiator. The polymerization was preceded in a living manner in all examined cases; producing nanoparticles coated with well defined poly(methyl methacrylate) (PMMA) brushes with molecular weight in the range of 35–48K. Furthermore, PMMA‐grafted zinc antimonate nanoparticles were characterized using Thermogravimetric analysis (TGA) that exhibit significant weight loss in the temperature range of 300–410 °C confirming the formation of polymer brushes on the surface with the graft density as high as 0.26–0.27 chains/nm². The improvement in the dispersibility of PMMA‐grafted zinc antimonate nanoparticles was verified using ultraviolet‐visible spectroscopy and transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Atom‐transfer radical grafting polymerization of 2‐methacryloyloxyethyl phosphorylcholine from silicon wafer surfaces

2‐Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was grafted from silicon wafer surfaces at room temperature by combining self‐assembly of initiator and surface‐initiated atom transfer radical polymerization. Two methods were used to control the grafting process. One was to add free initiator to the reaction system; the other was to add excess deactivator. The grafting densities up to 0.3 chains/nm² were obtained. The surface thickness increased linearly with MPC conversion. The thickness depended on catalyst and monomer concentrations, as well as activator/deactivator ratio. Poly(MPC) layers of >100 nm thick were obtained by optimizing the polymerization conditions. A second block of either poly(MPC) or poly[2‐(dimethylamino)ethyl methacrylate] was also grown from the grafted poly(MPC), demonstrating the system livingness. X‐ray photoelectron spectroscopy was used to examine the surface chemical compositions showed good agreement with the theoretical values. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2931–2942, 2004     

Novel superhydrophobic silica/poly(siloxane‐fluoroacrylate) hybrid nanoparticles prepared via two‐step surface‐initiated ATRP: Synthesis,characterization, and wettability

Poly(siloxane‐fluoroacrylate)‐grafted silica hybrid nanoparticles were prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP). The silica nanoparticles with α‐bromo‐ester initiator group for copper‐mediated ATRP were prepared by the self‐assembled monolayers of (3‐aminopropyl)triethoxysilane and 2‐bromoisobutyrate bromide. Well‐defined diblock copolymer brushes consisting of poly(methacryloxypropyltrimethoxysilane) and poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) blocks were obtained by using initial homopolymer brushes as the macroinitiators for the SI‐ATRP of the second monomer. Chemical compositions and structures of the nanoparticles were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Surface properties and morphology of the nanoparticles were investigated with X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle measurement. It is revealed that the surfaces of the nanocomposites are rough at the microscale and nanoscale. The formation reason of the superhydrophobic surfaces was also discussed in this work. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of PS and PDMAEMA mixed polymer brushes on the surface of layered silicate and their application in pickering suspension polymerization

An ammonium free radical initiator was ion exchanged onto the surface of clay layers. Polystyrene (PS) and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) mixed polymer brushes on the surface of clay layers were prepared by in situ free radical polymerization. PS colloid particles armored by clay layers with mixed polymer brushes were prepared by Pickering suspension polymerization. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the colloid particles. Clay layers on the surface of PS colloid particles can be observed. Because of the cationic nature of the PDMAEMA brushes the colloid particles have positive zeta potentials at low pH values. X‐ray photoelectron spectroscopy (XPS) was used to analyze the surface of the colloid particles. N_1s binding energy of PDMAEMA chains on the surface of clay layers was detected by XPS. The two peaks of the N_1s binding energy indicate two different nitrogen environments on the surface of clay layers. The peak with a lower binding energy is characteristic of neutral nitrogen on PDMAEMA chains, and the peak with a higher binding energy is attributed to protonated nitrogen on PDMAEMA chains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5759–5769, 2007     

Functionalization of carbon nanofibers (CNFs) through atom transfer radical polymerization for the preparation of poly(tert‐butyl acrylate)/CNF materials: Spectroscopic,thermal, morphological,and physical characterizations

Vapor‐grown carbon nanofibers (CNFs) were oxidized and functionalized for atom transfer radical polymerization (ATRP) of tert‐butyl acrylate (t‐BA) from the surface of the CNFs. The materials were characterized by solubility tests, Fourier‐transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscopy. The FTIR and electron microscopy results suggest that ATRP process was successfully used to graft poly(tert‐butyl acrylate) (poly(t‐BA)) chains from the surface of the fibers. Raman results strongly indicate the partial degradation of the graphitic layer of CNFs because of the chemical treatments. TGA results suggest that the presence of poly(t‐BA) leads to a decrease of the initial degradation temperature of the fibers. XRD and electron microscopy results indicate that the microstructure of fibers was not destroyed because of the oxidation and functionalization processes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3326–3335, 2008     

Light‐driven atom transfer radical polymerization on supramolecular complexes of conjugated polymers and single‐walled carbon nanotubes

Previous approaches used to decorate latently reactive conjugated polymer‐coated carbon nanotube complexes have utilized “grafting‐to” strategies. Here, we coat the carbon nanotube surface with a conjugated polymer whose side chains contain the radical initiator, α‐bromoisobutyrate, which enables atom transfer radical polymerization (ATRP) from the polymer–nanotube surface. Using light to generate Cu(I) in situ, ATRP is used to grow narrow dispersity polymer chains from the polymer–nanotube surface. We confirm the successful polymerization of (meth)acrylates from the polymer–nanotube surface using a combination of gel permeation chromatography and infrared spectroscopy. Strikingly, we demonstrate that nanotube optoelectronic properties are preserved after radical‐mediated polymer grafting using Raman spectroscopy and photoluminescence mapping. Overall, this work elucidates a method to grow narrow dispersity polymer chains from the polymer–nanotube surface using light‐driven radical chemistry, with concurrent preservation of nanotube optoelectronic properties. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2015–2020     

Poly(dicyclopentadiene)‐montmorillonite nanocomposite formation via simultaneous intergallery‐surface initiation and chain crosslinking using ROMP

Exfoliated poly(dicyclopentadiene) (pDCPD)—montmorillonite (MMT) nanocomposites were synthesized via intergallery‐surface‐initiated ring opening metathesis polymerization (ROMP). This is the first example of in situ polymerization of pDCPD from clay intergallery surfaces using ROMP. Grubbs catalyst was immobilized on the surface of MMT clay modified with vinylbenzyl dimethyloctadecyl ammonium chloride (VOAC), and DCPD polymerized from the clay surface while simultaneously crosslinking to form a thermoset nanocomposite in a one‐pot reaction. X‐ray diffraction and transmission electron microscopy analysis indicated that the resultant nanocomposites exhibited exfoliated morphologies with heterogeneous clay platelet distribution. Conventional bulk‐initiated nanocomposites containing VOAC modified MMT were also synthesized as a comparison, and these resulted in nanocomposites with intercalated morphologies. The differences between the morphologies demonstrated that growing polymer chains from the initiator sites on the intergallery surface of the clay platelets pushed the platelets apart during the polymerization of the intergallery‐surface‐initiated nanocomposites, aiding in the exfoliation process. Compression testing indicated that the intergallery‐surface‐initiated nanocomposites led to improvements of up to 50% in the compressive Young's Modulus, while the bulk‐initiated nanocomposites at the same clay loadings did not exhibit improved properties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Layer structure estimation of three‐dimensional crystal and two‐dimensional molecular film for fluorinated comb copolymers

Comb copolymers containing both hydrogenated and fluorinated side‐chains were prepared by copolymerization using acrylic or methacrylic monomers in several ratios. The crystal structures of these copolymers and layer structures of their organized molecular films were investigated by wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and out‐of plane X‐ray diffraction. Further, to selectively estimate the regularity of shorter fluorocarbon side‐chains, organized molecular films of copolymers were investigated by polarized near‐edge X‐ray adsorption fine structure (NEXAFS) spectroscopy. From the results of these measurements, it was inferred that these copolymers formed highly ordered layer structures, and a long spacing was predominantly determined by the arrangement of hydrogenated side‐chains, except in copolymers having extremely high fluorocarbon contents. In the case of the organized molecular films, the fluorinated side‐chains of methacrylate copolymers cannot form a highly ordered arrangement, whereas those of acrylate copolymers were oriented on monolayers. However, in both cases, the hydrogenated side‐chains predominantly formed layer structures in the organized films, and the fluorinated side‐chains did not contribute to the formation of the layer structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 534–546, 2008     

表面引发的原子转移自由基聚合法在聚偏二氟乙烯表面制备可控的聚甲基丙烯酸甲酯刷

采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。     

Air‐tolerantly surface‐initiated AGET ATRP mediated by iron catalyst from silica nanoparticles

Well‐defined polymer‐nanoparticle hybrids were prepared by a newly reported method: atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) mediated by iron catalyst. The kinetics of the surface‐initiated AGET ATRP of methyl methacrylate from the silica nanoparticles, which was mediated by FeCl₃/triphenylphosphine as a catalyst complex, ascorbic acid as a reducing agent, N,N‐dimethylformamide as the solvent in the presence of a “sacrificial” (free) initiator, was studied. Both the free and grafted polymers were grown in a control manner. The chemical composition of the nanocomposites was characterized by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. Thermogravimetric analysis was used to estimate the content of the grafted organic compound, and transmission electron micrographs was used to observe the core‐shell structure of the hybrid nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2006–2015, 2010     

Template atom transfer radical polymerization of a diaminopyrimidine‐derivatized monomer in the presence of a uracil‐containing polymer

Uracil‐derivatized monomer 6‐undecyl‐1‐(4‐vinylbenzyl)uracil and diaminopyrimidine‐derivatized monomer 2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine (DMP) were synthesized and polymerized by atom transfer radical polymerization (ATRP). A well‐defined, highly soluble, uracil‐containing polymer, poly[6‐undecyl‐1‐(4‐vinylbenzyl)uracil] (PUVU), was prepared in dioxane at 90 °C with CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine as the catalyst and methyl α‐bromophenylacetate as the initiator. PUVU was further used as a template for the ATRP of DMP. The enhanced apparent rate constant of the DMP polymerization in the presence of PUVU indicated that the ATRP of DMP occurred along the PUVU template. The template polymerization produced a stable and insoluble macromolecular complex, PUVU/poly(2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine). An X‐ray diffraction study confirmed that the complex had strandlike domains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6607–6615, 2006     

Crystallization and thermal properties of PLLA comb polymer

Poly(L ‐lactide) (PLLA) on poly(2‐hydroxyethyl methacrylate) (PHEMA) backbone was prepared by a combination of atom transfer radical polymerization (ATRP) and ring‐opening polymerization (ROP). The structure of the comb polymer was analyzed by wide angle X‐ray diffraction (WAXD), small angle X‐ray scattering (SAXS), and differential scanning calorimetry (DSC). WAXD result indicates that the comb polymer has α crystalline modification with a 10₃ helical conformation. Lamellar parameters of the crystalline structure were obtained by one‐dimension correlation function (1DCF) calculated from SAXS results. The calculations show that the thickness of crystalline layer is controlled by annealing temperature and comb structure. DSC was applied to study kinetics of the crystallization and melting behavior. Two melting peaks on melting curves of the comb polymer at different crystallization temperature were detected, and the peak at higher temperature is attributed to the melt‐recrystallization. The equilibrium melting temperature is found to be influenced by the comb structure. In this article the effects of the comb structure on Avrami exponent, equilibrium melting point and melting peak of the comb polymer were discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 589–598, 2008     

Surface‐initiated polymerization from poly(ethylene terephthalate)

The free‐radical polymerization of styrene initiated from a functionalized poly(ethylene terephthalate) (PET) surface yielded a tethered polymer layer. The anchoring of the initiator species on the PET surface was performed from surface‐reactive groups easily generated by an alkaline hydrolysis of PET. After each surface modification, PET films were characterized by X‐ray photoelectron spectroscopy, measurements of water contact angles, and time‐of‐flight secondary‐ion mass spectrometry. The influence of the polymerization duration, the grafted initiator density, and the grafting mode on the efficiency of the surface‐initiated polymerization of styrene was investigated. In some cases, the tethering of the polystyrene layer on PET could be a reversible process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1347–1359, 2003     

Surface functionalization of multi‐walled carbon nanotubes through surface‐initiated atom transfer radical polymerization of glycidyl methacrylate

Herein, we report the fabrication of glycidyl methacrylate (GMA) polymeric conjugates of shortened multi‐walled carbon nanotubes (sMWCNT). The synthesis method involves the attachment of initiator on the surface of nanotubes followed by surface initiated atom transfer radical polymerization (SI‐ATRP) of GMA from the initiator‐bound sMWCNT surface. This is achieved by the procedure consisting of three important steps: introduction of amino groups onto the sMWCNT and attachment of polymerization initiator, 2‐bromo‐2‐methylpropinonyl bromide, and polymerization of GMA. The structure and properties of the resultant polymeric conjugates were characterized by Fourier transform infrared (FT‐IR) spectroscopy, Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) and SEM. The FT‐IR analysis of polymeric conjugates shows infrared (IR) peaks characteristic of GMA. AFM, TEM and SEM images clearly show the formation of poly(glycidyl methacrylate)(PGMA) polymer on sMWCNT surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Homopolymer and block copolymer brushes on gold by living anionic surface‐initiated polymerization in a polar solvent

Living anionic surface‐initiated polymerization on flat gold substrates has been conducted to create uniform homopolymer and diblock copolymer brushes. A 1,1‐diphenylethylene (DPE) self‐assembled monolayer was used as the immobilized precursor initiator. n‐BuLi was used to activate the DPE in tetrahydrofuran at –78 °C to initiate the polymerization of different monomers (styrene, isoprene, ethylene oxide, and methyl methacrylate). Poly(styrene) (PS) and poly(ethylene oxide) (PEO) in particular were first investigated as grafted homopolymers, followed by their copolymers, including poly(isoprene)‐b‐poly(methylmethacrylate) (PI‐b‐PMMA). A combined approach of spectroscopic (Fourier transform infrared spectroscopy, surface plasmon spectroscopy, ellipsometry, X‐ray photoelectron spectroscopy) and microscopic (atomic force microscopy) surface analysis was used to investigate the formation of the polymer brushes in polar solvent media. The chemical nature of the outermost layer of these brushes was studied by water contact angle measurements. The effect of the experimental conditions (solvent, temperature, initiator concentration) on the surface properties of the polymer brushes was also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 769–782, 2006     

Synthesis of polymeric core–shell particles using surface‐initiated living free‐radical polymerization

An easy and novel approach to the synthesis of functionalized nanostructured polymeric particles is reported. The surfactant‐free emulsion polymerization of methyl methacrylate in the presence of the crosslinking reagent 2‐ethyl‐2‐(hydroxy methyl)‐1,3‐propanediol trimethacrylate was used to in situ crosslink colloid micelles to produce stable, crosslinked polymeric particles (diameter size ～ 100–300 nm). A functionalized methacrylate monomer, 2‐methacryloxyethyl‐2′‐bromoisobutyrate, containing a dormant atom transfer radical polymerization (ATRP) living free‐radical initiator, which is termed an inimer (initiator/monomer), was added to the solution during the polymerization to functionalize the surface of the particles with ATRP initiator groups. The surface‐initiated ATRP of different monomers was then carried out to produce core–shell‐type polymeric nanostructures. This versatile technique can be easily employed for the design of a wide variety of polymeric shells surrounding a crosslinked core while keeping good control over the sizes of the nanostructures. The particles were characterized with scanning electron microscopy, transmission electron microscopy, optical microscopy, dynamic light scattering, and Raman spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1575–1584, 2007