In situ atom transfer radical polymerization of styrene to in-plane functionalize graphene nanolayers: grafting through hydroxyl groups

We report synthesis of a novel diamine 1,2-bis(4-(Hydrazonomethyl)phenoxy)ethane (bis- HPE) and a derived novel polyimide. The diamine was reacted with PMDA and ODA to synthesize copolyimide. Unmodified and modified silica particles were dispersed in the polyimide to prepare polyimide-silica hybrids: (a) unmodified (PSH-UM), and (b) modified (PSH-M). The PSH-UM were prepared by generating silica particles in situ in PI. In PSH-M, structural group identical to PI, 2,6- bis(3-(triethoxysilyl)propyl)pyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone was introduced into silica nano-particles. The structural similarity enhanced compatibility between organic–inorganic components by like-like chemical interactions as both contain flexible alkyl groups. PSH-M have shown improved surface smoothness, hydrophobicity and thermal stability. Such properties are mandatory for stable coatings. The structure of silica and PI was affirmed by FTIR, EDX, and solid-state 29Si NMR spectroscopy. Morphological and thermal properties of the prepared PI-SiO₂ nano-composites were investigated by field emission scanning electron microscopy, atomic force microscopy, contact angle measurement and thermogravimetric analysis.     

Grafting polystyrene with various graft densities through epoxy groups of graphene nanolayers via atom transfer radical polymerization

A double bond and amine group containing chemical (OD) was synthesized by coupling reaction of ethylenediamine and 3‐(chlorodimethylsilyl)propyl methacrylate. Subsequently, graphene oxide (GO) was functionalized with OD in different densities via ring opening of its epoxy groups. The graphene containing double bond (GOD) was incorporated into polystyrene (PS) chains by a grafting through atom transfer radical polymerization. Grafting of OD at the surface of GO was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). The interlayer spacing of the graphenes was evaluated by X‐ray diffraction. Molecular weight and PDI values of the free and attached PS chains were studied by size exclusion chromatography. TGA was also used to study the degradation points, char values, and grafting ratios. Relaxation of PS chains in the presence of graphene layers was evaluated by differential scanning calorimetry. Scanning electron and transmission electron microscopies show that flat graphene layers are wrinkled during oxidation and functionalization processes. POLYM. COMPOS., 38:2450–2458, 2017. © 2015 Society of Plastics Engineers     

原子转移自由基法合成乙丙橡胶接枝物中的热聚合研究

采用原子转移自由基聚合法(ATRP)合成了三元乙丙橡胶与苯乙烯的接枝共聚物(EPDM-g-St),动力学研究表明聚合过程为“活性”聚合。在接枝聚合过程中发现了明显的苯乙烯热聚合现象。对接枝聚合中得到的均聚苯乙烯进行表征的结果表明,苯乙烯在ATRP接枝体系中的热聚合过程在一定程度上受到ATRP机理的控制;升高温度和延长反应时间使得热聚合更为显著。     

Edge‐functionalized graphene nanoplatelets with polystyrene by atom transfer radical polymerization: grafting through carboxyl groups

The surface modifier 3‐((4‐hydroxybutoxy)dimethylsilyl)propyl methacrylate (CD), which contains a double bond and a hydroxyl group, was synthesized through a coupling reaction of 1,4‐butanediol and (3‐methacryloxypropyl)dimethylchlorosilane. Subsequently, graphene oxide (GO) was functionalized with different amounts of CD from its edge carboxyl groups. Then, grafting through atom transfer radical polymerization of styrene in the presence of various amounts of the edge‐functionalized GO was carried out to evaluate the effect of graphene loading along with graft density. A peak at 3.8 ppm in the ¹H NMR spectrum of CD associated with the methylene adjacent to the Si–O group indicated a successful coupling reaction. Attachment of CD on the edges of GO was evaluated using X‐ray photoelectron and Fourier transform infrared spectroscopies. Expansion of GO interlayer spacing by functionalization was evaluated using X‐ray diffraction. The ordered and disordered crystal structure of carbon was studied using Raman spectroscopy. The close I_D/I_G values for GO and various kinds of functionalized graphenes show the preserved graphitic crystallite size. Relaxation behaviour of polystyrene chains in the presence of graphene nanoplatelets and also the effect of graft content on chain confinement were studied using differential scanning calorimetry. High‐graft‐density nanocomposites show higher glass transition temperatures. Morphology of graphene nanoplatelets was studied using scanning electron and transmission electron microscopies. The flat and smooth morphology of graphene nanoplatelets is disturbed and also the transparency of the nanoplatelets decreases during the oxidation and functionalization processes. © 2014 Society of Chemical Industry     

In‐plane functionalizing graphene nanolayers with polystyrene by atom transfer radical polymerization: Grafting from hydroxyl groups

Graphene oxide (GO) was prepared from the oxidation of graphite and then it was functionalized with (3‐aminopropyl)triethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, alpha‐bromoisobutyryl bromide (BiBB) was attached to the APTES groups to yield initiator anchored graphene nanolayers (GOHBr). Then, GOHBr was used in different amounts as the precursor for atom transfer radical polymerization of styrene to evaluate the effect of graphene loading along with the graft density on the properties of final product. Successful in‐plain attachment of APTES, BiBB, and polystyrene to GO was evaluated by Fourier transform infrared spectroscopy. Graphene interlayers expansion by oxidation and functionalization processes was evaluated using X‐ray diffraction. The ordered and disordered crystal structures of carbon were evaluated by Raman spectroscopy. Morphology of graphene nanolayers was studied by scanning electron microscopy and also transmission electron microscopy. POLYM. COMPOS., 35:386–395, 2014. © 2013 Society of Plastics Engineers     

m－DVB和p－DVB原子转移自由基聚合动力学

以氯端基聚苯乙烯为大分子引发剂,氯化亚铜／２,２’－联二吡喧为催化剂,邻二甲苯为溶剂,用气相色谱分别研究了对二乙烯基苯（ｐ－ＤＶＢ）和间二乙烯在苯（ｍ－ＤＶＢ）在１００￣１３０℃的原子转移自由基聚合动力学。结果表明,聚合符合表观一级反应动力学。ｐ－ＤＶＢ在１００,１１０,１２０、１３０℃的聚合速率常数分别为０．０７２,０．１２８,０．３７９,０．５４６ｈ＾－１,ｍ－ＤＶＢ在上述不同温度的聚合速率常     

L-menthol-based initiators for atom transfer radical polymerization of styrene

Two new atom transfer radical polymerization (ATRP) initiators, 2-isopropyl-5-methylcyclohexyl 2-bromopropanoate ( 1 ) and 2-Isopropyl-5-methylcyclohexyl 2-bromo-2-methylpropanoate ( 2 ), have been synthesized by the reaction of 2-bromopropanoyl bromide and 2-bromo-2-methylpropanoyl bromide, respectively, with L-menthol and characterized by ¹H and ¹³C NMR and FTIR spectroscopic studies. ATRP of styrene has successfully been carried out in a control manner using these initiators along with catalyst/ligand system consisting of Cu(I)Br/N,N,N ^/,N ^/,N ^//-pentamethyldiethylenetriamine. Polymerizations have yielded polystyrenes (PSts) of controlled molecular weight with low polydispersity index having a menthyl end group, as confirmed by ¹H NMR and gel permeation chromatography [GPC]. The controlled nature of the polymerization has also been confirmed by kinetic study of the polymerization process monitored via ¹H NMR and GPC. Initiator 2 has evolved as most efficient among the two. The obtained end-functional PSt has also been used as a macroinitiator for homochain extension with styrene and heterochain extension with methyl methacrylate to produce PSt-b-PMMA, showing the living nature of the polymerization process. In comparison with the PSt sample prepared using widely used initiator ethyl-2-bromo-isobutyrate with almost the same molecular weight and polydispersity, initiator 2 -made L-menthyl-capped PSt has shown higher light transmission properties of its dichloromethane solution at ~259 nm, higher thermal stability, lower glass transition temperature, a broad melting temperature, and higher surface roughness over its film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47964.     

Kinetic study of atom transfer radical polymerization of methyl methacrylate in ionic liquids

The kinetics of methyl methacrylate (MMA) homopolymerization performed by atom transfer radical polymerization (ATRP) is investigated in detail using ethyl‐2‐bromopropionate (EPN‐Br) as initiator, CuBr as catalyst, and pentamethyldiethylenetriamine (PMDETA) as ligand in ionic liquids (ILs) and acetonitrile. ILs in this research covered two different substitutional imidazolium cations and anions including halogen and halogen‐free ones. The typical cations include 1‐butyl‐3‐methylimidazolium, 1‐ethyl‐3‐methylimidazolium and the typical anions include bromide, tetrafluoroborate. The effects of solvents, temperature, and reaction ingredients ratios on the polymerization kinetics are all investigated in this article and the apparent energy of activation (ΔE) calculated for the ATRP of MMA in 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate is 6.95 KJ/mol. The number‐average molecular weights (M_n) increase linearly with conversion but are much higher than the theoretical values. It is probably due to the low concentration of deactivator at the early stage of polymerization and the lower bond energy of C‐Br in PMMA‐Br than that in EPN‐Br. Moreover, the catalyst is easily separated from the polymer and the regenerated catalyst is reused for more than three times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetic study of the atom transfer radical polymerization of n‐docosyl acrylate

The atom transfer radical polymerization (ATRP) of n‐docosyl acrylate (DA) was studied at 80°C in N,N‐dimethylformamide using the carbon tetrabromide/FeCl₃/2,2′‐bipyridine (bpy) initiator system in the presence of 2,2′‐azobisisobutyronitrile (AIBN) as the source of reducing agent. The rate of polymerization exhibits first‐order kinetics with respect to the monomer. The linear relationship between the molecular weight of the resulting poly(n‐docosyl acrylate) with conversion and the narrow polydispersity of the polymers indicates the living characteristics of the polymerization reaction. The significant effect of AIBN on the ATRP of DA was studied keeping [FeCl₃]/[bpy] constant. A probable reaction mechanism for the polymerization system is postulated to explain the observed results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2147–2154, 2005     

Reverse atom transfer radical polymerization of styrene in the presence of tetraethylthiuram disulfide

Reverse atom transfer radical polymerization (ATRP) of styrene initiated with tetraethylthiuram disulfide (TD)/cuprous bromide (CuBr)/2,2′-bipyridine (bpy) has been successfully carried out at 120 °C. The kinetic plot was first order in monomer. The measured number-average molecular weight was in good accordance with the theoretical one. Radical scavenger 1,1-diphenyl-2-picrylhydrazyl (DPPH) immediately terminated the reaction, which supported the radical essence of this polymerization. ¹H NMR and UV spectra analyses revealed α-S₂CNEt₂ and ω-Br end groups on the polystyrene chain. Conventional ATRP of methyl methacrylate could progress with the obtained polymer acting as the macroinitiator and CuBr/bpy or CuCl/bpy as the catalyst.     

Pyridylphosphine ligands for iron-based atom transfer radical polymerization of methyl methacrylate and styrene

Two pyridylphosphine ligands, 2-(diphenylphosphino)pyridine (DPPP) and 2-[(diphenylphosphino)methyl]pyridine (DPPMP), were investigated as complexing ligands in the iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and styrene with various initiators and solvents. In studies of their ATRP behavior, the FeBr₂/DPPP catalytic system was a more efficient ATRP catalyst for the MMA polymerization than the other complexes studied in this paper. Most of these systems were well controlled with a linear increase in the number-average molecular weights (M_n) vs. conversion and relatively low molecular weight distributions (M_w/M_n = 1.15-1.3) being observed throughout the reactions, and the measured molecular weights matched the predicted values with the DPPP ligand. The polymerization rate of MMA attained a maximum at a ratio of ligand to metal of 2:1 in p-xylene at 80 °C. The polymerization was faster in polar solvents than in p-xylene. The 2-bromopropionitrile (BPN) initiated ATRP of MMA with the FeX₂/DPPP catalytic system (X = Cl, Br) was able to be controlled in p-xylene at 80 °C. The polymerization of styrene was able to be controlled using the PECl/FeCl₂/DPPP system in DMF at 110 °C.     

Emulsion copolymerization of styrene and butyl acrylate by reverse atom transfer radical polymerization

Reverse atom transfer radical copolymerization of styrene (St) and butyl acrylate was carried out in emulsion under normal emulsion conditions, using CuBr₂/bpy complex as catalyst. The effects of surfactant type, initiator type and concentration, and CuBr₂ addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the Polysorbate 80 (Tween 80) and azodiisobutyronitrile gave the best exhibition in this system, polymer samples were got with narrow molecular‐weight dispersity (M_w/M_n = 1.1–1.2) and linear relationships of molecular weight versus monomer conversion, as well as a relatively low polydispersity index (<0.1). Through the GPC and SEM analysis, the polymerization processes under these conditions showed good living/control characteristics relative to the processes under normal emulsion polymerization, although the latex stability was susceptible to the CuBr₂ catalyst. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of graft copolymers from a linear polyolefin through a combination of coordination polymerization and atom transfer radical polymerization

This article reports on a facile route for the preparation of methyl acrylate and methyl methacrylate graft copolymers via a combination of catalytic olefin copolymerization and atom transfer radical polymerization (ATRP). The chemistry first involved a transforming process from ethylene/allylbenzene copolymers to a polyolefin multifunctional macroinitiator with pendant sulfonyl chloride groups. The key to the success of the graft copolymerization was ascribed to a fast exchange rate between the dormant species and active radical species by optimization of the various experimental parameters. Polyolefin‐g‐poly(methyl methacrylate) and polyolefin‐g‐poly(methyl acrylate) graft copolymers with controlled architecture and various graft lengths were, thus, successfully prepared under dilute ATRP conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

All solid-state polymer electrolytes prepared from a hyper-branched graft polymer using atom transfer radical polymerization

We propose an all solid-state (liquid free) polymer electrolyte (SPE) prepared from a hyper-branched graft copolymer. The graft copolymer consisting of a poly(methyl methacrylate) main chain and poly(ethylene glycol) methyl ether methacrylate side chains was synthesized by atom transfer radical polymerization changing the average chain distance between side chains, side chain length and branched chain length of the proposed structure of the graft copolymer. The ionic conductivity of the SPEs increases with increasing the side chain length, branched chain length and/or average distance between the side chains. The ionic conductivity of the SPE prepared from POEM₉ whose POEM content = 51 wt% shows 2 × 10⁻⁵ S/cm at 30 °C. The tensile strength of the SPEs decreases with increases the side chain length, branched chain length and/or average distance between the side chains. These results indicate that a SPE prepared from the hyper-branched graft copolymer has potential to be applied to an all-solid polymer electrolyte.     

苯乙烯/丙烯酸丁酯反向原子转移自由基乳液聚合的合成与表征

采用Tween 80为乳化剂,FeCl3.6H2O/EDTA/AIBN为催化引发体系,在乳液体系中对苯乙烯、丙烯酸丁酯进行反向原子转移自由基(RATRP)共聚合。考察了原料加入方式、过渡金属催化剂浓度及反应温度对RATRP乳液聚合影响。结果表明,得到聚合物的分子量与单体转化率呈线性增长,分子量分布较窄(PDI为1.40)的无规共聚物。借助于凝胶渗透色谱(GPC)和红外光谱仪(IR)对RATRP共聚乳液进行表征,表明加入催化体系进行RA-TRP乳液聚合是"活性"可控聚合。     

Polystyrene-attached graphene nanolayers by reversible addition-fragmentation chain transfer polymerization: a grafting from epoxy groups with various densities

Graphene oxide was chemically functionalized with a modifier synthesized from coupling reaction of ethylenediamine and 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid in low and high graft densities. Then, the modified graphenes were used in grafting from reversible addition-fragmentation chain transfer polymerization of styrene. Successful synthesis and grafting of modifier was approved by proton nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). Also, FTIR, X-ray photo electron spectroscopy, and Raman spectroscopy were used to confirm the successful grafting of modifier moieties. Molecular weight and polydispersity index of attached polystyrene chains were studied by size exclusion chromatography. Thermogravimetric analysis was used to investigate the degradation temperatures, char contents, and graft ratios. Weight ratio of modifier in modified graphenes is calculated to be 4.93 × 10^?2 and 12.23 × 10^?2 for low and high graft densities. Also, molar ratio of modifier is 121.22 and 300.71 μmol/g respectively. Scanning electron and transmission electron microscopies show that graphite layers with flat surface were wrinkled during the oxidation process and also polystyrene-grafted graphenes are observed as opaque layers.     

原子转移自由基聚合原理及应用

介绍了有关原子转移自由基聚合(ATRP)的聚合原理。最新研究表明:应用ATRP法进行聚合反应可以制备接枝聚合物、嵌段聚合物、超支化聚合物和其它有机/无机混合型聚合物等。ATRP在高分子聚合反应领域具有十分广阔的应用前景。     

Synthesis of triblock and random copolymers of 4-acetoxystyrene and styrene by living atom transfer radical polymerization

Triblock copolymers containing polystyrene (PSt) and poly(4-acetoxystyrene) (PAcOSt) segments have been prepared by atom transfer radical polymerization (ATRP). In the first step one of the two monomers was polymerized in bulk using the initiating system α,α′-dibromo-p-xylene/CuBr/2,2′-bipyridine (1/1/3). Subsequently the resulting telechelic polymers with active bromo end group structures were used as macroinitiators for the polymerization of the second monomer under ATRP conditions. This process gave PAcOSt-PSt-PAcOSt and PSt-PAcOSt-PSt triblock copolymers with predetermined molecular weights and narrow molecular weight distributions. Polymerization of a mixture of equal molar amounts of the two monomers yielded a random copolymer with narrow molecular weight distribution. Received: 25 June 1997/Revised: 25 August 1997/Accepted: 8 September 1997     

Controlled atom transfer radical polymerization of MMA onto the surface of high-density functionalized graphene oxide

We report on the grafting of poly(methyl methacrylate) (PMMA) onto the surface of high-density functionalized graphene oxides (GO) through controlled radical polymerization (CRP). To increase the density of surface grafting, GO was first diazotized (DGO), followed by esterification with 2-bromoisobutyryl bromide, which resulted in an atom transfer radical polymerization (ATRP) initiator-functionalized DGO-Br. The functionalized DGO-Br was characterized by X-ray photoelectron spectroscopy (XPS), Raman, and XRD patterns. PMMA chains were then grafted onto the DGO-Br surface through a ‘grafting from’ technique using ATRP. Gel permeation chromatography (GPC) results revealed that polymerization of methyl methacrylate (MMA) follows CRP. Thermal studies show that the resulting graphene-PMMA nanocomposites have higher thermal stability and glass transition temperatures (T_g) than those of pristine PMMA.     

Evaluation of the confinement effect of nanoclay on the kinetics of styrene atom transfer radical polymerization

The grafting through method was employed to study the effect of nanoclay confinement on the atom transfer radical polymerization (ATRP) of styrene. An ammonium salt containing a double bond on its structure was used as a clay modifier. Employing ATRP to polymerize styrene in the presence of modified montmorillonite resulted in a finely well‐defined polystyrene nanocomposite. The gas chromatography (GC) results showed the linear increase of ln(M₀/M) versus time, which indicated the controlled behavior of the polymerization. Another confirmation of the living nature of the polymerization was the linear increase of molecular weight against monomer conversion concluded from the gel permeation chromatography (GPC) data. Nanoclay exerted acceleration on the polymerization of free polystyrene chains. The polydispersity indexes of polymer chains increased by the addition of nanoclay. In the case of clay‐attached polystyrene chains, number and weight‐average molecular weights were lower than that of freely dispersed polystyrene chains. The polydispersity index of the clay‐attached chains was higher in respect to the freely dispersed polystyrene chains. The living nature of polymer chains was more elucidated by Fourier transform infrared spectroscopy (FTIR). Exfoliation of the clay layers in the polymer matrix of polystyrene nanocomposite containing the lowest amount of nanoclay has proven by Transmission Electron Microscopy (TEM). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011