Atom Transfer Radical Polymerization Polymerization Research Articles

A combining signal amplification of atom transfer radical polymerization and redox polymerization for visual biomolecules detection

A novel combination of atom transfer radical polymerization (ATRP) and redox polymerization is here used to allow instrument-free visualization of special biomolecules for which dynamic polymer growth is used in signal amplification. In this method, the convenient and mild redox polymerization-assisted amplification with cerium ammonium (IV) nitrate as oxidant at the second stage was achieved by directly using the hydroxyl groups from poly(hydroxyethyl methacrylate) (PHEMA) synthesized via ATRP at the first stage. The brushed polymers poly(hydroxylethyl methacrylate)-branched-poly (acrylamide) (PHEMA-branched-PAM) prepared by successive ATRP and redox polymerization in situ drastically grew up at the detected biomolecules spot to improve the visibility of biomolecule and simplify the detection procedure. With the proposed strategy, the signal amplification of streptavidin (SA) as model detected biomolecule was investigated on two different substrates such as silicon wafer and gold, respectively. As a result, detection limit of SA was demonstrated on the gold substrates where binding of 1.0 ng/mL SA was differentiable from the background using ellipsometry. Moreover, binding of 0.5 nmol/L DNA led to visually distinguishable spots on the gold surface under mild condition. The proposed method exhibited an efficient amplification performance for molecules detection, and paved a new way for visual diagnosis of biomolecules. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2791–2799

Synergistic effect on corrosion resistance of Phynox substrates grafted with surface-initiated ATRP (co)polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-hydroxyethyl methacrylate (HEMA).

Phynox is of high interest for biomedical applications due to its biocompatibility and corrosion resistance. However, some Phynox applications require specific surface properties. These can be imparted with suitable surface functionalizations of its oxide layer. The present work investigates the surface-initiated atom transfer radical polymerization (ATRP) of 2-methacryloyoxyethyl phosphorylcholine (MPC), 2-hydroxyethyl methacrylate (HEMA), and ATRP copolymerization of (HEMA-co-MPC) (block and statistic copolymerization with different molar ratios) on grafted Phynox substrates modified with 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid (BUPA) as initiator. It is found that ATRP (co)polymerization of these monomers is feasible and forms hydrophilic layers, while improving the corrosion resistance of the system.

Synthesis of star polymers by “core-first” one–pot method via ATRP: Monte Carlo simulations

Results of the simulation of star polymers synthesis by one–pot, core–first method are presented. The simulated ideal living polymerization process consists of two steps. In the first one (core growth) an atom transfer radical polymerization (ATRP) of a crosslinker is performed. When the crosslinker conversion is close to completion, a bifunctional monomer is added and the ATRP polymerization of the monomer takes place from the obtained cores to form linear arms of the stars. The simulation method is based on dynamic lattice liquid (DLL) algorithm, which takes into account changes of local dynamics resulting from polymerization and formation of complex polymer molecules. In the first stage of the synthesis (core formation), in addition to the effect of concentrations of initiator and crosslinker, the rate of intramolecular crosslinking is also very important. This process “consumes” the reactive crosslinker in the cores, limiting the core size and preventing further star–star coupling. The effect of various parameters on star size and internal structure was studied. These parameters involve the rate of intramolecular crosslinking, initial concentrations of the components and the moment of monomer addition. The results can be used as guidelines for the experimental work on star synthesis.

Phynox Improved Corrosion Resistance with MPC Initiated from Mixed Monolayers of Phosphonic Acids

This work investigated the grafting of 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid (BUPA) and 1-dodecylphosphonic acid (C12PA) to form (mixed) monolayers with different proportions of BUPA and C12PA on Phynox. The role and impact of these grafted molecules have been evaluated in terms of the corrosion resistance and the feasibility to act as a suitable platform for surface initiated atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC). It appeared that both molecules play an important role: BUPA to initiate the ATRP polymerization of MPC and C12PA to increase the resistance to corrosion of Phynox substrates. Moreover, the presence of C12PA in the mixed monolayer beneath the poly-2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (PMPC) layer has a beneficial impact in terms of corrosion resistance.

Ruthenocene-Containing Homopolymers and Block Copolymers via ATRP and RAFT Polymerization

Ruthenocene-containing methacrylate homopolymer, poly(2-(methacrylolyoxy)ethyl ruthenocenecarboxylate) (PMAERu), was prepared by controlled polymerization methods such as reversible addition–fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). Kinetic studies showed that both the RAFT and ATRP process of monomer 2-(methacryloyloxy)ethyl ruthenocenecarboxylate (MAERu) followed a controlled/“living” polymerization behavior. The obtained polymer PMAERu was fully characterized by NMR, gel permeation chromatography, UV–vis spectroscopy, cyclic voltammetry, thermogravimetric analysis, and differential scanning calorimetry. By using the ruthenocene-containing homopolymer as a Macro-RAFT agent and 2-bromoisobutyryl end-capped poly(ethylene oxide) (PEO-Br) as a macroinitiator, different amphiphilic diblock copolymers were synthesized via successful chain extension. These amphiphilic diblock copolymers can self-assemble into micelles with different morphologies, includ...

Atom transfer radical polymerization of hydrophilic monomers and its applications

Atom transfer radical polymerization (ATRP) has become one of the most widely used living radical polymerization techniques for preparation of polymers with pre-designed compositions, topologies and functionalities. Hydrophilic (co)polymers are broadly used in various fields, such as hybrid materials, surface modification and delivery carriers in biomedical areas because of their diverse functionalities and ideal characters, including their non-toxicity, biocompatibility and environmentally friendly nature. Polymerization of hydrophilic monomers by ATRP provides polymers with more colorful structures, as well as novel properties and extends the application scope of hydrophilic polymers due to its facile operation and commercially available catalysts, ligands and initiators of the methodology. This review focuses on ATRP of hydrophilic monomers, as well as its application as detailed in five aspects: (1) basic understanding of the ATRP mechanism and polymerization kinetics of hydrophilic monomers; (2) polymerization media for hydrophilic monomers; (3) topologies of polymers based on hydrophilic monomers; (4) polymerization by combination of ATRP with other techniques, and (5) applications of polymerization of hydrophilic monomers.

Novel polymeric solid acid catalysts for cellulose hydrolysis

Novel solid polymeric catalysts consisting of polymer chains have been synthesized to facilitate cellulose dissolution and catalyze its hydrolysis. Poly(styrene sulfonic acid) (PSSA) polymer chains have been grown from the substrate surface and used to catalyze biomass hydrolysis. Neighboring poly(vinyl imidazolium chloride) ionic liquid (PIL) polymer chains, also grown from the substrate surface, help solubilize lignocellulosic biomass and enhance the catalytic activity of the PSSA chains. The PSSA chains were synthesized via surface initiated atom-transfer radical polymerization (ATRP) whereas the adjacent PIL chains were synthesized via UV-initiated free radical polymerization. These novel polymeric solid acid catalysts demonstrate over 97% and 32% total reducing sugar (TRS) yields from cellulose hydrolysis in [EMIM]Cl and aqueous solutions respectively. The dual ATRP and UV-initiated polymerization schemes allow independent variation of the relative ratio of the two nanostructures as well as the chain length and density. This permits optimization of the catalytic activity for cellulose hydrolysis reaction. These catalysts are stable and maintain high catalytic activity after repeated runs.

"Paintable" 3D printed structures via a post-ATRP process with antimicrobial function for biomedical applications.

3D printing technology is becoming a new attractive manufacturing approach in medical and biomedical fields. In this paper, 3D printed structures were "painted" with functional polymer brushes via atom transfer radical polymerization (ATRP) to achieve antimicrobial properties for biomedical applications. An ATRP initiator was added into 3D printing ink without affecting the optical and polymerization properties. After the 3D printing process using the functionalized ink, the surface readily binds with the Br terminated initiator for the following surface modification. Moreover, since the initiator exists in the bulk material and thus the entire printed structure, if needed, any damaged surface can be easily re-painted with a single step of the ATRP polymerization process. To demonstrate the technique, 3-sulfopropyl methacrylate potassium salt (SPMA) was grafted onto the surface and the adhesion of bacteria was significantly reduced. In addition, the functionalized surface can also inhibit the growth of bacteria on the surface. Enabling new functions of the printed structures, the developed technique has significantly expanded the capability of 3D printing technology for biomedical applications.

Quasiliving atom transfer radical polymerization of styrene and n-butyl acrylate as non-fluorous monomers in a fluorinated solvent, benzotrifluoride

Quasiliving atom transfer radical polymerization (ATRP) of non-fluorous monomers, styrene and n-butyl acrylate, was attempted in benzotrifluoride (BTF; α,α,α-trifluorotoluene, TFT), the simplest trifluoromethylated aromatic compound, as an alternative solvent to widely used polymerization media in ATRP and other radical polymerizations, such as benzene, toluene, xylene, diphenylether etc., with toxic, carcinogenic or corrosive labels. In the absence of any other fluorinated additive, BTF was found to be a suitable reaction medium for ATRP of these monomers with the CuBr/N,N,N′,N″,N″-penta-methyldiethylenetetramine (PMDETA) non-fluorous catalyst system at 90 °C. The higher number average molecular weights than that of the theoretical ones at relatively low conversions in styrene polymerization with the 1-phenylethyl bromide (PhEtBr) initiator indicates quasiliving polymerization of styrene in BTF with slow initiation. This is confirmed by the linear correlation of the obtained data in the slow initiation plot, i.e. ln(1−f) + f versus ln(1−C), where f and C stand for the initiating efficiency and conversion, respectively. Quasiliving ATRP of n-butyl acrylate with rapid quantitative initiation was found by the ethyl-2-bromoisobutyrate (Et-2BriBu)/CuBr/PMDETA initiating system in BTF. In both cases, the absence of any kind of significant side reactions, i.e. chain transfer to solvent or irreversible termination, was observed. Thus, in contrast to the general perception of the immiscibility between fluorous and non-fluorous solvent/polymer systems, our findings indicate that BTF, as a fluorinated solvent, due to its unique properties, including its moderately high polarity, low vapor pressure and low toxicity etc., can be considered as an outstanding solvent with broad application possibilities for a large array of polymerization reactions and other chemical processes of non-fluorous monomers, polymers and many other compounds as well.

Synthesis and Characterization of Novel Polyacid-Stabilized Latexes

A series of novel polyacid macromonomers based on 2-hydroxypropyl methacrylate (HPMA) were prepared by atom transfer radical polymerization (ATRP) via a two-step route. First, a range of well-defined PHPMA homopolymer precursors were synthesized by ATRP using a tertiary amine-functionalized initiator, 2-(dimethylamino)ethyl-2-bromoisobutyrylamide, and a CuCl/2, 2'-bipyridine (bpy) catalyst in alcoholic media at 50 °C. ATRP polymerizations were relatively slow and poorly controlled in pure isopropanol (IPA), especially when targeting higher degrees of polymerization (DP > 30). Improved control was achieved by addition of water: low polydispersity (M(w)/M(n) < 1.25) PHPMA homopolymers of DP = 30, 40, 50, 60, or 70 were successfully prepared using a 9:1 w/w % IPA/water mixture at 50 °C. These PHPMA homopolymer precursors were then derivatized to produce the corresponding poly(2-(succinyloxy)propyl methacrylate) (PSPMA) macromonomers by quaternizing the tertiary amine end-group with excess 4-vinylbenzyl chloride, followed by esterification of the pendent hydroxyl groups using excess succinic anhydride at 20 °C. These polyacid macromonomers were evaluated as reactive steric stabilizers for polystyrene latex synthesis under either aqueous emulsion polymerization or alcoholic dispersion polymerization conditions. Near-monodisperse polystyrene latexes were obtained via aqueous emulsion polymerization using 10 wt % PSPMA macromonomer (with respect to styrene monomer) with various initiators as evidenced by scanning electron microscopy, disk centrifuge photosedimentometry and light scattering studies. PSPMA macromomer concentrations as low as 1.0 wt % also produced near-monodisperse latexes, suggesting that these PSPMA macromonomers are highly effective stabilizers. Alcoholic dispersion polymerization of styrene conducted in various ethanol/water mixtures with 10 wt % PSPMA(50) macromonomer produced relatively large near-monodisperse latexes. Increasing the water content in such formulations led to smaller latexes, as expected. Control experiments conducted with 10 wt % PSPMA(50) homopolymer produced relatively large polydisperse latexes via emulsion polymerization and only macroscopic precipitates via alcoholic dispersion polymerization. Thus the terminal styrene group on the macromonomer chains is essential for the formation of well-defined latexes. FT-IR spectroscopy indicated that these latexes contained PSPMA macromonomer, whereas (1)H NMR spectroscopy studies of dissolved latexes allowed stabilizer contents to be determined. Aqueous electrophoresis and X-ray photoelectron spectroscopy studies confirmed that the PSPMA macromonomer chains were located at the latex surface, as expected. Finally, these polyacid-stabilized polystyrene latexes exhibited excellent freeze-thaw stability and remained colloidally stable in the presence of electrolyte.

Original route to polylactide–polystyrene diblock copolymers containing a sulfonyl group at the junction between both blocks as precursors to functional nanoporous materials

Novel functionalized nanoporous polymeric materials could be derived from poly(D,L-lactide)-block-polystyrene (PLA-b-PS) diblock copolymers with a sulfonyl group at the junction between both blocks were synthesized by a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) using a synthetic difunctional initiator through a three-step sequential methodology. Different ω-bromo PLA polymers with various molar masses ranging from 3640 to 11,440gmol−1 were first produced by coupling ω-hydroxy PLA precursors to a chlorosulfonyl-functionalized ATRP initiator previously prepared, thus leading to the formation of suitable macroinitiators for the subsequent ATRP polymerization of styrene. Consequently, PLA-b-PS diblock copolymers were obtained with a finely tuned PLA volume fraction (fPLA) in order to develop a microphased-separation morphology. The resulting copolymers as well as the intermediate compounds were carefully analyzed by size exclusion chromatography and 1H NMR. Upon shear flow induced by a channel die processing, oriented copolymers were generally afforded as characterized by small-angle-X-ray scattering (SAXS). Such copolymers were finally submitted to mild alkaline conditions so as to hydrolyze the sacrificial PLA block, and the presence of the sulfonic acid functionality on the pore walls of the resulting nanoporous materials was evidenced by means of a post-modification reaction consisting in the corresponding sulfonamide formation.

ATRP with Alkyl Pseudohalides Acting as Initiators and Chain Transfer Agents: When ATRP and RAFT Polymerization Become One

AbstractAll controlled radical polymerization (CRP) procedures rely on a dynamic and rapid equilibrium between dormant and active species. This equilibrium can be established through different mechanisms and all the resulting CRP processes have their own advantages and limitations. Therefore, it becomes interesting to investigate the possibility of combining CRP techniques to eliminate specific drawbacks of each individual procedure. Atom transfer radical polymerization (ATRP) with alkyl pseudohalides acting as initiators and chain transfer agents was developed for that purpose. The process relies on a dual mechanism involving both activationdeactivation and reversible additionfragmentation chain transfer (RAFT). This peculiar characteristic of ATRP with alkyl pseudohalides acting as chain transfer agents made it possible to overcome some of the limitations typically associated with conventional ATRP and RAFT polymerization as well as to prepare new responsive materials.

Surface‐Initiated Controlled Radical Polymerization in Ordered Mesoporous Silicas

AbstractRecent advances in the synthesis of well‐defined high‐surface‐area mesoporous silica/polymer composites via surface‐initiated polymerization (“grafting from” method) and via attachment of preformed polymer chains (“grafting to” method) to surfaces of ordered mesoporous silicas (OMSs) are reviewed in the context of related research areas. Prior work on polymerizations in nanoscale confinements of OMSs is outlined and surface‐initiated polymerization in disordered mesoporous silicas is briefly discussed. Early work on the surface‐initiated radical polymerization initiated from OMS surface is reviewed and recent work involving OMS supports with large mesopores is discussed to illustrate the ability to form well‐defined polymer brushes in nanopores using atom transfer radical polymerization (ATRP). The synthesis of polymer brushes in mesopores through the combination of ATRP or other polymerizations and the “click” chemistry is also outlined.

Preparation of Polyelectrolyte Functionalized Multiwalled Carbon Nanotubes via Surface-Initiated Atom Transfer Radical Polymerization

Surface modification of multiwalled carbon nanotubes (MWNT) by polyelectrolyte can enhance the dispersibility of carbon nanotubes in various solvents. Hydroxyl groups were firstly introduced onto the surface of carbon nanotubes (CNT) via esterification of glycol with MWNT which previously treated by concentrated HNO3 and then excess thionyl chloride. Initiating sites (MWNT-Br or MWNT-Cl) for atom transfer radical polymerization (ATRP) were formed by reacting MWNT-OH with 2-bromoisobutyryl bromide or 2-chloropropionyl chloride. Grafting polymerization of poly(tert-butyl acrylate) (PtBA) or poly(4-vinylpyridine) (P4VP) from MWNT-Br or MWNT-Cl was carried out by surface-initiated ATRP polymerization. The content of grafted polymer, determined by thermal gravimetric analysis (TGA), was tuned through the feed ratio of monomer to the initiating-sites on MWNT. After hydrolysis (or quaternary amination) of the polymers, different types of polyelectrolyte-functionalized MWNT with good dispersibility in water were prepared successfully. All the materials were well characterized by TGA and infer-red spectrum (IR).

Straightforward Access to Amphiphilic Dual Bottle Brushes by Combining RAFT, ATRP, and NMP Polymerization in One Sequence

Molecular brush diblock copolymers were synthesized by the orthogonal overlay of the RAFT (reversible addition–fragmentation chain transfer), the ATRP (atom transfer radical polymerization), and the NMP (nitroxide-mediated polymerization) techniques. This unique combination enabled the synthesis of the complex amphiphilic polymers without the need of postpolymerization modifications, using a diblock copolymer intermediate made from two selectively addressable inimers and applying a sequence of four controlled free radical polymerization steps in total. The resulting polymers are composed of a thermosensitive poly(N-isopropylacrylamide) brush as hydrophilic block and a polystyrene brush as hydrophobic block, thus translating the structure of the established amphiphilic diblock copolymers known as macro surfactants to the higher size level of “giant surfactants”. The dual molecular brushes and the aggregates formed on ultra flat solid substrates were visualized by scanning force microscopy (SFM).

Preparation of Gold Nanoparticle– Poly(L‐menthyl methacrylate) Conjugates via ATRP Polymerization

AbstractPoly(L‐menthyl methacrylate) (PMenMA) is synthesized by atom transfer radical polymerization (ATRP) of methyl L‐mentholacrylate using bis[2‐(2‐bromoisobutyrooxy)ethyl]disulfide] ((BiBOE)2)S2) as the ATRP coinitiator. Reduction of hydrogen tetrachloroaureate(III) (HAuCl4 ·3 H2O) by Super‐Hydride in the presence of PMenMA yields gold nanoparticles (AuNP)–PMenMA conjugates in the size range of 2–20 nm, depending on the ratio of PMenMA and HAuCl4. AuNP–PMenMA is characterized by TEM, NMR, IR‐, and UV‐spectroscopy. The correlation of the ratio of (AuNP)–PMenMA conjugates and free PMenMA is analyzed by gel permeation chromatography (GPC).

Surface-initiated ATRP of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate on Phynox

Phynox is of high interest for technological applications due to its high corrosion resistance, mechanical properties and biocompatibility. In combination with these remarkable characteristics, some Phynox applications require specific surface properties that can be imparted with suitable surface functionalizations of the oxide layer. The present work aims at studying the surface-initiated atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC) on Phynox substrates, using grafted 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid as initiator. The ability of the initiator to bind Phynox substrates and act as an initiator for ATRP of MPC is investigated. It appears that ATRP polymerization of MPC on modified Phynox substrates already takes place in aqueous media at room temperature, but the yield at 90 °C is superior.

Kinetic Simulations of Atom Transfer Radical Polymerization (ATRP) in Light of Chain Length Dependent Termination

AbstractKinetic simulations using the composite kt model allows a better understanding of the effects of the persistent radical affecting ATRP or for that matter any activation–deactivation system. It also provides a better fit to experimental data in either bulk or solution conditions for ATRP polymerizations carried out at 110 °C. The results suggest that the composite model has broad utility over a wide range of experimental conditions and temperatures. The advantage of incorporating an accurate kt model is that one can then use simulations as predictive tool to obtain polymers with higher chain‐end fidelity or polymers with low PDI values. This becomes important when attempting to use the chain‐ends for further functionalization to make complex polymer architectures. This model can also be used in simulations of miniemulsion or seeded emulsions to determine the effect of compartmentalization with particle size.magnified image

Poly(isoglycerol methacrylate)-b-poly(d or l-lactide) Copolymers: A Novel Hydrophilic Methacrylate as Building Block for Supramolecular Aggregates

On the basis of a new acetal-protected glycerol monomethacrylate monomer (cis-1,3-benzylidene glycerol methacrylate/BGMA) a series of potentially biocompatible and partially biodegradable homo- and block copolymers were synthesized. ATRP polymerization of BGMA yielded well-defined polyacrylates with pendant benzylidene acetal groups and high glass transition temperatures (115−130 °C). This hydrophobic poly(cis-1,3-benzylidene glycerol methacrylate) could be readily transformed into the hydrophilic and water-soluble poly(1,3-dihydroxypropyl methacrylate), referred to as poly(isoglycerol methacrylate) (PIGMA). It exclusively contains primary hydroxyl groups and therefore differs significantly from the commonly known poly(glycerol methacrylate) (PGMA). Block copolymer systems based on poly(lactide) and BGMA were realized via two orthogonal living polymerization techniques starting from a bifunctional initiator, employing first atom transfer radical polymerization (ATRP) of BGMA and in the second step organo-...

Grafting Polymerization of N-isopropylacrylamide on the Surfaces of Silica by ATRP and Its Application in HPLC

Poly(N-isopropylacrylamide) was grafted on the surface of ultrafine silica beads through Atom Transfer Radical Polymerization (ATRP). The synthetic included the introduction of initiator and ATRP polymerization. Scanning electron microscopy revealed that a homogeneous and smooth poly(N-isopropylacrylamide (PNIPAm) layer was formed on the silica surface. The differential scanning calorimetry indicated the composite particles were thermosensitive. The polymer (PNIPAm) was cleaved from the silica composites to be analyzed. The molecular weight of the PNIPAm can be well-controlled by adjusting the feed ratio of the monomers and the polydispersity index was very narrow. The PNIPAm-modified silica particles were used as packing materials in high performance liquid chromatography (HPLC) for separating organic compounds. The result indicated that the satisfactory separations could be successfully achieved only by controlling the temperature of the column.