Combination Of Atom Transfer Radical Polymerization Research Articles

Synthesis of Poly(arylene vinylene)s with Different End Groups by Combining Acyclic Diene Metathesis Polymerization with Wittig‐type Couplings

AbstractA series of end‐functionalized poly(9,9′‐di‐n‐octylfluorene vinylene)s (EF‐PFVs) with different end groups were obtained by 1) synthesizing EF‐PFV with vinyl end groups by acyclic diene metathesis (ADMET) polymerization with a molybdenum catalyst and termination with an aldehyde and 2) subsequent olefin metathesis of the vinyl group with the molybdenum catalyst followed by Wittig‐type coupling with another aldehyde. The exclusive formation of EF‐PFVs containing a vinyl end group by the ADMET polymerization was confirmed by grafting PEG, and by the synthesis of amphiphilic triblock copolymers by combining atom transfer radical polymerization from the PFV chain end with PEG grafting through a click reaction. Various EF‐PFVs with different end groups, such as C6F5, pyridyl, ferrocenyl, and terthiophene, have thus been prepared. Their fluorescence spectra (e.g., intensities, emission wavelengths) were influenced by the end groups and the length of the conjugation.

PH and temperature responsiveness in AgNPs stabilized by a new poly(vinylidene fluoride) random graft copolymer

ABSTRACTPoly(vinylidene fluoride)(PVDF)‐graft‐random copolymers(PD) of diethyleneglycol methylether methacrylate(MeO2MA) and dimethylaminoethyl methacrylate(DMAEMA) are synthesized by a combined atom transfer radical coupling and atom transfer radical polymerization technique at three different co‐monomer compositions. The molar ratio of MeO2MA to DMAEMA in PD are measured to be 1:5.8, 1:1.3, and 1:0.5 for PD1, PD2, and PD3 graft copolymers. In PD2 the feed ratio and mole ratio are same indicating an azeotropic composition causing highest yield (89%) and highest molecular weight (9.29 × 105). The grafted chains of PD are temperature and pH responsive and in basic pH they show a sudden increase in size above certain temperature for LCST‐type phase transition, however, this is not observed at pH 4 and 7. PD can generate AgNPs under UV irradiation and morphology of PD at 30 °C varies with pH from vesicle to nanosphere. The AgNPs lie on the surface of the vesicles or assemble with the PD chains forming nanosphere morphology. At different pH, PD samples exhibit plasmon peaks at different wavelengths attributed to various size, shapes and cluster formation. The UV–vis spectra of AgNPs stabilized by PD1 and PD2 samples exhibits similar LCST‐type phase transition as observed above, but that of PD3 does not show any such transition. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 960–970

Block copolymer synthesis in one shot: concurrent metal-free ATRP and ROP processes under sunlight

A completely metal-free strategy was developed by combining Atom Transfer Radical Polymerization (ATRP) and Ring Opening Polymerization (ROP) for the syntheses of block copolymers.

Dithiobenzoic copper(II): A novel, facile, and stable mediating agent combining ATRP and RAFT features for reversible deactivation radical polymerization of methacrylates

Novel, facile, and stable mediating agent (dithiobenzoic copper(II)) combining atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer (RAFT) characteristics was firstly designed by replacing the halogen of ATRP metal catalyst with thiocarbonyl carboxylic group of RAFT agent. As two kinds of mediating agents (ATRP activator and RAFT agent) may be formed in situ during the polymerization process, the polymerization of various methacrylates can be controlled in presence of a high molar ratio of radical initiator to catalyst. Furthermore, the resultant polymer possessed dithiobenzoate chain-end functional group, which was confirmed by IH NMR analyses and chain-extension reaction.

PLLA Crystallization in Linear AB and BAB Copolymers ofl-Lactide and 2-Dimethylaminoethyl Methacrylate

Well-defined poly(l-lactide-b-2-dimethylaminoethyl methacrylate) (PLLA-b-PDMAEMA) linear AB block copolymers and BAB block copolymers with PLLA as the central block (PDMAEMA-b-PLLA-b-PDMAEMA) were synthesized by combined ring-opening polymerization and atom transfer radical polymerization. Molar masses of the PLLA block vary from 13K to 19K and the PDMAEMA block from 5K to 35K. Thermal properties, morphology, and crystallization kinetics of the copolymers were analyzed for crystallization conducted in the bulk, in thick and thin films, and in solution as well as for a limited number of stereocomplexes of diblock and triblock copolymers with poly(d-lactide) in thin films and of partially quaternized diblock copolymers. In the bulk, it is shown that crystallization rates are reduced and morphologies disordered when adding a PDMAEMA block to PLLA; these tendencies are more pronounced in the triblock compared to diblock copolymers of the same PDMAEMA content. Usually, G, the local growth rate, and K, the over...

Synthesis and characterization of new temperature-responsive nanocarriers based on POEOMA-b-PNVCL prepared using a combination of ATRP, RAFT and CuAAC

Narrowly distributed diblock copolymers comprising a non-linear poly(ethylene glycol) (PEG) analogue and a biocompatible temperature-responsive block were successfully synthesized for the first time through a “click” coupling approach, using the copper catalyzed azide-alkyne [3+2] dipolar cycloaddition (CuAAC) reaction. The alkyne-terminated poly(N-vinyl caprolactam) (PNVCL) was obtained by reversible addition fragmentation chain transfer (RAFT) polymerization and the α-azide terminated poly(oligo(ethylene oxide) methyl ether methacrylate (N3-POEOMA) was synthesized by supplemental activator and reducing agent (SARA) atom transfer radical polymerization (ATRP). The ensuing temperature-responsive POEOMA-b-PNVCL copolymers are hydrophilic but became amphiphilic at temperatures above the low critical solution temperature (LCST) of the PNVCL and self-assemble into organized nanostructures. The thermal induced self-assembly behavior of these block copolymers and its dependence on block composition and solution properties, were accessed by turbidimetry and dynamic light scattering (DLS) analysis. Faster heating rates promote the formation of smaller and more stable particles (Dh∼150–180) with narrow size particle distributions (PDI<0.1). TEM results revealed the formation of spherical aggregates at 45°C. The encapsulation of nile red (NR), a model hydrophobic drug, into the hydrophobic domain of the diblock copolymer nanostructures as well as its temperature-triggered release was demonstrated by fluorescence spectroscopy. A small drop of the solution temperature causes the disruption of the nanostructures and induces the fast release of the hydrophobic content.

Figure-Eight-Shaped and Cage-Shaped Cyclic Polystyrenes

Nonlinear polystyrenes (PS) with similar molecular weights but with different molecular structures having star-, figure-8-, and cage-shaped architectures were synthesized by combining atom transfer radical polymerization (ATRP) and click chemistry. Figure-8- and cage-shaped PS were fractionated by using a gradient normal phase liquid chromatography as confirmed by SEC-LS, MALDI–TOF MS, 1H NMR, and FT-IR spectrometry. Their purities were estimated by using a two-dimensional liquid chromatography (2D-LC). The glass transition temperatures of these topologically different polymers were in the order of cage-, figure-8-, and star-shaped polymers possibly due to the multiple links that constrain the overall molecular diffusivity in the case of multicyclic polymers (figure-8, and cage). Monte Carlo simulation on the glass transition behavior of model system also agreed well with the experimental results.

Influence of Polymer Chain Architecture of Poly(vinyl alcohol) on the Inhibition of Ice Recrystallization

Poly(vinyl alcohol) (PVA) is a water-soluble synthetic polymer well-known to effectively block the recrystallization of ice. The effect of polymer chain architecture on the ice recrystallization inhibition (IRI) by PVA remains unexplored. In this work, the synthesis of PVA molecular bottlebrushes is described via a combination of atom-transfer radical polymerization and reversible addition-fragmentation chain-transfer polymerization. The facile preparation of the PVA bottlebrushes is performed via the selective hydrolysis of the chloroacetate esters of the poly(vinyl chloroacetate) (PVClAc) side chains of a PVClAc precursor bottlebrush. The IRI efficacy of the PVA bottlebrush is quantitatively compared to linear PVA. The results show that even if the PVA chains are densely grafted onto a rigid polymer backbone, the IRI activity of PVA is maintained, demonstrating the flexibility in PVA polymer chain architecture for the design of synthetic PVA-based ice growth inhibitors.

The synthesis and photoactive properties of cyclic amphiphilic polymers with azobenzene in main chain

ABSTRACTThe cyclic amphiphilic polymers with azobenzene in main chain, cyclic azobenzene tetraethylene glycol polystyrene (cyclic‐Azo‐TEG‐PS) with different molecular weights, were successfully synthesized by combining atom transfer radical polymerization (ATRP) and Cu (I)‐catalyzed azide/alkyne cycloaddition (CuAAC). Gel permeation chromatography (GPC), proton nuclear resonance (1H NMR), Fourier transform‐infrared (FT‐IR), and matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectrometry were used to prove the complete conversion from linear polymers to cyclic ones. The thermal properties and photoisomerization behaviors of obtained cyclic polymers have been investigated by comparison with the linear analogues. The cyclic polymer displayed a higher glass transition temperature compared with the linear one, measured by differential scanning calorimetry (DSC). It was found that the trans‐to‐cis and cis‐to‐trans isomerization of cyclic polymers was both slower than that of their respective linear counterparts upon irradiation by UV/visible light. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1834–1841

Beyond State of the Art Honeycomb Membranes: High Performance Ordered Arrays from Multiprogrammable Linear‐Dendritic Block Copolymers

A new generation of honeycomb membranes is herein described from a novel library of multipurpose linear‐dendritic block copolymers. These are accomplished by combining atom transfer radical polymerization together with dendrimer chemistry and click reactions. The resulted amorphous block copolymers, with Tg between 30 and 40 °C, display three important functions, i.e., pore generating aromatic groups, crosslinking azides, and multiple dendritic functional groups. All block copolymers enable the successful fabrication of honeycomb membranes through the facile breath figure method. The peripheral dendritic functionality is found to influence the porous morphologies from closed pored structure with pore size of 1.12 μm2 to open pore structure with pore size 10.26 μm2. Facile UV crosslinking of the azides yields membranes with highly durable structural integrity. Upon crosslinking, the pH and thermal stability are extended beyond the noncrosslinked membranes in which the porous integrity is maintained up to 400 °C and pH 1–14. Taking into account the straightforward and cost‐efficient strategy to generate ordered, functional, and structurally stable honeycomb membranes on various solid substrates, it is apparent that these multipurpose block copolymers may unlock future applications including use as molds for soft lithography.

Synthesis of graft copolymer with pendant macrocycles via combination of ATRP and click chemistry

Graft copolymers with pendant macrocycles were synthesized via “graft onto” method. First, cyclic polystyrene (PS) was achieved by the combination of atom transfer radical polymerization (ATRP) and Cu-catalyzed azide–alkyne cycloaddition (CuAAc), and then an alkynyl group was introduced to cyclic PS. Meanwhile, poly(3-azide-2-hydroxypropyl methacrylate) (PGMA-N3) was synthesized by ATRP of glycidyl methacrylate (GMA) and successive ring-opening of pendant epoxide ring with NaN3. The graft copolymer was achieved by the following click reaction between PGMA-N3 and alkynyl-containing cyclic PS. GPC and 1H NMR were utilized to characterize the obtained graft copolymers, and a maximal grafting density of 20% was observed. Thermal behaviors of linear PS, cyclic PS and PGMA grafted with cyclic PS (PGMA-g-cPS) were investigated by differential scanning calorimeter (DSC), and Tg of PGMA-g-cPS is higher than those of linear and cyclic PS.

Fabrication of Two-Component, Brush-on-Brush Topographical Microstructures by Combination of Atom-Transfer Radical Polymerization with Polymer End-Functionalization and Photopatterning.

Poly(oligoethylene glycol methyl ether methacrylate) (POEGMEMA) brushes, grown from silicon oxide surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP), were end-capped by reaction with sodium azide leading to effective termination of polymerization. Reduction of the terminal azide to an amine, followed by derivatization with the reagent of choice, enabled end-functionalization of the polymers. Reaction with bromoisobutryl bromide yielded a terminal bromine atom that could be used as an initiator for ATRP with a second, contrasting monomer (methacrylic acid). Attachment of a nitrophenyl protecting group to the amine facilitated photopatterning: when the sample was exposed to UV light through a mask, the amine was deprotected in exposed regions, enabling selective bromination and the growth of a patterned brush by ATRP. Using this approach, micropatterned pH-responsive poly(methacrylic acid) (PMAA) brushes were grown on a protein resistant planar poly(oligoethylene glycol methyl ether methacrylate) (POEGMEMA) brush. Atomic force microscopy analysis by tapping mode and PeakForce quantitative nanomechanical mapping (QNM) mode allowed topographical verification of the spatially specific secondary brush growth and its stimulus responsiveness. Chemical confirmation of selective polymer growth was achieved by secondary ion mass spectrometry (SIMS).

Improved synthesis of bicyclic polystyrenes by ATRP and “click” reaction

A series of bicyclic polystyrenes were prepared by combining atom transfer radical polymerization and click coupling reaction. To investigate effect of experimental parameters, bicyclic polymers were prepared by changing types of ligands for click chemistry, concentration of polymers and coupling agents, feed rate of polymers and coupling agents, concentration of catalyst, and types of coupling agents. Purities of bicyclic polymers were estimated from SEC traces by Gaussian multiple peak fitting and subsequent peak integration. The purity of bicyclic polystyrene was achieved up to 78% when the reaction was conducted using CuBr/PMDETA catalyst and coupling agent having electron withdrawing group in diluted condition by slow addition of precursor polymer and coupling agent.

Synthetic of pH-Sensitive PEG-b-PHEMA(His) Polymers andthe Study of Micelle

通过点击化学(Click chemistry)与原子转移自由基聚合(ATRP)一锅法合成AB型嵌段聚合物聚乙二醇嵌段聚甲基丙烯酸羟乙酯(PEG-b-PHEMA),之后对所得聚合物进行组氨酸(His)修饰得到p H敏感型聚合物PEG-b-PHEMA(His),运用核磁共振(1H NMR)及凝胶渗透色谱(GPC)表征了该嵌段聚合物及组氨酸修饰后的产物的结构和分子量分布(Mn=8.2×103~13.0×103 g/mol,PDI=1.27~1.51),说明聚合物被成功地合成且具有较小的多分散系数.之后对嵌段聚合物PEG-b-PHEMA(His)进行了动态光散射(DLS)、透射电镜(TEM)和临界胶束浓度(CMC)的测试,结果表明,聚合物胶束呈球形且粒径分布均匀,并且粒径随组氨酸接枝率增大而减小.最后我们做不同接枝比的PEG-b-PHEMA(His)的酸碱滴定曲线,结果表明,组氨酸的接入使聚合物具备明显的p H响应能力,进一步的释药试验也证明了这一结果.

Synthesis and Phase Behavior of Poly(N-isopropylacrylamide)-b- Poly(L-Lysine Hydrochloride) and Poly(N-Isopropylacrylamide- co-Acrylamide)-b-Poly(L-Lysine Hydrochloride).

The synthesis of poly(N-isopropylacrylamide)-b-poly(L-lysine) and poly(N-isopropylacrylamide-co-acrylamide)-b-poly(L-lysine) copolymers was accomplished by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%). Lower yields (~50%) were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-acrylamide) were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L-lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS) and proton nuclear magnetic resonance spectroscopy (1H-NMR).

Synthesis and Characterization of Ureidopyrimidone Telechelics by CuAAC “Click” Reaction: Effect of Tg and Polarity

Telechelic oligomers functionalized with 2-ureido-4[1H]-pyrimidone (UPy), a quadruple hydrogen bonding group, have been synthesized using a combination of atom-transfer radical polymerization and click reaction. Ureidopyrimidone (UPy) synthons with propargyl and azide functionality were used for clicking with azido and propargyl telechelic oligomers, respectively. The effect of triazole linker and types of oligomers differing in Tg and polarity, such as poly(n-butyl acrylate) (PnBA), polystyrene (PS), and polybutadiene (PBd) on UPy hydrogen bonding have been examined. High solution viscosity and deviation from the normal terminal relaxation in melt state were observed, suggesting the presence of UPy aggregates that are in equilibrium between linear and network polymers. Differential scanning calorimetry studies confirm dissociation of UPy aggregates as an endothermic peak for PBd system, whereas the high Tg and polar polymers (PS and PnBA) had no such peaks associated with Tm indicating the significance of the polymer chain dynamics in supramolecular hydrogen bonding. The triazole linker interferes with the UPy association and reduces the sizes of hydrogen-bonded UPy aggregates and thereby improves the physical property of supramolecular polymers.

Preparation and Analysis of Bicyclic Polystyrene

Bicyclic polystyrene was prepared by combining atom transfer radical polymerization and click chemistry. The bicyclic polymer was separated from concurrently produced acyclic (branched) polymers through fractional precipitation, and its purity was quantified by two-dimensional liquid chromatography analysis. The structure of bicyclic polymer was characterized by SEC, MALDI–TOF MS, 1H NMR, and FT-IR.

Cyclic polymers and catenanes by atom transfer radical polymerization (ATRP)

The topologically interesting structures of cyclic polymers, catenanes and other macrocycles are of much interest for their unique chemical and physical properties. However, it is a challenge to design synthetic routes that afford controlled ring structures and connectivity, which is why the practical applications of these materials have not been explored. This review describes the advantages and disadvantages of ring expansion and ring closure methods for preparing cyclic polymers. This review also aims to provide a concise overview of the recent techniques of cyclization specifically by ring closure reactions from polymers grown primarily by atom transfer radical polymerization (ATRP). The ring closure techniques covered here are atom transfer radical coupling (ATRC), copper‐catalyzed Huisgen azide–alkyne cycloaddition, Diels–Alder cycloaddition and alkylation of carboxylate salts to form esters. Ring expansion and ring closure methods have also been used in the preparation of polymer catenanes. A combination of ATRP and ATRC has been applied to the synthesis of homopolymer and block copolymer catenanes using a supramolecular template with ATRP initiators.

Cyclic Amphiphilic Random Copolymers Bearing Azobenzene Side Chains: Facile Synthesis and Topological Effects on Self‐Assembly and Photoisomerization

In this article, well-defined cyclic amphiphilic random copolymers bearing azobenzene side chains and pendent carboxyl moieties, cyclic-P(BHMEm -co-AAn )s, are synthesized by combining atom transfer radical polymerization (ATRP) with Cu(I)-catalyzed azide/alkyne cycloaddition (CuAAC) "click" reaction and selective hydrolysis of tert-butyl ester. Successful synthesis of the cyclic-P(BHMEm -co-AAn )s is fully characterized and verified via conventional gel permeation chromatography, triple detection gel permeation chromatography, nuclear magnetic resonance, Fourier transform infrared, and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The cyclic topology induces profound effects on the glass transition temperatures, self-assembly behavior, and photoresponsive performance of the copolymers compared with their linear counterparts.

Preparation of a Tetrazolyl Monolithic Column via the Combination of ATRP and Click Chemistry for the Separation of Proteins

Tetrazolyl monolithic column is first prepared through the combination of atom transfer radical polymerization (ATRP) and "click chemistry" technique. In the ATRP fabrication process, vinyl ester resin is used as both the monomer and the cross-linking agent, and cetyl alcohol is used as the porogen, carbon tetrachloride as the initiator and ferrous chloride as the catalyst. The monolith is modified by click chemistry, which forms the tetrazolyl monolithic column. The chemical group of the prepared monolith is assayed by infrared spectroscopy, and its internal morphology is investigated by scanning electron microscopy. The pore size distribution is determined by a mercury porosimeter. What is more, the monolithic column was used as the stationary phase during high-performance liquid chromatography. Moreover, the monolith is used to separate lysozyme (Lys) from egg whites in a short time period (4 min). At the same time, the influences of buffer concentration and pH value on the elution of Lys are investigated. In addition, human serum albumin is successfully separated from human plasma by the prepared monoliths. The results show that click chemistry is an efficient method to modify the monoliths prepared by ATRP.