Synthesis Of Well-defined Poly Research Articles

Boron-Catalyzed C1 Copolymerization of Arsonium and Sulfoxonium Ylides toward Unrepresented Structures and Fluorescence Properties.

The first synthesis of well-defined poly(methylene-co-1,1-diphenylpropenenylene) (C1-co-C1'), equivalent to poly(ethylene-co-diphenylbutadiene) copolymers was accomplished by C1 copolymerization of novel diphenylpropenyl triphenyl arsonium ylides (Ph2AY) and dimethylsulfoxonium methylide (Me2SY) using B-thexylborepane as initiator. All polymerization conditions, including feed ratio, temperature, and reaction time, were optimized. A series of photoluminescent poly(ethylene-co-diphenylbutadiene)s were synthesized at different feed ratios, opening a new synthetic horizon for poly(ethylene-co-disubstitutedbutadiene) copolymers. Notably, a new C1 segment, arising from a double bond rearrangement, was confirmed by NMR, resulting in an unprecedented two-monomer three-structure random terpolymer. An unexpected red-shift phenomenon in the fluorescence spectra was observed with increasing the ratio of Ph2AY in the copolymer. This shift is attributed to the aggregation of diphenylbutadiene segment, similar to through-space conjugation (TSC), likely induced by a decrease in the crystallinity of copolymers. Furthermore, another disubstituted allylic triphenyl arsonium ylides, (E)-2-phenylbutenyl triphenyl arsonium ylide (MePhAY) was also synthesized and investigated. These additional compounds expand the knowledge and the potential applications of such copolymerization techniques in advanced materials.

Exploring the impact of process parameters on the metal-free light-catalyzed ATRP polymerization of PVDF-based block copolymers

The synthesis of well-defined poly(vinylidene fluoride) (PVDF)-based block copolymers has been an important topic in recent years to accurately modify its properties and to achieve high-quality composites. Atom transfer radical polymerization (ATRP) proved itself to be a viable technique for the controlled synthesis of PVDF-based block copolymers. Recently, organic photoredox catalysts (OPRCs) have been reported as effective photocatalysts in light-catalyzed ATRP. Here, we use three OPRs (perylene, 10-methylphenotiazine, 10-phenylphenotiazine) for the ATRP of methylmethacrylate using telechelic PVDF as macroinitiators. We explore the impact of three process parameters: the end group on the polymer chain, the concentration of MMA, and the concentration of the OPRC in solution. First, three different telechelic PVDF were tested under the same monomer and OPRC concentrations to select the best macroinitiator for this system. Then, the effects on the overall control and on the conversion when the concentration of monomer or OPRC is varied were evaluated.

Synthesis of well-defined poly(n-vinylpyrrolidone)/n-TiO2 nanocomposites by xanthate-mediated radical polymerization

For the first time formation of well-defined poly n-vinylpyrrolidone/n-TiO2 nanocomposite by xanthate-mediated radical polymerization was accomplished. The synthesis of polymer nanocomposite materials has been intensively studied due to their extraordinary properties and wide-spread potential applications. For this purpose, first 2‐propionic acid-O-ethyl xanthate, as a RAFT agent, was synthesized by the reaction of 2-bromopropionic acid with potassium O-ethyl xanthate with acetone as the solvent. A carboxylic group in the RAFT agent was attached to the n-TiO2 surface by metalation reaction. Then, RAFT polymerization of n-vinylpyrrolidone (NVP) was subsequently conducted to graft poly(n-vinylpyrrolidone) (PNVP) onto the exterior surface of n-TiO2 nanoparticles, forming a novel core–shell nanostructure with a mesoporous core and a polymeric nanoshell. The viscosimetry data and 1H NMR spectra were used to calculate the molecular weight of the polymer. The obtained results showed a good agreement withthe methods used. A significant enhancement in the stability of the composites was obtained as demonstrated by the TGA results. The SEM and TEM results showed that the polymer was formed on the surface of the particles. The XRD pattern of the nanoparticles of n-TiO2 presented the amorphous structure of the crystal morphology of the composites. The FTIR and UV–visible spectroscopy results proved that the PNVP chains were grafted onto the n-TiO2 nanoparticles by surface RAFT polymerization.

High-Throughput Preparation of Antibacterial Polymers from Natural Product Derivatives via the Hantzsch Reaction.

SummaryThe Hantzsch and free-radical polymerization reactions were combined in a one-pot high-throughput (HTP) system to simultaneously prepare 30 unique polymers in parallel. Six aldehydes derived from natural products were used as the starting materials to rapidly prepare the library of 30 poly(1,4-dihydropyridines). From this library, HTP evaluation methods led to the identification of an antibacterial polymer. Mechanistic studies revealed that the dihydropyridine group in the polymer side-chain structure plays an important role in resisting bacterial attachment to the polymer surface, thus leading to the antibacterial function of this polymer. This research demonstrates the value of multicomponent reactions (MCRs) in interdisciplinary fields by discovering functional polymers for possible practical applications. It also provides insights to further developing new functional polymers using MCRs and HTP methods with important implications in organic chemistry, polymer chemistry, and materials science.

Phosphoniums as catalysts for metal-free polymerization: Synthesis of well-defined poly(propylene oxide)

The anionic ring-opening polymerization of propylene oxide (PO) was initiated with glycerol and catalyzed by three new synthetic phosphonium salts, tetrakis (pyrrolidino) phosphonium (Py4P1+), tetrakis (piperidino) phosphonium (Pi4P1+), tetrakis (morpholino) phosphonium (Mo4P1+), and the known tetrakis [cyclohexyl (methyl) amino] phosphonium (Cy4P1+) and tetrakis [tris (dimethylamino) phosphonoamino] phosphazene (P5+). The effects of substituents on the polymerization behavior, especially the molecular weight and its distribution, degree of unsaturation, and the sequential structures of poly (propylene oxide) (PPO) were investigated. The structures of these catalysts and PPOs were characterized by FT-IR, 1H and 13C NMR, and GPC. The results indicate that Cy4P1+, Py4P1+, and Pi4P1+ have lower optimum reaction temperatures at 90, 70, and 70 °C, respectively, and are better than traditional catalysts KOH and double metal cyanide. PPO samples with high molecular weight, narrow polydispersity, and high functionality were accessible when catalyzed with Cy4P1+, Pi4P1+, and P5+ at the optimum temperature. Notably, Pi4P1+ formed unimodal distribution PPO with 9000 g/mol, 2.93 of functionality, and 0.008 mmol/g degree of unsaturation. Majority segments of PPO from five catalysts adopted the stereoregular head-to-tail structure, exhibiting excellent regularity.

Synthesis of Well-Defined Poly(N-H Benzamide-co-N-Octyl Benzamide)s and the Study of their Blends with Nylon 6.

We synthesized a series of copolybenzamides (PBA) through chain-growth condensation polymerization (CGCP) of 4-(octylamino)benzoate (M4OB) and methyl 3-(4-(octyloxy)benzylamino) benzoate (M3OOB) co-monomers. Well-defined copolybenzamides with close to theoretical molecular weights (Mn ≈ 10,000–13,000) and narrow molecular weight distributions (Mw/Mn < 1.40) were obtained. Selective removals of the protecting group (i.e., 4-(octyloxy)benzyl group) from the affording P(M3OOB-co-M4OB) copolybenzamides were subsequently performed to obtain P(M3NH-co-M4OB) copolymers. These novel N-H-containing copolybenzamides (named as PNHBA) can not only provide hydrogen bonds for polymer-polymer blends but also have good solubility in organic solvents. Miscibility of the PNHBA and Nylon 6 blends was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), FT-IR, contact angle analysis, transmission electron microscope (TEM), and dynamic mechanical analysis (DMA). This study illustrates a novel type of copolybenzamide with controlled molecular weight and narrow molecular weight distribution through an effective synthetic strategy, and can be applied to a practical blend of Nylon 6 with good miscibility.

Synthesis of well-defined poly (2-oxazoline) derivatives for biomedical applications

Synthesis of well-defined poly (2-oxazoline) derivatives for biomedical applications

Synthesis of Well-Defined Poly(acrylates) in Ionic Liquids via Copper(II)-Mediated Photoinduced Living Radical Polymerization

Herein we report the photoinduced living radical polymerization of acrylates in a variety of ionic liquids (ILs). 1-Ethyl-3-methylimidazolium ethyl sulfate [emim][EtSO4], 1-heptyl-3-methylimidazolium bromide [C7mim][Br], 1-hexyl-3-methylimidazolium tetrafluoroborate [C6mim][BF4], 1-hexyl-3-methylimidazolium hexafluorophosphate [C6mim][PF6], and 1-octyl-3-methylimidazolium hexafluorophosphate [C8mim][PF6] were employed as solvents for the homopolymerization of a variety of acrylates including methyl acrylate (MA), n-butyl acrylate (n-BA), ethylene glycol methyl ether acrylate (EGA), and poly(ethylene glycol) methyl ether acrylate (PEGA, Mn ≈ 480). Polymerization of MA, EGA, and PEGA in [C6mim][BF4], [C6mim][PF6], and [C8mim][PF6] proceeded in a controlled manner, as evidenced by kinetic studies, narrow molecular weight distributions (Đ ≈ 1.1), and quantitative conversions (>99%) within 30 min. MALDI-ToF-MS and 1H NMR confirmed very high end-group fidelity, which was further exemplified by in situ chain ext...

‘One pot’ synthesis of well-defined poly(aminophosphonate)s: time for the Kabachnik–Fields reaction on the stage of polymer chemistry

A multicomponent reaction (MCR) has been carried out on the platform of controlled radical polymerization (CRP) to construct a ‘one pot’ MCR-CRP system for the facile preparation of well-defined functional polymers. In the current work, a novel ‘one pot’ system has been built through a combination of the Kabachnik–Fields (KF) reaction and reversible addition fragmentation chain transfer (RAFT) polymerization. Compared to a traditional stepwise method and polymer post-polymerization modification, this novel ‘one pot’ system exhibited distinct advantages to much more facilely and efficiently prepared well-defined poly(aminophosphonate)s (polyAPPs). A series of unique polyAPPs have also been successfully prepared through this KF–RAFT system, suggesting this novel method is a general and versatile approach to prepare well-defined organophosphorous polymers.

Synthesis of well-defined poly(phenylcarbazole-alt-triphenylphosphine oxide) siloxane as a bipolar host material for solution-processed deep blue phosphorescent devices

Bipolar polysiloxane hosts for blue phosphorescent PLED are synthesized successfully. This work provides a new approach for the development of solution-processable polymers for high efficiency OLEDs

Poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) Four-arm Star Functional Copolymers by Quasiliving ATRP: Equivalent Synthetic Routes by Protected and Nonprotected HEMA Comonomers

Comprehensive investigations were carried out on the synthesis of well-defined poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) P(MMA-co-HEMA) copolymers, i.e., PMMA with predetermined average number of pendant hydroxyl functionalities, by using HEMA and trimethylsilyl-protected HEMA (TMS-EMA) under quasiliving ATRP conditions by a tetrafunctional initiator and CuCl/2,2′-bipyridyl (bpy) catalyst system in methanol at 10°C. It was found that these two synthetic routes, that is the direct and protected approaches, are equivalent in terms of yields, hydroxyl functionality and molecular weight distribution (MWD). Bulk copolymerization of MMA and HEMA by ATRP led to broad multimodal MWD in contrast to copolymers with narrow MWD in the presence of methanol. A two-step purification method applying silica-alumina chromatography followed by treatment with an acidic ion-exchange resin, used also as the deprotecting agent, was found to provide copolymers free of catalyst contamination. At higher monomer conversions, GPC analyses indicate the occurrence of chain-chain coupling by recombination of the macroradicals resulting in lower than theoretical apparent initiating efficiencies. According to the results on the effect of reaction time on monomer conversion, relatively short reaction times, less than 2 h, are sufficient to obtain high yields and PMMA with desired functionalities and MW under the applied quasiliving ATRP conditions. The resulting four-arm star hydroxyl-functional P(MMA-co-HEMA) copolymers offer a variety of new possibilities for the preparation of a variety of novel PMMA-based macromolecular architectures.

The synthesis of well-defined poly(vinylbenzyl chloride)-grafted nanoparticles via RAFT polymerization

We describe the use of one of the most advanced radical polymerization techniques, the reversible addition fragmentation chain transfer (RAFT) process, to produce highly functional core–shell particles based on a silica core and a shell made of functional polymeric chains with very well controlled structure. The versatility of RAFT polymerization is illustrated by the control of the polymerization of vinylbenzyl chloride (VBC), a highly functional monomer, with the aim of designing silica core–poly(VBC) shell nanoparticles. Optimal conditions for the control of VBC polymerization by RAFT are first established, followed by the use of the “grafting from” method to yield polymeric brushes that form a well-defined shell surrounding the silica core. We obtain particles that are monodisperse in size, and we demonstrate that the exceptional control over their dimensions is achieved by careful tailoring the conditions of the radical polymerization.

Assessment of end-group functionality in atom transfer radical polymerization of N-isopropylacrylamide

The “one-pot” “two-step” synthesis of well-defined poly(ethylene oxide-b-N-isopropylacrylamide-b-acrylamido-2-methyl-1-propane sodium sulfonate) (P[EO-b-NIPAm-b-AMPSNa]) triblock copolymers is reported in aqueous medium using atom transfer radical polymerization (ATRP) with Cu(I)Cl.Me6TREN (Me6TREN: tris[(2-dimethylamino)ethyl]amine) as catalyst and N,N-dimethylformamide (DMF) as cosolvent. Polymerization conditions leading to a high end-group functionality (EGF) during the first synthesis step, i.e. the formation of the P(EO-b-NIPAM) diblock copolymer, are selected based on kinetic modeling insights for the corresponding NIPAm ATRP homopolymerization. For these conditions, the significant influence of viscosity effects on the NIPAm ATRP kinetics is illustrated based on dynamic viscosity measurements of the saturated monomer solution and William-Landel-Ferry parameters for the polymer. The importance of cyclization and termination reactions for the loss of EGF is shown to be limited. Only at very high conversions, cyclization reactions can lead to a decrease of EGF to a minimal value of ca. 80%.

Synthesis of well-defined poly(vinyl ether)-based macromonomers having pendant glycerols via living cationic polymerization and their application to the preparation of core−shell polymer particles

A new vinyl ether monomer bearing a glycerol pendant moiety protected with an isopropylidene group (2-(2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-ethyl vinyl ether, IpGEVE) was designed as the precursor of a novel type of hydrophilic poly(vinyl ether) containing glycerol pendants. It was found that the polymerization of IpGEVE proceeded in a controlled manner, and the protecting groups of isopropylidene moieties could be cleaved with trifluoroacetic acid. Living cationic polymerization of IpGEVE with an initiator bearing a methacryloyl group (VEM-HCl) and subsequent deprotection of the pendant isopropylidene groups of the resultant precursor afforded a glycerol-substituted hydrophilic macromonomer MA-PGEVE. Nearly monodispersed polymer particles in the submicron size range were successfully obtained via dispersion copolymerization of MA-PGEVE with styrene.© 2013 Society of Chemical Industry

Synthesis of well-defined poly(2-(dimethylamino)ethyl methacrylate) under mild conditions and its co-polymers with cholesterol and PEG using Fe(0)/Cu(ii) based SARA ATRP

Atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with a mixed transition metal catalytic system consisting of Fe(0) and small amounts of CuBr2/PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) in water–isopropanol mixtures at 60 °C and 25 °C is reported and compared with commonly used CuBr/PMDETA-mediated ATRP systems. The obtained kinetics of polymerization showed that, in addition to the environmental attractiveness of this catalytic system, Fe/Cu mixed transition metal mediated ATRP of a DMAEMA monomer provides a significantly improved control of polymer chain growth, forming PDMAEMA of low dispersity values at all conversions. The controlled character of ATRP of DMAEMA was confirmed by the linear increase of molecular weights with monomer conversion, narrow molecular weight distributions, and re-initiation/chain extension experiments. The molecular structure of the obtained polymer(s) was confirmed by 1H nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. ATRP of DMAEMA was also extended to synthesis of functional bio-relevant polymers with cholesterol and poly(ethylene glycol) segments.

Mild-Temperature Mn2(CO)10-Photomediated Controlled Radical Polymerization of Vinylidene Fluoride and Synthesis of Well-Defined Poly(vinylidene fluoride) Block Copolymers

By contrast to typical high-temperature (100-250 °C) telo-/polymerizations of gaseous fluorinated monomers, carried out in high-pressure metal reactors, the visible light, Mn(2)(CO)(10)-photomediated initiation of vinylidene fluoride (bp = -83 °C) polymerization occurs readily from a variety of alkyl, semifluorinated, and perfluorinated halides at 40 °C, in low-pressure glass tubes and in a variety of solvents, including water and alkyl carbonates. Perfluorinated alkyl iodide initiators also induce a controlled radical polymerization via iodine degenerative transfer (IDT). While IDT proceeds with accumulation of the less reactive P(m)-CF(2)-CH(2)-I vs the P(n)-CH(2)-CF(2)-I chain ends, Mn(2)(CO)(10) enables their subsequent quantitative activation toward the synthesis of well-defined poly(vinylidene fluoride) block copolymers with a variety of other monomers.

Synthesis of well-defined poly(dimethylsiloxane) telechelics having nitrobenzoxadiazole fluorescent chain-ends via thiol-ene coupling

Well-defined PDMS telechelics having nitrobenzoxadiazole (NBD) fluorescent probes covalently attached at both chain-ends were prepared in two steps and a series of fractionation procedures starting from commercially available divinyl-terminated PDMS having a broad molar mass dispersity. First, thiol-ene coupling between 6-mercapto-1-hexanol and vinyl chain-ends allowed the formation of dihydroxy-terminated PDMS telechelics through the formation of a thioether linkage. The resulting material was then sequentially fractionated using dichloromethane/methanol mixtures to afford several well-defined dihydroxy-terminated PDMS fractions having sharp distributions of molar masses (Mn = 99.5–158 kDa and Đ < 1.2). The NBD fluorescent probes were then attached at both chain-ends by N,N′-dicyclohexylcarbodiimide/4-(dimethylamino)pyridine esterification coupling between the hydroxyl groups and 6-(7-nitrobenzofurazan-4-ylamino)hexanoic acid. The resulting fluorescent PDMS telechelics were characterized by SEC, 1H NMR, UV–visible, and fluorescence spectroscopies. These materials are suitable probes to investigate the dynamics of polymer chains in bulk or at interfaces by the fringe pattern fluorescent recovery after photobleaching technique. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

폴리(스티렌-이소부틸렌-스티렌) 삼중블록 공중합체의 합성, 분석 및 혈액적합성

The synthesis of well-defined poly(styrene-b-isobutylene-b-styrene) (SIBS) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) with styrene (St) using 1,4-di(2-chloro-2-propyl)benzene (DCC)/TiCl4 /2,6-di-tert-butylpyridine(DtBP) as an initiating system in methyl chloride (CH3Cl)/methylcyclohexane(MeChx) (50/50 v/v) solvent mixture at -80 ℃. The triblock copolymers exhibited excellent thermoplastic and elastomeric characteristics. Tensile strengths and Shore hardness increased with increasing polystyrene (PS) content, while elongation at break decreased. The blood-compatibility of SIBS was assessed by SEM observation of the platelet adhesion, blood clotting time and haemolysis ratio. The haemolysis ratios were below 5% which met the medical materials standard. The platelet adhesion test further indicated that SIBS block copolymers had a good blood compatibility.

Living cationic sequential block copolymerization: synthesis and characterization of poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) triblock copolymers

The synthesis of well-defined poly(4-(2-(tert-butyldimethylsiloxy)ethyl)-styrene-b-isobutylene-b-4-(2-(tert-butyldimethylsiloxy)ethyl)styrene)(PTBDMES-b-PIB-b-PTBDMES) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) and 4-(2-(tert-butyldimethylsiloxy)ethyl)styrene (TBDMES) using the capping-tuning technique in a one-pot procedure in methylcyclohexane/CH3Cl at −80 °C. Deprotection of the precursor triblock copolymer with tetrabutylammonium fluoride yielded poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) (PHOES-b-PIB-b-PHOES), with pendant hydroxyl groups along the hydrophilic backbone chains. FT-IR, NMR confirmed that hydrolysis was complete.

Synthesis of Well-Defined Poly(ethylene-alt-1-vinyladamantane) via Living Anionic Polymerization of 2-(1-Adamantyl)-1,3-butadiene, Followed by Hydrogenation

Anionic polymerization of 2-(1-adamantyl)-1,3-butadiene (1) was carried out either with s-BuLi in cyclohexane at 40 °C or with potassium naphthalenide in THF at −78 °C. The polymerizations of 1 quantitatively proceeded to afford the polymers possessing the predicted molecular weights based on the molar ratios between monomers and initiators and the narrow molecular weight distributions. The microstructure of the resulting poly(1) was affected by the initiators and the solvents. The contents of 1,4-repeating unit in poly(1)s obtained with s-BuLi in cyclohexane and with potassium naphthalenide in THF were 96 and 55%, respectively. The 1,4-rich poly(1) was completely converted into a novel saturated alternating copolymer, poly(ethylene-alt-1-vinyladamantane) (P(E-alt-VAd)), by the hydrogenation with p-toluenesulfonhydrazide. Poly(1) possessing the Mn value over 5000 was hardly soluble in common organic solvents, while the hydrogenated P(E-alt-VAd) was soluble in a wide variety of organic solvents. Novel well-defined block copolymers were anionically synthesized by the sequential copolymerization of 1 and styrene. The results of block copolymerization also demonstrated the living property of the propagating chain end of poly(1). The resulting poly(1) and P(E-alt-VAd) started to decompose from 280 and 380 °C in the TGA analyses, respectively. Poly(1) and P(E-alt-VAd) showed Tgs at 100 and 125 °C on the DSC thermograms.