Polystyrene‐block‐polylactide obtained by the combination of atom transfer radical polymerization and ring‐opening polymerization with a commercial dual initiator

A polystyrene (PS)‐b‐polylactide (PLA) block copolymer was prepared from the combination of atom transfer radical polymerization and ring‐opening polymerization with commercially available 2,2,2‐tribromoethanol as a dual initiator in a sequential two‐step procedure. Hydroxyl‐terminated polystyrene (PS‐OH)s with various molecular weights were first prepared with polydispersity indices lower than 1.3; these provided valuable macroinitiators for the polymerization of D,L ‐lactide. A block copolymer with a composition allowing the formation of hexagonally packed PLA cylinders in a PS matrix was then obtained. The PS‐b‐PLA thin films revealed, after vapor solvent annealing, a hexagonally packed organization of the PLA cylinders, which was oriented perpendicularly to the surface of the film. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Zinc‐based catalyst for the ring‐opening polymerization of cyclic esters

A zinc‐based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including L ‐lactide (L ‐LA) and 2‐methyl‐2‐carboxyl‐propylene carbonate (MBC). The polymerization of L ‐lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [M]₀ /[I] (molar ratio of monomer to initiator). Sequential polymerization of L ‐LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the L ‐LA bulk polymerization with a high monomer conversion. ¹³C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the D ‐LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and ring‐opening polymerization of macrocyclic aromatic sulfide oligomers

A series of macrocyclic(arylene sulfide) oligomers were synthesized by reaction of 4,4′‐oxybis(benzenethiol) with a number of difluoro compounds in dimethylformamide (DMF) in the presence of anhydrous K₂CO₃ under high dilution conditions. The difluoro compound can be 4,4′‐difluorobenzophenone, bis(4‐fluorophenyl)sulfone or 1,3‐bis(4‐fluorobenzoyl)benzene. Detailed structural characterization of these oligomers by matrix‐assisted laser desorption and ionization‐time of flight‐mass spectroscopy (MALDI‐TOF‐MS) demonstrated their cyclic nature. The MALDI‐TOF‐MS technique has proved to be a powerful tool to analyze these cyclics. These cyclic oligomers are amorphous and highly soluble in DMF and N,N′‐dimethyl acetamide. Moreover, these cyclic(arylene sulfide) oligomers readily underwent ring‐opening polymerization in the melt at 285 °C in the presence of 2,2′‐dibenzothiazole disulfide, affording linear, high molecular weigh poly(aromatic sulfide)s. These polymers are insoluble in most common solvents. Copyright © 2004 Society of Chemical Industry     

Preparation of polytetrahydrofuran monomethacrylate macromonomers by cationic ring‐opening polymerization of tetrahydrofuran

Polytetrahydrofuran monomethacrylate (MA‐PTHF) macromonomer was prepared by cationic ring‐opening polymerization(CROP) of tetrahydrofuran (THF) using boron trifloride etherate (BF₃ · OEt₂) as initiator and epichlorohydrin (ECH) as promoter. Two kinds of transfer agents were used: methacrylic acid (represented as TA1), and a mixture of methacrylic acid and sodium methacrylate (represented as TA2). The effects of polymerization conditions on molecular weight and molecular weight distribution of macromonomers were studied in this article, when the composition of reactants was kept constant. Under the same conditions, the molecular weight of macromonomer using TA2 is lower than that using TA1, which indicates that TA2 is more active than TA1. The molecular weight of MA‐PTHF macromonomer varies with the polymerization time before transfer agents were added (T1), but molecular weight distribution remains constant. When T1 is limited in 30 min, the apparent number‐average molecular weight of MA‐PTHF increases significantly with the increase of T1, and ranges from 5000 to 18,000. Hence, the molecular weight of MA‐PTHF macromonomer can be controlled by varying T1. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 810–815, 2000     

Synthesis of fluorescent poly(methyl methacrylate) via AGET ATRP

Polymerization of methyl methacrylate (MMA) was successfully carried out via activator generated by electron transfer for atom transfer radical polymerization technique with naphthalene-1,5-diyl-bis (2-bromo-2-methylpropanoate) as an initiator, CuCl₂/bpy complex as a catalyst and tin(II) 2-ethylhexanoate (Sn(EH)₂) as a reducing agent in anisole. The polymerization showed typical features of “living”/controlled radical polymerization such as a linear increase of the molecular weights of the polymers with monomer conversion and relatively narrow polydispersities throughout the polymerization process. The resultant fluorescent poly(methyl methacrylate) was characterized by nuclear magnetic resonance spectroscopy, infrared absorption spectroscopy, ultraviolet absorption spectrophotometry and fluorescence spectrophotometry.     

Novel comb‐structured‐polymer‐grafted carbon black by surface‐initiated atom transfer radical polymerization and ring‐opening polymerization

Novel comb‐structured‐polymer‐grafted carbon black (CB) was synthesized with a combination of surface‐initiated atom transfer radical polymerization and ring‐opening polymerization. First, poly(2‐hydroxyethyl methacrylate) (PHEMA) was grafted onto the CB surface by surface‐initiated atom transfer radical polymerization. The prepared CB‐g‐PHEMA contained 35.6–71.8% PHEMA, with the percentage depending on the molar ratio of the reagents and the reaction temperature. Then, with PHEMA in CB‐g‐PHEMA as the macroinitiator, poly(?‐caprolactone) (PCL) was grown from the CB‐g‐PHEMA surface by ring‐opening polymerization in the presence of stannous octoate. CB‐g‐PHEMA and CB‐g‐(PHEMA‐g‐PCL) were characterized with Fourier transform infrared, ¹H‐NMR, thermogravimetric analysis, dynamic light scattering, and transmission electron microscopy. The resultant grafted CB had a shell of PHEMA‐g‐PCL. On the whole, the CB nanoparticles were oriented in dendritic lamellae formed by these shells. This hopefully will result in applications in gas sensor materials and nanoparticle patterns. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Anionic ring‐opening polymerization of adipic anhydride initiated by potassium poly(ethylene glycol)ate

Poly(adipic anhydride) (PAA) was prepared by the ring‐opening polymerization of adipic anhydride (AA) initiated by potassium poly(ethylene glycol)ate. The effects of various factors, such as the amount of initiator, concentration of the monomer, reaction time and temperature, and polarity of the solvent on the polymerization were investigated. The crude polymerized product was a mixture of PAA homopolymer and poly(ethylene glycol)–poly(adipic anhydride) block copolymer, as confirmed by ¹H‐NMR and gel permeation chromatography. Chain‐transfer reactions occurred intensively for the AA polymerization in both the nonpolar solvent toluene and the polar solvents CHCl₃ and tetrahydrofuran, which predominantly determined the molecular weight and the monomer conversion for the polymerized product. The lower monomer conversion in toluene was ascribed to a lower livingness for the initiator in the nonpolar solvent when compared with other two, polar solvents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2194–2201, 2003     

Synthesis,characterization and catalytic activity of zinc complex for ring‐opening polymerization of lactide

In the present study, salicylaldimine zinc complex (Zn‐HMBED) was synthesized and its reactivity for the ring‐opening polymerization (ROP) of lactide was studied. The zinc complex was prepared by the reaction of zinc solution with one molar equivalent of salicylaldimine Schiff base ligand in methanol under a nitrogen atmosphere. Further, the complex was characterized by various spectroscopic methods, which showed tetrahedral geometry. X‐ray diffraction studies were used for the structure determination of the Schiff base. It was observed that the zinc complex is highly active towards the ROP of lactide. The rate of polymerization is heavily dependent on the initiator used. The zinc complex allows controlled ROP as revealed by the linear relationship between the percentage conversion and the number‐average molecular weight. Finally, a mechanism for the ROP of lactide is proposed by use of the above zinc complex. © 2016 Society of Chemical Industry     

One step synthesis and rapid ring‐opening polymerization of macrocyclic (arylene thioether ketone) oligomers

Well‐crystal macrocyclic (arylene thioether ketone) oligomers were synthesized under high dilution condition by the reaction of Na₂S with bis(4‐fluoro‐phenyl)‐methanone in 1‐methyl‐pyrrolidone (NMP). The oligomers were fully characterized by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra (MALDI‐TOF‐MS), high‐pressure liquid chromatography (HPLC), gel permeation chromatography (GPC), ¹H NMR, ¹³C‐NMR, and differential scanning calorimetry (DSC). According to DSC studies, uncatalyzed and rapid ring‐opening polymerization (ROP) of the oligomers took place instantly when they were heated to melting point. Extracted by dichloro‐methane, the obtained polymer neither loses any weight nor dissolves in boiling 1‐chloro‐ naphthalene. These facts indicated that there are no residual oligomers within the resultant polymer. The as‐prepared oligomers could be potentially used as high‐temperature hot‐melt adhesive at a high temperature > 350°C, and matrices for high‐performance composites and nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 161–166, 2006     

Zinc lactate‐catalyzed ring‐opening polymerization of trimethylene carbonate under microwave irradiation

Microwave‐assisted ring‐opening polymerization (MROP) of trimethylene carbonate (TMC) was carried out with four different types of zinc lactate, as the catalyst. Poly(trimethylene carbonate)s (PTMC) with a number–average molar mass ranging from 2990 to 75,410 g/mol and a TMC conversion ranging from 85.2% to 98.2% were synthesized effectively in 30 min at 120°C under microwave irradiation. The effects of the catalyst type, catalyst concentration, and microwave irradiation time on the MROP of TMC were studied. The MROP of TMC was much faster than that under conventional heating conditions. Thermal analysis suggested that PTMC with higher molar mass exhibited higher glass transition temperature (T_g) and thermal stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetics of the anionic ring‐opening polymerization of octamethylcyclotetrasiloxane initiated by potassium isopropoxide

Kinetics of the anionic ring‐opening polymerization of octamethylcyclotetrasiloxane (D₄) in bulk initiated by potassium isopropoxide was studied. Several promoters including N‐methyl‐2‐pyrrolidinone (NMP), N,N‐dimethylformamide (DMF), and diglyme were used. It is indicated that the reactions are first‐order in D₄ during the initial stage of polymerization. The polymerization rate of D₄ is influenced by a number of factors, such as the nature of promoters, the molar ratio of promoter to initiator (C_p/C_i ratio), and the reaction temperatures. With the use of NMP as promoter, the polymerization rate constant at 30°C is 10.482 h^?1 with the C_p/C_i ratio equal to 3.0. As the C_p/C_i ratio increases, the polymerization rate constant increases sharply and the cyclic oligomers content in polymer decreases evidently. The back‐biting reaction that leads to the formation of decamethylcyclopentasiloxane (D₅) occurred in the polymerization of D₄. The rate of the D₅ formation relatively to the rate of D₄ conversion increases with the conversion of D₄. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3510–3516, 2006     

Cure characterization of the ring‐opening metathesis polymerization of linseed oil‐based thermosetting resins

BACKGROUND: Bio‐based polymers from vegetable oils are excellent alternatives to petroleum‐based resins for both environmental and economic reasons. A detailed understanding of the cure behavior of bio‐based polymers is essential to optimize cure schedules and the final properties of the polymers. In this work, the cure of newly developed linseed oil‐based thermosetting resins, synthesized using Grubbs' first‐generation catalyst and a bis‐norbornadiene cross‐linking agent by ring‐opening metathesis polymerization, is characterized using differential scanning calorimetry (DSC) and parallel plate oscillatory rheometry. RESULTS: Experimental results reveal that the rate of cure increases and the gel time decreases with increasing cross‐linker loading; however, the activation energy of the cure does not vary systematically with cross‐linker loading. Phenomenological reaction models are used to describe the dynamic DSC measurements and to determine the kinetic parameters which facilitate cure predictions under isothermal conditions. CONCLUSION: This work demonstrates that the cure kinetics of a linseed oil‐based thermosetting resin can be controlled by varying the cross‐linker loading. Furthermore, the kinetic parameters and cure rates at any cross‐linker loading for this system can be described by a simple autocatalytic reaction model which facilitates development of cure schedules. Copyright © 2009 Society of Chemical Industry     

Synthesis of poly(arylene disulfide)–vermiculite nanocomposites via in situ ring‐opening polymerization of macrocyclic oligomers

Exfoliated poly(4, 4′‐oxybis(benzene)disulfide)/vermiculite (POBDS/VMT) nanocomposites were successfully synthesized via in situ melt intercalation of cyclo(4, 4′‐oxybis(benzene)disulfide) oligomers (COBDS) into octadecylammonium‐exchanged VMT (organo‐VMT). The POBDS/VMT nanocomposites were melt fabricated in a two‐step process. First, the COBDS/VMT nanocomposite precursor was fabricated by melt delaminating organo‐VMT with COBDS at a temperature slightly higher than its melting point. Subsequently, exfoliated POBDS‐VMT nanocomposites can be prepared in situ via instant melt ring‐opening polymerization of the COBDS‐VMT nanocomposite precursor. The nanoscale dispersion of VMT layers within POBDS polymer was confirmed by X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. High molecular weight POBDS polymer was formed in a few minutes at the same time as the nanocomposite formation. The results of dynamic mechanical analysis showed that the storage modulus and glass transition temperature of the nanocomposites are much higher than those of the POBDS matrix, even with a very small amount of VMT addition. This methodology provides a potential approach to synthesize high‐performance polymer/clay nanocomposites. Copyright © 2004 Society of Chemical Industry     

离子液体中采用AGET ATRP法制备MCC-g-PGMA

在氯化1-烯丙基-3-甲基咪唑([AMIM]Cl)离子液体中, 采用AGET ATRP技术, 以VC为还原剂、CuBr₂/乙二胺为催化体系, 成功制备了微晶纤维素接枝聚甲基丙烯酸缩水甘油酯(MCC-g-PGMA)分子。研究表明:[AMIM]Cl对微晶纤维素有较好的溶解性, 最佳反应条件为GMA/乙二胺/CuBr₂/VC摩尔比为100:4:1:1, 反应温度25℃, 反应时间4 h, 接枝效率可达54.56%, 分子量分布较窄为1.48。通过FT-IR、TEM和SEM测试表明:成功合成了MCC-g-PGMA接枝共聚物分子, PGMA接枝微晶纤维素后表面形态变得粗糙, 接枝共聚物在丙酮溶液中可自组装成150～200 nm的球形结构, 在药物载体领域具有良好的应用潜能。     

Single‐ and two‐step procedures of AGET emulsion ATRP of methyl methacrylate in a well‐mixed batch reactor

This study investigates the atom transfer radical emulsion polymerization of methyl methacrylate in a 2 L well‐mixed stirred batch reactor using activators generated by electron transfer as the initiation technique. The polymerization was carried out with ethyl‐2‐bromoisobutyrate as the initiator, copper bromide with 4,4′‐di‐5‐nonyl‐2,2′‐bipyridine as the catalyst system, Brij 98 as the surfactant, and ascorbic acid as the reducing agent. The reaction was carried out at constant temperature in the range of 50 to 70 °C under a blanket of nitrogen to minimize the presence of air in the system. Polymerizations were carried out according to single‐step and two‐step procedures. The coagulation was found to be a major problem, especially at high monomer conversion. However, adding more surfactant and lowering the reaction temperature weakened the effect of the coagulation but at the expense of the low monomer conversion. Measurement of molecular weight distribution and ? using gel permeation show that the two‐step techniques produced polymers with living features of atom transfer radical emulsion polymerization much better than those in the single‐step procedure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45308.     

Synthesis of poly(cyclooctene) by ring‐opening metathesis polymerization: Characterization and shape memory properties

Cis‐cyclooctene was polymerized via ring‐opening metathesis polymerization using a well‐defined ruthenium catalyst (Grubbs' type) under varying reaction conditions. Control over molecular weight was achieved by the inclusion of a chain transfer agent and its influence on the behavior of the obtained polymers was evaluated. The resulting polymers were characterized by means of differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. Taking into account their thermal behavior, samples of appropriate molecular weight were subjected to a suitable treatment by chemical crosslinking to obtain a material showing thermally induced shape memory effect. The material recovers its original shape after several cycles of deformation into different shapes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One‐step synthesis and ring‐opening polymerization of novel macrocyclic(arylene multisulfide) oligomers

A series of macrocyclic(arylene multisulfide) oligomers were synthesized under high dilution conditions by reacting diphenyl ether/diphenyl/diphenyl disulfide/diphenyl methane with dichloro disulfide in the presence of a trace amount of iron powder by a one‐step reaction. From MALDI‐TOF mass spectra, it was established that the repeating units of the cyclization ranged from two to seven and the unit of macrocyclic(arylene multisulfide) oligomers had one to seven sulfur atoms. The macrocyclic oligomers readily underwent ring‐opening polymerization in the melt, resulting in linear, high molecular weight polymultisulfides. DSC thermograms demonstrated that the four polymultisulfides, derived from the macrocyclic(arylene multisulfide) oligomers, are amorphous in nature. The macrocyclic(arylene multisulfide) oligomers and polymers were analyzed by MALDI‐TOF‐MS, IR, HPLC, NMR, DSC, and TGA methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 735–741, 2004     

Microwave‐irradiated ring‐opening polymerization of D,L‐lactide under atmosphere

Poly(D ,L ‐lactide) (PDLLA) was synthesized by microwave‐irradiated ring‐opening polymerization catalyzed by stannous octoate (Sn(Oct)₂) under atmosphere. The effects of heating medium, monomer purity, catalyst concentration, microwave irradiation time, and vacuum level were discussed. Under the appropriate conditions such as carborundum (SiC) as heating‐medium, 0.15% catalyst, lactide with purity above 99.9%, 450 W microwave power, 30 min irradiation time, and atmosphere, PDLLA with a viscosity–average molecular weight (M_η) over 2.0 × 10⁵ and a yield over 85% was obtained. The dismission of vacuum to ring‐opening polymerization of D ,L ‐lactide (DLLA) under microwave irradiation simplified the process greatly. The temperature under microwave irradiation and conventional heating was compared. The largely enhanced ring‐opening polymerization rate of DLLA under microwave irradiation was the coeffect of thermal effects and microwave effects. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2244–2247, 2006     

Synthesis and characterization of antimicrobial polylactide via ring‐opening polymerization and click chemistry methods

Novel biodegradable polylactide (PLA) copolymers bearing pendant antimicrobial agent groups were successfully fabricated with a combination of ring‐opening copolymerization and copper(I)‐catalysed azide–alkyne cycloaddition click reaction in a two‐step reaction procedure. First, biodegradable PLA copolymers bearing azido groups were synthesized by the ring‐opening copolymerization of l ‐lactide and 2,2‐ bis(azidomethyl)trimethylene carbonate in the presence of 1‐dodecanol as protic co‐initiator and tin(II) 2‐ethylhexanoate (Sn(Oct)₂) as the catalyst. Then, alkyne functionalized quaternary ammonium salts were attached onto the azido groups of the copolymers via a Huisgen 1,3‐dipolar cycloaddition reaction to give PLA imparting antimicrobial activity. The chemical structure and composition of the copolymers were clearly confirmed using ¹H NMR and Fourier transform infrared spectroscopies and gel permeation chromatography. Thermal phase transition temperatures (T_m and T_g) and the thermal stability of the polymers were investigated by DSC and TGA experiments, respectively. The antimicrobial activity tests were carried out against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacteria by the drop plate method. It was observed that antimicrobial agents are more active in the polymeric form than in the monomeric form. Also, the activity depends on the compositional ratio and the length of the alkyl group on the ammonium salts. © 2018 Society of Chemical Industry     

Surface‐initiated ring‐opening polymerization of ϵ‐caprolactone from the surface of PP film

This article presents the ring‐opening polymerization of ε‐caprolactone (ε‐CL) from PP film modified with an initiator layer composed of ? OSn(Oct) groups. This method consists of two steps: (1) Sn(Oct)₂ exchanged with the hydroxyl groups on the surface of PP film, forming the ? OSn(Oct) groups bonded on the surface; (2) surface‐initiated ring‐opening polymerization of ε‐CL with the ? OSn(Oct) groups. The initiator layer is characterized by attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR), contact angles, and X‐ray photoelectron spectroscopy (XPS). The growth of PCL chains from the initiator layer through ring‐opening polymerization is successfully achieved. ATR‐FTIR, XPS, and scanning electron microscope (SEM) are also used to characterize the grafted film. XPS results reveal that the PCL chains cover the surface of PP film after 4 h. The SEM images reveal that the PCL chain clusters grow into regular spheroidal particles, which can be changed into other different morphology by treated with different solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007