Synthesis and polymerization of styrene monomers bearing spiroorthoester structure and volume change during crosslinking by double ring‐opening of the pendant spiroorthoesters of the obtained polymers

Novel styrene monomers bearing a five or seven‐membered spiroorthoester structure (SOE5, SOE7) were synthesized and their radical polymerizations as well as volume change during crosslinking of the obtained polymers were investigated. SOE5 and SOE7 were prepared from 4‐vinylbenzyl glycidyl ether and γ‐butyrolactone or ε‐caprolactone using boron trifluoride diethyl ether complex as a catalyst, respectively. Radical polymerizations of these monomers using 2,2′‐azobisisobutyronitrile (AIBN) gave the corresponding styrene‐based polymers with keeping the spiroorthoester structures unchanged. These polymers could be transformed to networked polymers by heating with a sulfonium antimonate, a thermally latent cationic polymerization initiator. Copolymerization of SOE5 or SOE7 with styrene at various compositions was carried out to efficiently obtain the corresponding copolymers, respectively. These polymers and copolymers showed little volume shrinkage or slight volume expansion during the crosslinking. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1790–1795     

Expanding vinyl ether monomer repertoire for ring-expansion cationic polymerization: Various cyclic polymers with tailored pendant groups

Herein, we clarified the ring-expansion cationic polymerization with a cyclic hemiacetal ester (HAE)-based initiator was versatile in terms of applicable vinyl ether monomers. Although there was a risk that higher reactive vinyl ethers may incur β-H elimination of the HAE-based cyclic dormant species to irreversibly give linear chains, the polymerizations were controlled to give corresponding cyclic polymers from various alkyl vinyl ethers of different reactivities. Functional vinyl ether monomers were also available, and for instance a vinyl ether monomer carrying an initiator moiety for metal-catalyzed living radical polymerization in the pendant allowed construction of ring-linear graft copolymers through the grafting-from approach. Furthermore, ring-based gel was prepared via the addition of divinyl ether at the end of the ring-expansion polymerization, where multi HAE bonds cyclic polymers or fused rings were crosslinked with each other. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3082–3089     

Oligomeric Branched Polyethers with Multiple Hydroxyl Groups by Cationic Ring-Opening Polymerization for Inorganic Surface Modification

Summary: Cationic ring-opening polymerization of cyclic ethers (also esters and acetals) substituted with hydroxyl groups leads to branched multihydroxyl polymers. When 4-membered hydroxysubstituted oxetanes or 5-membered hydroxysubstuituted oxolanes (or lactone and 1,3-dioxolane) are used as monomers the polymerization products have limited molecular weights (about 1000). Polymerization of these monomers leading in situ to oligomeric products was used for inorganic surface modification. Successful polymerizations of oxetane as well as considered as difficult to polymerize 5-membered hydroxysubstituted cyclic monomers initiated from montmorillonite clay and silica nanoparticles surfaces were performed.     

Ketene acetal monomers: Cationic photopolymerization

A study of the photoinduced cationic polymerization of a novel series of cyclic and acyclic ketene acetal monomers was carried out. It was observed that the cyclic monomers underwent facile cationic polymerization to give high molecular weight polymers while the acyclic ketene acetals did not. Thermally induced polymerization was also observed on standing catalyzed by glass surfaces. Photoinduced cationic polymerizations employing both diaryliodonium and triarylsulfonium salt photoinitiators were studied. It was observed that the position and type of substitutents in the cyclic ketene acetals was the major factor in determining the proportion of vinyl and ring-opening polymerizations that take place. © 1996 John Wiley & Sons, Inc.     

超支化聚合物制备方法的研究进展

超支化聚合物是一类可以通过一步法来合成的具有高度支化结构的体型大分子.经过二十年的研究,超支化聚合物由于其独特的结构和性能特点以及可实现规模化生产的特点, 已经迅速成为一类重要的和具有广阔应用潜力的高分子材料.本文从单体类型的角度介绍了超支化聚合物的主要制备方法及其发展历程,主要涉及ABx型,AB*型,A2 B3型以及潜在ABx型单体(包括开环聚合和偶合单体法)等,同时论述了各制备方法的优点和局限性 .     

Organocatalytic copolymerization of mixed type monomers

Triggered by environmental concerns and the rising demands for metal-free polymers in e.g.bio-related and microelectronic applications,studies on organocatalytic polymerization have been launched and developed unprecedentedly during the last 15 years.A wide range of organic molecules are now available in polymer chemists' toolbox to choose from as catalysts for polymerization of (hetero)cyclic and polar vinyl monomers.Apart from the intrinsic merits such as lower toxicity and better solubility compared with (transition) metal catalysts/initiators,organocatalysts have also shown,in many cases,excellence to achieve high polymerization rates and/or good control (selectivity).In addition,particular natures and catalytic/activating mechanisms of organocatalysts have led to new opportunities for rational design and efficient synthesis of macromolecular architectures,i.e.chain structures,topological structures and functionalities.This mini-review is specially themed on pathways to construct copolymer chain structures by organocatalytic copolymerization of mixed type monomers (comonomers bearing different polymerizing moieties) and will be sectioned by different comonomer combinations,including cyclic monoesters of different sizes,cyclic monoesters and lactides,cyclic esters and cyclic carbonates or epoxides,heterocycles and vinyl monomers.     

Polymerization of cyclic imino ethers: From its discovery to the present state of the art

Topics concerning the cationic ring‐opening polymerization of cyclic imino ethers and functional material production based on the resulting polymers are reviewed. Cyclic imino ethers are readily subjected to isomerization polymerization via cationic initiators. Mechanistic studies have provided a new concept, electrophilic polymerization. Double isomerization polymerization and no‐catalyst alternating copolymerization are interesting examples that show characteristics of the ring opening of cyclic imino ethers. The living polymerization of these monomers affords precisely controlled polymeric materials. Through the use of the unique properties of the product polymers, various functional polymeric materials, such as polymeric nonionic surfactants, compatibilizers, hydrogels, stabilizers for dispersion polymerization, biocatalyst modifiers, and supramolecular assemblies, have been developed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 192–209, 2002     

手性乙烯基二联苯单体的合成与螺旋选择性聚合反应

设计、合成了一系列含有手性烷氧基末端的乙烯基二联苯单体,进行了普通自由基、原子转移自由基以及负离子聚合反应.所有单体中,只有手性烷氧基苯基位于乙烯基邻位的聚合物的比旋光度与其单体相比有比较大的区别,且在对应于其侧基的紫外吸收处呈现明显不同于单体的Cotton效应,说明可能形成了某一方向占优的螺旋构象.在所研究范围内,聚合条件和聚合物分子量对聚合物的旋光度没有明显的影响.比较负离子聚合和自由基聚合所获得聚合物的比旋光度发现,负离子聚合有利于增加聚合物螺旋链构象的完整性.切除能形成螺旋链的聚合物侧基上的手性烷氧基,所得到的聚合物虽然不含手性原子但依然表现出光学活性,说明其具有一定的手性记忆效应.     

活性阳离子聚合法合成嵌段共聚物的研究进展

在８０年代,阳离子聚合研究的一个最重要突破可能就是活性阳离子聚合。目前为止,有关活性阳离子聚合的新引发体系,新单体及合成应用等方面已取得巨大进展,本综述主要介绍利用活性阳离子聚合合成二、三元嵌段和多元嵌段共聚物的研究成果。     

Photoenzymatic RAFT Emulsion Polymerization with Oxygen Tolerance

Photoenzymatic reversible addition-fragmenatation chain transfer(RAFT) emulsion polymerization, surfactant-free or ab initio, of various monomers is reported with oxygen tolerance. In surfactant-free emulsion polymerizatoin, poly(N,N-dimethylacrylamide)s were used as stabilizer blocks for emulsion polymerization of methyl acrylate, n-butyl acrylate and styrene, producing well-defined amphiphilic block copolymers, including those with an ultrahigh molecular weight, at quantitative conversions. The controlled character of surfactant-free emulsion polymerization was confirmed by kinetic studies, chain extension studies and GPC analyses. Temporal control was demonstrated by light ON/OFF experiments. In ab initio emulsion polymerization of methyl acrylate and methyl methacrylate, low-dispersity hydrophobic polymers were synthesized with predictable molecular weights. This study extends the monomer scope suitable for photoenzymatic RAFT polymerization from hydrophilic to hydrophobic monomers and demonstrates that oxygen-tolerance can be equally achieved for emulsion polymerization with excellent RAFT control.     

Plasma polymerization using pulsed microwave power

Pulsed microwave power was used to polymerize a variety of monomers containing different functional groups. We examined the effects of pulse frequency and duty cycle on the deposition rates and the composition of the polymers. For monomers that do not contain oxygen we find that there is an increase in deposition rate with increasing pulse frequency and that the pulsed deposition rate is always less than the continuous power deposition rate. For monomers that contain oxygen, or for co-depositions of hydrocarbon monomers with O₂ or CO, we find that there is a decrease in deposition rate with increasing frequency, however the deposition rate using pulsed power is greater than the rate using continuous power. This result is shown to be related to the amount of etching that takes place during the deposition process. Infrared studies reveal that pulsed power can alter the composition of plasma polymers of some oxygen-containing monomers. The presence or absence of vinyl unsaturation, nitrile groups, or a cyclic structure have no effect on the polymerization process.     

Recent progress on the synthesis of cyclic polymers via ring-expansion strategies

Cyclic polymers are the simplest topological isomers of linear macromolecules, but exhibit properties that differ from linear chains in ways that remain imperfectly understood. The difficulty of synthesizing appropriately pure and high molecular weight cyclic samples has hindered experimental studies. Ring-closure methods, while versatile, are inherently limited in the range of molecular weights that can be achieved. Ring-expansion methods are a much more promising strategy toward obtaining high molecular weight cyclic polymers. The current review focuses on recent developments in ring-expansion polymerization strategies toward the synthesis of high molecular weight cyclic polymers. Significant progress in the last decade has made the synthesis of cyclic polymers possible by a variety of methods, such as ruthenium- and tungsten-catalyzed ring-expansion metathesis polymerization, organocatalytic and Lewis acid-catalyzed zwitterionic polymerization, RAFT and nitroxide-mediated radical polymerization, among many others. While the study of cyclic polymers has long been hampered by synthetic challenges, the recent resurgence of interest in this field presents an exciting opportunity for chemists. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2892–2902     

Insertion Homo‐ and Copolymerization of Diallyl Ether

The previously unresolved issue of polymerization of allyl monomers CH₂?CHCH₂X is overcome by a palladium‐catalyzed insertion polymerization of diallyl ether as a monomer. An enhanced 2,1‐insertion of diallyl ether as compared to mono‐allyl ether retards the formation of an unreactive five‐membered cyclic O‐chelate (after 1,2‐insertion) that otherwise hinders further polymerization, and also enhances incorporation in ethylene polymers (20.4 mol %). Cyclic ether repeat units are formed selectively (96 %–99 %) by an intramolecular insertion of the second allyl moiety of the monomer. These features even enable a homopolymerization to yield polymers (poly‐diallyl ether) with degrees of polymerization of DP_n≈44.     

氧负离子聚合在超支化聚合物合成中的应用

近年来,氧负离子聚合得到较快发展,单体种类已经由酯基的β位上含有供电性杂原子的甲基丙烯酸酯类扩展到环氧类、甲基丙烯酸羟酯类单体.氧负离子引发这两类单体聚合,可以得到新型结构的超支化聚合物.对氧负离子引发合成超支化聚合物的机理及其应用进行了综述.     

Metal-catalyzed living radical polymerization: discovery and developments

Control of radical polymerization has been one of the most challenging frontiers in polymerization chemistry. This review presents the discovery of metal-catalyzed living radical polymerization and recent developments in the evolution of catalysts in terms of versatility and activity, scope of monomers, controlled polymerization in water, catalyst removal, and precision synthesis of well-controlled polymers such as random, block, end-functionalized, and star polymers.     

Supramolecular Polymerization from Controllable Fabrication to Living Polymerization

Supramolecular polymers have attracted plenty of interest in the scientific community; however, developing controllable methods of supramolecular polymerization remains a serious challenge. This article reviews some recent developments of methods for supramolecular polymerization from controllable fabrication to living polymerization. Three facile methods with general applicability for controllable fabrication of supramolecular polymers have been established recently: the first method is a self‐sorting approach by manipulating ring–chain equilibrium based on noncovalent control over rigidity of monomers; the second is covalent polymerization from supramonomers formed by noncovalent interactions; and the third is supramolecular interfacial polymerization. More excitingly, living supramolecular polymerization has been achieved by two elegant strategies, including seeded supramolecular polymerization under pathway complexity control and chain‐growth supramolecular polymerization by metastable monomers. It is anticipated that this review may provide some guidance for precise fabrication of supramolecular polymers, leading to the construction of supramolecular polymeric materials with controllable architectures and functions.     

Detailed study of the ring-opening metathesis polymerization of norbornene bearing a five- or six-membered ring cyclic carbonate along with volume expansion

The ring-opening metathesis polymerization (ROMP) of norbornene derivatives bearing five- or six-membered cyclic carbonate ( 2 or 3 ) was carried out with a typical ruthenium catalyst [bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride], the so-called first-generation Grubbs catalyst, under various reaction conditions, to smoothly obtain the corresponding polyalkenamers ( 5 and 6 ) along with volume expansion. The number-average molecular weights (M_n's), 10% weight loss decomposition temperatures, glass-transition temperatures (T_g's), and volume expansion ratios of the resulting products depended on the polymerization conditions. The degree of volume expansion was mainly affected by M_n, T_g, and the cis/trans configuration of the exocyclic double bonds of the resulting polymers. The volume expansion was confirmed to specifically occur during the polymerization of the monomer bearing cyclic carbonate moieties, and similar ROMPs of monomers without cyclic carbonate, such as norbornene itself, the monomer 5,5-bis(methoxymethyl)bicyclo[2.2.1]hept-2-ene, and the monomer endo-N-methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylimide, proceeded along with volume shrinkage. Furthermore, an investigation of another type of polymerization, a vinyl-type one, of monomer 2 suggested that the volume expansion specifically took place in the ring-opening type of polymerization. In addition, the Sc(OTf)₃-mediated cationic ring-opening reaction of the cyclic carbonate moiety of polyalkenamer 5 smoothly proceeded along with volume expansion or nearly zero volume shrinkage to yield the corresponding networked polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 395–405, 2006     

A versatile method for cyclic polymers from conjugated and unconjugated vinyl monomers

A versatile method was introduced to prepare cyclic polymers from both conjugated and unconjugated vinyl monomers. It was developed on the combination of the RAFT polymerization and the self‐accelerating double strain‐promoted azide‐alkyne click (DSPAAC) reaction. In this approach, a switchable chain transfer agent 1 was designed to have hydroxyl terminals and a functional pyridinyl group. The protonation and deprotonation of pyridinyl group endowed the chain transfer agent 1 with a switchable control capability to RAFT polymerization of both conjugated and unconjugated vinyl monomers. Based on this, RAFT polymerization and the following hydroxyl end group modification were used to prepare various azide‐terminated linear polymers including polystyrene, poly(N‐vinylcarbazole), and polystyrene‐block‐poly(N‐vinylcarbazole). Using sym‐dibenzo‐1,5‐cyclooctadiene‐3,7‐diyne (DBA) as small linkers, the corresponding cyclic polymers were then prepared via the DSPAAC reaction between DBA and azide terminals of the linear precursors. Due to the self‐accelerating property of DSPAAC reaction, this bimolecular ring‐closing reaction could efficiently produce the pure cyclic polymers using excess molar amounts of DBA to linear polymer precursors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1811–1820     

Scalable ambient synthesis of water‐soluble poly(β‐hydroxythio‐ether)s

Proton transfer polymerization through thiol‐epoxy “click” reaction between commercially available and hydrophilic di‐thiol and di‐epoxide monomers is carried out under ambient conditions to furnish water‐soluble polymers. The hydrophilicity of monomers permitted use of aqueous tetrahydrofuran as the reaction medium. A high polarity of this solvent system in turn allowed for using a mild catalyst such as triethylamine for a successful polymerization process. The overall simplicity of the system translated into a simple mixing of monomers and isolation of the reactive polymers in an effortless manner and on any scale required. The structure of the resulting polymers and the extent of di‐sulfide defects are studied with the help of 13C‐ and ¹H‐NMR spectroscopy. Finally, reactivity of the synthesized polymers is examined through post‐polymerization modification reaction at the backbone sulfur atoms through oxidation reaction. The practicality, modularity, further functionalizability, and water solubility aspects of the described family of new poly(β‐hydroxythio‐ether)s is anticipated to accelerate investigations into their potential utility in bio‐relevant applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3381–3386     

Helical bias in supramolecular polymers accounts for different stabilities of kinetically trapped states

The idea to synthesize and self-assemble nano-graphenes with structural precision into supramolecular polymers is just one of Klaus Müllen's many pioneering contributions to the chemical sciences. To honor his impact in the field of polymer science, we here describe a study that combines experimental and computational methods in studying the stability of kinetically trapped states of supramolecular polymers. We show that the introduction of stereocenters in the sidechains allow helical supramolecular polymers based on chiral triphenylene-2,6,10-tricarboxamide monomers to escape a kinetic trap more efficiently than polymers based on their achiral analogs. Partial depolymerization of the kinetically trapped state by increasing the temperature followed by polymerization by lowering the temperature shows that monomers either polymerize on existing stacks or self-nucleate to form the thermodynamically more stable state. Chiral monomers prefer the latter more than achiral monomers.