Novel synthesis of photocrosslinkable polymers

A new preparative route to photocrosslinkable polymers in which the polymers are produced directly from the polymerization of vinyl monomers having photocrosslinkable groups has been investigated. The photosensitive resins thus produced have higher sensitivity and resolution than conventional photosensitive resins. The monomers were synthesized from the esterification of vinylphenols or vinyl β-chloroethyl ether with cinnamic acid, β-styrylacrylic acid, and their homologs, and from the etherification of vinyl β-chloroethyl ether with hydroxychalcones. Homopolymerizations of these monomers and their copolymerizations with other comonomers were investigated with the use of both radical and ionic initiators. It is shown that radical polymerization of the monomers gave soluble polymers only at low conversion. Anionic initiators did not initiate polymerization. Cationic polymerization imparted soluble polymers in high yield, except for the monomers bearing cyano groups, which generally gave insoluble polymers. Infrared and NMR spectroscopic investigation of the cationically obtained soluble polymers and comparative investigation by cationic polymerization of model compounds indicated that polymerization of the monomers proceeds through the vinyl double bond without affecting the photosensitive unsaturated bond. Thus, linear photocrosslinkable polymers with an intact photoreactive group may be produced by cationic polymerization. In general, these polymers have uniform structure and modifiable physical properties depending on the monomer used. The polymer thus obtained from β-vinyloxyethyl cinnamate has been shown to have excellent properties for use as a photo-resist.     

自由基嵌段共聚合新进展

本文引用５０多篇文章，按引发方式不同从顺序引发剂，ｉｍｉｆｅｒｔｅｒ法，高分子引发剂法和自由基性聚合等几方面综述了自由基嵌段共聚合近１０年来的新进展。     

Polymer Composites Based on Reactive Carboxylate-Alumoxanes

Summary: The possibility of applying basic aluminum carboxylates as the cross-linking monomers in radical polymerization processes as well as the initiators for ATRP of styrene and coordination ROP of heterocyclic monomers was examined. It was established, that aluminum carboxylates containing in their structure the acrylic and lauric acids derivatives show high activity in the copolymerization with vinyl monomers which results in the hybrid polymer networks formation. In the typical ATRP conditions, polymers grafted with styrene are obtained while basic aluminum 2-bromopropionate is used as the initiator. Hybrid composites i.e. core-shell nanospheres can be obtained in this way at low degree of polymerization. Nanoparticles of basic aluminum caroboxylates when reacted with triethylaluminum show high activity as initiators in the polymerization processes of ε-caprolactone, trimethylene carbonate as well as propylene and ethylene oxides. Cross-linked products in the form of a gel were formed as the result of ROP in such systems. However, linear polymers characterized by M_n above 10⁴ and PDI ≥ 1.9 were obtained after aluminum residuals removal.     

Development of methods for synthesis of surface-modified fluoropolymer-containing composite materials

The results of studies into development of methods for synthesizing new modified fluoropolymer-containing composite materials were summarized. The issues covered include: new modes and initiation methods of graft polymerization of fluoromonomers onto the surface of items of various nature and dispersity without homopolymer formation; nature of the surface active centers of the modified material and how it affects the kinetics and mechanism of both postradiation graft polymerization of tetrafluoroethylene and the subsequent chemical modification of the graft-polymer; major mechanisms and methods of blocking the terminal radicals of the grafted fluoropolymer layer, including those based on reaction with some perfluoroolefins at their double bond, yielding stable long-lived radicals, which allows controlling the physicochemical properties of composite materials; and new methods of synthesis of selective biocompatible sorbents with specific adsorption properties. Accelerating effect of oxygen on polymerization was analyzed, and the phenomenon of ozone initiation of low-temperature polymerization of tetrafluoroethylene was revealed and examined; a new class of high-performance polymerization initiators, namely, perflouroolefin ozonides, was synthesized; and new methods of initiation of polymerization and copolymerization of fluoromonomers, as well as of some other monomers with their use were developed.     

Diaryliodonium salts as thermal initiators of cationic polymerization

Diaryliodonium salts (I) undergo efficient thermal decomposition in the presence of copper (II) compounds. Such systems can be employed as a novel class of latent thermal initiators for cationic polymerization. An investigation of the mechanism of the reaction demonstrated that the copper (II) compound is first reduced to the corresponding copper (I) compound, which subsequently reduces the diaryliodonium salt. The cationic polymerization of some typical monomers using these new initiators was carried out to demonstrate the scope of their utility.     

The anionic ring-opening polymerization and copolymerization of cyclic carbonates

Cyclic carbonates are eligible to ring-opening polymerization using a wide variety of initiators such as carbanionic or alcoholate species as well as initiators known to be effective for the ring-opening polymerization of lactones and for the group transfer polymerization of vinyl monomers. Depending on the catalyst, high molecular weight polymers may be obtained in high yields (kinetically controlled regime) or a ring-chain equilibrium is observed upon end-biting, back-biting and transesterification reactions (thermodynamically controlled regime). The polymerizability of the cyclic carbonates is strongly dependent on their structure. Five-membered cycles generally cannot be polymerized, whereas six-membered cycles can be polymerized and copolymerized in an ideal manner. The polymerizability of higher cyclics, in particular when containing aromatic ring systems, is highly dependent on the substitution pattern of the aromatics. Since the active species in the polymerization of aliphatic cyclic carbonates was disclosed to be of alcoholate type, a copolymerization with ϵ-caprolactone is easily achieved, the reactivity of the cyclic carbonate, however, being by far larger than that of the lactone. On the other hand, the copolymerization with pivalolactone exerts a different behaviour, since the active species of the growing pivalolactone chain after a few steps assumes the character of a carboxylate anion which is unable to promote the ring-opening polymerization of cyclic carbonates. Since carbanionic species may be used as initiators for the ring-opening polymerization of cyclic carbonates, polystyryl, polybutadienyl, and polyisoprenyl anions may be used as initiators to achieve the corresponding block copolymers. To obtain block copolymers with poly(methyl methacrylate) blocks a group transfer polymerization of the respective acrylate has to be performed, followed by the polymerization of the cyclic carbonate. The latter, however, rather proceeds by a metal- free anionic process than by a group transfer process. The ring-opening polymerization and copolymerization of cyclic carbonates allows the preparation of a broad variety of new polymers with remarkable properties.     

A Comparative Study of Methyl Methacrylate/Butyl Acrylate Copolymerization Kinetics by Atom‐Transfer and Conventional Radical Polymerization

Methyl methacrylate and butyl acrylate monomers are copolymerized by atom‐transfer radical polymerization, affording polymers with well‐controlled molecular weight and low polydispersity. A kinetic analysis of this system is compared with the corresponding free‐radical polymerization system. The copolymerization rate follows an opposite trend to that observed in conventional copolymerization. This fact is attributed to a smaller population of radicals generated in the reaction, since the relative fraction of propagating radicals is the same as that in classical copolymerization.     

Polymerization and copolymerization studies on vinyl fluoride

The polymerization of vinyl fluoride has been studied in the temperature range of 0–50°C. with the aid of different types of initiators. Ziegler-Natta systems based on vanadyl acetylacetonate and AIR(OR)Cl compounds showed good activity. Enhanced reaction rates and higher polymerization degrees were achieved with boron alkyls (and, to a lesser degree, Cd, Zn, and Be alkyls) activated by oxygen. With either types of initiator, the main features and the kinetic parameters of the polymerization were determined. In all cases, the polymerization is considered to be of the free-radical type, though some properties (crystallinity, melting temperature) of the polymer are shown to be markedly improved over the previously described high-pressure polymer. This is chiefly ascribed to an improved degree of chemical regularity of the chains. The copolymerization of vinyl fluoride in the presence of the cited initiators was studied with a number of monomers. The values of the copolymerization parameters allow us to obtain Q (0.010 ± 0.005) and e (?0.8±0.2) values and to discuss the reactivity of vinyl fluoride in radical chain propagation.     

Polymerization of amphiphilic quaternary ammonium salts of acrylic,methacrylic, and ethacrylic acids

The polymerization behavior of dodecyltri-methylammonium methacrylate, and hexadecyltrimethylammonium acrylate, methacrylate and ethacrylate as amphiphilic monomers bearing a polymerizable double bond outside the micelle shell was investigated in micellar solution. Although the monomers did not have spontaneous polymerizability, they polymerized in the presence of both oil-soluble and water-soluble radical initiators, in spite of the difference of the expected location solubilizing initiator molecules. The profit based on micelle-forming of the monomer on the polymerization in water disappeared by the addition of sodium chloride into the polymerizing system due to the increased dissociation between cationic micelles and the polymerizable counter ions.     

The cationic polymerization and copolymerization of isopropenylmetallocene monomers

Three types of isopropenylmetallocene monomers were synthesized and subjected to polymerization and copolymerization by cationic initiators; (1) isopropenylferrocene (IF); (2) (η⁵-isopropenylcyclopentadienyl)dicarbonylnitrosylmolybdenum (IDM); and (3) 1,1′-diisopropenylcyclopentadienylstannocene (DIS), and related derivatives of each. IF was synthesized by a three-step procedure involving the acetylation of ferrocene, conversion of the latter to 2-ferrocenyl-2-propanol, and dehydration of the carbinol. IF was homopolymerized under various cationic initiation conditions, but only low molecular weight homopolymers were obtained. Copolymerization of IF with styrene and with p-methoxy-α-methylstyrene also gave only low molecular weight products. The formation of only low molecular weight polymers in all polymerization reactions is believed to result from the effect of the unusually high stability of ferrocenyl carbenium ions on its propagation reaction. The observed polymerization behavior of α-trifluoromethylvinylferrocene is in accord with this conclusion. IDM and DIS did not form polymeric products under cationic conditions, although copolymers could be obtained for each of these monomers and styrene with a free radical polymerization initiator (AIBN).     

Synthesis,characterization, and application of helical polymers

This review mainly describes the asymmetric synthesis of optically active polymers with helical conformation. Bulky methacrylates such as triphenylmethyl methacrylate and 1-phenyldibenzosuberyl methacrylate give one-handed helical and optically active polymers with almost perfectly isotactic main chain conformation by polymerization with chiral anionic initiators. The radical polymerization and copolymerization of these monomers under chiral conditions also afford optically active polymers with prevailing one-handed helicity. N, N-Disubstituted acrylamides also give optically active, helical polymers in the asymmetric anionic polymerization. Optically active polyisocyanates with a prevailing one-handed helical structure have been prepared in the copolymerization of an achiral isocyanate with a small amount of an optically active isocyanate and also in the polymerization of alkyl and aromatic isocyanates with optically active lithium alkoxide or amide compounds. The existence of a stable helical structure for polychloral has been successfully proved with the helical oligomers of chloral. One-handed helical polyisocyanides have been prepared by helix-sense-selective polymerization of bulky isocyanides and also by the cyclopolymerization of a 1, 2-diisocyanobenzene derivative with the Pd complex of a one-handed helical oligomer.     

Hybrid copolymerization of cyclic and vinyl monomers

In this work,we report the hybrid copolymerization of various cyclic monomers and vinyl monomers.Our studies demonstrate that 1-tert-butyl-4,4,4-tris-(dimethylamino)-2,2-bis[tris(dimethylamino) phophoranyliden-amino]-2 5,5-catenadi(phosphazene) (t-BuP 4) can catalyze the hybrid copolymerization of caprolactone (CL),lactide (LA) or cyclic carbonate ester with acrylate or methyl acrylate.However,the polymerization of cyclosiloxane with vinyl monomers yields two corresponding homopolymers,and the polymerization of lactone with acrylonitrile (AN) produces only polyacrylonitrile.Clearly,the extent of matching of activity between a monomer and an active center determines whether or not there is hybrid copolymerization.     

Scope and limitations of 1,1-diphenylethylene chemistry in anionic polymer synthesis

The scope and limitations of the addition reactions of simple and polymeric organolithium compounds with substituted 1,1-diarylethylenes to prepare in chain- and chain-end functionalized polymers is presented. The application of this general living functionalization reaction for the preparation of ω-functionalized polymers is illustrated for hydroxyl, carboxyl, dimethylamine, and primary amine groups, as well as for the fluorescent naphthalene and pyrene labels. The use of this chemistry to prepare functionalized initiators is described, as well as the copolymerization of substituted 1,1-diphenylethylenes with monomers to prepare in-chain functionalized polymers with alternating structures.     

Radiation-induced solid-state copolymerization of maleic anhydride and acenaphthylene

Radiation-induced solid-state copolymerization of the maleic anhydride–acenaphthylene system was carried out for the purpose of studying the solid-state polymerization of vinyl compounds in a binary system. Melting point measurement confirmed that this binary monomer system forms a eutectic mixture in the solid state. The solid-state polymerization of these monomers proceeds at maximum rate at the eutectic composition, and the polymerization products consist of a mixture of polyacenaphthylene and 1:1 maleic anhydride–acenaphthylene alternating copolymer. Since the 1:1 copolymer was obtained in solution polymerization also and maleic anhydride did not homopolymerize in solid state, it is considered that the solid-state copolymerization of maleic anhydride and acenaphthylene occurs in a liquidlike state at the boundary of the two monomer crystals.     

Anionic Polymerization and Copolymerization of Hydrocarbon Monomers Catalyzed by Organobarium Initiators

The barium salt of the dimeric dianion of 1,1-diphenylethylene (Ba-DPhE) initiates polymerization and copolymerization of monomers capable of anionic polymerization (butadiene, isoprene, styrene) in ethereal and hydrocarbon solvents. Ba-DPhE is more stereospecific in butadiene polymerization (up to 70% of cis-1, 4-units in hydrocarbon medium) than initiators based on other metals of Groups I and II. The relative reactivity of monomers in copolymerization processes in THF decreases in an order typical for anionic polymerization: styrene > butadiene > isoprene. The most interesting feature of organobarium initiators is their ability to form random butadiene-styrene copolymers with high cis-1,4-butadiene unit content when copolymerization proceeds in a hydrocarbon medium.

A new phenomenon in anionic polymerization, the dependence of diene units structure on copolymer composition, was observed. Thus an increase of styrene content in butadienestyrene copolymer leads to conversion of cis-1,4-butadiene units into trans-1,4-units (in benzene) or to conversion of 1,4-units to 1,2-units (in THF). Similarly, an increase of butadiene content in its copolymer with isoprene (in benzene) leads to conversion of cis-1,4-isoprene units into trans-1,4-units.

Spectrophotometric, conductometric, and viscometric methods were used to study organobarium active centers. Certain anomalies connected with the formation of specific aggregates due to coupling of bifunctional hydrocarbon chains with bivalent counterions were observed.     

Anionic polymerization. IV. Effect of crown ethers on alkylsodium initiator

The polymerization of butadiene and copolymerization of butadiene-styrene with alkylsodium catalyst modified by crown ethers in hydrocarbon solvent has been investigated. This catalyst system produced polybutadiene of high viscosity (2.0–5.0) and high vinyl content (80%) in high conversion (75–95%). These results are in contrast to those obtained with aliphatic ether-modified alkylsodium polymerization which typically gives products of low molecular weight and at low conversion. The copolymerization of butadiene-styrene with alkylsodium catalyst modified by crown ethers gave a copolymer which did not contain block styrene. Although the copolymer did not contain block styrene, there was an unusually high level of incorporation of styrene in the copolymer at low conversion. This behavior is quite different from either modified organolithium or unmodified organosodium initiators, in which the styrene is uniformly and randomly incorporated along the chain.     

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     

Initiator effect on the cationic ring‐opening copolymerization of 2‐ethyl‐2‐oxazoline and 2‐phenyl‐2‐oxazoline

The aim of this research was to study the effect of the initiator on the resulting monomer distribution for the cationic ring‐opening copolymerization of 2‐ethyl‐2‐oxazoline (EtOx) and 2‐phenyl‐2‐oxazoline (PhOx). At first, kinetic studies were performed for the homopolymerizations of both monomers at 160 °C under microwave irradiation using four initiators. These initiators have the same benzyl‐initiating group but different leaving groups, Cl^?, Br^?, I^?, and OTs^?. The basicity of the leaving group affects the ratio of covalent and cationic propagating species and, thus, the polymerization rate. The observed differences in polymerization rates could be correlated to the concentration of cationic species in the polymerization mixture as determined by ¹H NMR spectroscopy. In a next‐step, polymerization kinetics were determined for the copolymerizations of EtOx and PhOx with these four initiators. The reactivity ratios for these copolymerizations were calculated from the polymerization rates obtained for the copolymerizations. This approach allows more accurate determination of the copolymerization parameters compared to conventional methods using the composition of single polymers. When benzyl chloride (BCl) was used as an initiator, no copolymers could be obtained because its reactivity is too low for the polymerization of PhOx. With decreasing basicity of the used counterions (Br^? > I^? > OTs^?), the reactivity ratios gradually changed from r_EtOx = 10.1 and r_PhOx = 0.30 to r_EtOx = 7.9 and r_PhOx = 0.18. However, the large difference in reactivity ratios will lead to the formation of quasi‐diblock copolymers in all cases. In conclusion, the used initiator does influence the monomer distribution in the copolymers, but for the investigated system the differences were so small that no difference in the resulting polymer properties is expected. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4804–4816, 2008     

Mechanochemically initiated polymerizations. VIII. Influence of chemical nature of monomers

The article presents some results which prove that vinylic, acrylic, dienic, and cyclic monomers, as well as substances which cannot be polymerized by conventional methods (acetonitrile) are activated under the influence of mechanical energy, by vibratory milling, and participate in polymerization and copolymerization reactions.     

蛋白质接枝共聚研究进展

接枝共聚是一种有效的化学修饰方法,经过接枝改性后,高分子化合物的物理、机械和化学性质都能得到改善。文章从引发体系、接枝单体两个方面综述了酪蛋白和丝素蛋白的接枝共聚改性机理以及接枝产物的结构和性能。接枝反应中引发剂浓度和接枝单体浓度都有一个最佳值,接枝产物的热性能和力学性能都有所提高。