Synthesis of novel organoboron polymers by haloboration polymerization of bisallene compounds and their reactions

Summary. Novel organoboron polymers were prepared by haloboration polymerization of bisallene compounds. The polymers obtained have allylborane halide units in their main chain and can be expected as a novel type of reactive polymers. For example, the polymer prepared by haloboration polymerization between tribromoborane (1) and 1,2,10,11-dodecatetraene (2 b) was subjected to chain transformation reaction (dichloromethyl methyl ether rearrangement) to give the corresponding polyalcohol or polyketone. Haloboration-phenylboration polymerization of aliphatic bisallenes by using diphenylbromoborane also gave the corresponding polymers. Received: 8 July 1997/Revised: 23 July 1997/Accepted: 28 July 1997     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary Organoboron polymers were prepared by hydroboration polymerization between various dienes and thexylborane. These polymers were reacted with -furyllithium followed by the treatment with acetic acid and then by the oxidative treatment to give the corresponding polyalcohols having primary and tertiary hydroxyl groups. The structures of the polyalcohols obtained were characterized by¹H-NMR compared with that for model compound, which was prepared by the reaction of dioctylthexylborane with -furyllithium. These conversions from organoboron polymers to polyalcohols include the migrations of two polymeric chains from boron atom to carbon and the ring-opening of furan ring.For parts I, II, and III, see references 4, 5 and 6, respectively.     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary Organoboron polymers consisting of carbon-boron bonds in the main chains were prepared by hydroboration polymerization of various dienes with thexylborane. These polymers were reacted with α-furyllithium followed by treatment with acetic acid to give the corresponding poly(alcohol)s. This conversion includes the migrations of two polymeric main chains from boron atom to carbon and the reductive cleavage of carbon-boron bonds in the resulting boron-containing polymers. The structures of the poly(alcohol)s obtained were characterized by ¹H-NMR in comparison with that of model compound, which was prepared by the reaction of dioctylthexylborane with α-furyllithium followed by reductive treatment. The organoboron polymer prepared from 1,7-octadiene and thexylborane was also reacted with dichloromethyl methyl ether followed by acidolysis to form hydrocarbon polymer without obvious scission of polymeric main chain. See references     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary Hydroboration polymerization of diolefin gives an organoboron polymer, which can be regarded as a polymer homologue of trialkylborane. The organoboron polymers obtained were reacted with ,-dichloromethyl methyl ether (DCME) followed by the oxidative treatment to produce the corresponding poly(alcohol)s in high yields.Part II: Polym. Bull. 25,1 (1991)     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary This paper describes a novel methodology for the preparation of poly(ketone). An organoboron polymer was prepared by polyaddition between thexylborane and 1,7-octadiene, which was reacted with potassium cyanide in the presence of trifluoroacetic anhydride. After oxidation of the reaction mixture, the corresponding poly(ketone) was obtained.     

Stable organoboron polymers prepared by hydroboration polymerization of dienes with tripylborane

Summary Hydroboration polymerization between diene monomers and 2,4,6-triisopropylphenylborane (tripylborane) gave organoboron main-chain polymers. The polymerization was carried out by adding a diene monomer to a THF solution of tripylborane at room temperature under nitrogen. The obtained polymers were found to be more stable compared with the polymers prepared from thexylborane or mesitylborane. Received: 27 November 2000/Accepted: 11 December 2000     

Synthesis of poly(cyclodiborazane)s by hydroboration polymerization of dicyano compounds with tripylborane

Summary Hydroboration polymerizaton of dicyano compounds was examined by using tripylborane, which is known as a fairly stable hydroborating agent, to give the corresponding poly(cyclodiborazane)s in good yields. The number average molecular weights of the obtained polymers were in the range of several thousands. These polymers exhibited high stability toward air and moisture. Received: 9 July 1999/Revised version: 27 July 1999/Accepted: 2 August 1999     

Synthesis of acrylate polymers by a novel emulsion polymerization for adhesive applications

Pressure‐sensitive adhesives (PSAs) are viscoelastic–elastomeric materials that can adhere strongly to solid surfaces with light contact pressure and a short contact time. Polyacrylates produced by solution polymerization are used widely because of their good adhesive properties. A novel emulsion polymerization was established to improve the low physical properties of PSA on the basis of conventional poly(n‐butyl acrylate) (PBA) by emulsion polymerization. PBA latex was synthesized by the emulsion polymerization of 50 wt % n‐butyl acrylate mixed with 15 wt % ethyl acetate (EA) with Emal‐10P and Emulgen‐920 as anionic and nonionic surfactants, respectively, at 70°C. Potassium persulfate (KPS) or a combination of KPS and dicumyl peroxide (DCP) was used as the initiator. The KPS/DCP system gave a very high‐molecular‐weight PBA of a narrow molecular weight distribution with a weight‐average molecular weight/number‐average molecular weight value of 1.01–1.03 in 15 min. The PSA tape was prepared by the casting of the PSA latex onto a corona poly(ethylene terephthalate) film as an adherent to obtain a 50‐μm‐dry‐thickness film. The PSA tape produced from PBA by the novel emulsion polymerization showed better adhesive properties, such as 180° peel adhesion, shear holding power, and rolling ball tack tests according to JIS and ASTM standards, than PSA tape produced from solution polymerization. The occlusion of a small amount of EA in emulsion particles before polymerization was found to give higher properties than those of PBA prepared by the addition of EA to the PBA latex after polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:413–421, 2006     

Synthesis of star polymers by organized polymerization of macromonomers

Vinylbenzyl-terminated polyisoprene (PI) macromonomers were synthesized by the coupling reaction of the corresponding living anions with p-chloromethylstyrene. PI stars were prepared by the free-radical crosslinking of PI macromonomers with divinylbenzene (DVB) in n-heptane. No macrogelation was observed during polymerization. The radical copolymerization of PI macromonomer with DVB led to microgelation in micelles formed by PI macromonomers in the selective solvent (organized polymerization). The arm number of star polymers depended strongly on the concentration ratio of DVB to macromonomer ends.     

Synthesis and characterization of telechelic polymers obtained by micellar polymerization

Summary The synthesis, characterization and rheological properties in aqueous solution of two telechelic polymers of different structures and size are reported: they are water soluble polyacrylamides, hydrophobically modified with linear and di-substituted hydrophobic initiators. The polymers were prepared via free radical micellar polymerization. The results of static light scattering (SLS), showed similar weight-average molecular weights (M_w) in all of the synthesized polymers. No signal corresponding to the presence of the hydrophobic group of the initiator could be observed by ¹H NMR; however, the presence of these hydrophobic groups was demonstrated using rheological measurements.     

通过自由基聚合精密合成功能高分子及齐聚物

1前言自由基聚合与α-烯烃的配位聚合是2种在工业上极重要、应用很广的合成方法。但是,在自由基中间体中由于存在二分子终止(自由基再结合及歧化)现象,所以长期以来普遍认为,从原理上讲,自由基聚合的精密控制是很困难的。自20世纪80年代以来,研究者们开展了"精细自由基"(活性自由基)聚合的研究(见图1,2)。日本泽本光男等进行了过渡金属催化自由基聚合研究(图3),使这一课题迎来了新局面。泽本等人认为,以下3点值得关注:     

Synthesis of aromatic carboxyl functionalized polymers by atom transfer radical polymerization

The synthesis of aromatic carboxyl functionalized polymers by atom transfer radical polymerization is described. The α‐bromo‐p‐toluic acid ( 1 ) initiated polymerization of styrene in the presence of copper(I) bromide and 2,2′‐bipyridyl affords quantitative yields of the corresponding aromatic carboxyl functionalized polystyrene ( 2 ). Polymerization proceeded via a controlled free radical process to afford quantitative yields of the corresponding aromatic carboxyl functionalized polymers with predictable molecular weights (M_n = 1600–25 900 g mol⁻¹), narrow molecular weight distribution (M_w /M_n = 1.1–1.40) and an initiator efficiency above 0.87. The polymerization process was monitored by gas chromatographic analysis. The functionalized polymers were characterized by thin layer chromatography, size exclusion chromatography, spectroscopy, potentiometry and elemental analysis. © 2000 Society of Chemical Industry     

Synthesis and characterization of fluorene end-labeled polymers prepared by nitroxide-mediated polymerization

The fluorene-based alkoxyamine 9-(2,2,6,6-tetramethyl-4-hydroxypiperidinyloxy)fluorene was prepared and investigated as a unimolecular initiator in the nitroxide-mediated polymerization (NMP) of styrene. Reactions performed in either bulk or ethereal solvents at 125 °C generated polymers possessing low polydispersity indices (PDIs) and number average molecular weight (M_n) values close to those anticipated based on monomer-to-initiator ratios. A linear relationship between monomer conversion and M_n values was observed by analysis of reaction aliquots with ¹H NMR and gel permeation chromatography (GPC), while PDI values remained low throughout. Analysis of the polymers by UV–vis spectroscopy indicated that approximately 80% of the polymer chains were labeled with the fluorene chromophore, while fluorescence spectroscopy was used to verify that the fluorene was polymer-bound.     

Synthesis of heat- and solvent-resistant polymers by radical polymerization of trifluoromethyl-substituted N-phenylmaleimides

The radical polymerization of the three kinds of fluorine-containing maleimides, that is, N-[2-(trifluoromethyl)phenyl]maleimide (2TFPhMI), N-[3-(trifluoromethyl)phenyl]maleimide (3TFPhMI), and N-[4-(trifluoromethyl)phenyl]maleimide (4TFPhMI) was carried out in the presence of a radical initiator in benzene at 60°C. The polymerization reactivity of these fluorine-containing maleimides and the properties of the resulting polymers were examined in comparison with the results for the methyl-substituted phenylmaleimides. The trifluoromethyl-substituted maleimides readily polymerized to give polymers in high yields as well as a methyl-substituted one. The resulting polymers showed an excellent resistance against organic solvents; especially, poly(4TFPhMI) was insoluble in the most common solvents. The onset temperature of thermal decomposition of the fluorine-containing polymers (T_init> = 352–368°C) was similar to that of poly(N-phenylmaleimide) (T_init = 364°C) and slightly lower than those for the methyl-substituted one (T_init = 388–402°C). The glass transition temperature of the polymers was dependent on the position of the trifluoromethyl group. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1703–1708, 1998     

Gradient polymers by diffusion polymerization

Gradient polymers are multicomponent polymers whose structures or compositions are not macroscopically homogeneous, but vary as a function of position in the sample. One method to prepare such polymers is by diffusing a guest monomer into a host polymer and then polymerizing the monomer in position to retain the concentration gradient created by the diffusion. One series of such type of materials was prepared by diffusing acrylonitrile into polystyrene. The gradient profile was determined by analyzing the nitrogen content in succeeding layers of the sample. These gradient polymers exhibit improved resistance to hydrocarbon solvents. The second series of gradient polymers was made by diffusion of methyl acrylate into poly(methyl methacrylate). These materials are shown to possess substantially increased fracture strain. Eyring's stress-biased activated rate theory of yielding was used to rationalize the observed toughening effect in gradient polymers.     

Synthesis of polymers having arylene-vinylene units by palladium-catalyzed hydroarylation polymerization of diethynylbenzene derivatives

Summary Arylene-vinylene-containing polymers with fully aromatic backbone structures were prepared by the palladium-catalyzed hydroarylation polymerization of diethynylbenzene derivatives with diiodobenzene and alkylmalonate anions as a hydride source. For instance, the polymerization of 1,4-bis(4'-dodecyloxy)phenylethynylenebenzene, diiodobenzene, and sodium diethyl benzylmalonate was carried out at 80°C for 2 days in 1,4-dioxane in the presence of Pd(OAc)₂ / tri-o-tolylphosphine (7 equiv. to Pd) to produce a polymer (M _n= 6,390, M _w/M _n= 1.53) in high yield (86 %). Using various diethynylbenzene derivatives, polymers having arylene-vinylene units were also obtained in high yields. Received: 16 December 1999/Accepted: 20 January 2000     

Effect of addition of organoaluminum and organoboron compounds in the stereospecific polymerization of acrylonitrile using dialkylmagnesium as catalyst

An attempt was made to clarify the effect of addition of organoaluminum and organoboron compounds in the stereospecific polymerization of acrylonitrile (AN) initiated by dialkylmagnesium (R₂Mg) above 100°C. The triad isotacticity (i.e. the content of mm (m: meso)) as well as the viscosity-average molecular weight (M?_v) of polyacrylonitrile (PAN) increased when trialkylaluminum (R₃Al) and trialkylboron (R₃B) were used as additives. Diisobutylaluminum hydride [(i-C₄H₉)₂AlH] was found to be the best additive. in the stereospecific polymerization of AN, giving PAN with higher (mm) content (0.63), higher M?_v value (5.2 × 10⁴), and a yield approximately double that obtained using (n-C₆H₁₃)₂Mg alone. When the (n-C₆H₁₃)₂Mg/(i-C₄H₉)₂AlH system was used, the yield, (mm), and M?_v of PAN increased with polymerization temperature (T_p); maximum values of yield, (mm), and M?_v were obtained at c. 130°C. The optimum amount of additives was approximately equimolar to R₂Mg as initiator. The ¹³C chemical shift of α-carbon in R₂Mg at 90°C shifted by mixing with R₃Al and R₃B, respectively, indicating the existence of interaction between R₂Mg and the additives. The main role of the additives is considered to be suppression of the self-association of R₂Mg by strong interaction with R₂Mg.     

Synthesis of well-defined star-branched polymers by stepwise iterative methodology using living anionic polymerization

This article reviews the synthesis of regular and asymmetric star-branched polymers with well-defined structures by methodologies using living anionic polymerization, especially focusing on the synthetic approaches accessible for precisely controlled architectures of star-branched polymers concerning molecular weight, molecular weight distribution, arm number, and composition. The reason for selecting living anionic polymerization from many living/controlled polymerization systems so far developed is that this living polymerization system is still the best to meet the strict requirements for the precise structures of star-branched polymers. Furthermore, we herein mainly introduce a novel and quite versatile stepwise iterative methodology recently developed by our group for the successive synthesis of many-armed and multi-compositional asymmetric star-branched polymers. The methodology basically involves only two sets of the reaction conditions for the entire iterative synthetic sequence. The reaction sequence can be, in principle, limitlessly iterated to introduce a definite number of the same or different polymer segments at each stage of the iteration. As a result, a wide variety of many-armed and multi-compositional asymmetric star-branched polymers can be synthesized.