Synthesis Of Hyperbranched Polymers Research Articles

精密金属集積能を有するポリフェニルアゾメチン新ナノ構造体

Novel dendritic polyphenylazomethines (DPAs) were synthesized up to the fourth generation by the convergent method via dehydration of aromatic ketones with aromatic amines in the presence of titanium (IV) tetrachloride. DPAs show high thermal stability and high solubility unlike the con-ventional linear polyphenylazomethines. Novel cyclic phenylazomethine trimers (CPAs) were syn-thesized in a one-step dehydration of the 4-aminobenzophenone derivatives in the presence of TiCl4 or p-toluenesulfonic acid (PTS). When using TiCl4 as the dehydration agent, the introduction of bulky substituents as the α-position of the substrate enhanced the yields of the CPAs. On the other hand, PTS served as an effective catalyst for the synthesis of the phenyl-substituted CPA. Cyclization in hyperbranched polymer synthesis was first controlled on the basis of a steric effect using a Lewis acid with bulky ligands. A novel dendrimer with a cyclic structure was quantitatively obtained via controlled cyclization using a monomer with a bulky dendron.

Synthesis of a novel one‐pot approach of hyperbranched polyurethanes and their properties

AbstractA new method for the synthesis of hyperbranched polymers involving the use of ABx macromonomers containing linear units have been investigated. Two types of novel hyperbranched polyurethanes have been synthesized by a one‐pot approach. The structures of monomers and polymers were characterized by elemental analysis, 1H NMR, 13C NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The hyperbranched polymers have been proven to be extremely soluble in a wide range of solvents. Polymer electrolytes were prepared with hyperbranched polymer, linear polymer as the host, and lithium perchlorate (LiClO4) as the ion source. Analysis of the isotherm conductivity dependence of the ion concentration indicated that these hyperbranched polymers could function as a “solvent” for the lithium salt. The conductivity increased with the increasing concentration of hyperbranched polymers in the host polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 344–350, 2002

Controlled Cyclotrimerization in Hyperbranched Polymer Synthesis

Cyclization in hyperbranched polymer synthesis was first controlled on the basis of a steric effect using a Lewis acid with a bulky ligand. Only phenylazomethine oligomers having a cyclic structure were formed during the polymerization of 4,4‘-diaminobenzophenone in the presence of TiCl4(THF)2 as a Lewis acid with bulky ligands. The structure of a cavity in an isolated cyclic oligomer was determined by X-ray crystal analysis. Controlled cyclization is applied for hyperbranched polymer synthesis, and a novel dendrimer with a cyclic structure was quantitatively obtained via controlled cyclization on the basis of a steric effect using a monomer with a bulky dendron.

Hyperbranched Polymers Made from A2- and BB′2 -Type Monomers, 3. Polyaddition ofN-Methyl-1,3-propanediamine to Divinyl Sulfone

The new approach to the synthesis of hyperbranched polymers from commercially available A 2 - and BB' 2 -type monomer has been developed further. In this work, hyperbranched poly(sulfone amine)s with multiple amino end groups were prepared by direct polyaddition of N-methyl-1,3-propanediamine (NPA, BB' 2 ) to divinyl sulfone (DV, A 2 ). The polymerization mechanism is presented and demonstrated with FT-IR, HPLC, and MS. During the reaction, the secondary amino groups of NPA react with the vinyl groups of DV within 12 s, generating dimers that can be regarded as new AB' 2 -type monomers. Further polymerization of the new monomers leads to hyperbranched poly(sulfone amine)s. The influence of the reaction conditions, such as the feed ratio and solvents, on the polymerization has been investigated. When the molar feed ratio of DV to NPA is equal to 1 (A/B/B' = 2/1/2), no crosslinking is observed in water or organic solvents. When the feed ratio of DV to NPA is equal to 3/2 (A/B/B' = 3/1/2), no gelation occurs in chloroform or other organic solvents, such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. Interestingly, when the polymerization was carried out in water with a feed ratio of 3/2, the reaction mixture got turbid within 20-30 min and gelation occurred with 15-20 h.

Synthesis of Hyperbranched Polymers by Anionic Self-Condensing Vinyl Polymerization

Anionic self-condensing vinyl polymerization is achieved from an in situ creation of a vinyl monomer bearing an active anion by the reaction of equimolar amount of 1,3-diisopropenylbenzene (DIPB) and butyllithium in THF at 30°C. Onset of the intermolecular-equilibrium between isopropenyl groups (α-methylstyrene) and isopropenyl-α-methylstyryllithium sites of the oligomer restricts the growth of hyperbranched poly-(DIPB) in THF at –40°C. Addition of a small amount of styrene interrupts this equilibrium. Conversion of isopropenyl-α-methylstyryllithium into styryllithium sites quickly directs the consumption of styrene and concurrent intermolecular-condensation into remaining α-methylstyrene groups of the oligomers. Thus, the equilibrium is reestablished and it has been shifted to the right by one or more α-methylstyrene units that increase the molecular weight of the hyperbranched living polymer. Repeated small additions of styrene are attended by impressive multiplications of molecular weights. Up to seven generations of hyperbranched polymers have been synthesized as reported in this paper; the polymers exhibit high molecular weight and broad molecular weight distributions (1.8 < M̄w/M̄n < 4). The Mark-Houwink exponent, α, is found to be 0.38 indicating a densely packed three-dimensional structure resulting from the hyperbranched topology.

Preparation of water-soluble hyperbranched poly(sulfone-amine)s by polyaddition of N-ethylethylenediamine to divinyl sulfone

The new approach for synthesis of hyperbranched polymers from commercially available A2 and BB′2 type monomers has been further developed. Water-soluble hyperbranched poly(sulfone-amine)s with multiple amino end groups were prepared by direct polyaddition of divinyl sulfone (DV, A2) to N-ethylethylenediamine (NDA, BB′2). Effects of reaction conditions such as the feed ratio and solvents on the polymerization have been investigated. When the feed ratio of DV to NDA was equal to 1, no gelation occurred during the polymerization in water or organic solvents. Similarly, when the feed ratio of DV to AP was equal to 3/2, no insoluble or cross-linked material was observed in chloroform or other organic solvents such as N,N-dimethylforamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone. Interestingly, when water was used as solvent, the reaction mixture got turbid within 15–20min and gelation occurred within 12–15h. The turbid mixture formed during initial stage becomes a transparent solution in aqueous acid, which was coined as ‘pseudo-gelation’. The solubility of the resulting polymer in water is as high as 1.68g/ml. The degree of branching (DB) of all the resulting hyperbranched polymers is higher than 50% and the highest one is 70.9%. The reaction mechanism is presented and demonstrated with FTIR, HPLC and MS. During polymerization, secondary amino groups of NDA react rapidly with vinyl groups of DV within 12s dominantly generating dimers which can be regarded as a new AB′2 type monomer. Further polymerization of the new monomers leads to hyperbranched poly(sulfone-amine)s.

Solid‐supported synthesis of hyperbranched polymer with β,β‐diethynylstyryl units

Solid‐supported synthesis of hyperbranched polymer with β,β‐diethynylstyryl units

An efficient route for the synthesis of hyperbranched polymers and dendritic building blocks based on urea linkages

A highly efficient synthetic route, based on the quantitative reaction between amine and isocyanate functionalities, was used successfully for the synthesis of hyperbranched polymers and dendritic building blocks based on urea linkages. The thermal decomposition of 3,5-diamino benzoyl azide or 5-amino isophthaloyl azide generated in situ the corresponding phenyl isocyanates, which were then polymerized to give wholly aromatic hyperbranched polyureas. Hyperbranched polyurea with amine chain ends was soluble in common organic solvents. The degree of branching, as calculated with 1H NMR, was 0.55. Diethyl 5-amino isophthalate and Boc-protected 5-amino isophthaloyl azide were used for the successful stepwise synthesis of dendritic wedges based on urea linkages. The thermal generation of the isocyanate functionality with gaseous nitrogen as the side product and its quantitative reaction with amine groups were the salient features of this convergent synthesis. This eliminated the use of chromatographic purification, an inherent part of other convergent growth approaches, and made it a very efficient synthetic route for the synthesis of dendritic wedges. The products were characterized by 1H NMR, 13C NMR, and electron spray mass spectroscopy (ESMS) techniques. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1295–1304, 2001

Solid-supported synthesis of hyperbranched polymer with ?,?-diethynylstyryl units

Two novel aromatic polyamide supports bearing aromatic bromine and iodine functionality have been synthesised and tested for the solid-supported polymerization of AB2 type monomer 4-(5-hexynyloxy)-β,β-dibromostyrene via Pd-catalysed cross-coupling of vinyl halides and terminal acetylenes. It was found that the solid-supported polymerization leads to a decrease in molecular weight and increase in the degree of branching from 17 000–18 000 g mol−1 to 8000–4000 g mol−1 and from 30–35 % to 50–65 %, respectively, compared to solution polymerization. All other things being equal, the decrease in molecular weight of hyperbranched polymer on solid-supported polymerization is a function of the distance between adjacent active sites of the polymer support. © 2001 Society of Chemical Industry

Hyperbranched polymers with a degree of branching of 100%

4-Methoxy-4'-(3-N-maleimidopropoxy)benzaldazine has been prepared and used for the synthesis of hyperbranched polymers by,criss-cross'-cycloaddition. In this type of reaction two unsaturated groups, such as the maleic imide groups, are added to the azine function. Hence, the azine behaves as a difunctional system, and therefore 4-Methoxy-4'-(3-N-maleimidopropoxy)benz-aldazine is an AB 2 monomer, with the maleic imide group being the A-function, and the azine group representing the B 2 part. The nature of this cycloaddition reaction ensures the coupled reaction of the two B-functions of each monomer unit. Consequently, the resulting polymer consists exclusively of branched and terminal repeating units and therefore has a degree of branching of 100%.

Synthesis of hyperbranched polymers from commercially available A2 and BB′2 type monomers

This work describes a new strategy for the preparation of hyperbranched polymers from commercially available A2 and BB′2 type monomers without any catalysts; the rapid reaction of A groups with B groups results in the formation of dimers that can be regarded as a new sort of AB′2 type monomer; further polymerization of AB′2 gives hyperbranched polymers; through this approach a new kind of water-soluble hyperbranched polysulfone-amine was synthesized by polyaddition of N-methylpropane-1,3-diamine (BB′2) to divinyl sulfone (A2).

Hyperbranched Polymers Made from A2 and BB‘2 Type Monomers. 1. Polyaddition of 1-(2-Aminoethyl)piperazine to Divinyl Sulfone

A new strategy for synthesis of hyperbranched polymers from commercially available A2 type and BB‘2 type monomers has been developed. In the first part of this series, hyperbranched polysulfone−amine with multiamino groups is prepared by polyaddition of 1-(2-aminoethyl)piperazine (BB‘2) to divinyl sulfone (A2) without any catalysts. The products are soluble in water and organic solvents such as N,N-dimethylformamide, chloroform, and N-methyl-2-pyrrolidone. The polymerization mechanism has been investigated with FTIR, HPLC, and MS. During the reaction, secondary amino groups of 1-(2-aminoethyl)piperazine react rapidly with vinyl groups of divinyl sulfone within 15 s, forming dominant dimers and some other species. The dimer can be considered as a new AB‘2 type of monomer. Further reactions among AB‘2 molecules and AB‘2 with other species result in the formation of hyperbranched polymers. The degree of branching of the resulting polymer is higher than 50%. No gelation occurs in solution polymerization when the A2 to BB‘2 ratio equals 1. Similarly, there is no gelation in solution polymerization if the feed ratio of A2 to BB‘2 is 3/2; however, gelation does occur when the resulting polymer is separated from the solution. There are both terminal amino groups and vinyl groups in the hyperbranched polysulfone−amine if the feed A2 to BB‘2 ratio is 3/2, which further react with each other in bulk state resulting in a cross-linked material. If the terminal amino groups are protected by hydrochloride acid in advance in the solution, then no gelation can be observed after the product is separated from the solution.

Synthesis of hyperbranched polymers by self-addition free radical vinyl polymerization of photo functional styrene

The hyperbranched polystyrenes are prepared by the self-addition free radical vinyl polymerization of N,N-diethylaminodithiocarbamoylmethyletyrene (DTCS). DTCS monomers play an important role in this polymerization system as an inimer that is capable of initiating living radical polymerization of the vinyl group. The compact nature of the hyperbranched macromolecules is demonstrated by viscosity measurements compared to the linear analogues.

Novel synthesis and characterization of hyperbranched polymers

We approached a novel synthesis of hyperbranched polymers via living anionic polymerization. The first-generated star polymer (1G-S) was prepared by copolymerization of poly(4-methylstyrene)-block-polystyrene diblock anions with a small amount of divinylbenzene. The peripheral 4-methylstyrene units in the arm were metalated with s-butyllithium/tetramethylethylenediamine complex in cyclohexane. The second-generated hyperbranched polymers (2G-H) were prepared by equilibrium polymerization of such 1G-S polyanions with α-methylstyrene in tetrahydrofuran at −78°C, and subsequently the terminal branch ends were capped with a small amount of 4-methylstyrene. The characterization of such hyperbranched polymers was carried out in detail. The ratio values of radius of gyration (RG) to hydrodynamic radius (RH) for the 2G-H were in the range of 0.96–1.18. The 2G-H behaved like soft spheres or loose star-structures that were constructed with flexible chains in the inner parts.

Controlled Synthesis of Hyperbranched Polymers by Slow Monomer Addition to a Core

Continuous, slow addition of AB2 monomer (3,5-diiodophenylacetylene) to a solution of a multifunctional core results in high molecular weight hyperbranched phenylacetylene polymers with narrow polydispersites. Control over the molecular weight (Mw = 8−90 kDa) was achieved by varying the monomer:core ratio from 17.5 to 560. At low ratios (<140, Mw = 49 kDa), monomodal molecular weight distributions were observed by SEC. A bimodal distribution was observed at higher ratios. Using an azobenzene functionalized core, in combination with SEC photodiode array detection, it was found that the core was not uniformly distributed over the entire bimodal distribution but rather predominantly found in the high molecular weight part of the distribution. The polydispersities of the hyperbranched polymers were found to decrease with increasing degree of polymerization and with increasing core functionality. Our experimental results are in good qualitative agreement with computer simulations reported by Frey et al. and th...

Synthesis of hyperbranched polymers via proton-transfer polymerization of acrylate monomer containing two hydroxy groups

The hyperbranched polymer 2 was produced via triphenylphosphine initiated polymerization of the acrylate monomer 1 containing two hydroxy groups. The reaction resulting in 2 is based on a Michael-type addition followed by a proton-transfer process. The molecular weights evaluated by VPO measurements were vanging between 1 170–2 700 g/mol. The results of the methanolysis experiments of the polymers were used to determine the degrees of branching, that ranged between 0.45 and 0.60. In this polymerization, the hydroxy groups of the monomer and of the polymer are latent propagating species, which are converted into the corresponding anions, which are the actual propagating species active during the proton-transfer reactions. The proton-transfer occur frequently during this polymerization in order to afford the formation of hyperbranched polymers.

An approach to hyperbranched polymers with a degree of branching of 100%

General guidelines for the design of monomers for the synthesis of hyperbranched polymers without linear units are presented. The synthesis of one monomer fulfilling these requirements and the first results of the polymerization of this monomer are described. 4-(3-Maleimidopropoxy)-4′-methoxybenzaldehyde azine was used as a monomer of the AB2-type in a “criss-cross” cycloaddition with the maleimide group as A-function and the azine as two B-groups. Melt condensation of this monomer gave a polymer (Mn = 5700) which showed 1H and 13C NMR spectra corresponding well to the expected completely branched structure.

An approach to hyperbranched polymers with a degree of branching of 100%

General guidelines for the design of monomers for the synthesis of hyperbranched polymers without linear units are presented. The synthesis of one monomer fulfilling these requirements and the first results of the polymerization of this monomer are described. 4-(3-Maleimidopropoxy)-4'-methoxybenzalde-hyde azine was used as a monomer of the AB 2 -type in a criss-cross' cycloaddition with the maleimide group as A-function and the azine as two B-groups. Melt condensation of this monomer gave a polymer (M n = 5 700) which showed 1 H and 13 C NMR spectra corresponding well to the expected completely branched structure.

Novel Nickel(II)- and Palladium(II)-Based Catalytic Systems for the Synthesis of Hyperbranched Polymers from Ethene

Novel Nickel(II)- and Palladium(II)-Based Catalytic Systems for the Synthesis of Hyperbranched Polymers from Ethene

Effect of Core-Forming Molecules on Molecular Weight Distribution and Degree of Branching in the Synthesis of Hyperbranched Polymers

The polydispersity index, the molecular weight distribution (MWD), and the degree of branching ( ) are calculated for hyperbranched polymers obtained in self-condensing vinyl polymerization of AB* monomers in the presence of a core-forming molecule (i.e. a multifunctional initiator, Bf*). Two cases are considered: (a) batch polymerization, i.e., with all components mixed together; (b) semibatch polymerization, i.e., slow addition of the monomer to the core-forming molecule. The results obtained for the latter case are also valid for polycondensation of AB2 monomers. The presence of core-forming molecules leads to a considerable narrowing of the MWD's, the polydispersity index decreasing with increasing initiator functionality, f. In the batch process, we find w/ n ≈ 1 + n/f2 and in the semibatch mode w/ n ≈ 1 + 1/f. The degree of branching obtained in semibatch mode approaches = 2/3, which is higher than for the synthesis using a batch process with or without initiator. The polymers resulting from semibatch mode are predicted to consist of highly branched cores, while the outer parts of the molecules contain the majority of the functional groups. Thus, they are closer to dendrimers than the polymers obtained in batch mode.