Catalyst-transfer condensation polymerization for precision synthesis of π-conjugated polymers

2012 ◽  
Vol 85 (3) ◽  
pp. 573-587 ◽  
Author(s):  
Tsutomu Yokozawa ◽  
Yutaka Nanashima ◽  
Haruhiko Kohno ◽  
Ryosuke Suzuki ◽  
Masataka Nojima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Conjugated Polymers ◽  
Ni Catalyst ◽  
Condensation Polymerization ◽  
End Groups ◽  
Precision Synthesis ◽  
Polymerization Method ◽  
Low Solubility ◽  
End Group ◽  
Coupling Polymerization

Catalyst-transfer condensation polymerization, in which the catalyst activates the polymer end-group, followed by reaction with the monomer and transfer of the catalyst to the elongated polymer end-group, has made it feasible to control the molecular weight, polydispersity, and end-groups of π-conjugated polymers. In this paper, our recent progress of Kumada–Tamao Ni catalyst-transfer coupling polymerization and Suzuki–Miyaura Pd catalyst-transfer coupling polymerization is described. In the former polymerization method, the polymerization of Grignard pyridine monomers was investigated for the synthesis of well-defined n-type π-conjugated polymers. Para-type pyridine monomer, 3-alkoxy-2-bromo-5-chloromagnesiopyridine, afforded poly(pyridine-2,5-diyl) with low solubility in the reaction solvent, whereas meta-type pyridine monomer, 2-alkoxy-5-bromo-3-chloromagnesio-pyridine, yielded soluble poly(pyridine-3,5-diyl) with controlled molecular weight and low polydispersity. In Suzuki–Miyaura catalyst-transfer coupling polymerization, t-Bu3PPd(Ph)Br was an effective catalyst, and well-defined poly(p-phenylene) and poly(3-hexylthiophene) (P3HT) were obtained by concomitant use of CsF/18-crown-6 as a base in tetrahydrofuran (THF) and a small amount of water.

Precision Synthesis of n-Type π-Conjugated Polymers in Catalyst-Transfer Condensation Polymerization

2012 ◽  
Vol 1 (7) ◽  
pp. 862-866 ◽  
Author(s):  
Tsutomu Yokozawa ◽  
Yutaka Nanashima ◽  
Yoshihiro Ohta
Keyword(s):  
Conjugated Polymers ◽  
Condensation Polymerization ◽  
Precision Synthesis

Spreading Characteristics of Molecularly Thin Lubricant on Surfaces With Groove-Shaped Textures: Effects of Molecular Weight and End-Group Functionality

2003 ◽  
Vol 125 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Hedong Zhang ◽  
Yasunaga Mitsuya ◽  
Maiko Yamada
Keyword(s):  
Molecular Weight ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Ising Model ◽  
Monte Carlo Simulations ◽  
Simulation Method ◽  
Solid Surfaces ◽  
The Monte Carlo Method ◽  
End Groups ◽  
End Group

Effects of molecular weight and end-group functionality on spreading of molecularly thin perfluoropolyether (PFPE) film over solid surfaces with groove-shaped textures have been studied by experiments and Monte Carlo simulations. In the experiments, lubricant spreading on a surface with groove-shaped textures was measured by making use of the phenomenon in which diffracted light weakens in the lubricant-covered region. It is found that grooves serve to accelerate spreading and this effect increases for deeper grooves, and also the accelerating rate becomes larger for a lubricant having a larger molecular weight or functional end-groups. In the simulations, the Monte Carlo method based on the Ising model was extended to enable us to evaluate the effect of molecular weight on the spreading of non-functional lubricant inside a groove. The validity of the newly developed simulation method was well confirmed from the agreement between the simulation and experimental results.

Catalyst-Transfer Condensation Polymerization for the Synthesis of Well-Defined Polythiophene with Hydrophilic Side Chain and of Diblock Copolythiophene with Hydrophilic and Hydrophobic Side Chains

2007 ◽  
Vol 19 (5-6) ◽  
pp. 684-699 ◽  
Author(s):  
Tsutomu Yokozawa ◽  
Isao Adachi ◽  
Ryo Miyakoshi ◽  
Akihiro Yokoyama
Keyword(s):  
Block Copolymer ◽  
Feed Ratio ◽  
Ni Catalyst ◽  
Chain Growth ◽  
Condensation Polymerization ◽  
Block Copolymerization ◽  
Ni Catalysts ◽  
Linear Relationships ◽  
A Chain ◽  
Polymerization Method

Chain-growth condensation polymerization of 2-bromo-5-chloromagnesio-3-[2-(2-metho-xyethoxy)ethoxy]methylthiophene (2) with Ni catalysts was studied, and the block copolymer of poly2 and poly(3-hexylthiophene) was synthesized by this polymerization method. The polymerization of 2 depended on the ligands of the Ni catalyst, and poly2 with the lowest polydispersity was obtained when 1,2-bis(diphenylphosphino)ethane (dppe) was used as the ligand. The linear relationships between the conversion of 2 and Mn of the polymer and between the feed ratio of 2 to the Ni catalyst and Mn of the polymer indicate that this polymerization proceeds in a chain-growth polymerization manner via a catalyst-transfer condensation polymerization mechanism. The block copolymerization of 2 and 2-bromo-5-chloromagnesio-3-hexylthiophene (1) was then carried out in four ways by changing the order of polymerization of the two monomers and the catalysts. It turned out that the block copolymer was obtained without the formation of the homopolymers by the polymerization of 1 with Ni(dppe)Cl2 or Ni(dppp)Cl2 (dppp = 1,2-bis(diphenylphosphino)propane), followed by the postpolymerization of 2. Of the two catalysts, Ni(dppe)Cl2 resulted in narrower polydispersity of the block copolymer.

Polysulfide Polymers

1951 ◽  
Vol 24 (3) ◽  
pp. 709-723
Author(s):  
E. M. Fettes ◽  
J. S. Jorczak
Keyword(s):  
Molecular Weight ◽  
Stress Relaxation ◽  
Cross Linking ◽  
Condensation Polymerization ◽  
Solvent Resistance ◽  
Polymer Properties ◽  
End Groups ◽  
Different Types ◽  
Liquid Polymers ◽  
Polysulfide Polymers

Abstract The chemistry of the condensation polymerization is reviewed briefly. The structures of the polymeric products as well as the effects of copolymerization, cross-linking, end groups, and molecular weight upon polymer properties are discussed. The composition and properties of the commercial crude rubbers, water dispersions, and liquid polymers are presented together with ideas on the mechanism of their vulcanization. The reason for the odor of polysulfide polymers is discussed. Some information is presented on solvent resistance, stress relaxation, and other characteristics of the polymers. Applications for the different types of products are summarized.

High-Throughput Synthesis of Oligo(ε-caprolactone) / Oligotetrahydrofuran Based Polyurethanes

MRS Advances ◽  
2018 ◽  
Vol 3 (49) ◽  
pp. 2965-2973
Author(s):  
M. Balk ◽  
A. Lendlein ◽  
M. Behl
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
High Throughput ◽  
Melting Transition ◽  
Multiblock Copolymers ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
End Groups ◽  
Model Components ◽  
End Group

ABSTRACTRobot assisted synthesis as part of high-throughput (HT) technology can assist in the creation of polymer libraries, e.g. polymers with a variety of molecular weights, by automatizing similar reactions. Especially for multiblock copolymers like polyurethanes (PUs) synthesized from telechels via polyaddition reaction, the adjustment of equivalent molar amounts of reactants requires a comprehensive investigation of end group functionality.In this work, PUs based on oligo(ε-caprolactone) (OCL) / oligotetrahydrofuran (OTHF) as model components were designed utilizing HT synthesis enabling the quantitative determination of the optimized ratio between reactive end-groups via fully automated syntheses without major characterization effort of end group functionality. The semi-crystalline oligomeric telechelics were connected with a diisocyanate and OCL with a molecular weight of 2, 4, or 8 kg∙mol-1 was integrated. Here, optimized molecular weights between 90 ± 10 kg∙mol-1 (in case of OCL 8 kg∙mol-1) and 260 ± 30 kg∙mol-1 (in case of OCL 2 kg∙mol-1) were obtained with an isocyanate content of 120 mol%, whereby 100 mol% of isocyanate groups resulted only in molecular weights between 60 ± 6 kg∙mol-1 (OCL 8 kg∙mol-1) and 80 ± 10 kg∙mol-1 (OCL 2 kg∙mol-1). In addition to the optimized ratio between isocyanate and hydroxy end groups, quantitative influences of the OCL chain length and overall molecular weights of PUs on thermal and mechanical properties were detected. The melting temperatures (Tms) of OCL and OTHF domains were well separated for PUs of low molecular weight, the temperature interval between the Tms decreased when the molecular weight of the PUs was increased, and were even overlapping towards one broad Tm, when OCL 2 kg∙mol-1 was incorporated. The storage modulus E’ was highly dependent on OCL chain length exhibiting an increase with increasing molecular weight of OCL from 220 MPa to 440 MPa at 0 °C and decreased with increasing chain length of PUs. The elongation at break (εb) was analyzed below and above Tm of OTHF resulting in εb = 780-870% at 0 °C and εb = 510-830% at 30 °C for PUs of high molecular weight. Accordingly, stretchability of PUs was almost independent of the state of OTHF (semi crystalline or amorphous) but correlated with the OCL precursor chain length (increasing εb with increasing chain length) and overall molecular weight of PUs (PUs at higher molecular weight exhibited higher εb). Hence, the analysis of these quantitative influences between macromolecular structure of multiblock copolymers and the resulting properties (well separated Tms versus overlapping melting transition, improvement of stretchability) would enable the design of new tailored PUs.

scholarly journals The Enzymatic Phosphorylation of Nucleic Acids and Its Application to End-Group Analysis

1966 ◽  
Vol 49 (6) ◽  
pp. 81-97 ◽  
Author(s):  
Charles C. Richardson ◽  
Bernard Weiss
Keyword(s):  
Molecular Weight ◽  
Group Analysis ◽  
Single Strand ◽  
Selective Labeling ◽  
Phosphodiester Bond ◽  
Polynucleotide Kinase ◽  
End Groups ◽  
Hydroxyl Termini ◽  
End Group

Polynucleotide kinase catalyzes the transfer of a phosphate group from ATP to the 5'-hydroxyl termini of polynucleotides. Selective labeling of the 5'-hydroxyl termini of DNA with polynucleotide kinase has been used to study the number and the identity of the 5'-terminal residues of bacteriophage DNA's, and to examine the nature of the phosphodiester bond cleavages produced by endonucleases and by sonic irradiation. The intact strands of T7 DNA bear 5'-phosphoryl end-groups; only deoxyadenylate and deoxythymidylate are present as 5'-terminal residues. The intact strands of native λ-DNA bear 5'-hydroxyl end-groups. M13 DNA, a circular molecule, cannot be phosphorylated. End-group labeling of DNA provides a method for determination of molecular weight; calibration against other DNA preparations is not required. The molecular weight of a single strand of T7 DNA, determined by end-group labeling, is 13.1 x 106; the molecular weight of a single strand of λ-DNA is 16.0 x 106. These values are in agreement with molecular weight estimates by sedimentation analysis and electron microscopy. Sonic irradiation of DNA has been shown to favor the production of polynucleotides terminated by 5'-phosphomonoester groups. All four deoxyribonucleotides are present as 5'-terminal residues of sonicated DNA.

Effects of End-Group Functionality and Molecular Weight of Ultra-Thin Liquid Lubricant Films on Contact Slider Dynamics in Hard Disk Drives

2004 ◽  
Author(s):  
Norio Tagawa ◽  
Yoshiaki Tashiro ◽  
Atsunobu Mori
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
Hard Disk Drives ◽  
Lubricant Film ◽  
Disk Drives ◽  
Lubricant Film Thickness ◽  
Liquid Lubricant ◽  
End Groups ◽  
End Group ◽  
Contact Slider

This paper describes the effect of end-group functionality and molecular weight of ultra-thin liquid lubricant films on contact slider dynamics in hard disk drives. In the experiments, the contact slider dynamics as well as ultra-thin liquid lubricants behavior are investigated using three kinds of lubricants which have different end-groups and molecular weight as a function of lubricant film thickness. The dynamics of a contact slider is mainly monitored using Acoustic Emission (AE). The disks are also examined with a scanning micro-ellipsometer before and after contact slider experiments. It is found that the lubricant film thickness instability due to de-wetting occurs as a result of slider-disk contacts, when the lubricant film thickness is thicker than one monolayer. Their unstable lubricant behavior depends on the chemical structure of functional end-groups and molecular weight. In addition, it is also found that the AE RMS values, which indicate the contact slider dynamics, are almost equivalent, independent of the end-groups and molecular weight for the lubricants, when the lubricant film thickness is around one monolayer. The molecular weight, however, affects the contact slider dynamics, when the lubricant film thickness is less than one monolayer. In other words, the AE RMS values increase remarkably as the molecular weight for the lubricant increases. When the lubricant film thickness is more than one monolayer, the AE RMS values decrease because of the effect of mobile lubricant layer, while the lubricant de-wetting instability affects the contact slider dynamics. Therefore, it would be concluded that the lubricant film thickness should be designed to be around one monolayer thickness region in order to achieve contact recording for future head-disk interface.

Synthesis of nylon 6-clay hybrid

1993 ◽  
Vol 8 (5) ◽  
pp. 1179-1184 ◽  
Author(s):  
Arimitsu Usuki ◽  
Yoshitsugu Kojima ◽  
Masaya Kawasumi ◽  
Akane Okada ◽  
Yoshiaki Fukushima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Group Analysis ◽  
Nylon 6 ◽  
Layer Silicate ◽  
End Groups ◽  
Anion Site ◽  
The Difference ◽  
Silicate Layers ◽  
End Group

It was found that montmorillonite cation exchanged for 12-aminolauric acid (12-montmorillonite) was swollen by ∊-caprolactam to form a new intercalated compound. Caprolactam was polymerized in the interlayer of montmorillonite, a layer silicate, yielding a nylon 6-clay hybrid (NCH). The silicate layers of montmorillonite were uniformly dispersed in nylon 6. The carboxyl end groups of 12-aminolauric acid in 12-montmorillonite initiated polymerization of ∊-caprolactam, and as 12-montmorillonite content became larger, the molecular weight of nylon was reduced. From the result of end-group analysis, carboxyl end groups were more than amino end groups. The difference between the carboxyl and the amino end groups was attributed to ammonium cations (-NH3+) of nylon molecules, because the difference agreed with the anion site concentration of the montmorillonite in NCH. It is suggested that the ammonium cations in nylon 6 interact with the anions in montmorillonite.

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