Stille Catalyst‐Transfer Polycondensation Using Pd‐PEPPSI‐IPr for High‐Molecular‐Weight Regioregular Poly(3‐hexylthiophene)

A commercially available palladium N‐heterocyclic carbene (Pd‐NHC) precatalyst is used to initiate chain‐growth polymerization of 2‐bromo‐3‐hexyl‐5‐trimethylstannylthiophene. The molecular weight of the resultant poly(3‐hexylthiophene) can be modulated (7 to 73 kDa, Đ = 1.14 to 1.53) by varying the catalyst concentration. Mass spectrometry data confirm control over the polymer end groups and ¹H NMR spectroscopy reveals that the palladium catalyst is capable of “ring‐walking”. A linear relationship between M_n and monomer conversion is observed. Atomic force microscopy and X‐ray scattering verify the regioregular nature of the resultant polythiophene.

     

Synthesis and Properties of Novel Side‐Chain Sulfonated Poly(Arylene Ether Sulfone)s for Proton Exchange Membranes

A series of novel side‐chain sulfonated poly(arylene ether sulfone) (SPAES) multiblock and random copolymers were synthesized by condensation polymerization from a new disulfonated aryl sulfone monomer, 4,4′‐difluoro‐2,2′‐bis(3‐sulfobenzoyl)diphenyl sulfone disodium salt (DFBSPS). The chemical structures of DFBSPS and the SPAESs were characterized by proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FTIR) spectra. The SPAES membranes prepared by solution cast method exhibited high tensile strength (50–71 MPa) and high radical oxidative stability. They could keep their morphology and maintain proton conductivities after hydrolysis test in 95 °C water for 1000 h. They also showed smaller swelling ratio in in‐plane direction than in through‐plane direction and such an anisotropic effect was more significant for the multiblock copolymers than for the random ones. The multiblock copolymer membranes exhibited higher proton conductivity than the random ones with similar ion exchange capacities (IECs). Preliminary hydrogen‐oxygen fuel cell tests were performed at 60 °C and 80% relative humidity (RH). The results showed that the single cell equipped with the multibiock copolymer membrane SB3 exhibited 0.12 W cm^?2 higher maximum output power density than the one equipped with the random copolymer membrane SR3 (with the same IEC), indicating much better performance of the former. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2304–2313     

Hyperbranched Polyethylenes and Functionalized Polymers by Chain Walking Polymerization with Pd‐Diimine Catalysis

Chain walking polymerization (CWP) with Pd‐diimine catalysis represents a novel concept for the synthesis of hyperbranched polyethylenes (HBPEs) and functionalized polymers from ethylene stocks. This article summarizes recent developments in this research area. The properties of HBPEs have recently been studied and their application as lubricant viscosity additives, polymer processing aids, and polymers for the functionalization and solubilization of carbon nanotubes in organic solvents have been explored, with some outstanding features having been discovered. Using the CWP strategy, we have also synthesized a range of functionalized HBPEs covalently tethered with a variety of functional groups, including POSS nanoparticles, ATRP‐initiating sites, methacryloyl and acryloyl double bonds, and backbone‐incorporated functionalized ring units.

     

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.     

Synthesis and Characterization of Phenolphthalein‐Containing Sulfonated Poly(arylene ether phosphine oxide)s by Direct Polycondensation for Proton Exchange Membrane

A series of novel phenolphthalein‐containing sulfonated poly(arylene ether phosphine oxide)s (sPAEPP) with various sulfonation degrees were synthesized by direct polycondensation. The structure of sPAEPP was confirmed by ¹H‐NMR, ¹³C‐NMR, and IR spectroscopy. The high‐molecular weight of these polymers was determined by gel permeation chromatography (GPC). The transparent, tough, and flexible membranes could be achieved by solution casting. The macroscopic properties and microstructure of the obtained membranes were investigated in detail. The results showed that these sPAEPP membranes displayed excellent properties in terms of swelling, proton conductivity, and methanol permeability. For example, sPAEPP‐100 membrane exhibited an appropriate water uptake of 33.1%, a swelling ratio of only 11.7% (lower than 20.1% of Nafion 117), a proton conductivity of 0.11 S cm^?1 (similar to that of Nafion 117) at 80 °C, and a methanol permeability of 4.82 × 10^?7 cm² s^?1. Meanwhile, it also presented outstanding oxidative stability. Atomic force microscope (AFM) micrographs showed that the hydrophilic domains of the sPAEPP‐100 membrane formed connected and narrow ionic channels, which contributed to its high proton conductivity and good dimensional stability. As a result, sPAEPP‐100 membrane displays excellent application prospect for fuel cells. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1097–1104     

Lewis Acid Catalyzed Asymmetric Three‐Component Coupling Reaction: Facile Synthesis of α‐Fluoromethylated Tertiary Alcohols

A chiral dicationic palladium complex is found to be an efficient Lewis acid catalyst for the synthesis of α‐fluoromethyl‐substituted tertiary alcohols using a three‐component coupling reaction. The reaction transforms three simple and readily available components (terminal alkyne, arene, and fluoromethylpyruvate) to valuable chiral organofluorine compounds. This strategy is completely atom‐economical and results in perfect regioselectivities and high enantioselectivities of the corresponding tertiary allylic alcohols in good to excellent yields.     

Novel Water‐Soluble Poly(m‐benzamide)s: Precision Synthesis and Thermosensitivity in Aqueous Solution

Summary: Chain‐growth polycondensations of 3‐aminobenzoic acid methyl esters 1a and 1b , bearing a tri‐ or tetra(ethylene glycol) methyl ether unit on the amino group, respectively, were carried out with lithium hexamethyldisilazide (LiHMDS) as a base and phenyl 4‐methylbenzoate ( 2 ) as an initiator in THF at 0 °C. The poly(m‐benzamide)s obtained in the presence of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) possessed narrow molecular weight distributions ( < 1.2) with molecular weights that were determined by the feed ratios of [ 1 ]₀/[ 2 ]₀. Poly 1a and poly 1b were each soluble in water and exhibited a lower critical solution temperature (LCST) in water. Furthermore, the phase separation in water depended on the length of the oligo(ethylene glycol) side chain and on the molecular weight and molecular weight distribution of poly 1 .

Thermally sensitive water‐soluble poly(m‐benzamide)s.     

Synthesis of Poly(ethylene oxide)s Bearing Functional Groups along the Chain

Well‐defined poly(ethylene oxide)s (PEOs) bearing reactive sites regularly distributed along the chain have been synthesized by the polycondensation of PEO containing a central tertiary amino group with dichloromethane, followed by quaternization with suitable reagents to obtain polyzwitterionic or cationic PEOs with alkyl, allyl, or fluorocarbon pendant groups. The pendant allyl groups have been converted into primary amino groups by reaction with 2‐aminoethanethiol hydrochloride to obtain polyamino‐functionalized PEO.

Polyfunctional PEOs bearing different pendant groups.     

Synthesis and proton conductivity of sulfonated,multi‐phenylated poly(arylene ether)s

A series of sterically‐encumbered, sulfonated, poly(arylene ether) copolymers were synthesized and their proton conductivity examined. The series was prepared by copolymerizing a novel monomer, 2″,3″,5″,6″‐tetraphenyl‐[1,1′:4',1″:4″,1″':4″',1″″‐quinquephenyl]‐4,4″″‐diol, with 4,4'‐difluorobenzophenone and bisphenol A. Subsequent sulfonation and solution casting provided membranes possessing ion exchange capacities of 1.9 to 2.7 mmol/g and excellent mechanical properties (Young's modulus, 0.2–1.2 GPa; tensile strength, 35–70 MPa; elongation at break, 62–231%). Water uptake ranged from 34 to 98 wt% at 80 °C/100% RH. Proton conductivities ranged between 0.24 to 16 mS/cm at 80 °C/60% RH, and 3 to 167 mS/cm at 80 °C/95% RH. TEM analysis of the polymers, in the dehydrated state, revealed isolated spherical aggregates of ions, which presumably coalesce when hydrated to provide highly conductive pathways. The strategy of using highly‐encumbered polymer frameworks for the design of mechanically‐robust and dimensionally‐stable proton conducting membranes is demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2579‐2587     

Magnetite tethered mesoionic carbene‐palladium (II): An efficient and reusable nanomagnetic catalyst for Suzuki‐Miyaura and Mizoroki‐Heck cross‐coupling reactions in aqueous medium

In this paper, a highly active, air‐ and moisture‐stable and easily recoverable magnetic nanoparticles tethered mesoionic carbene palladium (II) complex (MNPs‐MIC‐Pd) as nanomagnetic catalyst was successfully synthesized by a simplistic multistep synthesis under aerobic conditions using commercially available inexpensive chemicals for the first time. The synthesized MNPs‐MIC‐Pd nanomagnetic catalyst was in‐depth characterized by numerous physicochemical techniques such as FT‐IR, ICP‐AES, FESEM, EDS, TEM, p‐XRD, XPS, TGA and BET surface area analysis. The prepared MNPs‐MIC‐Pd nanomagnetic catalyst was used to catalyze the Suzuki–Miyaura and Mizoroki–Heck cross‐coupling reactions and exhibited excellent catalytic activity for various substrates under mild reaction conditions. Moreover, MNPs‐MIC‐Pd nanomagnetic catalyst could be easily and rapidly recovered by applying an external magnet. The recovered MNPs‐MIC‐Pd nanomagnetic catalyst exhibited very good catalytic activity up to ten times in Suzuki–Miyaura and five times in Mizoroki–Heck cross‐coupling reactions without considerable loss of its catalytic activity. However, MNPs‐MIC‐Pd nanomagnetic catalyst shows notable advantages such as heterogeneous nature, efficient catalytic activity, mild reaction conditions, easy magnetic work up and recyclability.     

Synthesis of π‐Conjugated Polymer Consisting of Pyrrole and Fluorene Units by Ru‐Catalyzed Site‐Selective Direct Arylation Polycondensation

Polycondensation of 1‐(2‐pyrimidinyl)pyrrole with 2,7‐dibromo‐9,9‐dioctylfluorene via Ru‐catalyzed direct arylation gives the corresponding conjugated polymer with a molecular weight of 19 800 in 86% yield. The introduction of directing group, 2‐pyrimidinyl substituent, into the pyrrole monomer induces ortho‐metalation and provides the site‐selective direct arylation polycondensation at the α‐position of pyrrole unit without the protection of β‐position. The removal of 2‐pyrimidinyl substituent on the pyrrole unit proceeds efficiently and results in the enhancement of coplanarity along the main chain of the polymer.

     

聚外消旋乳酸的IPDI溶液扩链

以异佛尔酮二异氰酸酯(IPD I)为扩链剂,以外消旋乳酸(D,L-LA)直接熔融聚合合成的低分子量聚外消旋乳酸(PDLLA)为预聚体,在四氢呋喃溶液中进行扩链得扩链产物Ⅰ。Ⅰ用粘均分子量(Mη),IR,1H NMR,DSC及X-射线衍射等表征。与2,4-甲苯二异氰酸酯(TD I)的扩链产物(Ⅱ)比较,Ⅰ成功地引入了NH和IPD I反应后的刚性片段,使M,ηTg,Tm,结晶度等相应提高。但由于IPD I反应活性不如TD I,故反应速率比用TD I时慢;Ⅰ分子中脂肪环的刚性不如苯环,TⅠg低于TⅡg。     

Synthesis of Poly(arylene ether amide)s Containing CF3 Groups by Nitro Displacement Reaction of AB‐Type Monomers

New poly(arylene ether amide)s with trifluoromethyl pendent groups were prepared via nucleophilic nitro displacement reaction of AB‐type monomers. 4‐Nitro‐3‐trifluoromethyl‐[N‐(4‐hydroxyphenyl)]benzamide ( 3 ) and 4‐nitro‐3‐trifluoro‐methyl‐[N‐(3‐hydroxyphenyl)]benzamide ( 4 ) gave polymers with weight‐average molecular weights over 42 000 g/mol and glass transition temperatures of 269°C and 213°C, respectively. Both polymers were soluble in common organic solvents including THF, and formed transparent films upon casting.     

Synthesis and property comparison of isomeric AB‐type homo‐ and copoly(etherimide)s

AB‐type homo‐ and copoly(etherimide)s were prepared by the polymerization of 3‐ and 4‐(3,4‐dicarboxyphenyloxy)aniline hydrochlorides ( 3A and 4A ) at 160 °C in dimethylacetamide in the presence of triethylamine and triphenyl phosphite. After the structures of the polymers were characterized, their solubilities, ultraviolet–visible (UV–vis) absorption behaviors, thermal properties, and crystallinities were measured, and these properties are discussed with respect to the structure of the homopolymers and the composition of the copolymers. Poly(etherimide) (PEI) derived from 3A [PEI( 3A )] was amorphous and soluble in chloroform on heating, whereas that derived from 4A [PEI( 4A )] was crystalline and insoluble in common organic solvents even on heating. In UV–vis absorption spectra, PEI( 4A ) showed a small bathochromic shift relative to N‐phenylphthalimide, but PEI(3A) did not. PEI(3A) revealed a glass‐transition temperature (T_g) at 195 °C, but no T_g was detectable for PEI( 4A ). All the measured physical properties of the copoly(etherimide)s showed a good dependence on their composition between PEI( 3A ) and PEI( 4A ). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 402–410, 2000     

Synthesis of Novel μ‐Star Copolymers with Poly(N‐Octyl Benzamide) and Poly(ε‐Caprolactone) Miktoarms through Chain‐Growth Condensation Polymerization,Styrenics‐Assisted Atom Transfer Radical Coupling,and Ring‐Opening Polymerization

Star copolymers are known to phase separate on the nanoscale, providing useful self‐assembled morphologies. In this study, the authors investigate synthesis and assembly behavior of miktoarm star (μ‐star) copolymers. The authors employ a new strategy for the synthesis of unprecedented μ‐star copolymers presenting poly(N‐octyl benzamide) (PBA) and poly(ε‐caprolactone) (PCL) arms: a combination of chain‐growth condensation polymerization, styrenics‐assisted atom transfer radical coupling, and ring‐opening polymerization. Gel permeation chromatography, mass‐analyzed laser desorption/ionization mass spectrometry, and ¹H NMR spectroscopy reveal the successful synthesis of a well‐defined (PBA₁₁)₂‐(PCL₁₅)₄ μ‐star copolymer (M _n,NMR ≈ 12 620; Đ = 1.22). Preliminary examination of the PBA₂PCL₄ μ‐star copolymer reveals assembled nanofibers having a uniform diameter of ≈20 nm.

     

New Poly(arylene ethynylene)s Consisting of Electron‐Deficient Aryleneimide Units

Summary: A new class of poly(arylene ethynylene)s (PAEs) containing an electron‐deficient N‐alkylphthalimide unit was prepared by means of a Sonogashira reaction. Complete solubility of the PAEs was observed by utilizing a 2,6‐diisopropylphenyl side chain. The chemical structure of the novel soluble polymer 3c was confirmed by NMR spectra, whereas the insoluble polymers were characterized by elemental analysis and IR spectra. Fluorescence measurements of 3c indicate a rigid structure and high symmetry in the excited state.

     

Isomerization polymerization and copolymerization of glycidyl alkanoates catalyzed by methylaluminum bis(2,6‐di‐t‐butyl‐4‐methylphenoxide)

The isomerization polymerizations of glycidyl propionate (1b), octanoate (1c), and stearate (1d) with methylaluminum bis(2,6‐di‐tert‐butyl‐4‐methylphenoxide) (3) were investigated. The polymerizations selectively gave poly(2‐alkyl‐1,3‐dioxolane‐4,2‐diyloxymethylene)s (2), although the polymer yield as well as the polymer molecular weight significantly decreased as the acyl chain of 1 was lengthened. These polymers readily hydrolyzed to glycerin and the corresponding fatty acids under mild conditions. The copolymerizations of glycidyl acetate (1a) with these monomers were also examined. In any combination, the composition of the obtained copolymer was essentially identical with the feed ratio, while both copolymer yield and molecular weight decreased as the feed of 1a was decreased. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 435–444, 1999 (See graphics.)     

Coupling selectivity in the radical‐controlled oxidative polymerization of 4‐phenoxyphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) complex

Various effects on the coupling selectivity of the oxidative polymerization of 4‐phenoxyphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) halogeno complex [Cu(tacn)X₂] are described. With respect to the amount of the catalyst and the nature of the halide ion (X) of Cu(tacn)X₂, the coupling selectivity hardly changed. The Cu(tacn) catalyst possessed a turnover number greater than 1860. As the temperature of the reaction and the polarity of the reaction solvent were elevated, the C O coupling at the o‐position increased, but the C C coupling was not involved. For the polymerization in toluene at 80 °C, poly(1,4‐phenylene oxide), obtained as a methanol‐insoluble part, showed the highest number‐average molecular weight of 4000 with a melting point (T_m) of 195 °C. Only a slight change in the coupling selectivity was observed in the presence or absence of hindered amines as the base. Surprisingly, however, the C O selectivity decreased from 100 to 24% with less hindered amines, indicating that the selectivity drastically changed from a preference for C O coupling to a preference for C C coupling. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4792–4804, 2000     

One‐Pot Three‐Component Synthesis of α‐Amino Nitriles Catalyzed by 2,4,6‐Trichloro‐1,3,5‐triazine (Cyanuric Acid)

A simple and efficient method has been developed for the synthesis of α‐amino nitriles from aldehydes, amines and trimethylsilyl cyanide (Me₃SiCN) in the presence of a catalytic amount of cyanuric acid at room temperature.     

New Strategy for Enzymatic Synthesis of High‐Molecular‐Weight Poly(butylene succinate) via Cyclic Oligomers

Summary: High‐molecular‐weight poly(butylene succinate) (PBS) is prepared by the lipase‐catalyzed polymerization of dimethyl succinate and butane‐1,4‐diol via the formation of cyclic oligomers as a new strategy for the green production of bio‐based plastics. The cyclic oligomer is first produced by the lipase‐catalyzed condensation of dimethyl succinate and butane‐1,4‐diol in a dilute toluene solution using lipase from Candida antarctica, followed by the ring‐opening polymerization of the cyclic oligomer in a more concentrated solution or in bulk with the same lipase to produce PBS with an of 130 000. On the other hand, PBS is produced with an of 45 000 by direct polycondensation.

The lipase‐catalyzed preparation of PBS by two routes.