Polymer‐supported reagents,catalysts, and sorbents: Evolution and exploitation—A personalized view

The solid‐phase method for oligopeptide synthesis was introduced by Professor Bruce Merrifield in 1963, but in practice the origins of polymer‐supported reagents, catalysts, and so forth trace back to the early development of ion exchange and catalysis by sulfonic acid resins. This highlight summarizes how the evolution of solid‐phase organic synthesis occurred in parallel with the development of supported reactive species and indicates the interchange between these areas in the last 30 years or so. The treatment is essentially a personalized one as seen from the author's own laboratory in the United Kingdom and is not intended to review the whole field. The emergence of the international series of conferences on polymer‐supported organic chemistry is emphasized as a key development that stimulated and maintained the area before its importance was recognized more widely by both academic and industrial chemists. The requirement of robotic technologies, as the basis for high‐throughput combinatorial and parallel synthesis in the pharmaceutical industry, has brought the relevance of supported chemistry to the attention of all synthetic chemists. At the same time, the recognition that all industrial chemical processes need to meet appropriate environmental standards has focused attention on the use of heterogenized reactive species as a potentially important technology for achieving the greening of chemistry. These two factors have brought polymer‐supported reactive chemistry to center stage, so to speak, and the early principles laid down over 2 decades ago are now being developed and exploited at an amazing rate. From a rather slow start, through a number of ups and downs in its development, the area of polymer‐supported chemistry now seems poised to join the more routine world of synthesis and to become a methodology used by all as and when appropriate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2364–2377, 2001     

Green polymer chemistry using nature's catalysts,enzymes

The use of enzymes as catalysts for organic synthesis has become an increasingly attractive alternative to conventional chemical catalysis. Enzymes offer several advantages including high selectivity, ability to operate under mild conditions, catalyst recyclability, and biocompatibility. Although there are many examples in the literature involving enzymes for the synthesis of polymers, our search showed that very little had been done in the area of polymer modification. In this article, we will discuss enzyme catalysis in general and highlight our recent results concerning precision polymer functionalization using enzymatic catalysis—“green polymer chemistry.” © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2959–2976, 2009     

Use of an isotactic‐propylene/hexene copolymer as a new,versatile, soluble support

The use of isotactic‐poly(propylene‐co‐hexene) (iPPH) as new polymeric scaffold for synthesis as well as a phase‐selective, soluble polymer support for homogeneous catalysis is described. It was possible to functionalize olefin‐terminated iPPH using standard organic transformations. Each derivative could be isolated and purified using typical precipitations into a minimum amount of polar solvent, negating the need for wasteful work up and chromatographic procedures. Furthermore, it was demonstrated that an iPPH‐supported DMAP could serve as a recoverable, recyclable catalyst. Published 2013. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 600–605     

Synthesis, characterization and evaluation of sulfonic resins as catalysts

Ion-exchange resins have been often used as catalysts especially those based on styrene-divinylbenzene copolymers with sulfonic acid groups in the aromatic rings of polymer chains. That is due to the advantages of heterogenous catalysis over the homogeneous acid catalysis. Moreover, resin catalysts can often lead to high selectivity in organic reactions due to the matrix effects. Therefore, the study of copolymers synthesis conditions to determine the type of polymer structure produced as well as the characterization of sulfonic resins obtained thereof are of great interest. The current paper describes the synthesis, characterization and evaluation as catalysts of sulfonic resins derived from polymer supports synthesized by aqueous suspension polymerization of styrene and divinylbenzene. The reaction conditions were varied and polymer supports with different physical properties and morphological characteristics were obtained. The polymer supports were chemically modified by sulfonation. The resultant sulfonic resins had their catalyst activity evaluated in the esterification of acetic acid with n-butanol.     

Organic light‐emitting device dark spot growth behavior analysis by diffusion reaction theory

Dark spot growth rate tracing experiments performed on an organic light‐emitting device show that moisture entering into the device is relatively properly fitted by Fick's diffusion equation in the substrate/indium tin oxide (ITO)/hole transport layer (HTL)/silver (Ag) structure. It is believed that the moisture is dissolved into the polymer layer, which results in a decrease in the diffusion coefficient in the device with the substrate/ITO/HTL/electroluminescent (EL) polymer/Ag structure. The diffusion and chemical reaction occurring in the cathode layer further decreases the diffusion coefficient in the device with the substrate/ITO/HTL/EL polymer/calcium/Ag structure. Useful parameters, such as diffusion and solubility constants, describing possible mechanisms happening during dark spot growth on organic light‐emitting diode devices are extracted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1697–1703, 2001     

Synthesis and characterization of soluble fluorine‐containing polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene

The synthesis and properties of a class of soluble fluorine‐containing aromatic polyimides are described. Substituents of trifluoromethyl groups on the aromatic rings of paralinked aromatic ether diamine conferred the polymer prepared thereof with enhanced solubility, low‐moisture absorption, and low dielectric constants. The polyimides also exhibited exceptional thermal stability, good mechanical properties, and excellent hygrothermal resistance. These outstanding combined features ensure the polymers are desirable candidate materials for advanced microelectronics applications. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2581–2590, 2001     

Synthesis and characterization of soluble polyimides derived from 2,2′‐Bis(3,4‐dicarboxyphenoxy)‐9,9′‐spirobifluorene dianhydride

The synthesis of aromatic poly(ether imide)s containing spirobifluorene units in the polymer backbone is described. 2,2′‐Bis(3,4‐dicarboxyphenoxy)‐9,9′‐spirobifluorene dianhydride, which was used as a new monomer, was synthesized with 2,2′‐dihydroxy‐9,9′‐spirobifluorene as the starting material. In the spiro‐segment, the rings of the connected bifluorene were orthogonally arranged. This bis(ether anhydride) monomer was employed in reactions with a variety of aromatic diamines to furnish poly(ether imide)s, involving an initial ring‐opening polycondensation and subsequent chemically induced cyclodehydration. Excellent solubility in common organic solvents at room temperature, good optical transparency, and high thermal stability are the prominent characteristic features of these new polymers, which can be attributed to the presence of spiro‐fused orthogonal bifluorene segments along the polymer chain. The glass‐transition temperatures of the polyimides were 240–293 °C, and the 5% weight‐loss temperatures were greater than 500 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 262–268, 2002     

Design of polyethers,thioethers, and amines with pendent iron moieties

Soluble organoiron polyethers, thioethers, and amines were synthesized via nucleophilic aromatic substitution reactions. The synthesis of these classes of organometallic polymers involved either the reaction of cyclopentadienyliron complexes of dichloroarenes with various oxygen and sulfur dinucleophiles or the reaction of ether‐ or amine‐containing diiron complexes with dithiols. Polymerization reactions with the diiron complexes gave rise to organoiron polymers with alternating ether/thioether or amine/thioether bridges. Removal of the iron moieties from the backbone of these polymers allowed for the production of the corresponding organic materials. Furthermore, the organometallic polymers had much higher solubilities than their organic analogues. Thermogravimetric analysis of the organoiron polymers indicated that the polymers lost their metallic moieties at approximately 200 °C, whereas degradation of the polymer backbones occurred around 500 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1216–1231, 2001     

Preparation of polymer optical fibers doped with nonlinear optical active organic chromophores

We synthesized two novel organic nonlinear optical chromophores—chiral S(+)‐N‐[p‐(4‐nitrostyryl) phenyl] prolinol and non‐chiral [p‐(4‐nitrostyryl) phenyl] piperdine—as potential laser‐active dyes for photonic applications. Both materials show good optical transmittance in the telecommunication frequency region, desirable solubility in acrylic polymer optical fiber matrices, and attractive fluorescence properties that are advantageous for laser‐gain materials and devices. Subsequently, these two chromophores were incorporated into poly(methyl methacrylate) and poly(ethyl methacrylate) and drawn into polymer optical fibers. The relevant properties of these organic dye‐doped fibers have been studied, revealing essential attributes of laser‐active characteristics. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1794–1801, 2001     

Copper and iron complexes as visible‐light‐sensitive photoinitiators of polymerization

The utilization of visible lights for the fabrication of polymeric materials is recognized as a promising and environmentally friendly approach. This process relies on the photochemical generation of reactive species (e.g., radicals, radical cations, or cations) from well‐designed photoinitiators (PIs) or photoinitiating systems (PISs) to initiate the polymerization reactions of different monomers (acrylates, methacrylates, epoxides, and vinyl ethers). In spite of the fact that metal complexes such as ruthenium‐ or iridium‐based complexes have found applications in organic and polymer synthesis, the search of other low‐cost metal‐based complexes as PISs is emerging and attracting increasing attentions. Particularly, the concept of the photoredox catalysis has appeared recently as a unique tool for polymer synthesis upon soft conditions (use of light emitting diodes and household lamp). This highlight focuses on recently designed copper and iron complexes as PI catalysts in the application of photoinduced polymerizations (radical, cationic, interpenetrated polymer networks, and thiol‐ene) or controlled radical polymerization under visible light irradiation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2673–2684     

Synthesis and characterization of soluble polyimides derived from [1,1′;4′,1″]terphenyl‐2′,5′‐diol and biphenyl‐2,5‐diol

Two series of polyimides based on laterally attached p‐terphenyl and biphenyl groups were synthesized. The solubility and thermal properties were studied using DSC, thermogravimetric analysis, and the solubility test. These polymers exhibited good thermal stability and excellent solubility. The high solubility for both polymer series was attributed to the non‐coplanarity of diamine monomers and the use of fluorinated dianhydride, whereas the slightly better solubility for polymers based on p‐terphenyl was attributed to further weakening of interchain interaction of the polymers. Both polymer series exhibited glass‐transition temperatures (T_g's) in the range of 244–272 °C. The T_g's of polymers containing laterally attached p‐terphenyls were higher than those of their counterparts containing biphenyls by 5–17 °C. This was attributed to the formation of an interdigitated structure that hinders the segmental movement of polymer chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2998–3007, 2001     

Polyolefin soluble polyisobutylene oligomer‐bound metallophthalocyanine and azo dye additives

Metallophthalocyanines prepared with polyisobutyl (PIB) substituents have very high solubility in organic solvents including saturated hydrocarbons, toluene, and other low polarity organic solvents. In heptane, PIB‐bound metallophthalocyanines have solubility of about 0.1 g/mL at 25 °C, solubility values that are significantly higher than other substituted metallophthalocyanines. PIB terminally functionalized with metallophthalocyanines as well as PIB containing terminal azo dye groups also dissolve in molten hydrocarbon polymers like polyethylene or polypropylene. Thus, these highly chromogenic PIB‐bound dyes can be incorporated uniformly into the polyolefins to form colored polymer solids on cooling. Because only a low concentration of a highly hydrocarbon compatible dye is used, the crystallinity and thermal properties of the colored polyolefin products are not significantly affected. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 545–551     

Organic negative‐resistance devices using PPV containing electron‐transporting groups on the main chain

A kind of novel structure polymer, a poly(phenylenevinylene) (PPV) derivative containing electron‐transporting groups on the main chain (OPPV), was developed according to the polycondensation mechanism. The I–V characteristics at the low‐voltage region with negative differential resistance were observed in the same model of organic light‐emitting diodes with the OPPV polymer. The different external parameters, including the device structure, layer thickness, morphology, and homogeneity of indium tin oxide and the polymer, were also investigated. The performance improvement in the organic negative differential resistance and a possible mechanism are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 589–593, 2001     

Synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles

In this article we describe the synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles (DENs). These materials are synthesized by a template approach in which metal ions are extracted into the interior of dendrimers and then subsequently chemically reduced to yield nearly size-monodisperse particles having dimensions of less than 3 nm. Monometallic, bimetallic (including core/shell), and semiconductor nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticle replica but also to stabilize the nanoparticle, makes it possible to tune solubility, and provides a means for immobilization of the nanoparticle on solid supports. These materials have a number of potential applications, but the focus here is on catalysis. Homogeneous catalytic reactions, including hydrogenations, Heck coupling, and Suzuki reactions, in water, organic solvents, biphasic fluorous/organic solvents, and liquid and supercritical CO2 are discussed. In many cases it is easy to recycle catalytic DENs. DENs can also be immobilized on supports, such as silica and titania, and used for heterogeneous catalysis. Bimetallic DENs are shown to have particularly interesting catalytic properties. In addition to a discussion of current progress in this field, a number of intriguing questions related to the properties and potential applications of these materials are examined.     

Synthesis and properties of a new photostable polymer: Perylene-3,4,9,10-tetracarboxylic acid-bis-(N,N′-dodecylpolyimide)

The synthesis of perylene-3,4,9,10-tetracarboxylic acid-bis(N,N′-dodecyl-polyimide) (poly PTDI) and polyamic acid has been achieved from perylene dianhydride and dodecylamine. It was found that this new polyimide has very high thermal photostability. Poly PTDI decomposes at 475°C and shows weak fluorescence compared with the monomer PTDI possibly due to aggregration in the polymer. Its solubility in some of the common organic solvents, acetonitrile, dimethyl formamide, etc., makes spectroscopic and photochemical studies and applications possible in the liquid phase. The emission characteristics are similar to mono PTDI. Poly PTDI, a luminescent electron acceptor polymer, is a new reliable probe for a photosensitizer at energy transfer and election transfer photochemical reactions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2137–2142, 1997     

Metal‐induced optical sensing and optical switching in poly(pyridyl phenylene)

The synthesis of a conjugated polymer containing pyridyl units in the polymer backbone was successfully carried out with 2,6‐dibromopyridine and a diboronic acid derivative via the Suzuki coupling reaction. This polymer had a number‐average molecular weight of 4000 and excellent solubility in conventional organic solvents; this suggested the effect of the incorporation of dialkoxy side chains. A metallochromic phenomenon with ferric ions was clearly observed in spin‐coated films and solutions of the polymer. The response of the absorption and the fluorescence changes of the polymer films were rapid and were reproduced more than 15 times. A lightly bound intermolecular interaction between the pyridine ligand and cation was presumed to be responsible for the facile optical switching property of the polymer films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2444–2450, 2004     

The tenth anniversary of Suzuki polycondensation (SPC)

This article describes the successful transfer of the Suzuki cross-coupling (SCC) reaction to polymer synthesis, one of the major developments within the last decade of polymer synthesis. The polymers prepared by Suzuki polycondensation (SPC) and its Ni-catalyzed reductive counterpart are soluble and processable poly(arylene)s that, because of their rigid and conjugated backbones, are of interest for the materials sciences. Achievable molar masses easily compete with those of traditional polyesters and polyamides. This article also provides insight into some synthetic problems associated with the transfer of SCC from low molar mass organic chemistry to high molar mass polymer chemistry by addressing issues such as monomer purity, stoichiometric balance, achievable molar masses, and defects in the polymer structure. Although the emphasis of this article is synthetic and structural issues, some potential applications of the polyarylenes obtained are briefly mentioned. Together with the enormous developments in the areas of metallocene, ring-opening metathesis, and acyclic diene metathesis polymerization, the success of SPC impressingly underlines the increasing importance of transition-metal-catalyzed CC-bond-forming reactions in polymer synthesis. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1533–1556, 2001     

树状大分子在有机合成中的应用

近20年来树状大分子由于其特殊的结构而引起了科学家们的广泛关注;作为一类新型的高负载量载体应用于有机合成和催化是树状大分子重要的应用领域之一。本文主要介绍树状大分子和树脂固载树状大分子两类载体,重点对它们作为高负载量载体在有机合成和非均相催化反应中的应用研究进行了总结。     

树状大分子在有机合成中的应用

近20年来树状大分子由于其特殊的结构而引起了科学家们的广泛关注;作为一类新型的高负载量载体应用于有机合成和催化是树状大分子重要的应用领域之一。本文主要介绍树状大分子和树脂固载树状大分子两类载体,重点对它们作为高负载量载体在有机合成和非均相催化反应中的应用研究进行了总结。     

Donor–acceptor copolymers for red‐ and near‐infrared‐emitting polymer light‐emitting diodes

We report a comparative study of two organic soluble, vinylene‐based, alternating donor–acceptor copolymers with 1,4‐(2,5‐dihexadecyloxyphenylene) as the donor; the acceptor is either a 2,5‐linked pyridine or a 5,8‐linked 2,3‐diphenylpyrido[3,4‐b]pyrazine. The polymers are synthesized via a Heck coupling methodology from a dihalo monomer and a divinyl monomer to yield number‐average molecular weights of 16,000 g/mol for the pyridine polymer (PPyrPV) and 6500 g/mol for the pyridopyrazine polymer (PPyrPyrPV), with high solubility in common chlorinated solvents and lower solubility in less polar solvents (e.g., tetrahydrofuran). Thin‐film measurements show band gaps of 2.2 and 1.8 eV for PPyrPV and PPyrPyrPV, respectively. Both polymers exhibit photoluminescence in solution and in the solid state and exhibit electroluminescence when incorporated into light‐emitting diodes. In this case, a broad red emission centered at 690 nm for PPyrPV and a near‐infrared emission centered at 800 nm for PPyrPyrPV have been observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1417–1431, 2005