A hybrid‐type,chiral π‐conjugated polymer wrapped with polyhedral oligomeric silsesquioxanes

A novel hybrid‐type chiral binaphthyl‐based polyarylene derivative with polyhedral oligomeric silsesquioxanes (POSS) units 2a was prepared by Suzuki–Miyaura coupling polymerization from a chiral (R)‐6,6′‐dibromo‐2,2′‐diPOSS‐substituted 1,1′‐binaphthyl derivative 1a and p‐biphenylene diboronic acid. As a reference, a binaphthyl‐based polyarylene derivative without POSS unit 2b was also prepared. The obtained polymers were studied with thermogravimetric analysis, optical rotations, circular dichroism (CD), ultraviolet‐visible, and photoluminescence (PL) spectra. Gel permeation chromatography measurements of 2a and 2b showed that their number‐average molecular weights were 13,300 and 16,500, respectively. The thermal stability of POSS‐modified polymer 2a (temperature of 10% weight loss; T₁₀ = 380 °C) was extremely high compared with that of polymer without POSS unit 2b (T₁₀ = 335 °C) due to the siliceous bulky POSS segments on the side chains. The specific optical rotation [α]_D was ?66.7° (c 0.06, CHCl₃) for 2a and ?62.3° (c 0.06, CHCl₃) for 2b . The CD spectra showed that these two polymers had very similar and strong Cotton effects. Film polymer 2a showed almost the same PL spectrum as that in dilute CHCl₃ solution, indicating that bulky POSS units strongly suppressed intermolecular aggregation of the π‐conjugated polymer backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6035–6040, 2008     

A solution‐processible poly(p‐phenylene vinylene) without alkyl substitution: Introducing the cis‐vinylene segments in polymer chain for improved solubility,blue emission,and high efficiency

A soluble all‐aromatic poly(2,5‐diphenyl‐1,4‐phenylenevinylene) (2,5‐DP‐PPV) is synthesized by utilizing aromatic phosphonium and aldehyde monomers through Wittig reaction. The H¹ NMR and FTIR measurements indicate that over 50% content of cis‐vinylene units exist in polymer backbone. The diphenyl‐substituted benzaldehyde monomer plays an important role to enhance cis‐products (Z‐selectivity) in Wittig reactions. The twisted cis‐segments in polymer backbone reduce the interchain interactions and enhance the solubility of such all‐aromatic PPV derivative in common organic solvents. 2,5‐DP‐PPV exhibits good solubility in common organic solvents, such as tetrahydrofuran and chloroform. The polymer film exhibits a blue light emission (λ_max = 485 nm) and a very high photoluminescence efficiency of 78%. The cis‐trans photo isomerization of this polymer in solution and the impact on the optical properties are also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5242–5250, 2008     

Supramolecular Graft Copolymerization of a Polyester by Guest‐Selective Encapsulation of a Self‐Assembled Capsule

Repeating guest units of polyesters poly‐(R )‐ 2 were selectively encapsulated by capsule 1 (BF₄)₄ to produce supramolecular graft polymers. The encapsulation of the guest units was confirmed by ¹H NMR spectroscopy. The graft polymer structures were confirmed by the increase in the hydrodynamic radii and the solution viscosities of the polyesters upon complexation of the capsule. After the capsule was formed, atomic force microscopy showed extension of the polyester chains. The introduction of the graft chains onto poly‐(R )‐ 2 resulted in the main chain of the polymer having an M ‐helical morphology. The complexation of copolymers poly‐[(R )‐ 2 ‐co ‐(S )‐ 2 ] by the capsule gave rise to the unique chiral amplification known as the majority‐rules effect.     

Synthesis and photoluminescence behaviors of anthracene‐layered polymers

Novel anthracene‐layered polymers containing fluorescence quenchers such as ferrocene and nitrobenzene units at the polymer termini were designed and synthesized. Their optical properties were investigated in detail. The photoluminescence spectra of the polymers were featureless without vibrational structures, indicating that the anthracenes are effectively interacting each other in a single polymer chain in the excited state. Fluorescence emission from the layered anthracene units was effectively quenched by the aromatic units at the polymer termini owing to energy and electron transfer through a single polymer chain. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2815–2821     

Synthesis and characterization of polyethylene chains grafted onto the sidewalls of single‐walled carbon nanotubes via copolymerization

Polyethylene (PE) chains grafted onto the sidewalls of SWCNTs (SWCNT‐g‐PE) were successfully synthesized via ethylene copolymerization with functionalized single‐walled carbon nanotubes (f‐SWCNTs) catalyzed by rac‐(en)(THInd)₂ZrCl₂/MAO. Here f‐SWCNTs, in which α‐alkene groups were chemically linked on the sidewalls of SWCNTs, were synthesized by Prato reaction. The composition and microstructure of SWCNT‐g‐PE were characterized by means of ¹H NMR, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analyses (TGA), field‐emission scanning electron microscope (FESEM), and transmission electron microscope (TEM). Nanosized cable‐like structure was formed in the SWCNT‐g‐PE, in which the PE formed a tubular shell and several SWCNTs bundles existed as core. The formation of the above morphology in the SWCNT‐g‐PE resulted from successfully grafting of PE chains onto the surface of SWCNTs via copolymerization. The grown PE chains grafted onto the sidewall of the f‐SWCNTs promoted the exfoliation of the mass nanotubes. Comparing with pure PE, the physical mixture of PE/f‐SWCNTs and in situ PE/SWCNTs mixture, thermal stability, and mechanical properties of SWCNT‐g‐PE were higher because of the chemical bonding between the f‐SWCNTs and PE chains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5459–5469, 2007     

Quinoxaline‐based D‐A conjugated polymers for organic solar cells: Probing the effect of quinoxaline side chains and fluorine substitution on the power conversion efficiency

We describe the successful synthesis of four novel donor‐acceptor (D‐A) type copolymers, referred to as PQxBT , PQxFBT , TQxBT , and TQxFBT . The effects of using a fluorinated bithiophene (FBT) and varying the side‐chain moieties tethered to the quinoxaline (Qx) unit (electron‐withdrawing group in the polymer backbone) on the physical properties and photovoltaic performance were investigated. Specifically, the four polymers were synthesized using either alkoxyphenyl (P) or alkylthiophene (T) units anchored to the quinoxaline in the polymer backbone. The FBT‐bearing polymers, PQxFBT and TQxFBT , displayed more redshifted absorption spectra and higher crystallinity owing to the greater planarity of their polymer backbone as compared to the non‐fluorinated polymers. The TQxFBT copolymer, equipped with both the alkylthiophene side chains and FBT, exhibited face‐on orientation in film state and a well‐mixed nanophase morphology in TQxFBT :PC₇₁BM blend films. The photovoltaic device fabricated from TQxFBT :PC₇₁BM exhibited the highest power conversion efficiency of 4.18%. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1209–1218     

Synthesis and characterization of chiral poly(l‐lactide‐b‐hexyl isocyanate) macromonomers with norbornenyl end groups and their homopolymerization through ring opening metathesis polymerization to afford polymer brushes

We report the synthesis of the novel half‐titanocene alkoxide complex bischloro‐η⁵‐cyclopentadienyl(bicyclo[2.2.1]‐hept‐5‐en‐2‐oxy) titanium (IV), [CpTiCl₂(O‐NBE)]. This complex was employed for the synthesis of chiral poly(l ‐lactide‐b‐hexyl isocyanate) diblock copolymer bearing a norbornene end group with sequential addition of monomers. The poly(hexyl isocyanate) block is chiral due to the last l ‐lactide unit of the poly(l ‐lactide) block. This macromonomer was polymerized towards a chiral polymer brush structure with polynorbornene backbone and chiral poly(l ‐lactide‐b‐hexyl isocyanate) side chains using Grubbs first‐generation catalyst. The polymers were characterized using size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), and circular dichroism (CD) spectroscopy and their thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1102–1112     

Naphthodithiophene‐Diketopyrrolopyrrole‐Based donor–Acceptor alternating π‐Conjugated polymers for Organic thin‐Film transistors

Novel naphtho[1,2‐b:5,6‐b′]dithiophene (NDT) and diketopyrrolopyrrole (DPP)‐containing donor‐acceptor conjugated polymers (PNDTDPPs) with different branched side chains were synthesized via Pd(0)‐catalyzed Stille coupling reaction. Octyldodecyl (OD) and dodecylhexadecyl (DH) groups were tethered to the DPP units as the side chains. The soluble fraction of PNDTDPP‐OD polymer in chloroform has much lower molecular weight than that of PNDTDPP‐DH polymer. PNDTDPP‐DH polymer bearing relatively longer DH side chains exhibited much better charge‐transport behavior than PNDTDPP‐OD polymer with shorter OD side chains. The thermally annealed PNDTDPP‐DH polymer thin films exhibited an outstanding charge carrier mobility of ～1.32 cm² V^?1 s^?1 (I_on/I_off ～ 10⁸) measured under ambient conditions, which is almost six times higher than that of thermally annealed PNDTDPP‐OD polymer thin films. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5280–5290     

Tuning the low critical solution temperature of polymer brushes grafted on single‐walled carbon nanotubes and temperature dependent loading and release properties

A nondestructive method was developed for grafting and retrieving polymer brushes from single‐walled carbon nanotubes (SWCNT)s based on mussel‐inspired chemistry. Thermo‐responsive polymer brushes were grafted on SWCNTs by coating the tubes with polydopamine as a reactive underlayer and sequential surface‐initiated atom transfer radical polymerization of oligo(ethylene glycol) methacrylate (OEGMA, M_n = 475) and 2‐(2'‐methoxyethoxy)ethyl methacrylate (MEO2MA). Copolymer brushes were retrieved from the SWCNTs using 1 M NaOH to destroy the crosslinked polydopamine coating, and after that, the pristine properties of the SWCNTs were preserved. The low critical solution temperature (LCST) and molecular weight of the copolymer were measured using a nephelometer and gel permeation chromatograph, respectively. The loading and release behavior of Rhodamine 6G on responsive polymer‐grafted SWCNTs demonstrates that the copolymer brushes confer the SWCNTs an LCST dependence. This method can accurately confirm the molecular weights and polydispersity of stimuli‐responsive polymers grafted on any other nanoparticles and predict their controlled release behavior. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1807–1814     

Synthesis,solid‐state,and charge‐transport properties of conjugated polythiophene‐S,S‐dioxides

An alkylated semiconducting polymer comprising alternating bithiophene‐[all]‐S,S‐dioxide and aromatic monothiophene units in the polymer backbone was synthesized with the intent of modifying the energy gap and lowest unoccupied molecular orbital for use as a stable n‐type semiconductor. Films spun from this semiconducting polymer were characterized utilizing X‐ray scattering, near edge X‐ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy, and thin‐film field effect transistors to determine how oxidation of the thiophene ring systems impacts the structural and electronic properties of the polymer. The thiophene‐S,S‐dioxide polymers have lower optical and electrical band gaps than corresponding thiophene polymers. X‐ray scattering results indicate that the polymers are well ordered with the π–π stacking distances increased by 0.4 Å relative to analogous thiophene polymers. The electrical stability of these polymers is poor in transistors with a drop in the field effect mobility by approximately one order of magnitude upon addition of just 5% of the thiophene‐S,S‐dioxide unit in a copolymer with thiophene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

A novel one‐dimensional double‐chain‐like ZnII coordination polymer: poly[bis(1‐benzyl‐1H‐imidazole‐κN3)tris(μ‐cyanido‐κ2C:N)(cyanido‐κC)disilver(I)zinc(II)]

One of most interesting systems of coordination polymers constructed from the first‐row transition metals is the porous Zn^II coordination polymer system, but the numbers of such polymers containing N‐donor linkers are still limited. The title double‐chain‐like Zn^II coordination polymer, [Ag₂Zn(CN)₄(C₁₀H₁₀N₂)₂]_n, presents a one‐dimensional linear coordination polymer structure in which Zn^II ions are linked by bridging anionic dicyanidoargentate(I) units along the crystallographic b axis and each Zn^II ion is additionally coordinated by a terminal dicyanidoargentate(I) unit and two terminal 1‐benzyl‐1H‐imidazole (BZI) ligands, giving a five‐coordinated Zn^II ion. Interestingly, there are strong intermolecular Ag^I…Ag^I interactions between terminal and bridging dicyanidoargentate(I) units and C—H…π interactions between the phenyl rings of BZI ligands of adjacent one‐dimensional linear chains, providing a one‐dimensional linear double‐chain‐like structure. The supramolecular three‐dimensional framework is stabilized by C—H…π interactions between the phenyl rings of BZI ligands and by Ag^I…Ag^I interactions between adjacent double chains. The photoluminescence properties have been studied.     

“Click” generation of a conjugated polymer library for SWNT dispersion

Noncovalent functionalization of single‐walled carbon nanotubes (SWNTs) with conjugated polymers enhances SWNT processability and allows for selective dispersion of various SWNT species. Selective dispersions can be obtained by tuning the nature of the polymer, which can involve using various polymer backbones or side‐chains. However, a clear understanding of selectivity determinants is elusive, as the degree of polymerization (DP) has a large effect on SWNT selectivity. Additionally, preparing libraries of conjugated polymers with varying functionality while keeping DP consistent is difficult. Here, we report the utilization of a strained cyclooctyne‐containing conjugated polymer that serves as a versatile scaffold, enabling systematic preparation of a small library of conjugated polymers with different side‐chain functionality, while maintaining a consistent DP. The resulting polymers were used as dispersants for SWNTs, forming supramolecular polymer‐SWNT complexes that were characterized by UV‐Vis‐NIR absorption and Raman spectroscopy. In the series of polymers, we were able to probe the effect of small changes within the side chains, such as the incorporation of a carbonyl group or an aromatic unit, on the quality of the polymer‐SWNT dispersion. The results of these studies provide new insight into the factors that dictate the ability of a polymer to form strong interactions with SWNTs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2053–2058     

Non‐centrosymmetric CuSCN Based Coordination Polymers with Substituted Pyrazine and Pyrimidine Ligands

Non‐centrosymmetric one‐ to three‐dimensional CuSCN‐based coordination polymers with substituted pyrazine or pyrimidine spacer ligands can be prepared by self‐assembly in acetonitrile solution at 100 °C. Both [CuSCN(2 NCpyz)₂] ( 1 ) (2 NCpyz = 2‐cyanopyrazine) and [CuSCN(4 HOpym)₂] ( 3 ) (4 HOpym = 4‐hydroxypyrimidine) contain single zigzag CuSCN chains as their central backbone and crystallise in polar space groups (monoclinic Cm and orthorhombic Ama2). In [(CuSCN)₂(μ‐2 Mepyz)] ( 2 ) (2 Mepyz = 2‐methylpyrazine), [(CuSCN)₂] staircase double chains are connected by bridging 2 Mepyz ligands to afford a lamellar polymer (triclinic P 1). Whereas [CuSCN(5 Brpym)] ( 4 ) (5 Brpym = 5‐bromopyrimidine) with its honeycomb [CuSCN] layers is chiral (monoclinic P2₁), both 3 D polymers [(CuSCN)₂(μ‐pym)] ( 5 ) and [(CuSCN)₃(μ‐4 Mepym)] ( 6 ) (4 Mepym = 4‐methylpyrimidine) contain polar coordination networks (orthorhombic Fdd2 and monoclinic Pc). The CuSCN framework in ( 5 ) consists of thiocyanate bridged [CuS] chains, that in 6 of interlocked [CuSCN] and [Cu₂S(SCN)] sheets.     

Synthesis,photophysics, theoretical modeling,and electroluminescence of novel 2,7‐carbazole‐based conjugated polymers with sterically hindered structures

2,7‐dibromo‐N‐hexylcarbazole is successfully synthesized in three steps with an overall 37% yield. Novel 2,7‐carbazole‐based sterically hindered conjugated polymers are further synthesized. In the backbone structure of polymer P1 , alkylated bithiophene moiety is β‐substituted with dodecyl chains on both thiophene rings, adopting the tail‐to‐tail configuration. While for polymers P2 and P3 , partially planarized thieno[3,2‐b]thiophene moiety ( P2 ) and β‐pentyl substituted thieno[3,2‐b]thiophene ( P3 ) are incorporated. All polymers demonstrate efficient blue‐to‐green light emission, good thermal stability (T_d ≥ 379 °C), and high glass transition temperatures (T_g = 118 °C). The optical and electronic properties of the resulted polymers are tuned by the incorporated alkyl chains. For instance, the incorporation of β‐pentyl group in thieno[3,2‐b]thiophene moiety endows P3 with blue‐shifted photophysical spectra, reduced fluorescence quantum yield and larger band gap in comparison with P2 . The steric effect of incorporated alkyl chains is further illustrated by geometry optimization of three model oligomers (analogues to the repetition units of P1–P3 ) using density functional theory. Sterically hindered polymers P1 and P2 exhibit high charge transport ability and moderate electroluminescent properties in primarily tested single‐layer light‐emitting diodes (configuration: ITO/PEDOT:PSS/Polymer/Ca/Ag). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7725–7738, 2008     

Solid state self‐assembly of the single‐walled carbon nanotubes and poly(γ‐benzyl‐l‐glutamate)s with different conformations

A series of pyrenyl‐terminated poly(γ‐benzyl‐l ‐glutamate)s (py‐PBLGs) with controlled polymer molecular weight (M_W = 2.3–14.8 kg mol^?1) and molecular weight distribution (PDI = 1.17–1.55) have been prepared from 1‐pyrenemethylamine hydrochloride‐mediated ring‐opening polymerization (ROP) of γ‐benzyl‐l ‐glutamic acid based N‐carboxyanhydride (BLG‐NCA). FTIR analysis revealed that the py‐PBLG₉ was conformationally heterogeneous with 35.0% α‐helix, 55.6% β‐sheet, and 9.4% random coil conformations in the solid state, whereas the py‐PBLG₆₆ adopts 100% α‐helix conformation. Py‐PBLGs promote the dispersion of SWCNTs in organic solvents and in the PBLG solid through π–π interaction, as evidenced by the Raman spectroscopic studies. WAXD analysis revealed that the SWCNTs significantly affect the ordering of the py‐PBLG self‐assembly: the long range hexagonal packing of py‐PBLG₆₆ rods is notably enhanced by the addition of SWCNTs, whereas the lamellar packing of py‐PGLG₉ β‐sheets is weakened. In the hexagonal lattice, the SWCNTs are intercalated parallel to the py‐PBLG₆₆ rods, in contrast to the normal orientation of the SWCNTs with respect to the extended py‐PBLG₉ chains in the β‐sheets. The relative packing structure also affects the intermolecular interaction among the PBLGs: SWCNTs promote the interaction among the py‐PBLG₉ chains packed in a lamellar structure and weaken the intermolecular interaction among the py‐PBLG₆₆ columnar hexagonal array. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4489–4497     

Enrichment of large‐diameter semiconducting single‐walled carbon nanotubes by a mixed‐extractor strategy

In this work, we report a new mixed‐extractor strategy to improve the sorting yield of large‐diameter semiconducting single‐walled carbon nanotubes (s‐SWCNTs) with high purity. In the new mixed‐extractor strategy, two kinds of conjugated polymers with different rigidity, poly(9,9‐n‐dihexyl‐2,7‐fluorene‐alt‐9‐phenyl‐3,6‐carbazole) (PDFP) and poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole) (P8BT), are used to sort large‐diameter s‐SWCNTs through two simple sonication processes. To our surprise, although PDFP itself shows no selectivity toward s‐SWCNTs, it can greatly enhance the sorting yield of P8BT. Using the PDFP/P8BT mixed‐extractor method, the yield of sorted s‐SWCNTs has been enhanced by 5 times with a purity above 99 % in comparison to that using P8BT single‐extractor method. In addition, the photoluminescence (PL) excitation maps shows that the PDFP/P8BT mixed‐extractor system not only enhances the sorting yield substantially, but also tends to be enrichment of (15,4) SWCNTs with the diameter of 1.36 nm.     

The effect of molecular weight on the separation of semiconducting single‐walled carbon nanotubes using poly(2,7‐carbazole)s

The use of selective interactions between conjugated polymers and single‐walled carbon nanotubes has emerged as a promising method for the separation of nanotubes by electronic type. Although much attention has been devoted to investigating polyfluorenes and their ability to disperse semiconducting carbon nanotubes under specific conditions, other polymer families, such as poly(2,7‐carbazole)s, have been relatively overlooked. Poly(2,7‐carbazole)s have been shown to also preferentially interact with semiconducting carbon nanotubes, however a detailed investigation of polymer parameters, such as molecular weight, has not been performed. We have prepared seven different molecular weights of a poly(2,7‐carbazole), from short chain oligomers to high molecular weight polymers, and have investigated their effectiveness at dispersing semiconducting single‐walled carbon nanotubes. Although all polymer chain lengths were able to efficiently exfoliate carbon nanotube bundles using a mild dispersion protocol, only polymers above a certain threshold molecular weight (M_n ～ 27 kDa) were found to exhibit complete selectivity for semiconducting nanotubes, with no observable signals from metallic species. Additionally, we found the quality of separation to be strongly dependent on the ratio of polymer to carbon nanotube. Contrary to previous reports, we have found that an excess of poly(2,7‐carbazole) leads to incomplete removal of metallic carbon nanotubes. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2510–2516     

Side‐Chain Engineering of Benzodithiophene‐Fluorinated Quinoxaline Low‐Band‐Gap Co‐polymers for High‐Performance Polymer Solar Cells

A new series of donor–acceptor co‐polymers based on benzodithiophene and quinoxaline with various side chains have been developed for polymer solar cells. The effect of the degree of branching and dimensionality of the side chains were systematically investigated on the thermal stability, optical absorption, energy levels, molecular packing, and photovoltaic performance of the resulting co‐polymers. The results indicated that the linear and 2D conjugated side chains improved the thermal stabilities and optical absorptions. The introduction of alkylthienyl side chains could efficiently lower the energy levels compared with the alkoxyl‐substituted analogues, and the branched alkoxyl side chains could deepen the HOMO levels relative to the linear alkoxyl chains. The branched alkoxyl groups induced better lamellar‐like ordering, but poorer face‐to‐face packing behavior. The 2D conjugated side chains had a negative influence on the crystalline properties of the co‐polymers. The performance of the devices indicated that the branched alkoxyl side chains improved the V_oc, but decreased the J_sc and fill factor (FF). However, the 2D conjugated side chains would increase the V_oc, J_sc, and FF simultaneously. For the first time, our work provides insight into molecular design strategies through side‐chain engineering to achieve efficient polymer solar cells by considering both the degree of branching and dimensionality.     

Poly[2,7‐(9,9‐dihexylfluorene)‐alt‐pyridine] with donor‐acceptor architectures: A new series of blue‐light‐emitting alternating copolymers

A novel series of well‐defined alternating poly[2,7‐(9,9‐dihexylfluorenyl)‐alt‐pyridinyl] (PDHFP) with donor‐acceptor repeat units were synthesized using palladium (0)‐catalyzed Suzuki cross‐coupling reactions in good to high yields. In this series of alternating polymers, 2, 7‐(9,9‐dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by ¹H‐NMR and ¹³C‐NMR, gel permeation chromatography (GPC), thermal analyses, and UV‐vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148 °C, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390 °C in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para‐linkage (2,5‐linkage) of the pyridinyl units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4792–4801, 2004     

Synthesis of a nano‐sized chiral imprinted polymer and its use as an (S)‐atenolol carrier in the bulk liquid membrane

In this work, nanosized chiral imprinted polymers containing (S)‐atenolol ((S)‐ATN) selective sites were synthesized by using suspension polymerization in silicon oil. (S)‐ATN, methacrylic acid, and ethylene glycol dimethacrylate were used as enantiomerically pure template, functional monomer, and cross‐linker, respectively. The prepared chiral imprinted polymers were used as the carrier elements in a bulk liquid membrane (BLM). (S)‐ATN transport capability of the chiral imprinted polymers was compared with that of the nonimprinted polymer. It was shown that chiral imprinted polymers could transport (S)‐ATN through the BLM more effectively than (R)‐ATN, whereas no difference in the facilitated transport was observed between (R)‐ATN and (S)‐ATN when using nonimprinted polymer particles as the carrier element in the BLM. A kinetic model was proposed for the transportation of (S)‐ATN through the chiral imprinted polymers based BLM. It was found that the extraction of ATN from the source to the membrane controls the chiral separation process. It was also found that the pH of source and receiving phases as well as the racemic ATN concentration in source phase had very crucial effect on the chiral separation efficiency.