Aromatic poly(ester imide)s and poly(amide imide)s having 1,1′‐binaphthyl‐2,2′‐diyls in the main chain

Two new 1,1′‐binaphthyl‐2,2′‐diyl‐based dianhydrides, i. e., 2,2′‐bis(3,4‐dicarboxybenzamido)‐1,1′‐binaphthyl dianhydride (BNDADA) and 2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride (BNDEDA), were synthesized and polymerized with various aromatic diamines to afford polyimides through the traditional two‐step method. The polyimides with inherent viscosities ranging from 0.27 to 0.70 dl·g^–1 showed excellent solubilities in polar solvents such as DMAc, DMSO and NMP etc., except of the poly(ester imide) prepared from BNDEDA and benzidine. Poly(ester imide)s based on BNDEDA can also be readily dissolved in weakly polar solvents such as THF, CH₂Cl₂ and CHCl₃. The glass transition temperatures of these polyimides are in the range of 210–310°C; the 5% weight loss temperatures are in the range of 390–465°C in nitrogen and 384–447°C in air. These polymers form light yellow, tough films that were transparent above 365 nm. The effects of different flexible units attached in the 2‐ and 2′‐positions, i. e., amide, ester and ether, on the properties of the polyimides obtained are discussed.     

Synthesis and Characterization of New Organosoluble Polyamides and Polyimides Based on 2,2‐Bis[4‐ (4‐aminophenoxy)‐3,5‐dimethylphenyl]‐ hexafluoropropane

A new hexafluoro‐containing diamine monomer, 2,2‐bis[4‐(4‐aminophenoxy)‐3,5‐dimethylphenyl]hexafluoropropane ( TBAPHP ), was synthesized in three steps, starting from hexafluoroacetone sesquihydrate and 2,6‐xylenol. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce a series of polyamides and polyimides, respectively. The polyamides were prepared under Yamazaki reaction conditions. The polyimides were prepared by a two‐stage procedure that included a ring‐opening polyaddition yielding poly(amic acid)s, followed by a cyclodehydration to polyimides. The obtained polymers had inherent viscosities of 0.52–0.82 dL·g^–1. All of the polymers dissolved in polar solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N,N‐dimethylformamide. The polyimides derived from 4,4′‐oxydiphthalic anhydride and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride exhibited an excellent solubility and were dissolved in cyclohexanone, pyridine, tetrahydrofuran, and chloroform. These polymers showed glass transition temperatures of 231–301°C and decomposition temperatures at 10% weight loss ranging from 470 to 495°C in nitrogen and from 473 to 505°C in air. The tough and flexible polymer films obtained from solution casting showed tensile strengths of 78–96 MPa and tensile moduli of 2.0–2.4 GPa. Polymers containing methyl substituents had higher solubilities and T_g values than those without methyl substituents. In addition, the hexafluoroisopropylidene‐containing polymers exhibited a higher solubility and thermal stability than those containing isopropylidene units. UV‐visible absorption spectra revealed that the polyimides showed a better transparency than the polyamides.     

Synthesis and Characterization of Constitutional Isomeric Poly(amide‐ester)s from Adipoyl Chloride and 4‐(2‐Aminoethyl)phenol

Ordered [head‐to‐head (H‐H) or tail‐to‐tail (T‐T)] poly(amide‐ester) ( 6 a ) was prepared by polycondensation from adipoyl chloride ( 1 ) and N,N ′‐bis(4‐hydroxy phenethyl)adipamide ( 5 ), which was prepared from the selective acylation of 4‐(2‐aminoethyl)phenol ( 2 ) with N,N ′‐adipoylbis[benzoxazoline‐2‐thione] ( 4 ). And H‐T ordered poly(amide‐ester) ( 6 b ) was prepared by self‐polycondensation of 4‐carboxy‐N‐(4‐hydroxyphenethyl)‐adipamide ( 7 ) in the presence of DBOP. Random poly(amide‐ester) ( 6 c ) was synthesized by polymerization of 1 with 2 . The microstructure of the polymers obtained was investigated by ¹H and ¹³C NMR spectroscopy, and it was found that the polymers obtained had the expected ordered structure. Furthermore, DSC and WAXD results demonstrated that the constitutional regularity of polymers influenced their thermal properties and crystallinity.     

Novel fluorinated polymers by radical polyaddition of bis(α‐trifluoromethyl‐β‐difluorovinyl) dicarboxylate with ether

To develop the radical polyaddition reaction of bis(α‐trifluoromethyl‐β‐difluorovinyl) terephthalate (BFP) with 1,4‐dioxane, bis(α‐trifluoromethyl‐β‐difluorovinyl) cyclohexane‐1,4‐dicarboxylate (FDFC) and bis(α‐trifluoromethyl‐β‐difluorovinyl) adipate (FDFA) were prepared and polyadditions with 1,4‐dioxane, diethyl ether, and 1,2‐dimethoxyethane were examined in the presence of benzoyl peroxide (BPO). The molecular weight of the polymer obtained from FDFC with dioxane was 2.9×10³. A polymer with a molecular weight of 4.5×10³ was obtained by the reaction of FDFA with 1,4‐dioxane initiated with BPO. Polyaddition reactions of FDFC or FDFA with 1,2‐dimethoxyethane or diethyl ether were found to produce linear polymers which are soluble in common organic solvents. These results suggested that 1,4‐dioxane, diethyl ether and 1,2‐dimethoxyethane work as monomers in this reaction system. Postpolymerization of the polymer obtained from BFP with 1,4‐dioxane was also examined to yield a polymer of higher molecular weight compared to that of the starting polymer. A postulated polymerization mechanism of BFP with 1,4‐dioxane is briefly discussed.     

Synthesis and Characterization of Wide‐Bandgap Conjugated Polymers Consisting of Same Electron Donor and Different Electron‐Deficient Units and Their Application for Nonfullerene Polymer Solar Cells

Substantial development has been made in nonfullerene small molecule acceptors (NFSMAs) that has resulted in a significant increase in the power conversion efficiency (PCE) of nonfullerene‐based polymer solar cells (PSCs). In order to achieve better compatibility with narrow‐bandgap nonfullerene small molecule acceptors, it is important to design the conjugated polymers with a wide bandgap that has suitable molecular orbital energy levels. Here two donor–acceptor (D–A)‐conjugated copolymers are designed and synthesized with the same thienyl‐substituted benzodithiophene and different acceptors, i.e., poly{(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)‐alt‐(1,3‐bis(2‐octyldodecyl)‐1,3‐dihydro‐2H‐dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2‐d]imidazol‐2‐one‐5,8‐diyl) } ( DTBIA , P1 ) and poly{(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)‐alt‐(2‐(5‐(3‐octyltridecyl)thiophen‐2‐yl)dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2‐d]thiazole‐5,8‐diyl)} ( TDTBTA , P2 ) (and their optical and electrochemical properties are investigated). Both P1 and P2 exhibit similar deeper highest occupied molecular orbital energy level and different lowest unoccupied molecular orbital energy level. Both the copolymers have complementary absorption with a well‐known nonfullerene acceptor ITIC‐F. When blended with a narrow‐bandgap acceptor ITIC‐F, the PSCs based on P1 show a power conversion efficiency of 11.18% with a large open‐circuit voltage of 0.96 V, a J_sc of 16.89 mA cm^?2, and a fill factor (FF) of 0.69, which is larger than that for P2 counterpart (PCE = 9.32%, J_sc = 15.88 mA cm^?2, V_oc = 0.91 V, and FF = 0.645). Moreover, the energy losses for the PSCs based on P1 and P2 are 0.54 and 0.59 eV, respectively. Compared to P2, the P1‐ based PSCs show high values of incident photon to current conversion efficiency (IPCE) in the shorter‐wavelength region (absorption of donor copolymer), more balanced hole and electron mobilities, and favorable phase separation with compact π–π stacking distance.     

Synthesis of Alternating Low‐Bandgap Conjugated Polymers Based on Dithieno[2,3‐d:2′,3′‐d′]naphtho[1,2‐b:3,4‐b′]dithiophene and Enhancement of Photovoltaic Properties with Solvent Additives

Two alternating low‐bandgap conjugated polymers with 10,11‐di(3,7‐dimethyloctyloxy)di‐thieno[2,3‐d:2′,3′‐d′]naphtho[1,2‐b:3,4‐b′]dithiophene (NDT) as electron‐donor moieties and N,N′‐di(2‐hexyldecyl)isoindigo (ID) or bis(thieno‐2‐yl)‐N,N′‐bis(2‐hexyldecyl)‐1,4‐dioxo‐pyrrolo[3,4‐c]pyrrole (DPP) as electron‐acceptor moieties, respectively named as PNDT‐ID and PNDT‐DPP, are firstly synthesized and characterized. The polymers exhibit appropriate energy levels, good solution processabilities and broad light absorption properties; the power conversion efficiencies (PCEs) of 0.16%–0.19% for the photovoltaic solar cells (PVCs) from the blend films of the polymers and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) are very low. The performances of the PVCs from the polymers are remarkably increased when a very small amount of 1,8‐diiodooctance (DIO) or diphenyl sulfide (DPS) is used as solvent additives, and the maximal PCEs of 3.79% and 5.01% are respectively achieved in the PVCs from the blend films of PNDT‐ID/PC₇₁BM (W:W, 1:1.5) and PNDT‐DPP/PC₇₁BM (W:W, 1:1.5), with DPS as solvent additives under 100 mW cm^?2 illumination (AM 1.5G).

     

Novel Organosoluble Poly(amide‐imide)s Derived from Kink Diamine Bis[4‐(4‐trimellitimidophenoxy)phenyl]‐diphenylmethane. Synthesis and Characterization

A new kink diimide‐dicarboxylic acid, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]diphenylmethane (BTPDM), was synthesized by the condensation reaction of bis[4‐(4‐aminophenoxy)phenyl]diphenylmethane (BAPDM ) with trimellitic anhydride. A series of new poly(amide‐imide)s were prepared by direct polycondensation of BTPDM and various aromatic diamines in N‐methyl‐2‐pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers were produced in high yield revealing moderate to high inherent viscosities of 0.80–0.89 dL·g^–1. Wide‐angle X‐ray diffractograms revealed that the polymers are amorphous. Most of the polymers exhibit good solubility and could be readily dissolved in various solvents such as NMP, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, dimethyl sulfoxide, pyridine, cyclohexanone and tetrahydrofuran. These poly(amide‐imide)s have glass transition temperatures between 244–248°C and show 10% weight loss in the range of 453–469°C under a nitrogen atmosphere. The tough polymer films, obtained by casting from DMAc solution, had tensile strengths ranging between 82 and 95 MPa and tensile moduli ranging between 1.7 and 1.9 GPa.     

Anionic Polymerizations of 1‐Adamantyl Methacrylate and 3‐Methacryloyloxy‐1,1′‐biadamantane

Anionic polymerizations of 1‐adamantyl methacrylate ( 1 ) and 3‐methacryloyloxy‐1,1′‐biadamantane ( 2 ) were carried out in THF at ?50 to ?78 °C for 24 h. The initiator employed was either [1,1‐bis(4′‐trimethylsilylphenyl)‐3‐methylpentyl]lithium ( 3 )/lithium chloride, or diphenylmethylpotassium. The polymerizations of 1 and 2 proceeded quantitatively to afford the polymers having the predicted molecular weights based on the molar ratios of monomers and initiators and the narrow molecular weight distributions (M _w/M _n = 1.05–1.18), indicating the living character of the polymerization systems of 1 and 2 . Novel well‐defined block copolymers, poly[ 2 ‐block‐(tert‐butyl methacrylate)], poly( 2 ‐block‐isoprene‐block‐ 2 ), and poly[[(2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methyl methacrylate]‐block‐ 2 ], were anionically synthesized by the sequential copolymerization of 2 and comonomers. The poly( 2 ) had the significantly higher glass transition temperature (T_g) of 236 °C and decomposed over 370 °C, while poly( 1 ) started to decompose at around 320 °C before its T_g was reached. This thermal stability can be explained by the substituent effects of the bulky adamantyl and 1,1′‐biadamantyl moieties.

     

Synthesis and Properties of Novel Cardo Aromatic Poly(ether oxadiazole)s and Poly(ether‐amide oxadiazole)s

A series of polyhydrazides and poly(amide hydrazide)s bearing ether and cardo groups were prepared from three bis(ether carboxylic acid)s, 1,1‐bis[4‐(4‐carboxyphenoxy)phenyl]cyclohexane, 5,5‐bis[4‐(4‐carboxyphenoxy)phenyl]‐4,7‐methanohexahydroindan and 9,9‐bis[4‐(4‐carboxyphenoxy)phenyl]fluorene, or their diacyl chlorides with terephthalic dihydrazide, isophthalic dihydrazide and p‐aminobenzoyl hydrazide via the phosphorylation reaction or the low‐temperature solution polycondensation. The resulting hydrazide‐containing polymers exhibited inherent viscosities in the range of 0.35–0.71 dL·g^–1. All the hydrazide polymers were found to be amorphous as determined by X‐ray diffraction analysis and soluble in many organic polar solvents, and most of them afforded flexible and tough films by solvent casting. The hydrazide polymers had glass transition temperatures (T_g) between 157 and 197°C. All hydrazide polymers could be thermally converted into the corresponding oxadiazole polymers approximately in the region of 270–370°C, as evidenced by the DSC thermograms. The oxadiazole polymers showed a slightly enhanced crystallinity and an increase of T_g and a dramatically decreased solubility compared to their hydrazide prepolymers. They exhibited T_g's of 218–259°C and showed insignificant weight loss up to 450°C.     

High‐Detectivity All‐Polymer Photodetectors with Spectral Response from 300 to 1100 nm

Broad‐response and high‐detectivity for all‐polymer photodetectors based on p‐ and n‐type semiconducting polymers have been achieved through optimization of polymer property and film microstructure. The electron‐donating units in the p‐type polymers affect a great deal of the polymer properties such as solubility, absorption spectra, and electronic energy levels, which in turn can influence the device performance. The polymer (P3) based on dithienopyrrole and diketopyrrolopyrrole is most promising for photodetector applications, as it possesses the suitable energy level with regard to the n‐type polymer and exhibits appropriate film morphology and molecular stacking with aid of 1,8‐diiodooctane as an additive during film processing. The photodetector based on P3/poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (PNDI) exhibits good response from 300 to 1100 nm and nearly constant detectivity (D*) above 10¹² Jones at 330–980 nm, rendering a great potential of all‐polymer photodetectors for practical applications.

     

Protection and Polymerization of Functional Monomers, 31. Living Anionic Polymerization of Styrene Derivatives m,m′‐Disubstituted with Acetal‐Protected Monosaccharide Residues

Two new styrene derivatives m,m′‐disubstituted with acetal‐protected monosaccharide residues, 3,5‐bis(1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose‐3‐oxymethyl)styrene ( 1 ) and 3,5‐bis(1,2:3,4‐di‐O‐isopropylidene‐α‐D ‐galactopyranose‐6‐oxymethyl)styrene ( 2 ) were synthesized viahigh yielding eight reaction steps starting from isophthalic acid. Their anionic polymerizations were carried out with sec‐BuLi in THF at –78°C for 30 min. Both monomers, 1 and 2 , were found to undergo living anionic polymerization to afford quantitatively the polymers of predictable molecular weights and narrow molecular weight distributions (M̄_w/M̄_n < 1.08). Novel AB and BA diblock copolymers of 1 and styrene were also successfully synthesized. Complete deprotection of the acetal protective groups by treatment with trifluoroacetic acid was achieved to quantitatively regenerate D ‐glucose and D ‐galactose. The resulting polymers were highly water‐soluble polymers as expected.     

Novel Semi‐Fluorinated Poly(ether imide)s Derived From 4‐(p‐Aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl

An unsymmetrical diamine monomer 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl has been synthesized successfully. This monomer leads to the synthesis of different novel poly(ether imide)s when reacted with different dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA), and oxy diphthalic anhydride (ODA). The poly(ether imide) prepared from this monomer on reaction with 6FDA is soluble in several organic solvents such as N‐methylpyrolidinone (NMP), dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), tetrahydrofuran (THF), and CHCl₃. The poly(ether imide)s prepared from BTDA and ODA are soluble in NMP, DMF, and DMAc but not in THF or CHCl₃, whereas the polymer prepared from PMDA is soluble only in NMP. The water uptake value for these poly(ether imide) films is very low (0.2–0.5%), and exhibited low dielectric constants (2.81 at 1 MHz). The polymers exhibited high thermal stability up to 532 °C in air for 5% weight loss, and high glass transition temperatures up to 288 °C. The polymer exhibited high tensile strength up to 135 MPa, modulus 3.2 GPa, and elongation at break up to 25%, depending on the exact polymer structure.

The structure of the poly(ether imide) synthesised from 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane. This polymer was soluble in many organic solvents.     

Synthesis,Characterization and Field‐Effect Transistor Performance of Poly[2,6‐bis(3‐alkylthiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]diselenophene]s

Benzo[1,2‐b:4,5‐b′]diselenophene (BDS) has been incorporated for the first time in a polymer. bis(Stannyl)‐functionalized BDS was copolymerized with 3,3′‐bis(alkyl)‐5,5′‐bithiophenes (dodecyl and tetradecyl side chains) through Stille copolymerization, to yield p‐type polymer semiconductors for organic field‐effect transistor application. The electronic and structural effect of the selenium atoms, compared to sulphur atoms in analogous copolymers, is described. The molecular weight has a decisive influence on the photophysical properties and supramolecular ordering, expressed in field‐effect transistor measurements. Saturation mobilities around 10^?2 cm² · V^?1s^?1 are obtained on standard silicon substrates.

     

New Silicon‐Containing Polyquinolines: Synthesis,Characterization, and Electroluminescence

Summary: This study reports the synthesis, characterization, and electroluminescent device application of three new silicon‐containing polyquinolines: poly(2,2′‐(bis(p‐phenyl)diphenylsilane)‐6,6′‐bis(4‐phenyl quinoline)), poly(2,2′‐(bis(p‐phenyl)octylmethylsilane)‐6,6′‐bis(4‐phenyl quinoline)), and poly(2,2′‐(bis(p‐phenyl)diphenylsilane)‐6,6′‐bis(4‐hexylquinoline)). The polymers with alkyl side chains were soluble in organic solvents. The new polymers showed robust thermal properties with glass transitions of 161–339 °C. Cyclic voltammetry of the polymers revealed quasi‐reversible reductions with onsets of ?1.55 to ?1.71 V (vs SCE) and corresponding electron affinities of 2.69–2.85 eV. Organic light‐emitting devices using new polyquinolines as emissive materials showed blue (CIE coordinates = 0.21, 0.20) or blue‐green (0.23, 0.36) electroluminescence with a moderate brightness (≈140 cd · m^?2) and efficiency (0.04%). The results demonstrate that silicon‐containing polyquinolines are promising n‐type wide band‐gap semiconductors for organic electronics.

Structures of new Si‐containing polyquinolines.     

New Spiro‐Functionalized Polyfluorenes: Synthesis and Properties

Summary: The synthesis of several new spirocycloalkane functionalized polyfluorenes is described. Poly[2,7‐(9,9‐dioctylfluorene)‐alt‐2′,7′‐spiro(cyclohexane‐1,9′‐fluorene)] ( PF1 ), poly[2,7‐(9,9‐dioctylfluorene)‐co‐2′,7′‐spiro(cyclohexane‐1,9′‐fluorene)] ( PF2 ), poly{2′,7′‐bis[(9,9‐dioctylfluoren‐2‐yl)]‐spiro(cyclohexane‐1,9′‐fluorene)‐7,7‐diyl} ( PF3 ), poly[2,7‐(9,9‐dioctylfluorene)‐alt‐2′,7′‐spiro(cyclopropane‐1,9′‐fluorene)] ( PF4 ) and poly[2,7‐(9,9‐dioctylfluorene)‐co‐2′,7′‐spiro(cyclopropane‐1,9′‐fluorene)] ( PF5 ) were synthesized by Pd(0) and Ni(0) mediated coupling reactions. All polymers were characterized by NMR, UV‐vis, DSC‐TGA and PL. Efficient prevention of interchain interactions by the spirocyclohexane moieties guarantees pure blue emission from pristine PF1 – 3 as revealed by solid state PL spectra. On the other hand, solid state PL spectra of PF4 and PF5 are characterized by an additional emission band in the green region. Thermal annealing on PF1 – 3 at 150 °C under nitrogen atmosphere does not cause any substantial changes in their solid state PL spectra, whereas after carrying out the same treatment for 20 h at 110 °C under air the polymers show a low‐energy emission band in the green region which is presumably brought about by chemical modifications.

Structure of spiro‐functionalized polyfluorenes synthesized in this study.     

Highly Active Single‐Site Catalysts for the 1,4‐cis Polymerization of Butadiene from Allylneodymium(III) Chlorides and Trialkylaluminiums – A Contribution to the Activation of Tris(allyl)neodymium(III) and the Further Elucidation of the Structure‐Activity Relationship

To further elucidate the structure‐reactivity relationship in the allylneodymium complex‐catalyzed 1,4‐cis polymerization of butadiene, the following catalyst systems are investigated in toluene more thoroughly: Nd(C₃H₅)₂Cl·1,4‐dioxane, Nd(C₃H₅)Cl₂·2.5 tetrahydrofuran (THF)/5–30 AlMe₃ and preformed Nd(C₃H₄R)₃ in combination with 2 Ph₃CCl, 2 Ph₃CCl/5 AlEt₃; 2 AlMe₂Cl, 2 AlMe₂Cl/30 AlMe₃; 2 AlEt₂Cl and 2 AlEt₂Cl/10 AlEt₃. From the catalytic activity, cis selectivity, polydispersity, degree of polymerization as a function of conversion, as well as the comparison of theoretical and experimental chain length and kinetic analysis, essential conclusions can be drawn concerning the formation reaction and structure of the real catalyst complex and the course of the polymerization reaction. For the combinations of Nd(C₃H₄R)₃ with 2 AlMe₂Cl/30 AlMe₃, 2AlEt₂Cl and 2 AlEt₂Cl/10AlEt₃, the rate law r_P = k_P[Nd][BD]² is derived with the values for k_P of 3.4 (at 35°C), 2.0 and 1.5 L²/(mol²·s¹) (at 50°C), respectively. In each case the formation of a η³‐butenyl bis(η⁴‐butadiene)neodymium(III) complex [Nd(η³‐C₃H₄R)(η⁴‐C₄H₆)₂(ClAlR′₂C₃H₄R)₂] (R′ = Me, Et) is assumed. The insertion reaction proceeds according to the π‐allyl insertion mechanism, and the high cis‐selectivity in accordance with the anti‐cis and syn‐trans correlation is a consequence of the preferential η⁴‐cis coordination of butadiene.     

Synthesis and structural characterisation of hyperbranched poly(benzyl ether) analogs with 1,3,5‐s‐triazine moiety

Hyperbranched poly(benzyl ether) analogs with the 1,3,5‐s‐triazine moiety were prepared by direct polymerization of AB₂ type monomers, 2,4‐bis(4‐hydroxyphenyl)‐6‐(4‐bromomethylphenyl)‐1,3,5‐s‐triazine. The triazine rings influenced the structural and material characteristics of these hyperbranched polymers. In the hyperbranched poly(benzyl ether) analog, only the O‐alkylated structure, instead of the C‐alkylated branches, was observed, possibly due to the electron‐withdrawing nature of the triazine ring which restrains C‐alkylation on the phenyl group of the monomer. The triazine moieties play an important role in producing the structural regularity of hyperbranched poly(benzyl ether) analogs.     

Oxygen Scavenging and Oxygen Barrier Poly(1,2‐butadiene) Films Containing an Iron‐Complex Catalyst

Tough films of poly(1,2‐butadiene) are prepared by introducing small amounts of the less toxic iron complex N,N′‐bis(salicylidene)ethylenediamine‐benzylimidazole and methyl linoleate. The catalytic activity of the iron complex for air oxidation of unsaturated groups is substantially higher than those of previously reported films. The oxygen scavenging capacity of the films is up to 200 mL (oxygen gas at STP) g(film)^?1 after 1 month, based on oxidative consumption of the poly(1,2‐butadiene) double bonds, which is more than twice that of a previously reported poly(1,4‐butadiene) film containing a cobalt complex catalyst and a film containing reduced iron powder. The oxygen absorption and scavenging of the films is independent of humidity and is maintained over 1 month. The results suggest that the combination of poly(1,2‐butadiene) and the iron complex catalyst is a promising oxygen scavenging material for active oxygen barrier films.     

Asymmetric induction in the cyclopolymerization of divinyl ethers derived from (R)- or (S)-3,3′-dimethyl-1,1′-bi-2-naphthol

Optically active divinyl ethers, (?)-(R)- and (+)-(S)-2,2′-bis[2-(2-vinyloxyethoxy)ethoxy]-3,3′-dimethyl-1,1′-binaphthyl [(R)- 1b and (S)- 1b ] were polymerized to produce chiral poly(crown ether)s. Their optical rotation was found to be profoundly influenced by the polymerization conditions. When increasing the monomer concentration from 0,1 to 0,3 mol · 1^?1, after polymerization with SnCl₄ in CH₂Cl₂ at 0°C, the optical rotation of the resulting polymers is drastically changed from +44,5° to ?17,3° for (R)- 1b and from ?35,6° to +20,9° for (S)- 1b . The analysis of ¹H NMR showed that the polymers have changed their optical rotation due to a configuration which has a tendency to be preferentially racemic diad at higher monomer concentrations in a nonpolar solvent. There are indications that the twist of 2,2′-binaphtyl moieties, the methyl groups in 3-, and 3′-positions as steric barrier, and the intramolecular solvation of the growing carbo-cation cooperatively control the propagation to induce the asymmetry in the main chain.     

Formation of Macrocycles in the Synthesis of Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl)

A series of polymerizations of 3,6‐dibromo‐9‐(2‐ethylhexyl)carbazole was carried out in different monomer concentrations using standard Yamamoto reaction conditions. It was found that the molecular weight of the resulting poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) strongly depends on the monomer concentration in the reaction mixture. Matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) measurements confirmed the formation of low‐molar‐mass cyclic oligomers of the 3,6‐disubstituted carbazole. In this paper we describe, for the first time, the formation of large amounts of a cyclic tetramer and of higher macrocycles in the synthesis of poly(N‐alkyl‐3,6‐carbazoles) by the Yamamoto method. This seems to be a limiting factor in the synthesis of high molecular weight poly(N‐alkyl‐3,6‐carbazole)s. The optical, thermal, and electrochemical properties of poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) have been investigated. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is thermally stable, with 5% weight loss at 460 °C in nitrogen. The polymer exhibits a weak blue fluorescence with a maximum at 425 nm. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is electrochemically stable, its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are ?5.0 and ?1.6 eV, respectively.