Synthesis of aromatic polyethers by Scholl reaction. V. Synthesis and polymerization of 1,3-bis[4-(1-naphthoxy) benzoyl]benzene, 1,4-bis[4-(1-naphthoxy)benzoyl]benzene,bis[4-(1-naphthoxy)phenyl]methane, 1,3-bis[4-(1-naphthoxy) phenylmethyl]benzene,and 1,4-bis-[4-(1-naphthoxy)phenylmethyl]benzene

This article describes the synthesis and the cation-radical polymerization (Scholl reaction) of 1,3-bis[4-(1-naphthoxy) benzoyl] benzene ( 6 ) and 1,4-bis[4-(1-naphthoxy) benzoyl]- benzene ( 7 ) initiated by FeCI₃. This polymerization produced poly(ether ether ketone ketone)s (PEEKK) of number average molecular weight (M?_n) up to 5400 g/mol. The synthesis of bis[4-(1-naphthoxy) phenyl] methane ( 8 ), 1,3-bis[4-(1-napthoxy) phenylmethyl] benzene ( 9 ), and 1,4-bis[4-(1-naphthoxy) phenylmethyl] benzene ( 10 ) are also described. Polyethers of M?_n up to 15400 g/mol at a FeCl₃/monomer molar ratio of 2/1 were obtained. An increased polymerizability of the monomers 9 and 10 containing two CH₂ groups versus that of the corresponding monomers containing two carbonyl groups ( 6 and 7 ) was observed. This enhanced polymerizability was explained based on the increased nucleophilicity of monomers 9 and 10 .     

Synthesis of aromatic polyethers by Scholl reaction. VII. Oxidative polymerization of 2,2-bis[4-(1-naphthoxy)phenyl]propane and 2,2-bis [4-(1-naphthyl)phenyl]propane

The synthesis and the mechanism of oxidative polymerization of 2,2-bis[4-(1-naphthoxy)phenyl]propane ( 4 ) and 2,2-bis[4-(1-naphthyl)phenyl]propane ( 9 ) are presented. Both monomers polymerize by two different propagation steps. The first one represents a cation-radical dimerization of the naphthyl groups to dinaphthyl structure. H⁺[FeCl₄]^? generated from the first propagation step initiates a transalkylation reaction which provides structural units containing isopropylidenic groups inserted between phenyl and naphthyl, and between two naphthyl groups, respectively. Since the phenyl groups resulted from the second propagation reaction are unreactive in both the oxidative coupling and the transalkylation steps this polymerization reaction leads to polymers with low molecular weights containing phenyl chain ends.     

Radical and cationic polymerizations of 3‐ethyl‐3‐methacryloyloxymethyloxetane

3‐Ethyl‐3‐methacryloyloxymethyloxetane (EMO) was easily polymerized by dimethyl 2,2′‐azobisisobutyrate (MAIB) as the radical initiator through the opening of the vinyl group. The initial polymerization rate (R_p) at 50 °C in benzene was given by R_p = k[MAIB]^0.55 [EMO]^1.2. The overall activation energy of the polymerization was estimated to be 87 kJ/mol. The number‐average molecular weight (M?_n) of the resulting poly(EMO)s was in the range of 1–3.3 × 10⁵. The polymerization system was found to involve electron spin resonance (ESR) observable propagating poly(EMO) radicals under practical polymerization conditions. ESR‐determined rate constants of propagation (k_p) and termination (k_t) at 60 °C are 120 and 2.41 × 10⁵ L/mol s, respectively—much lower than those of the usual methacrylate esters such as methyl methacrylate and glycidyl methacrylate. The radical copolymerization of EMO (M₁) with styrene (M₂) at 60 °C gave the following copolymerization parameters: r₁ = 0.53, r₂ = 0.43, Q₁ = 0.87, and e₁ = +0.42. EMO was also observed to be polymerized by BF₃OEt₂ as the cationic initiator through the opening of the oxetane ring. The M?_n of the resulting polymer was in the range of 650–3100. The cationic polymerization of radically formed poly(EMO) provided a crosslinked polymer showing distinguishably different thermal behaviors from those of the radical and cationic poly(EMO)s. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1269–1279, 2001     

Polymerization of 2‐pentene with Ni(II) α‐diimine complex/M‐MAO catalyst and structure of the polymer

Polymerization of 2‐pentene with [ArN?C(An)C(An)·NAr)NiBr₂ (Ar?2,6‐iPr₂C₆H₃)] ( 1‐Ni) /M‐MAO catalyst was investigated. A reactivity between trans‐2‐pentene and cis‐2‐pentene on the polymerization was quite different, and trans‐2‐pentene polymerized with 1‐Ni /M‐MAO catalyst to give a high molecular weight polymer. On the other hand, the polymerization of cis‐2‐butene with 1‐Ni /M‐MAO catalyst did not give any polymeric products. In the polymerization of mixture of trans‐ and cis‐2‐pentene with 1‐Ni /M‐MAO catalyst, the M_n of the polymer increased with an increase of the polymer yields. However, the relationship between polymer yield and the M_n of the polymer did not give a strict straight line, and the M_w/M_n also increased with increasing polymer yield. This suggests that side reactions were induced during the polymerization. The structures of the polymer obtained from the polymerization of 2‐ pentene with 1‐Ni /M‐MAO catalyst consists of ? CH₂? CH₂? CH(CH₂CH₃)? , ? CH₂? CH₂? CH₂? CH(CH₃)? , ? CH₂? CH(CH₂CH₂CH₃)? , and methylene sequence ? (CH₂)_n? (n ≥ 5) units, which is related to the chain walking mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2858–2863, 2008     

Vinylation and polymerization with trivinylaluminum. II. Synthesis of α,ω-diene-polyisobutylene

The polymerization of isobutylene by 3-chloro-1-butene/trivinylaluminum (V₃Al) and t-butyl chloride/V₃Al initiator systems with methyl chloride and methylene chloride as solvents has been investigated in the range from ?30 to ?72?C. The rate of polymerization increases with decreasing temperatures from ?30 to ?50°C and then decreases when the temperature is further lowered, for example, to ?72°C. Mayo plots and a determination of the number of polymer molecules n? formed per molecule of initiator employed suggests a transfer-less, i.e., termination-dominated system. A critical analysis shows that for systems containing both free ions and ion pairs, the Mayo equation is meaningful only when the degree of dissociation α remains constant over the whole [M] range investigated. This condition is achieved in RCl/V₃Al-initiated systems by using an initiator (t-BuCl) for which the rate of catalyst destruction is insignificant compared to rate of initiation, R_i, i.e., initiation efficiency, f ≈ 1 and R_i independent of [M]. Polyisobutylene, containing, 1.8 ± 0.1 terminal unsaturation, has been synthesized by the use of 3-chloro-1-butene initiator in conjunction with V₃Al coinitiator, and avenues for further efficient synthesis of α,ω-diene-polyisobutylenes have been outlined.     

Energetische Betrachtungen zur Intramolekularen Solvatisierung von Ionen bei der Elektronenstoss-Induzierten Fragmentierung von α,ω-Bis-(Trimethylsilyl)-Äthern

By means of AP measurements it has been shown that the stable [M? CH3]+ ions from α,ω-bis(trimethylsilyl) ethers of the type TMS? o? (CH₂)_n? O? TMS (n = 2 to 7) do not possess a cyclic structure.     

Radical heterogeneous polymerization behavior of N‐methyl‐α‐fluoroacrylamide in benzene

The polymerization of N‐methyl‐α‐fluoroacrylamide (NMFAm) initiated with dimethyl 2,2′‐azobisisobutyrate (MAIB) in benzene was studied kinetically and with electron spin resonance. The polymerization proceeded heterogeneously with the highly efficient formation of long‐lived poly(NMFAm) radicals. The overall activation energy of the polymerization was 111 kJ/mol. The polymerization rate (R_p) at 50 °C is given by R_p = k[MAIB]^0.75±0.05 [NMFAm]^0.44±0.05. The concentration of the long‐lived polymer radical increased linearly with time. The formation rate (R_p?) of the long‐lived polymer radical at 50 °C is expressed by R_p? = k[MAIB]^1.0±0.1 [NMFAm]^0±0.1. The overall activation energy of the long‐lived radical formation was 128 kJ/mol, which agreed with the energy of initiation (129 kJ/mol), which was separately estimated. A comparison of R_p? with the initiation rate led to the conclusion that 1‐methoxycarbonyl‐1‐methylethyl radicals (primary radicals from MAIB), escaping from the solvent cage, were quantitatively converted into the long‐lived poly(NMFAm) radicals. Thus, this polymerization involves completely unimolecular termination due to polymer radical occlusion. ¹H NMR‐determined tacticities of resulting poly(NMFAm) were estimated to be rr = 0.34, mr = 0.48, and mm = 0.18. The copolymerization of NMFAm(M₁) and St(M₂) with MAIB at 50 °C in benzene gave monomer reactivity ratios of r₁ = 0.61 and r₂ = 1.79. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2196–2205, 2001     

Hydrogels Composed of Organic Amphiphiles and α‐Cyclodextrin: Supramolecular Networks of Their Pseudorotaxanes in Aqueous Media

Mixtures of N‐alkyl pyridinium compounds [py‐N‐(CH₂)_nOC₆H₃‐3,5‐(OMe)₂]⁺(X^?) ( 1b Cl: n=10, X=Cl; 1c Br: n=12, X=Br) and α‐cyclodextrin (α‐CD) form supramolecular hydrogels in aqueous media. The concentrations of the two components influences the sol–gel transition temperature, which ranges from 7 to 67 °C. Washing the hydrogel with acetone or evaporation of water left the xerogel, and ¹³C CP/MAS NMR measurements, powder X‐ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that the xerogel of 1b Cl (or 1c Br) and α‐CD was composed of pseudorotaxanes with high crystallinity. ¹³C{¹H} and ¹H NMR spectra of the gel revealed the detailed composition of the components. The gel from 1b Cl and α‐CD contains the corresponding [2]‐ and [3]pseudorotaxanes, [ 1b? (α‐CD)]Br and [ 1b? (α‐CD)₂]Br, while that from 1c Br and α‐CD consists mainly of [3]pseudorotaxane [ 1c? (α‐CD)₂]Br. 2D ROESY ¹H NMR measurements suggested intermolecular contact of 3,5‐dimethoxyphenyl and pyridyl end groups of the axle component. The presence of the [3]pseudorotaxane is indispensable for gel formation. Thus, intermolecular interaction between the end groups of the axle component and that between α‐CDs of the [3]pseudorotaxane contribute to formation of the network. The supramolecular gels were transformed into sols by adding denaturing agents such as urea, C₆H₃‐1,3,5‐(OH)₃, and [py‐N‐nBu]⁺(Cl^?).     

Characterization of anomeric differences of ammonium-bound monomeric and dimeric complex ions of 1α- and 1β-azido-pentofuranosyl derivates by kinetic method

Relative stabilities (ΔG^c) of ammonium-bound monomers and dimers of anomeric β- -pentofuranosyl 1α- and 1β-azide derivates are determinate using the kinetic method by measuring relative rates of competitive collision-induced dissociations of dimeric [ANH₄B]⁺ and trimeric [A₂NH₄B]⁺ or [ANH₄B₂]⁺ cluster ions. Comparison between calculated ammonium affinities (AAs) and relative stabilities (ΔG^c) of ammonium-bound monomers shows qualitative correlations between both thermochemical quantities, but in two examples the activation barrier differences of competitive fragmentation channels cause a large disparity between both thermochemical data. Therefore, the most stable ammonium-bound monomers of the anomeric lα- and lβ-2,3,5-tri-O-benzyl-β- -arabino-pento-furanosyl azides possess the lowest ammonium affinities and the highest relative stabilities. Two different relative stabilities measured for the same ammonium-bound homo- or hetero-dimers indicate dissimilar activated barriers of trimers transition states for dimer formations. The activated barriers of trimers depend on the relative stabilities of ammonium-bound monomer within the trimeric cluster ions.     

Platinum(IV) complexes with α,ω-bis(pyrazol-1-yl) alkanediyl and diethyl ether/thioether ligands. Crystal structures of dibromodimethyl[1,2-bis(pyrazol-1-yl)ethane]platinum(IV) and trimethyl-bis[2-(pyrazol-1-yl)ethyl]etherplatinum(IV) tetrafluoroborate

Reactions of the flexible α,ω-bis(pyrazol-1-yl) compounds 1,2-bis(pyrazol-1-yl)ethane (L1), 1,8-bis(pyrazol-1-yl)-n-octane (L2), bis[2-(pyrazol-1-yl)ethyl]ether (L3) and bis[2-(pyrazol-1-yl)ethyl]thioether (L4) with precursor organometallic platinum complexes ([(PtBr₂Me₂)_n], [(PtIMe₃)₄] and [(PtMe₂(cod)]/I₂) are described herein. The spectroscopic characterization of the platinum(IV) products of these reactions [PtBr₂Me₂{pz(CH₂)_mpz}], m = 2 (1) or 8 (2), [PtI₂Me₂{pz(CH₂)₂pz}] (3), [PtMe₃(pzCH₂CH₂OCH₂CH₂pz)][BF₄] (4) and [PtMe₃(pzCH₂CH₂SCH₂CH₂pz)][CF₃SO₃] (5), where ‘pz’ is pyrazol-1-yl, is discussed. Furthermore, solid state structures of 1, a complex with a seven-membered chelate ring, and 4, a complex bearing the neutral κ²N,N′,κO ligand bis[2-(pyrazol-1-yl)ethyl]ether (L3) are reported.     

Poly-Diels-Alder Addition with a Bisoxazole as Bisdiene and a Bismaleinimide as Bisdienophile

Abstract

The poly-Diels-Alder addition between the new bisdiene 1,4-bis(5-methoxy-2-oxazolyl)benzene (4) and N,N′-hexamethylene-bis[2-(2,5-dihydro-2,5-dioxo-pyrrole-1-yl) acetamide] (7) is described. The structure of the resulting polyadduct 12 was proved by ¹H NMR spectroscopy with the aid of the low-molecular-weight model compounds 1,4-bis(1,3-dihydro-7-hydroxy-1,3-dioxo-2-phenyl-pyrrolo[3,4-c] pyridine-4-yl)benzene (9) and N,N'-hexamethylene-bis[2-(1, 3-dihydro-7-hydroxy-6-methyl-1,3-dioxo-4-phenyl-pyrrolo [3,4-c]pyridine-2-yl)acetamide] (11). The reaction proceeds via the aromatization of the primarily formed cycloadducts. Polyadduct 12 shows a number average degree of polymerization P_n of about 11 – 12 (M_n = 8500 ? 9200 g/mol), calculated from ¹H NMR endgroup signals.     

Living cationic isomerization polymerization of β-pinene. III. Synthesis of end-functionalized polymers and graft copolymers

α-End-functionalized polymers and macromonomers of β-pinene were synthesized by living cationic isomerization polymerization in CH₂Cl₂ at −40°C initiated with the HCl adducts [ 1; CH₃CH(OCH₂CH₂X)Cl; X = chloride ( 1a ), acetate ( 1b ), and methacrylate ( 1c )] of vinyl ethers carrying pendant substituents X that serve as terminal functionalities. In conjunction with TiCl₃(OiPr) and nBu₄NCl, these functionalized initiators led to living β-pinene polymerization where the carbon–chlorine bond of 1 was activated by TiCl₃(OiPr). Similarly, end-functionalized poly(p-methylstyrene)-block-poly(β-pinene) were also obtained. ¹H-NMR analysis showed that the polymers possess controlled molecular weights (DP _n = [M]₀/[ 1 ]₀) and number-average end functionalities close to unity. The end-functionalized methacrylate-capped macromonomers form 1c were radically copolymerized with methyl methacrylate (MMA) to give graft copolymers carrying poly(β-pinene) or poly(p-methylstyrene)-block-poly(β-pinene) as graft chains attached to a PMMA backbone. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1423–1430, 1997     

Living cationic polymerization of isobutyl propenyl ether as β-substituted vinyl ether

Isobutyl propenyl ether [IBPE; CH₃CH=CH? OCH₂CH(CH₃)₂] was polymerized with a mixture of hydrogen iodide and iodine (HI/I₂ initiator) in n-hexane at ?40°C to yield living polymers with a nearly monodisperse molecular weight distribution (MWD) (M?_w/M?_n ≈ 1.1). The number-average molecular weight (M?_n) of the polymers increased proportionally to IBPE conversion and further increased when a new monomer feed was added to a completely polymerized solution. The M?_n was controlled by the initial concentration of hydrogen iodide if the acid was charged in excess over iodine. In polymerization by iodine alone the M?_n of the polymers obtained in nonpolar solvents (n-hexane and toluene) also increased with conversion, but their MWD was broader (M?_w/M?_n = 1.3–1.4) than in the HI/I₂-initiated systems under similar conditions. The iodine-initiated polymerization in polar CH₂Cl₂ solvent, in contrast, led to nonliving polymers with a broad MWD (M?_n/M?_n = 1.6–1.8) and M?_n, independent of conversion. The living polymerization of IBPE was also compared with that of the corresponding isobutyl vinyl ether, to determine the effect of the β-methyl group in IBPE.     

Synthesis,kinetic study,and application of Ti[O(CH2)4OCHCH2]4 in ring‐opening polymerization of ε‐caprolactone and radical polymerization

Ti[O(CH₂)₄OCH?CH₂]₄, used for the ring‐opening polymerization (ROP) of ε‐caprolactone, was synthesized through the ester‐exchange reaction of titanium n‐propoxide and 1,4‐butanediol vinyl ether, and its chemical structure was confirmed by nuclear magnetic resonance (¹H NMR) and thermogravimetric analysis (TGA). The mechanism and kinetics of Ti[O(CH₂)₄OCH?CH₂]₄‐initiated bulk polymerization of ε‐caprolactone were investigated. The results demonstrate that Ti[O (CH₂)₄OCH?CH₂]₄‐initiated polymerization of ε‐caprolactone proceeds through the coordination‐insertion mechanism, and all the four alkoxide arms in Ti[O (CH₂)₄OCH?CH₂]₄ share a similar activity in initiating ROP of ε‐caprolactone. The polymerization process can be well predicted by the obtained kinetic parameters, and the activation energy is 106 KJ/mol. Then, the rheological method was employed to investigate the feasibility of producing the crosslinked poly(ε‐caprolactone)‐poly (n‐butyl acrylate) network by using Ti[O(CH₂)₄OCH?CH₂]₄ as the ROP initiator. The tensile test demonstrates that the in situ generated crosslinked PCL‐PBA network in PMMA matrix provides the possibility of ameliorating the tensile properties of PMMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7773–7784, 2008     

Aromatic poly(amic acids): Fundamental structural studies

Aromatic poly(amic acids) derived from pyromellitic dianhydride and 4,4′,-diaminodiphenyl ether were characterized by dilute solution techniques. Number-average molecular weights M?_n of 13 samples ranged from 13,000 to 55,000 (DP 31–131). Weight-average molecular weights M?_w of 21 samples ranged from 9,900 to 266,000. The ratio M?_w/M?_n was between 2.2 and 4.8. Heterogeneous polymerization yielded higher molecular weight polymer than homogeneous polymerization. The molecular weight could be varied systematically by control of stoichiometric imbalance. Use of very pure monomers and solvent gave polymers of relatively high number-average molecular weight (～50, 000) and the most probable molecular weight distribution M?_w/M?_n = 2. Impure monomers and/or solvent resulted in lower number-average molecular weight (M?_n ? 20,000–30,000) and wider distributions (M?_w/M?_n = 3–5). The Mark-Houwink relation obtained was [η] = 1.85 × 10^?4M?_w^0.80 The exponent is characteristic of moderately extended solvated coils. The unperturbed chain dimensions (r₀² /M)^1/2 were 0.848 A., and the steric factor σ was 1.24 which is close to the limiting value of unity for an equivalent chain with free internal rotations. The sedimentation constant–molecular weight relation was S₀ = 2.70 × 10^?2M?_w^0.39. This exponent is consistent with the Mark-Houwink exponent.     

Metallderivate von Molekülverbindungen. V. Synthese und Struktur von Hexakis{lithium-[tris(trimethylsilyl)silyl]tellanid}—Cyclopentan (1/1)

Metal Derivatives of Molecular Compounds. V. Synthesis and Structure of Hexakis{lithium-[tris(trimethylsilyl)silyl]tellanide}—Cyclopentane (1/1) . Lithium [tris(trimethylsilyl)silyl]tellanide—DME (1/1) [1 b] prepared from lithium tris(trimethylsilyl)silanide—DME (2/3) [3] and tellurium, reacts with hydrogen chloride in toluene to form [tris(trimethylsilyl)silyl]tellane ( 1 ) [1 b]. Subsequent metalation of this compound with lithium n-butanide gives lithium [tris(trimethylsilyl)silyl]tellanide ( 2 ) free of coordinating solvent. Pale yellow crystals are obtained from cyclopentane solution. An X-ray structure determination {P1 ; a = 1 558.5(7); b = 1 598.4(8); c = 1 643.5(6) pm; α = 117.64(4); β = 91.63(3); γ = 117.19(3)°; Z = 1; R = 0.032} shows them to be the (1/1) packing complex ( 2 ′) of hexakis{lithium-[tris(trimethylsilyl)silyl]tellanide} and disordered cyclopentane molecules —{Li? Te? Si[Si(CH₃)₃]₃}₆ · C₅H₁₀.     

Living cationic polymerization of vinyl ethers with a urethane group

To study the possibility of living cationic polymerization of vinyl ethers with a urethane group, 4‐vinyloxybutyl n‐butylcarbamate ( 1 ) and 4‐vinyloxybutyl phenylcarbamate ( 2 ) were polymerized with the hydrogen chloride/zinc chloride initiating system in methylene chloride solvent at ?30 °C ([monomer]₀ = 0.30 M, [HCl]₀/[ZnCl₂]₀ = 5.0/2.0 mM). The polymerization of 1 was very slow and gave only low‐molecular‐weight polymers with a number‐average molecular weight (M_n) of about 2000 even at 100% monomer conversion. The structural analysis of the products showed occurrence of chain‐transfer reactions because of the urethane group of monomer 1 . In contrast, the polymerization of vinyl ether 2 proceeded much faster than 1 and led to high‐molecular‐weight polymers with narrow molecular weight distributions (MWDs ≤ ～1.2) in quantitative yield. The M_n's of the product polymers increased in direct proportion to monomer conversion and continued to increase linearly after sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixture, whereas the MWDs of the polymers remained narrow. These results indicated the formation of living polymer from vinyl ether 2 . The difference of living nature between monomers 1 and 2 was attributable to the difference of the electron‐withdrawing power of the carbamate substituents, namely, n‐butyl for 1 versus phenyl for 2 , of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2960–2972, 2004     

A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron,Gallium, Silicon,and Tin in Bridging Positions

The enantiomerically pure dibromoferrocene 3 [(S_p,S_p)‐1,1′‐dibromo‐2,2′‐di(isopropyl)ferrocene], equipped with two iPr groups in α positions, was prepared using known “Ugi amine” chemistry. Species 3 was targeted in order to gain access to new [1]ferrocenophanes ([1]FCPs) to be used as monomers for ring‐opening polymerization. The iPr groups on the sandwich unit were introduced to stabilize bridging moieties, as well as to increase solubilities of targeted metallopolymers. The planar chiral dibromide 3 can quantitatively be lithiated at 0 °C [2 equiv nBuLi, hexanes/thf (9:1), 30 min]. Salt‐metathesis reactions with respective element dichloride species gave chiral [1]FCPs with a variety of bridging moieties [ER_x=Ga[2‐(Me₂NCH₂)C₆H₄] ( 4 a ), SiMe₂ ( 4 b ), SntBu₂ ( 4 c ), BNiPr₂ ( 4 d )]. The new [1]FCPs were fully characterized including single‐crystal X‐ray analysis. The stabilizing iPr groups on the Cp rings increase the thermal stabilities of 4 b – d compared to known [1]FCPs, equipped with the same bridging moieties. All three compounds 4 b – d are volatile and could be isolated by vacuum sublimation. Our new approach to [1]FCPs has the potential to overcome many of the existing difficulties in ferrocenophane chemistry, such as limited stability of starting monomers and low solubilities of resulting polyferrocenes.     

非离子型可聚合聚氨酯/苯乙烯的超浓乳液聚合

研究了以非离子型可聚合聚氨酯(PUAG)和苯乙烯(St)为混合单体的超浓乳液聚合, 并且考察了n(NCO)/n(OH)摩尔比、复合乳化剂体系质量浓度[E]、不同乳化剂的种类、引发剂质量浓度[I]、单体体积分数(或分散相体积分数, 也称内相比Φ)、聚合温度等因素对聚合稳定性、动力学的影响. 同时结合光相关光谱(PCS)测定了聚合物乳胶粒子大小和粒径分布, 用透射电子显微镜(TEM)观察了粒子形态, 结果表明: 当n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, [I]＝0.8% g/g (PUAG-St), [E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O时, 超浓乳液不仅有较好的聚合稳定性和较快的聚合速率, 而且粒径小分布均匀. 同时, 在此条件下的表观动力学表达式和表观活化能分别确定为R_p＝k[I]^0.50[E]^0.73[M]^0.54和 E_a＝29.7 kJ/mol. 热失重分析(TGA)进一步表明: 调节PUAG的含量可以达到对聚苯乙烯的改性, 提高聚苯乙烯的热稳定性.     

Polymerization by oxidation coupling. I. A study of the oxidation of 2,6-diphenylphenol to poly(2,6-diphenyl-1,4-phenylene ether)

The synthesis of poly(2,6-diphenyl-1,4-phenylene ether), by the oxidative coupling of 2,6-diphenylphenol has been studied. Procedures were found which demonstrated that polymers of very high molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\overline M _n > 200{\rm 000; }\left[ \eta \right]_{{\rm CHCl}_{\rm 3} }^{25^\circ {\rm C}} > 1.1{\rm }{{{\rm dl}} \mathord{\left/ {\vphantom {{{\rm dl}} g}} \right. \kern-\nulldelimiterspace} g}} \right) $\end{document} could be made with a copper-amine catalyst system. A low nitrogen-to-copper ratio (1 N atom/Cu atom) was necessary to obtain the very high molecular weights under the conditions of these reactions. A variety of amines formed active catalysts; the effectiveness of mono- and bis- primary, secondary, and tertiary amines were compared. Effects of the type of copper halide, reaction temperature, desiccants, addition rates of 2,6-di-phenylphenol, and solvents were also examined. Samples of polymer were isolated at different times during the polymerization. Measurements of viscosity, osmotic pressure, light scattering, gel permeation, phenolic hydroxyl groups, and nitrogen content were made on various samples over a range of intrinsic viscosities of 0.05–0.59 dl/g. A very narrow molecular weight distribution was found for all samples. Hydroxyl endgroup analyses indicated that the concentration of phenolic endgroups per mole of polymer does not change during the polymerization. The presence of some side reactions is indicated by nitrogen analyses. The relationships between the intrinsic viscosity in chloroform at 25°C and M?_n and M?_w are: log [η] = ?3.97 + 0.72₇ log M?_n and log [n] = ?3.56 + 0.62₄ log M?_w.