The equilibrium and kinetic rigidity of additive poly(trimethylsilyltricyclononenes) with one and two Si(CH<Subscript>3</Subscript>)<Subscript>3</Subscript> groups in monomer unit

The homologous series of additive poly[3-(trimethylsilyl)tricyclononene-7] with two heminal substituents Si(CH₃)₃ in the side cycle of the monomer unit is studied for the first time via the methods of viscometry and static and dynamic light scattering in the range of molecular masses of (29–770) × 10³. The scaling ratios for the intrinsic viscosity and the coefficient of translational diffusion of macromolecules in toluene at 298 K are obtained, and the equilibrium rigidity of the polymer chain is determined. The hydrodynamic and conformation properties of the polymer are compared to an analog with only one Si(CH₃)₃ substituent in the monomer unit. It is found that the introduction of the second side substituent in the heminal position increases the equilibrium rigidity of the additive poly[3-(trimethylsilyl)tricyclononene-7] by 1.4 times and has a far stronger effect on the kinetic rigidity of the polymer. With the use of the ¹Н NMR relaxation method, it is shown that the mobility of side groups of the polymer with two substituents decreases significantly and the correlation times of hydrogen atoms of Si(CH₃)₃ groups exceed some 20 times the corresponding values for the analog with one Si(CH₃)₃ group in the monomer unit cycle.     

Membrane separation of multicomponent mixture of alkanes C1–C4

The membrane separation of the four-component mixture of gaseous alkanes C₁–C₄ is studied. Homogeneous films based on two high-permeable polymers, namely, addition-type poly[3-(trimethylsilyl)tricyclononene-7] and poly[3,4-bis(trimethylsilyl)tricyclononene-7], are used as membranes. Separation of the multicomponent mixture of hydrocarbons on these polymers follows the same trends as separation of binary mixtures CH₄-C₄H₁₀ on polyacetylenes. In the presence of higher hydrocarbons, the permeability coefficients of methane decrease and the permeates become enriched with higher hydrocarbons. During separation of the multicomponent mixture, permeability coefficients P(C₄H₁₀) attain high values (up to 12000 Barrers).     

Bromination of poly[1-(trimethylsilyl)-1-propyne] with different microstructures and properties of bromine-containing polymers

The interaction between poly[1-(trimethylsilyl)-1-propyne] with different microstructures and bromine has been studied in carbon tetrachloride and chlorobenzene at 25–120°C. Depending on the process conditions, polymers containing up to 26 wt % bromine are formed; that is, every other unit of the polymer chain is brominated. Polymers enriched with cis structures are brominated through trimethylsilyl groups, and the process is unaccompanied by polymer chain degradation. The bromination of samples containing predominantly trans-structures is nonselective, and the reaction is accompanied by polymer degradation. The solubility of brominated poly[1-(trimethylsilyl)-1-propyne] in different media and the gas permeability of films made of this polymer are estimated.     

Kinetics of weight loss and chain scission in the thermooxidative degradation of poly[1-(trimethylsilyl)-1-propyne] films

The kinetic model of thermooxidative degradation in air, proposed to be valid for poly(2-hexyne) in predicting the lifetime of substituted polyacetylenes, was applied to poly[1-(trimethylsilyl)-1-propyne] films, with the differences in the oxidative behavior of both polyacetylenes noted. The effect of the molecular weight of the sample on the degradation process was analyzed. Kinetics of weight loss and chain scission were modeled, and the kinetic parameters were calculated. Also, the evolution of weight loss was related to the chain scission. The proposed model was validated with data reported in the literature. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4309–4317, 1999     

Molecular simulation and experimental study of substituted polyacetylenes: fractional free volume, cavity size distributions and diffusion coefficients

Glassy, disubstituted acetylene-based polymers exhibit extremely high gas permeabilities and high vapor/gas selectivities, which is quite unusual for conventional glassy polymers such as polysulfone. Diffusion coefficients of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) and poly[diphenylacetylene] (PDPA) were obtained using both molecular simulation and experimental techniques. PTMSDPA, a disubstituted glassy acetylene-based polymer, exhibits higher diffusivity than its desilylated analogue, PDPA. Simulation results are in good agreement with experimental data. Cavity size (free volume) distributions of both polymers are also obtained using an energetic-based algorithm (in't Veld et al., J. Phys. Chem. B 2000, 104, 12028) developed recently. Larger cavities in PTMSDPA contribute to its higher diffusivity, and higher permeability.     

Comparison of gas diffusion in poly[1‐(trimethylsilyl)‐1‐propyne] and poly(dimethylsiloxane) by atomistic modeling

Diffusion of light gases in poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP) and poly(dimethylsiloxane) (PDMS) was investigated by a molecular dynamics technique. Diffusion coefficients of helium and neon in PTMSP were larger than those in PDMS due to the larger free volume fraction of PTMSP in spite of its higher chain rigidity. This indicates that the amount of the free volume fraction is a more important factor than the redistribution of the free volume for the diffusion of light gases in either polymer. Conformational relaxation was not observed during the simulations for either PTMSP or PDMS, and therefore only thermal fluctuations could redistribute the free volume in both polymers. The higher chain flexibility of PDMS seems to redistribute the free volume more effectively by thermal fluctuation.     

Surface characterization and liquid crystal alignment behavior of comb-like poly(oxyethylene)/poly(3-hexylthiophene) blend films

The blend surfaces of poly[oxy(n-decylsulfonylmethyl)ethylene] (CH(3)-10SE) and poly (3-hexylthiophene) (P3HT) with different weight ratios were prepared by spin coating the polymer solution mixtures. In this study, their surface properties such as surface morphology, chemical composition, molecular structure, and wettability were systematically studied and correlated with liquid crystal (LC) alignment behaviors on the blend films. Therefore, we found that CH(3)-10SE part with a well-ordered side chain structure predominantly affects the both of wettability and LC alignment behavior of the blend films while there was no clear association between the wettability and the LC alignment behavior.     

Hydrodynamic and electrooptical properties of star-shaped heteroarm fullerene (C60)-containing polymers in solutions

Star-shaped heteroarm polymers with a C₆₀ branching center and polystyrene and poly(2-vinylpyridine) arms of equal molecular masses have been studied by the methods of molecular hydrodynamics (translational diffusion and viscometry) and electrooptics (the Kerr effect). The experimental hydrodynamic data are interpreted in terms of the regular star model. The molecular masses and hydrodynamic sizes of star-shaped heteroarm polymers in solutions are estimated. A comparison of these values with the corresponding parameters of linear polymer-analogs (polystyrene and poly(2-vinylpyridine)) makes it possible to characterize the branching degree of macromolecules. The study of the electrooptical properties of the heteroarm polymer in benzene demonstrates the tendency of macromolecules toward aggregation.     

Hydrodynamic, conformational, and electrooptical properties of cylindrical dendrimers with dendron ionic addition in solutions

Cylindrical dendrimers of first, second, and third generations with side dendrons based on L-aspartic acid which are attached to poly(styrenesulfonic acid) chains via ionic bonds are studied by molecular hydrodynamic, optical, and electrooptical measurements. Macromolecules of the said dendrimers demonstrate significant kinetic rigidity in external electric and hydrodynamic fields simultaneously with moderate equilibrium chain rigidity. The comparative analysis of the experimental data on various cylindrical dendrimers with the polyvinyl backbone and L-aspartic acid-based dendrons is performed. It has been shown that, in solvents not disturbing intramolecular hydrogen bonds between side dendrons, the conformational and dynamic properties of various cylindrical dendrimers are similar. The molecular characteristics of cylindrical dendrimers in non-dissociating solvents are insignificantly affected by the mode of dendron attachment to the backbone (covalent or ionic binding).     

Preparation and near-infrared optical limiting property of fluorene-containing functional polyacetylene

A novel functional polyacetylene containing fluorene group as a pendant,poly（2-（p-methylstyrene）-7-acetylene-9,9-dioctyl-fluorene）, was synthesized in moderate yield by[Rh（nbd）Cl]₂-Et₃N catalyst.The structures and properties of monomer and polymer were characterized and evaluated with FTIR,NMR,UV-vis,GPC and Z-scan,respectively.The results show that the incorporation of fluorene into polyacetylene has endowed the resultant polymer with well optical limiting properties for laser at wavelength 780 nm based on two-photon absorption mechanism.     

New imidazoisoquinoline ladder polymers

In previous studies on poly{(7-oxo-7, 10H-benz[de]imidazo[4′,5′:5,6]-benzimidazo-[2,1-a]isoquinoline-3,4:10,11-tetrayl)-10-carbonyl} it was observed that the polymer exhibits very unusual film-forming properties. The ladder polymer forms supermolecular aggregates in solution which translates to a high degree of interchain packing in the bulk. New ladder imidazoisoquinoline polymers have been prepared in an effort to relate the variance of molecular structure to the aggregation behavior of this class of polymers. The polymers were prepared from the solution polycondensation of 1,4,5,8-naphthalene tetracarboxylic acid or dianhydride with 1,2,5,6-tetraaminonaphthalene, 2,3,7,8-tetraaminophenazine and 2,3,7,8-tetraaminodibenzofuran. It was found that the extent of interchain packing in the bulk is dependent to a large degree on the molecular geometry of the polymer backbone.     

Diffusivity of gases and main-chain cooperative motions in plasticized poly(vinyl chloride)

Permeability and time-lag measurements for H₂ and CO in poly(vinyl chloride) (PVC) plasticized with tricresyl phosphate show that the apparent diffusion coefficients at first decrease as the plas-ticizer concentration is increased. The diffusion coefficients then increase as the additive concentration is raised above 15 wt %. These changes in the apparent diffusion coefficients can be related to the behavior of a variety of mechanical properties and are attributed to antiplasticization and plasticization effects of low and high concentrations of tricresyl phosphate, respectively. The antiplasticization-plasticization effects reflect altered molecular motions of the polymer. Carbon-13 NMR rotating-frame relaxation rate measurements show directly that the cooperative main-chain molecular motions of PVC are reduced when the additive acts as an antiplasticizer and are increased when the polymer is plasticized. Both the apparent diffusion coefficient and the rotating-frame relaxation rate have a similar dependence on additive concentration. An application of the molecular theory of diffusion of Pace and Datyner accounts qualitatively for the way in which additives alter the average chain interaction energy, cooperative polymer main-chain motions, and the diffusion coefficients of gaseous penetrants.     

Hydrodynamic, electrooptical, and conformational properties of fullerene-containing poly(2-vinylpyridines) in solutions

For C₆₀ fullerene-containing poly(2-vinylpyridines) synthesized by anionic polymerization, the molecular mass and hydrodynamic size of macromolecules in solutions have been determined by molecular hydrodynamics (translational diffusion and viscometry) and electrooptics in dilute benzene and THF solutions. Under the same conditions in the molecular mass range (9.8–123) × 10³, the hydrodynamic behavior of linear poly(2-vinylpyridines) and their molecular-mass dependences have been examined and the conformational characteristics of macromolecules have been established. The branching of macromolecules has been characterized by comparing the properties of star-shaped fullerene-containing and linear poly(2-vinylpyridines). With consideration of the hydrodynamic data interpreted within the framework of regular star model, it is inferred that on average three to four linear polymer chains with a molecular mass of (8 ± 3) × 10³ for each chain are attached to a fullerene core of C₆₀ in molecules of fullerene-containing poly(2-vinylpyridines). The specific Kerr constant of fullerene-containing poly(2-vinylpyridines) in dilute benzene solution is ?(14 ± 1) × 10^?12 cm⁵/[g (300 V)²]. As evidenced by the electrooptical data, the incorporation of fullerene into the polymer weakens self-association of macromolecules in solution.     

Thermal degradation of a polyphenylimide-quinoxaline in air and under vacuum

Three samples of poly{2,2′-[N,N′-bis(1,4-phenylene)benzophenone-3,3′,4,4′-tetracarboxylimide-6,6′-bis(3-phenyl-quinoxaline)]} (PPIQ), were prepared, differing in molecular weights and polymer chain endings. Their thermal degradation in vacuo and in air was determined by isothermal weight loss measurements. As in the case of poly-[2,2′-(1,4-phenylene)-6,6′-bis(3-phenylquinoxaline)] (PPQ), the temperature coefficients of thermal degradation in air were independent of molecular weight. However, in contrast, the temperature coefficients were independent of the type of polymer endgroups. It is, therefore, concluded that, contrary to amino-terminated PPQ's, polymer chain-end unzipping of PPIQ is of minor importance during thermal-oxidative degradation.     

Hydrodynamic and conformational properties of silicon-substituted addition-type polynorbornene macromolecules

Seven polynorbornene samples containing trimethylsilyl side groups that were prepared by the addition polymerization of 5-trimethylsilyl-2-norbornene in the presence of catalytic systems (π-C₅H₉NiCl)₂-methylaluminoxane and nickel naphthenate-methylaluminoxane have been studied by translational isothermal diffusion and viscometry. The molecular masses of the polymer samples are measured. Kuhn-Mark-Houwink equations for diffusion coefficient D and intrinsic viscosity [η] are determined in toluene at 25°C: D = 6.94 × 10^?4 M ^?0.61 and [η] = 1.53 × 10^?3 M ^0.82. The equilibrium rigidity of polymers chains is estimated as A = 47 ± 9 Å. The conformational features of the silicon-containing polynorbornene are analyzed by the PM3 quantumchemical semiempirical method on the basis of simulation of its decamer chain fragments. In terms of microstructure and equilibrium rigidity, the above-described addition poly(trimethylsilylnorbornene) is close to poly(trimethylsilylpropyne) synthesized using niobium pentachloride as a catalyst. This finding explains similar membrane gas-separation properties of these polymers.     

Molecular weight dependence of emission intensity and emitting sites distribution within single conjugated polymer molecules

We investigated exciton migration, trapping and emission processes occurring within a single conjugated polymer molecule by means of superresolution fluorescence localization microscopy. This methodology allowed us to locate the spatial distribution of emitting sites within single chains with nanometre precision. The study was done on individual poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) molecules with average molecular weights ranging from 215,000 to 1,440,000 and with narrow weight distributions. We found that the mean emission intensity increases proportionally to the polymer molecular weight. The localization experiments suggest that the emitting sites are distributed nearly uniformly within a single chain and that the sites are on average 10 nm apart, irrespective of the molecular weight of the polymer. Furthermore, spatial contours formed by all the combined emitting sites within one chain show elongated shapes, in agreement with a rod-like structure of MEH-PPV in a collapsed state.     

Synthesis and comparison of the structure–property relationships of symmetric and asymmetric water‐soluble poly(p‐phenylene)s

Sodium salts of water‐soluble polymers poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(hexyloxy)‐1,4‐phenylene]} ( P1 ), poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(dodecyloxy)‐1,4‐phenylene]} ( P2 ), poly{[2,5‐bis(3‐sulfonatopropoxy)‐1,4‐phenylene]‐alt‐[2,5‐bis(dibenzyloxy)‐1,4‐phenylene]} ( P3 ), poly[2‐hexyloxy‐5‐(3‐sulfonatopropoxy)‐1,4‐phenylene] ( P4 ), and poly[2‐dodecyloxy‐5‐(3‐sulfonatopropoxy)‐1,4‐phenylene] ( P5 )] were synthesized with Suzuki coupling reactions and fully characterized. The first group of polymers ( P1 – P3 ) with symmetric structures gave lower absorption maxima [maximum absorption wavelength (λ_max) = 296–305 nm] and emission maxima [maximum emission wavelength (λ_em) = 361–398 nm] than asymmetric polymers P4 (λ_max = 329 nm, λ_em = 399 nm) and P5 (λ_max = 335 nm, λ_em = 401 nm). The aggregation properties of polymers P1 – P5 in different solvent mixtures were investigated, and their influence on the optical properties was examined in detail. Dynamic light scattering studies of the aggregation behavior of polymer P1 in solvents indicated the presence of aggregated species of various sizes ranging from 80 to 800 nm. The presence of alkoxy groups and 3‐sulfonatopropoxy groups on adjacent phenylene rings along the polymer backbone of the first set hindered the optimization of nonpolar interactions. The alkyl chain crystallization on one side of the polymer chain and the polar interactions on the other side allowed the polymers ( P4 and P5 ) to form a lamellar structure in the polymer lattice. Significant quenching of the polymer fluorescence upon the addition of positively charged viologen derivatives or cytochrome‐C was also observed. The quenching effect on the polymer fluorescence confirmed that the newly synthesized polymers could be used in the fabrication of biological and chemical sensors. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3763–3777, 2006     

烷基步长对聚丙烯酸修饰咔唑电聚合的影响

合成了含有不同烷基链取代的N-丙烯酰氧癸基咔唑(MACZ10)和N-丙烯酰氧十二烷基咔唑(MACZ12), 通过自由基聚合得到聚N-丙烯酰氧烷基咔唑(PMACZ). 分子量分析表明, 随着烷基链长度的增加, 聚合物分子量减小, 分布变宽. 荧光光谱表明, 随着烷基链长度的增加, 聚合物在353 nm处的发射峰逐渐减弱. 在四氢呋喃和体积分数为10%三氟化硼乙醚与四氟化硼四丁基胺的混合电解质溶液中, 直接阳极氧化PMACZ获得自支撑交联网状的聚(聚N-丙烯酰氧烷基咔唑)(PPMACZ)薄膜. PPMACZ薄膜具有良好的氧化还原活性、热稳定性和蓝色发光性能, 聚合物氧化还原可逆性随着烷基链长的增加而增加, 且发射峰变宽.     

Well-defined boron-containing polymeric lewis acids

A general new route to well-defined polymeric Lewis acids via borylation of silylated polymers is reported. Trimethylsilylated polystyrene (PS-Si) of controlled molecular weight and low polydispersity (PDI < 1.15) was obtained via atom transfer radical polymerization (ATRP) of 4-(trimethylsilyl)styrene. The functional polymer PS-Si was quantitatively borylated using BBr3 to give poly(4-dibromoborylstyrene) (PS-B), a novel soluble boron-containing polymeric Lewis acid. PS-B readily reacted with nucleophiles serving as a precursor to a family of new polymers with boron centers of variable Lewis acidity. Reaction of PS-B with Cu(C6F5) gave the highly Lewis acidic polymer poly[4-bis(pentafluorophenyl)borylstyrene], the first polymeric analogue of tris(pentafluorophenyl)borane.     

Ferroelectric liquid crystalline polymers based on mesogens with halogen-containing terminal groups

A new series of halogen-containing side chain ferroelectric liquid crystal polymers was synthesized. Mesophases were characterized by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction and molecular simulation. The behaviour of the liquid crystalline phase was investigated with variation of chiral centres, spacer units and grafted ratios. It was found that the thermal stability and temperature range of the chiral smectic C phase decreased with increasing length of the oligo-oxyethylene spacer, and decreasing mesogenic group content. The bulky substituent attached to the chiral centre reduces molecular packing in smectic liquid crystal phases, which disturbs the orientation of the side chain liquid crystal polymer. Furthermore, the influence of molecular structure on electrooptical properties of FLCPs has been studied by broad band dielectric spectroscopy (from 0.1 to 1 ×10 6 Hz).