A method for the synthesis of polymer photochromic composites containing photochromic nitro-substituted spiropyran via mechanical mixing in melt is developed, and dependences of the spectral and kinetic properties of the samples on the nature of chosen thermoplastic polymer matrices (polyolefins, polycarbonate) and their processing temperatures are studied.

To develop materials with new mechanical and improved rheological properties on the basis of common polyolefins, ultrahigh-molecular-weight PE and HDPE of medium molecular masses, the polymers have been modified with low-molecular-mass additives: crystalline organic disulfides (dithiaalkanes), liquid oligomer phenylmethylsiloxane, and oligooxypropylene glycol. It has been shown that the studied disulfide additives at low concentrations (up to 10% of the mass of PE) have no significant effect on the content and quality of the crystalline phase of HDPE. (The degree of crystallinity, enthalpy, and melting temperature change weakly.) In this case the plasticity of the modified PE improves: the tensile modulus and dynamic modulus decrease, whereas the elongation at break increases. In the presence of organic disulfides, the effective viscosity of the PE melt decreases. Unlike oligomeric phenylmethylsiloxane and oligooxypropylene glycol, dithiaalkanes are inert to the components of metallocomplex catalysts. Thus, the modification of PE with the aforementioned additives may be performed via their addition to the final polymer or in the course of the synthesis of the polymer.

Macromolecular SymposiaVolume 296, Issue 1 p. v-xix ContentsFree Access Macromol. Symp. 296 First published: 29 November 2010 https://doi.org/10.1002/masy.201090028AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume296, Issue1Special Issue: Modern Trends in Polymer Science – EPF'09 –October 2010Pages v-xix RelatedInformation

The polarized Raman spectroscopy is employed in the study of structural modifications in the films of isotactic polypropylene (PP) whose chain contains ethylene, 1-butene, 1-hexene, 1-octene, and 4-metyl-pentene-1, which represents an isomer of 1-hexene. It is demonstrated that the phase and conformational compositions of copolymer molecules depend on the comonomer content and the side-chain length of the second monomer. The content of the PP molecules in the helical conformation in the crystalline and amorphous phases of the copolymers monotonically decreases with increasing content of the second monomer. The decrease in the content of helical macromolecules in the crystalline phase is faster than the decrease in the amorphous phase. At a certain content of comonomers, the total content of the helical fragments decreases with increasing length of the side chain of the second monomer. The structures and Raman spectra of the copolymers of propylene with 1-hexene and 4-methyl-1-pentene are similar.

The copolymerization of propylene with 1-octene in liquid propylene is carried out in the presence of a highly active homogeneous ansa-m etallocene catalyst with the C 2-symmetry rac-Me2Si(4-Ph-2- MeInd)2ZrCl2 activated by methyl aluminoxane and in the presence of ansa- metallocene C4H6Si(2-Et4- PhInd)2ZrCl2 (rac: meso = 2:1) supported on silica gel treated with methylaluminoxane. In the case of the heterogenized metallocene, (iso-C 4 H 9 )3Al is used as a cocatalyst. The copolymers of propylene and 1-octene containing up to 24 and 9.3 mol% units of the second comonomer are prepared with the homogeneous and heterogenized systems, respectively. The copolymerization of propylene with 1-octene in liquid propylene shows the azeotropic (ideal) character, and the distribution of comonomer units in the copolymers is close to statistical. The modification of PP with even small amounts of 1-octene affects the regularity of polymer chains, molecular-mass characteristics of the copolymers, their melting temperature, and the degree of crystallinity and makes it possible to vary their rigidity and elasticity in a wide range. The character of changes in thermal and mechanical properties is almost the same for the copolymers synthesized with homogeneous and heterogenized catalysts.

Nascent form of random copolymers of propylene with ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 809 and 841 cm(-1). The first line corresponds to vibrations of polypropylene helical chains in the crystalline phase, while the second one is associated with vibrations of polypropylene helical chains having isomeric defects. Raman data confirm that conformational composition and phase state of copolymer macromolecules strongly depend on the comonomer content as well as on the size of the comonomer units.

The effect of dc discharge on norbornene-ethylene copolymer films containing 30 and 60% norbornene was studied. It was found that plasma treatment leads to substantial changes in the surface properties of the copolymer, the enhancement of wettability, and an increase in the work of adhesion and surface energy, including its polar term. The change in the surface structure of the films was investigated by means of Fourier-transform IR spectroscopy. Transparent and colorless triplexes with a light transmission of 86–90% were prepared on the basis of the discharge-modified copolymer films and a cycloaliphatic epoxy resin.

Исследовано воздействие разряда постоянного тока на пленки сополимеров этилена и норборнена, содержащие 30 и 60% норборнена. Установлено, что воздействие плазмы приводит к существенному изменению поверхностных свойств сополимеров – увеличению смачиваемости, работы адгезии и поверхностной энергии, в том числе ее полярного компонента. Методом Фурье-ИК-спектроскопии изучено изменение структуры поверхности пленок. На основе модифицированных в разряде пленок сополимера и циклоалифатической эпоксидной смолы получены прозрачные и бесцветные триплексы, обладающие светопропусканием 86–90%.

Results of comprehensive systematic physicochemical studies of the blends of ethyl cellulose and butadiene-acrylonitrile rubbers are reported. It is shown that the addition of butadiene-acrylonitrile rubbers to ethyl cellulose results in the formation of ethyl cellulose-butadiene-acrylonitrile rubber thermoelastoplastic complexes due to the elastification of the thermoplastic polymorphous structure of ethyl cellulose with enhanced impact strength and heat resistance.

The copolymerization of ethylene with propylene in the liquid propylene initiated by ansa -metallocenes of the C 1 symmetry, rac -[1-(9-η 5 -fluorenyl)-2-(5,6-cyclopenta-2-methyl-1-η 5 -indenyl)ethane]zirconium dichloride and rac -[1-(9-η 5 -fluorenyl)-2-(5,6-cyclopenta-2-methyl-1-η 5 -indenyl)ethane]hafnium dichloride, activated by methylaluminoxane has been studied. Triisobutylaluminum has been used as a cocatalyst. The propylene-ethylene copolymers thus prepared contain 5–60 mol % ethylene units. The reactivity ratios have been measured. In the case of the zirconocene-based catalyst, the molecular mass of the copolymers decreases with an increase in the content of ethylene units. The reverse situation is observed in the case of the hafnocene-based catalytic system. The copolymers are characterized by the low T g values (down to −45°C). Incorporation of a small amount of ethylene units (5 mol %) results in a rise in the elastomeric behavior of the polymers.

Bulk propylene polymerization in the presence of ansa-metallocenes with C-2 and C-1 symmetries has been studied. The catalytic activity, polymerization kinetics, and the molecular weight of polypropylene (PP) depend strongly on catalyst formation conditions. Mixtures of rac and meso isomers of metallocenes make it possible to rapidly produce a high-molecular-weight isotactic PP with high stereoregularity and mechanical characteristics and thus skip the stage of the isolation of pure rac isomer in the catalyst synthesis. The ability of triisobutylaluminum to serve as a cocatalyst is studied for ansa-metallocenes of C-1 symmetry. In this case, the molecular weight of PP is higher, indicating that organoaluminum compounds participate in chain termination reactions. An increase in the reaction temperature results in an increase in the stereoregularity and crystallinity of PP. Polypropylene synthesized using ansa-metallocenes of C-1 symmetry has good elastomeric properties.

Three new titanium complexes bearing salicylidenimine ligands-bis[(salicylidene)-2,3,5,6-tetrafluoroanilinato] titanium (IV) dichloride (1), bis[(3,5-di-tertbutylsalicylidene)-2,3,5,6-tetrafluoroanilinato]titanium(IV) dichloride (2), and bis[(3,5-di-tert-butylsalicylidene)-4-trifluoromethyl-2,3,5,6-tetrafluoroanilinato]titanium(IV) dichloride (3)-were synthesized. The catalytic activities of 1-3 for ethylene polymerization were studied with poly(methylaluminoxane) (MAO) as a cocatalyst. Complex 1 was inactive in ethylene polymerization. Complex 2 at a molar ratio of cocatalyst to pre catalyst of Al-MAO/Ti = 400-1600 showed very high activity in ethylene polymerization comparable to that of the most efficient metallocene complexes and titanium compounds with phenoxy imine and indolide imine chelating ligands. It gave linear high-molecular-weight polyethylene [weight-average molecular weight (M-w) greater than or equal to 1,700,000. weight-average molecular weight/number-average molecular weight (M-w/M-n) = 4-5] with a melting point of 142degreesC. The ability of the 2/MAO system to copolymerize ethylene with hexene-1 in toluene was analyzed. No measurable incorporation of the comonomer was observed at 1:1 and 2:1 hexene-1/ethylene molar ratios. However, the addition of hexene-1 had a considerable stabilizing effect on the ethylene consumption rate and lowered the melting point of the resultant polymer to 132degreesC. The 2/MAO system exhibited low activity for propylene polymerization in a medium of the liquid monomer. The polymer that formed was high-molecular-weight atactic polypropylene (M-w similar to 870,000, M-w/M-n = 9-10) showing elastomeric behavior. The activity of 3/MAO in ethylene polymerization was approximately 70 times lower than that of the 2/MAO system. (C) 2005 Wiley Periodicals, Inc.

Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-1 H-indenyl) ethanes 1a,b and C1-symmetric metallocenes, viz., rac-1-(η5-fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-η5-inden-1-yl) ethanezirconium dichloride (9) and rac-1-(η5-fluoren-9-yl)- 2-(2-methyl-5, 6-dihydrocyclopenta [f]η5-inden-1-yl)ethanehafnium dichloride (10), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 10 were established by X-ray diffraction analysis. The synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30–70°C. It was demonstrated that triisobutylaluminum can be used as a cocatalyst. In this case, the molecular weight of PP increases by a factor of ∼2. An increase in the reaction temperature leads to an increase in stereoregularity and crystallinity of PP. The polymer synthesized at high temperatures crystallizes in the γ form. The resulting PP is characterized by a wide range of properties from rigid crystalline thermoplastic to amorphous elastomeric. Samples, which have a high molecular weight and moderate isotacticity, exhibit high elastomeric and durability properties.

The titanium salicylideneimino complex TiCl 2 {η 2 -1-[NR=C(H)]-2-O-3,5-Bu t 2 -C 6 H 2 } 2 (R = 2,3,5,6-F 4 C 6 H) was synthesized. In the presence of polymethylaluminoxane, the complex efficiently catalyzes polymerization of ethylene and, to a lesser degree, atactic propylene. The resulting polymers are characterized by high melting points, molecular weights, and polydispersity indices, as well as elastomeric (polypropylene) properties.

The copolymerization of propylene and 1-hexene initiated by isospecific catalytic systems containin ansa-metallocene complexes with a C-2 symmetry, rac-Me2Si(Ind)(2)ZrCl2 and rac-Me2Si(4-Ph-2-Me-Ind)(2)ZrCl2), and a syndiospecific catalytic system based on a C-s symmetric complex Ph2C(Cp)(Flu)ZrCl2 was studied. Polymethylaluminoxane or a mixture of polymethylaluminoxane and Al-i-Bu-3 was used as a cocatalyst. The addition of small amounts of 1-hexene to the reaction mixture brings about activation of isospecific catalytic systems. The activity of 1-hexene in copolymerization varies in the sequence: rac-Me-2 Si(Ind)(2)ZrCl2 < rac-Me2Si(4-Ph-2-Me-Ind)(2)ZrCl2 < Ph2C(CP)(Flu)ZrCl2. It was shown that the resulting copolymers are characterized by a monomer unit distribution close to random (r(1)r(2) = 0.7-1.9). An optimum Al-i-Bu-3 : Zr ratio ensuring a marked reduction in the consumption of poly methylaluminoxane with a concomitant increase in the copolymer yield was determined. It was shown that the incorporation of even small amounts of 1-hexene (0.9-12.0 mol %) into PP chains leads to a decrease in its melting temperature and degree of crystallinity and causes an appreciable rise in the elasticity and impact strength of the final polymers.