Chemical modification of copoly(methylsilylene/1,4-phenylene) by Pt-catalyzed hydrosilation reactions with functionally substituted alkenes

Copoly(methyl-3-biphenoxypropylsilylene 1,4-phenylene), copoly(methyl-3-cyanopropylsilylene 1,4-phenylene), copoly(methyl-3-ethoxypropylsilylene 1,4-phenylene), copoly(methyl-3-phenoxypropylsilylene 1,4-phenylene), and copoly(methyl-4,7,10,13-tetraoxatetradecanylsilylene 1,4-phenylene) have been prepared by platinum-catalyzed hydrosilation graft reactions between poly (methylsilylene 1,4-phenylene) and appropriate functionally substituted alkenes. These polymers have been characterized by¹H,¹³C, and²⁹Si NMR as well as by FT-IR and UV-vis spectroscopy. The molecular weight distribution of these polymers has been determined by gel permeation chromatography (GPC), and their glass transition temperatures (T _e) by DSC.     

Hydride transfer to some initiators of cationic polymerization

Summary The hydride transfer from xanthene to stable carbenium salts with different cation electrophilities: 2,4,4'-trichlorotriphenylmethylhexachloroantimonate, triphenylmethylhexafluoroarsenate, triphenylmethylhexachloroantimonate, 4,4,4'-trimethyltriphenylmethylhexachloroantimonate and tropylium hexachloroantimonate is investigated. The reaction is controlled by the absorption of the carbenium ions in the visible region of their electronic spectra. The formation of the product of the reaction — triphenylmethane — is detected by gas chromatography and NMR spectroscopy. The rate constants and the reaction order are determined. The acceleration of the hydride transfer on UV-irradiation of the reaction mixture is shown.Paper presented at VII International Symposium Polymers '80, Varna, Bulgaria     

Preparation of poly(alkylvinylether)s for nonlinear optical applications

Summary 3,5-Dimethoxy-4-(2-vinyloxyethoxy)-4-nitrostilbene 2 and 3,5-dimethoxy-4-(2-vinyloxyethoxy)-2,4-dinitrostilbene 5 were prepared by the reactions of 2-iodoethyl vinyl ether with 3,5-dimethoxy-4-hydroxy-4-dinitrostilbene 1 and 3,5-dimethoxy-4-hydroxy-2,4-dinitrostilbene 4, respectively. Monomers 2 and 5 were polymerized with cationic initiators to obtain polymers with the NLO-phores 3,5-dimethoxy-4-oxy-4-nitrostilbene and 3,5-dimethoxy-4-oxy-2,4-nitrostilbene in the side chain. The resulting polymer 3 and 6 were soluble in DMSO and DMF. The inherent viscosities of polymers were in the range of 0.28–0.33 dL/g in DMSO. Polymers 3 and 6 showed good thermal stabilities in their TGA thermograms, and the T_g values from DSC thermograms were in the range of 81–87°C.     

Thermoplastic elastomers by hydrogen bonding

Summary Poly(butadienes) were modified by an ene-reaction using 4-phenyl-1, 2,4-triazoline-3,5-dione (1) 3-nitro-4-hydroxyphenyl-1, 2,4-triazoline-3,5-dione (2) and 4-hydroxyphenyl1, 2,4-triazoline-3,5-dione (3). The resulting hydrogen bond complexes between urazole groups act as thermoreversible crosslinks and alter the melt rheological behaviour. While dimeric chelate-like complexes are formed in polymers modified with 1 or 2, a three dimensional structure of hydrogen bond complexes is formed if 3 is used as the modifying agent. The thermorheologically complex behaviour of the latter material is interpreted by structural changes in the three dimensional structure with temperature.     

Thermotropic polyester: the influence of the spacer on the physical properties

Thermotropic polyesters prepared from series of 4,4-dihydroxy-,w-diphenoxy alkanes and 4,4-dichloroformyl-,w-diphenoxy alkanes are well known. The substitution of a methylenic spacer by an oxyethylenic spacer in the main chain of these polyesters drastically modifies their physical properties, particularly the mesogenic transition temperatures, as can be observed by DSC and thermooptical analysis. The thermal stability and the polymer solubility in common organic solvents of these polymers did not show a significant change. The physical properties of the two thermotropic polyesters prepared in diphenyl ether were evaluated.     

The electrochemical properties of polyaniline derivatives: poly(4,4′-diphenylamine methylenes) and poly(4,4′-diphenylimine methines)

Summary The electrochemical properties of poly(4,4-diphenylamine methylenes) and poly(4,4-diphenylimine methines) were investigated by cyclic voltammetry. A dehydrogenation reaction occured when poly(4,4-diphenylamine methylenes) underwent a electrochemical reaction and transformed to poly(4,4-diphenylimine methines). The fully oxidized poly(4,4-diphenylimine methines) had the electrochemical band gaps of 1.60–1.72 eV, which were found to significantly smaller than those of the fully reduced poly(4,4-diphenylamine methylenes).     

Photochromic polymers

Summary Two soluble photochromic polymers containing 1-(ß-hydroxyethyl)-3,3-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2-indoline] bound on a variously long side chain were prepared. It was found that the discolouration process depends on the length of the side chain to which the photochromic centre is bound.     

Syntheses and properties of polyimides based on bis(p-aminophenoxy)biphenyls

Three biphenyl unit-containing diamines,4,4-bis(p-aminophenoxy)biphenyl (III_a), 2,2-bis(p-aminophenoxy)biphenyl (III_b), and 3,3,5,5-tetramethyl-4,4-bis(p-aminophenoxy)biphenyl (III_c), were prepared by the chlorodisplacement ofp-chloronitrobenzene with 4,4-biphenol (I_a), 2,2-biphenol (I_b), and 3,3,5,5-tetramethyl-4,4-biphenol (I_c), respectively, giving the corresponding bis(nitrophenoxy) compounds II_a-c, followed by catalytic reduction with palladium (Pd) and hydrazine. Three series of polyimidesp-PI,o-PI, and Me-PI were prepared from diamines III_a-c and aromatic tetracarboxylic dianhydrides via a two-stage procedure that included ring-opening polyaddition to give poly(amic acid)s followed by thermal cyclodehydration to polyimides. The resultant three series of poly(amic acid)s had inherent viscosities of 1.09–2.83, 0.78–1.93, and 1.55–3.09 dL/g, respectively. Almost all the poly(amic acid)s could be solution-cast and thermally converted into transparent, flexible, and tough polyimide films. All the polyimides were characterized by solubility, tensile test, wide-angle X-ray scattering measurements, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Effects of the structures of aromatic diamines and dianhydrides on the properties of polyimides were investigated.     

Comparison of some 4- and 4,4′-substituted derivatives of stilbene for their reactivities towards the benzoyloxy radical

Summary 4-Fluoro- and 4,4-difluorostilbene are similar in their reactivities towards the benzoyloxy radical; a similar conclusion has been reached in respect of 4-chloro- with 4,4-dichlorostilbene and 4-phenyl-with 4,4-diphenylstilbene. These results have been obtained by consideration of the numbers of benzoate and phenyl end-groups in poly (methyl methacrylate) made using benzoyl peroxide in the presence of the appropriate derivative of stilbene.     

Synthesis of new metal-containing side-chain monomers and polymers

New metal-containing vinyl monomers, hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl]benzoyloxy}methacrylate, and the corresponding homopolymers and random copolymers with hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate were synthesized. The compounds were characterized by¹H NMR; their thermal behavior was investigated by means of differential scanning calorimetry. Monomers and polymers containing the ferrocene unit melt at lower temperatures than those derived from the cyclopentadienyl managanese tricarbonyl moiety. The melting temperatures of the monomers and polymers ranged from 399 to about 515 K, Both monomers and polymers failed to exhibit mesogenic behavior. Values ofM _n,M _w,M _w/M _n, and degree of polymerization were obtained by gel permeation chromatography. TheM _n ranged from 16,500 for the copolymer containing hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl] benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 26,000 for the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio.M _w/M _n ranged from 1.6 in the case of the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 2.2 in the case of poly(hexyl-6-oxy{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate).     

Enzymatic degradation of side chains of soluble polymers. Rate of release of 4-methyl-2-nitroaniline as a function of the side chain length

Summary A series of water-soluble polymers was prepared, formed in the copolymerization of 4-nitrophenol esters of methacryloylated -amino acids with N-(2-hydroxypropyl) methacrylamide and containing c. 3 mol.% of reactive groups. Groups degradable with chymotrypsin were bound to ends of variously long side chains by a polymeranalogous reaction with L-phenylalanine-4-methyl-2-nitroanilide. The dependence of the rate of degradation of 4-methyl-2-nitroaniline on the length of the side chain was investigated.     

The dispersion of polymethylsilsesquinoxane into polyimide

Summary Through the pretreatment of 4, 4-oxydianiline(ODA) with polyhydrogenmethylsiloxane (PHMS) using sodium hydroxide as a catalyst and subsequent reaction of this pretreated PHMS-ODA with 3, 3, 4, 4-benzophenonetetracarboxylic dianhydride(BTDA), polysiloxane can be attached to the polyamic acid by the silyl ester bond. By the thermal treatment of this polysioloxane—polyamic acid compound, well dispersed polymethylsilsesquinoxane(PMSQ) into polyimide can be obtained.     

Chelating polymers

Summary Chelating polymers were synthesized by polymer analogous reaction of polyethyleneimine with chelating agents: 2-hydroxy-4[2-chloroethanoyl]benzophenone, butanoic-4-oxo-4-(2-hydroxy-5-methyl-phenyl)acid and 4,4-o-o-succinoyl-bis-resorcylaldehyde. The chelating agents were characterized by IR, ¹H NMR and ¹³C NMR spectroscopy.The polychelates are insoluble in water and common organic solvents and they were characterized by IR spectroscopy. These polymers were contacted with an aqueous solution of copper(II), nickel(II) and cobalt(II).     

Ethynylene-disilanylene copolymers

Polymers of structure (SiR₂SiR₂-C C-SiR₂SiR₂-C C) _n , in which ethynylene units alternate with disilylene units, have been prepared by two routes: (a) condensation of dichlorodisilanes with dilithium derivatives of 1,2-diethynyldisilanes and (b) ring-opening polymerization of strained cyclic disilanylene-acetylnes, (SiR₂SiR₂C C)₂. The polymers display UV absorption near 240 nm indicative of – conjugation between the Si₂ and the C C moieties. Polymers with R=R=n-Bu or R=n-Bu, R=Ph, undergo solid-state transitions to form liquid crystalline mesophases resembling those observed for many poly(silylenes). Single crystals were obtained for the polymer with R=R=CH₃, by precipitation from dilute cyclohexane solution. The solid-state properties and structures of this family of polymers are discussed.This paper was presented at the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Ruthenium catalyzed regioselective step-growth copolymerization of 4′-methoxyacetophenone,or 4′-phenoxyacetophenone and α, ω-dienes

Summary Ruthenium catalyzed step growth copolymerization of 4-methoxyacetophenone or 4-phenoxyacetophenone and ,-dienes such as 1,3-divinyltetramethyldisiloxane or 3,3,6,6-tetramethyl-3,6-disila-1,7-octadiene give copolymers which have respectable molecular weights. The synthesis and characterization of these copolymers is reported. Higher molecular weight copolymers are quite thermally stable.     

Synthesis and polymerization of 2-(β-N-3′-halogencarbazolylethyl)-2-oxazolines

Summary The synthesis of three novel oxazoline monomers,all of which contain 3-halogen substituted carbazolyl groups [i.e., 2-(-N-3 chlorocarbazolylethyl)-2-oxazoline, 2-(-N-3 bromocarbazolylethyl)-2-oxazoline and 2-(-N-3 iodocarbazolylethyl)-2-oxazoline]and their polymerization is described.     

Shape-Selective Alkylation of Biphenyl over H-[Al]-SSZ-31 with Propylene

Isopropylation of biphenyl (BP) over [Al]-SSZ-31, a large-pore, one-dimensional zeolite has been studied. Effects of temperature, pressure and SiO₂/Al₂O₃ ratio were examined. SSZ-31 was found to be an active catalyst in the isopropylation of biphenyl with propylene. The selectivity for 4-isopropylbiphenyl (4-IPBP) and 4,4-diisopropylbiphenyl (4,4-DIPB) was high among isopropylbiphenyl (IPBP) and diisopropylbiphenyl (DIPB) isomers, respectively, indicating SSZ-31 shows shape-selective catalysis. The selectivity for 4,4-DIPB decreased with temperature increase; correspondingly the selectivity for thermodynamically more stable isomers (3,3- and 3,4 DIPB) increased with temperature. The yield of IPBP isomers decreased while that of DIPB isomers increased with temperature increase. Pressure showed less effect on conversion; however, increase in pressure suppresses the isomerization of 4,4-DIPB to 3,3- and 3,4-DIPB. Conversion decreased with increase in SiO₂/Al₂O₃ ratio. At low SiO₂/Al₂O₃ ratio of 136, relatively high triisopropylbiphenyl (TriIPB) isomers were formed in bulk products and their amount decreased with increase in SiO₂/Al₂O₃ ratio.     

Effects of Hydrothermal Treatment Conditions on the Catalytic Activity of HZSM-5 Zeolites in the Methylation of 4-Methylbiphenyl with Methanol

The objective of this work is to study the effects of hydrothermal treatment conditions on the methylation of 4-methylbiphenyl (4-MBP) with methanol under fixed-bed down-flow conditions. The results show that hydrothermal treatment temperature has a marked effect on the activity and selectivity in the methylation of 4-MBP with methanol. 4-MBP conversion decreases and the selectivity to 4,4-dimethylbiphenyl (4,4-DMBP) increases with an increase in the hydrothermal treatment temperature. The optimal temperature range is between 400 and 550 °C. After hydrothermal treatment, the catalytic selectivity to 4,4-DMBP is up to 70%, while the 4-MBP conversion is about 12%. The high selectivity over hydrothermally treated ZSM-5 largely results from the suppression of 4,4-DMBP secondary reactions such as isomerization and dealkylation, as demonstrated by the reaction of 4,4-DMBP as reactant over hydrothermally treated ZSM-5 and the parent zeolite.     

Isotopic exchange between H2 and D2 by the Rideal-Eley mechanism

The rate of the reaction, H₂+D₂ 2HD, is very rapid at –160 °C on the catalyst Cp₂Th-(CH₃)₂/dehydroxylated Al₂O₃, activated in H₂+D₂ and believed to contain supported Cp₂ThH⁺(Cp = ⁵-pentamethylcyclopentadienyl). Even at –195 °C, the turnover frequency is greater than 0.1 sec^–1 at atm. Strong evidence is adduced that the exchange proceeds by a Rideal-Eley process, i.e. by a four-center transition state involving Th-H+D-D.     

New phenothiazine-containing monomers and polymers

Summary Three new phenothiazine-containing electrono-donor monomers: methacryloyl-2-hydroxyethyl-2-(N-phenothiazinyl)propionate (i) acryloyl-2-hydroxyethyl-2-(N-phenothiazinyl) propionate (ii) and 2-(N-phenothiazinyl) propionic acid vinyl ester (iii) were synthesized and radically polymerized. The ionization potentials of poly(i), poly(iii) and of the model for the structural unit of the acrylic polymers: acetyl-2-hydroxyethyl-2-(N-phenothiazinyl) propionate determined with two small acceptors were discussed in terms of sterical hindrances.