Structural characterization and thermal behaviour of block copolymers of polydimethylsiloxane and polyamide having trichlorogermyl pendant groups

Block copolymers having a pendant trichlorogermyl group as a part of polyamide segment? (CO? R′? CO? NH? Ar? NH? )_xCO? R′? CO? and polydimethylsiloxane of general formula [(? CO? R′? CO? HN? Ar? NH)_x? CO? R′? CO? NH(CH₂)₃SiO(CH₃)₂ ((CH₃)₂SiO)_ySi(CH₃)₂(CH₂)₃ NH? ]_n (where R′ = CH₂CH(GeCl₃), CH(CH₃)CH(GeCl₃), CH(GeCl₃)CH(CH₃); Ar = C₆H₄, (? C₆H₃? CH₃)₂, (? C₆H₃? OCH₃)₂, 2,5‐(CH₃)₂? C₆H₂, C₆H₄? O? C₆H₄) were prepared by a polycondensation reaction and characterized using CHN and Ge analysis, Fourier transform infrared (FTIR) and ¹H NMR spectroscopy, thermogravimetric analysis (TGA) and molecular weight determination. They have a lamellar structure with weight‐average molecular weight in the range 1.21 × 10⁵–4.79 × 10⁵ g mol^?1. These copolymers display two glass transition temperatures and have an average decomposition temperature of 489 °C. TGA, FTIR and gas chromatography/mass spectrometry studies indicate that degradation of these block copolymers results in carbon monoxide, oligomeric siloxanes and polyamide fragments. They are thermally stable due to the hydrogen bonded interlinked chains of polyamide, while they absorb water due to the presence of Ge? Cl bonding. Copyright © 2010 Society of Chemical Industry     

Helical and random coil conformations of N‐propargylamide polymer and copolymers

An N‐propargylamide monomer, CH?CCH₂NHCOC(CH₃)₂CH₂CH₃ (monomer 9), was polymerized in the presence of (nbd)Rh⁺B^?(C₆H₅)₄ (nbd represents norbornadiene) in CH₂Cl₂, CHCl₃, tetrahydrofuran or dimethylformamide, to provide polymers with moderate number‐average molecular weights (M_n = 8700–12 100 g mol^?1) in high yields (≥92%). The resulting poly(N‐propargylamide) (polymer 9) dissolves almost completely in CHCl₃ (>95%). According to the UV‐visible spectra, measured at various temperatures, polymer 9 forms relatively stable helices over a wide temperature range (35–65 °C). Moreover, it exhibits reversible conformational transitions from an ordered helix to a random coil. On copolymerization of monomer 9 with CH?CCH₂NHCO(CH₂)₃CH₃ (monomer 4) or CH?CCH₂NHCO(CH₂)₇CH₃ (monomer 8), the solubility of polymer 9 improves noticeably. All the copolymers form helices under the experimental conditions. From the viewpoint of monomers 4 and 8, copolymerization with monomer 9 is favorable in terms of the copolymers forming helices. These findings reveal that the helical content and thermodynamic stability of the helices formed in the copolymers are likely to be controlled by selecting a suitable comonomer and by adjusting the composition of the copolymer. Copyright © 2007 Society of Chemical Industry     

Water and oil repellency of polysiloxanes with highly fluorinated alkyl side chains

A series of fluorinated polysiloxanes (FLSs) with the 3,3,4,4,5,5,6,6,6‐nonafluorohexyl group (C₄F₉C₂H₄? ), 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11‐heptadecafluoroundecyl group (C₈F₁₇C₃H₆? ), 3‐(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [HDFNAG; C₈F₁₇(C?O)NHC₃H₆? ], and 3‐(N‐methyl‐2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [C₈F₁₇(C?O)N(CH₃)C₃H₆? ] were synthesized. Their homopolymers (homo‐FLSs) and copolymers with dimethylsiloxane (co‐FLSs) were included. The polyester fabrics were treated with these FLSs, and their water and oil repellency was evaluated. These fabrics showed a moderate to good level of water repellency but a poor to zero level of oil repellency, except for those fabrics treated with homo‐FLSs with HDFNAG. The characterization of the surface chemical composition by X‐ray photoelectron spectroscopy showed that the concentration of fluorine at the surface was not particularly high for poly(ethylene terephthalate) films treated with homo‐FLSs with HDFNAG. Differential scanning calorimetry measurements of these FLSs revealed that only homo‐FLSs with HDFNAG had a high melting temperature of 75.7°C. These two measurements suggested that the reason the fabrics treated with homo‐FLSs with HDFNAG showed good oil repellency was not because the concentration of fluorine at the surface was much higher than for the others but because the reorientation of HDFNAG did not take place for its packing after contact with oil. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1085–1091, 2003     

Polymers and copolymers based on vinyl tetrazoles, 2. Alkylation of poly(5-vinyl tetrazole)

Alkylation of poly(5-vinyl tetrazole) with dimethyl sulfate and tert-butyl alcohol as well as with alkyl halides RHal (R?CH₃, C₂H₅, CH₂? CH?CH₂, n-C₄H₉, t-C₄H₉) has been studied under various conditions in order to develop a new method of synthesis of tetrazole-containing polymers having a complex of valuable properties. The kinetic study of the process and comparison of isomeric compositions and spectroscopic characteristics (IR, ¹H NMR and ¹³C NMR) of poly(N-alkyl-5-vinyl tetrazole)s synthesized by alkylation of poly(5-vinyl tetrazole) and of those prepared by (co)polymerization of the corresponding vinyl tetrazoles have been carried out. The alkylation is found to proceed to high conversion extents (up to 99.8%) and enables to obtain a wide variety of polymeric products having the composition, structure and properties very similar to those of homo- and copolymers.     

Glow discharge polymerization of tetramethylsilane by capacitive coupling of 20 kHz frequency and surface hardening of polyethylene sheet

Glow discharge polymerizations of tetramethylsilane (TMS) were performed by the capacitive coupling of a 20 kHz frequency in comparison with those by the inductive coupling of a 13.56 MHz frequency. The polymers prepared by the former coupling were poorer in carbon and hydrogen, but richer in silicon than those prepared by the latter coupling. These two polymers showing similar infrared spectra contained CH₃, CH₂, CH, Si? O? C, Si? O? Si, Si? CH₃, and Si? CH₂? CH₂? Si groups. Some physical properties involving surface energy, thermal stability, and absorption spectra in the regions of the UV and visible light were determined. This coating procedure was applied for surface hardening of a polyethylene sheet. The surface hardness of the polyethylene sheet was enhanced by a coating of plasma films prepared from TMS or the TMS/O₂ mixtures. Surface hardness was determined by the pencil method and hardness was enhanced from 2B to 2H. The adhesion between these plasma films and polyethylene sheet was good even when immersed in 0.9% NaCl solution at 40°C for 10 days.     

Ionic polymers with expanded π‐conjugation systems derived from through‐space interaction in piperazinium and homopiperazinium rings

Reactions of N‐(2,4‐dinitrophenyl)‐4‐arylpyridinium chlorides (aryl (Ar) = phenyl and 4‐biphenyl) with piperazine or homopiperazine caused opening of the pyridinium ring and yielded polymers that consisted of 5‐piperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂)₂N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) or 5‐homopiperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂CH₂)(CH₂CH₂)N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) units. ¹H NMR spectral analysis suggested that the π‐electrons of the penta‐2,4‐dienylideneammonium group of the polymers were delocalized. UV‐visible spectral measurements revealed that the π‐conjugation system expanded along the polymer chains because of the orbital interaction between electrons of the two nitrogen atoms of the piperazinium and homopiperazinium rings. However, the π‐conjugation length depended on the distance between the two nitrogen atoms; that is, the polymers containing the piperazinium ring had a longer π‐conjugation length than those containing the homopiperazinium ring. Conversion of the piperazinium and homopiperazinium rings from the boat to the chair form led to a decrease in the π‐conjugation length. The surface of pellets that were molded from the polymers exhibited metallic luster, and these polymers underwent electrochemical oxidation in solution. Copyright © 2010 Society of Chemical Industry     

The Chemistry and Properties of a New Range of Fluorochemical Surface Active Agents

The unique properties of surface active agents which comprise a perfluoroalkyl group of about eight carbon atoms linked to a hydrophilic group have been recognised for some time. For example, such surfactants give very low surface tensions to aqueous systems, they are very effective at low concentrations, they have activity in organic systems, they are often stable in hostile environments and they can exhibit oil and water repellency when they are absorbed on substrates. Prior to the work described in this paper, the fluorochemical group for these surfactants had been made by two routes, electrochemical fluorination and telomerisation. Both of these suffer certain disadvantages so a programme of work was initiated to see whether another route to suitable perfluoroalkyl compounds could be discovered. Work in our laboratories showed that when tetrafluoroethylene is treated with fluoride ion in an aprotic solvent such as dimethylformamide, a mixture of oligomers ranging from trimers to heptamers is produced. These oligomers are highly branched unsaturated compounds. The pentamer is the most abundant and the manner in which its chemistry has been exploited to yield surfactants with a highly branched fluorochemical group (unlike those prepared by other methods) is outlined. For example, the pentamer will react with phenol or substituted phenols to give phenyl ethers, C₁₀F₁₉OC₆H₄X (X = H or a substituent). Such ethers can be converted into surface active compounds by either the introduction of hydrophilic groups onto the benzene ring (e. g. sulphonation) or by converting existing substituents into hydrophilic groups (e. g. if X = CH₃, by oxidation to COOH). Hydrophilic groups may be attached directly to the fluorocarbon by for example reacting the pentamer with a hydroxyl-ended ethylene oxide condensate (C₁₀F₂₀+HO(CH₂CH₂O)_nR→C₁₀F₁₉O(CH₂CH₂O)_nR + HF). Reaction of TFE-pentamer with inorganic nucleophiles e. g. OH-, can cause a certain amount of degradation but the products of such degradation can be used to give other surface active compounds.     

Thermal decomposition of aluminium hydroxycarboxylates—lactate,citrate and tartrate

The thermal transformation of anhydrous alumina obtained by the decomposition of the lactate, citrate and tartrate of aluminium has been examined by thermal analysis(TGA and DTA), infrared spectrophotometry and X-ray diffraction study. It is found that under an atmosphere of air the thermal decomposition of aluminium hydroxycarboxylates to anhydrous amorphous alumina, which transforms to α-alumina via γ-, δ- and θ-aluminas, proceeds as follows for Al[CH₃CH(OH)COO]₃, the decomposition of skeleton and the combustion of its decomposition products; for Al[CH₂C(OH)CH₂(COO)₃] and Al₂{[CH(OH)COO]₂}₃, dehydroxylation, decomposition of skeleton and the combustion of its decomposition products.     

Surface modifications of polymers with fluorine-containing plasmas: Deposition versus replacement reactions

Surfaces of polyethylene; poly(vinyl fluoride), poly(vinylidene fluoride), poly(tetrafluoroethylene), cellulose acetate butyrate, and polyoxymethylene were modified in various cold plasma reactions; feed gases to the plasma reactor were trifluoromethane, hexafluoroethane, and tetrafluoromethane. Using X-ray photoelectron spectroscopy (ESCA) to characterize the surfaces, it was established that the plasma reactions lead to fluorinated surfaces containing ? CF₃, ? CF₂, and ? CF groups, All of these fluorinated surfaces exhibit advancing contact angles (with water) larger than 900. However, differences in the ESCA spectra, weight-gain/-loss measurements and scanning-electron-microscopy (SEM) photographs reveal that the mechanisms of fluorination in the various plasma environments are markedly different. The CF₃H gas polymerizes in the gas phase of the plasma and deposits a smooth, fluorinated film on polymers and other substrates. The C₂F₆ plasma simultaneously etches polymers and polymerizes onto polymer surfaces. The CF₄ plasma etches and reacts with the polymer surface but does not polymerize. For polyoxymethylene, the combined roughening (by etching) and fluorination of the surfaces lead to completely non-wettable surfaces (water contact angle approximately 180°). The highly non-wettable surfaces of these two polymers are believed to result from the physical etching and roughening at a very fine scale (approximately five micrometers) while the outermost surfaces are reacting to become highly fluorinated.     

Vinyl ether‐based polyacetal polyols with various main‐chain structures and polyurethane elastomers prepared therefrom: Synthesis,structure, and functional properties

Novel acid degradable polyacetal polyols and polyacetal polyurethanes able to controlled acid degradation were developed. Polyacetal polyols with various main‐chain structures were synthesized by polyaddition of various vinyl ethers with a hydroxyl group [4‐hydroxy butyl vinyl ether (CH₂?CH? O? CH₂CH₂CH₂CH₂? OH), 2‐hydroxy ethyl vinyl ether (CH₂?CH? O? CH₂CH₂? OH), diethylene glycol monovinyl ether (CH₂?CH? O? CH₂CH₂OCH₂CH₂? OH), and cyclohexanedimethanol monovinyl ether (CH₂?CH? O? CH₂? C₆H₁₀? CH₂? OH)] with p‐toluenesulfonic acid monohydrate (TSAM) as a catalyst in the presence of the corresponding diols [1,4‐butandiol (HO? CH₂CH₂CH₂CH₂? OH), ethylene glycol (HO? CH₂CH₂? OH), diethylene glycol (HO? CH₂CH₂OCH₂CH₂? OH), and 1,4‐cyclohexanedimethanol (HO? CH₂? C₆H₁₀? CH₂? OH)], respectively. Polyacetal polyurethanes were prepared by a two‐step polymerization, using the synthesized polyacetal polyols, 4,4′‐diphenylmethane diisocyanate (MDI), and 1,4‐butandiol (BD) as a chain extender. Depending on the main‐chain structures, these polyurethanes had different glass transition temperature (from ?44 to 19 °C) and properties such as hydrophobic or hydrophilic. Polyurethanes containing the hydrophilic main‐chain exhibited the thermoresponsiveness and had the certain volume phase transition temperature (VPTT). The polyacetal polyurethanes were flexible elastomers around room temperature (～25 °C) and thermally stable (T_d ≥ 310 °C) and additionally exhibited smooth degradation with a treatment of aqueous acid in THF at room temperature to give the corresponding raw material diols. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44088.     

Convenient Modular Syntheses of Fluorous Secondary Phosphines and Selected Derivatives

Reactions of the fluorous primary phosphines R_fn(CH₂)₂PH₂ [R_fn=(CF₂)_n−1CF₃; n=6, 8, 10] and R_fn′CHCH₂ [(n′=6, 8, 10) (1 : 1; THF, reflux) in the presence of AIBN give the title compounds [R_fn(CH₂)₂][R_fn′(CH₂)₂]PH [n/n′=6/6 ( 4 , 55%), 8/8 ( 5 , 58%), 10/10 ( 6 , 53%), 8/6 ( 7 , 52%), 10/8 ( 8 , 51%)] as low-melting white solids on up to 10-g scales. The chiral tertiary phosphine [R_f6(CH₂)₂][R_f8(CH₂)₂][R_f10(CH₂)₂]P ( 9 ) is similarly prepared from 7 and R_f10CHCH₂ in the presence of VAZO (neat, 100 °C; 67%). The reaction of 5 and THF⋅BH₃ yields the phosphine borane 5 ⋅BH₃ (95%). Additions of triphosgene [(CCl₃O)₂CO] to 5 or R_f8(CH₂)₂PH₂ give [R_f8(CH₂)₂]₂PCl or R_f8(CH₂)₂PCl₂, which are characterized in situ. The CF₃C₆F₁₁/toluene partition coefficients of 4 – 9 increase with the number and lengths of the R_fn segments.     

Vinyl‐addition copolymerization of norbornene and polar norbornene derivatives using novel bis(β‐ketoamino)Ni(II)/B(C6F5)3/AlEt3 catalytic systems

Copolymerization of norbornene (NBE) and polar norbornene derivatives undergoes vinyl polymerization by using novel catalyst systems formed in situ by combining bis(β‐ketoamino)Ni(II) complexes {Ni[R₁C(O)CHC(NR₃)R₂]₂ (R_l = R₂ = CH₃, R₃ = naphthyl, 1 ; R₁ = R₂ = CH₃, R₃ = C₆H₅, 2 ; R₁ = C₆H₅, R₂ = CH₃, R₃ = naphthyl, 3 ; R_l = R₂ = CH₃, R₃ = 2, 6‐(CH₃)₂C₆H₃, 4 ; R₁ = R₂ = CH₃, R₃ = 2, 6‐′Pr₂C₆H₃ 5 ; R₁ = C₆H₅, R₂ = CH₃, R₃ = 2, 6‐′Pr₂C₆H₃, 6 )} and B(C₆F₅)₃/AlEt₃ in toluene. The 1 /B(C₆F₅)₃/AlEt₃ catalytic system is effective for copolymerization of NBE with NBE OCOCH₃ and NBE CH₂OH, respectively, and copolymerization activity is followed in the order of NBE CH₂OH > NBE OCOCH₃ > NBE CN. The molecular weights of the obtained poly(NBE/NBE CH₂OH) reached 5.97 × 10⁴ to 2.07 × 10⁵ g/mol and the NBE CH₂OH incorporation ratios reached 7.0–55.4 mol % by adjusting the comonomer feedstock composition. The copolymerization of NBE and NBE CH₂OH also depend on catalyst structures and activity of catalyst followed in the order of 2 > 1 > 3 > 5 > 4 > 6 . The molecular weights and NBE CH₂OH incorporation ratios of poly(NBE/NBE CH₂OH) were adjustable to be 1.91–5.37 × 10⁵ g/mol and 9.5–41.1 mol %  OH units by using catalysts 1 – 6 . The achieved copolymers were confirmed to be vinyl‐addition type, noncrystalline and have good thermal stability (T_d = 380–410°C). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and permeability properties of crosslinkable elastomeric poly(vinyl allyl dimethylsilane)s

This article presents the results of a systematic synthesis study of elastomeric crosslinkable polysilicon olefins, the related thermal crosslinking kinetics, and the main permeability parameters recorded for inorganic gases (He, N₂, O₂, and CO₂) and C₁–C₇ hydrocarbons. Poly(vinyl allyl dimethylsilane) (PVADMS; glass‐transition temperature < 273°K) was obtained by the anionic polymerization of bifunctional vinyl allyl dimethylsilane monomer. The polymers were amorphous, high molecular compounds with mixed carbo‐heterochain structures containing double bonds capable of intermolecular crosslinking under a thermal treatment. Thus, thermally crosslinked polymers exhibited a high resistance toward exposure to organic vapors, unlike noncrosslinked PVADMS. IR spectroscopy was used to investigate the polymer structural changes induced by the thermal treatment. An original technique based on a differential method was used to measure gas permeability during thermal crosslinking. PVADMS possessed higher permeability for C₁–C₇ hydrocarbons than for inorganic gases (excluding CO₂), even after crosslinking. Permeability coefficients ranging from 140 to 1780 Barrer for He and CH₄ were found before crosslinking; the thermal crosslinking induced a nonlinear permeability decrease that could be correlated with the disappearance of the double bonds in the polymer structures, that is, cis‐CH?CH? , trans‐CH?CH? , and CH₂?CH? in the side‐chain position. According to the found properties, PVADMS could be used as a prospective material for the preparation of highly permeable selective membranes suitable for lower hydrocarbon and volatile organic compound recovery from various chemical and petrochemical process streams. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 927–935, 2005     

Polymerisation von Vinylchlorid bei Atmosphärendruck. 2. Chemische und spektroskopische Methoden zur Charakterisierung von U-PVC

PVC, which was polymerized at atmospheric pressure (so called U-PVC) contains relatively high concentrations of defects contrary to normal PVC. The number of chain scissions in U-PVC determined by ozonolytic cleavage resulted in values between 0.026 and 0.058 per 100 monomer units (100 VC). The determination of allylic and tertiary chlorine was done by selective reaction of U-PVC with phenol and NMR-spectroscopic investigations of the phenolized polymers. The average ‘labile chlorine’ content amounts to 0.65/100 VC. Hydroxyl radicals formed during the decomposition of the initiator (K₂S₂O₈) resulted in alcoholic endgroups in U-PVC, which were detectable in the IR-spectrum at 3580 cm^?1. The termination with hydroxyradicals also led to structures at the chain ends changing into ß-chloraldehyde groups accompanied by HCl-elimination. The corresponding signal in the IR-spectrum appeared at 1720 cm^?1. U-PVC raw material contained about two branch points per 100 VC. The CCl₄ extracts of the same polymers revealed the ten-fold content of branching. The olefinic structures ? CH?CH? CHCl? and ? CHCl? CH?CH₂ were determined by NMR-spectroscopy. The concentrations of each ranged from 0.25 to 0.3/100 VC. A typical double bond for U-PVC at the chain ends represented the structure ? CH?CH? CH₂Cl, which was preferably present in the low molecular weight material.     

Surface properties of perfluoroalkylethyl acrylate/n-alkyl acrylate copolymers

Wetting behavior of perfluoroalkylethyl acrylate (FA)/n-alkyl acrylate (AA) copolymers with the various length of side chains of the AAs is discussed from a standpoint of surface molecular mobility. The copolymerization reactivity ratio indicates that these polymers are random copolymers. The surface properties were studied by measuring dynamic contact angle, static contact angle and freeze-dried X-ray photoelectron spectroscopy, and the bulk properties by wide-angle X-ray diffraction and differential scanning calorimetry. The advancing contact angles for water were independent of side-chain length of AAs and were almost constant at 120°. We have attributed this phenomenon to the orientation of perfluoroalkyl groups (R_f groups, C_xF_2x+1) in air, which is independent of side-chain length of AAs. On the contrary, the receding contact angles showed small values of about 45° when n numbers below 8 and increased when n numbers above 12. This can be explained as follows. High wettability during the receding process at the n numbers below 8 results from regression of R_f groups at the water–solid interface caused by minimization of the interface free energy. The low wettability during the receding process at the n numbers above 12 shows that R_f groups cannot regress due to its crystallization. This mechanism is also supported by other measurements. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1741–1749, 1999     

Inhibition Performance of Amphoteric Fluorinated Surfactant and its Mixed Systems on Carbon Steel in Hydrochloric Acid

C₈F₁₇SO₂NH(CH₂)₃N(CH₃)₂(CH₂COO)Na (PNHD) is a novel amphoteric fluorinated surfactant. The corrosion inhibition of PNHD and its mixed systems with cetyl trimethylammonium bromide (CTAB) or octylphenol ethoxylate 9.5 EO (TX‐10) for carbon steel Q235 in 1.0 M HCl solution was studied in this paper. The corrosion inhibition efficiency (η) was determined by weight loss, electrochemical methods and scanning electron microscope. The values of η from the three methods were almost identical. The hydrophilic head group of PNHD has two lone pairs of electrons at the nitrogen atoms, suggesting a chemisorption mechanism between carbon steel and surfactant. The PNHD and mixed systems inhibitors acted as a mixed inhibitor; there is interaction between PNHD and CTAB or TX‐100. A compact protective film was formed in PNHD and its mixed systems.     

Models of intermediates in metallocene-catalyzed alkene polymerizations: observation of a d0 cationic titanium–alkyl-alkene complex and decomposition by β-allyl elimination

Low temperature activation of Cp^*₂Ti[η¹,η¹- CH₂CH(CH₂CHCH₂)CH₂] (3) with [HN(CH₃)(C₆H₅)₂] [B(C₆F₅)₄] led to the formation of Cp^*₂Ti[η¹,η²-CH₂CH(CH₃)CH₂CHCH₂][B(C₆F₅)₄] (6) as determined by ¹H NMR spectroscopy. Cp^*₂Ti[η¹,η²-CH₂CH(CH₃)CH₂CHCH₂][B(C₆F₅)₄] undergoes rapid quantitative β-allyl elimination at temperatures as low as −140 °C. The resulting cationic titanium allyl complex [Cp^*₂Ti(η³-CH₂CHCH₂)][B(C₆F₅)₄] (4) exhibits a static structure at low temperatures, but interconversion of η³–η¹ binding modes can be observed at higher temperatures. Lineshape analysis of this process yielded ΔG³(−10 °C)= 13.7 ± 0.6 kcal mol⁻¹, ΔH³=9.8 ± 0.6 kcal mol⁻¹, and ΔS³=−15 ± 3 eu. The use of neutral borane B(C₆F₅)₃ also resulted in β-allyl elimination with the formation of [Cp^*₂Ti(η³-CH₂CHCH₂)][CH₂=CHCH₂B(C₆F₅)₃] (8).     

Preparation and properties of functionalized polyorganosiloxanes

A series of linear functionalized polyorganosiloxanes of the type Me₃SiO[MeSiO(CH₂)_nR]_x(Me₂SiO)_ySiMe₃, where n = 2, R = —(CH₂)NMe₂; n = 1, R = —(CH₂)OEt; n = 4, R = —(CH₂)COOEt; n = 3, R = —(CH₂)Me, have been prepared and characterized. Functional group loadings of ∼4 mol % (x = 1, y = 25), ∼11 mol % (x = 3, y = 23), and ∼30 mol % (x = 8, y = 18) were obtained by reacting commercially available copolymers Me₃SiO(MeSi{H} O)_x(Me₂SiO)_ySiMe₃ with the appropriate ratios of_x:_y, with the required quantities of HO(CH₂)_nR, using dichloro(1,5-cyclooctadiene)platinum(II) as catalyst. Amine, ether, ester, and alkyl functionalized siloxanes were obtained in good yields after purification, and each fluid polymer has been characterized by ¹H and ¹³C-nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectral measurements, elemental analysis, viscosity, surface tension, and density measurements. The functionalized polymers exhibit Newtonian behavior over the range of shear rates 0.4–79.4 s⁻¹, and significant viscosity enhancements were observed for all functionalized polymers compared with poly(dimethylsiloxane) fluids of similar chain lengths. The functionalized siloxanes exhibited in almost all cases an increase in both viscosity and density as the functional group loading increased. The surface tensions of the polymers have also been determined and lie within the range 18.8–22.3 mN m⁻¹. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 808–817, 2001     

Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.     

Polymers with mesogenic elements and flexible spacers in the main chain: Aromatic-aliphatic polyesters

A new series of aromatic-aliphatic polyesters of general structure: R₁ = terphenyl, biphenyl, stilbene R₂ = (CH₂)_n; ? CH₂? C(Me)₂? CH₂? ;? CH₂;? C(Et)₂? CH₂? ; (CH₂? CH₂? O)_n CH₂? CH₂? has been synthesised. The existence of thermotrpic liquid crystalline phases has been shown by polarised light microscopy. The texture observations have suggested the existence of nematic, S_A or/and S_C phases depending on the chemical structure. The temperature of transition between the phases and, as a consequence, the range of mesomorphism are highly dependent upon the chemical structure. The clearing point is high, even for the longest aliphatic group, while the melting point is depressed.