Characterization and self-assembly of poly[sodium N-(11-acrylamidoundecanoyl)-l-alaninate] in water

A vesicle-forming amino acid derivatized surfactant, sodium N-(11-acrylamidoundecanoyl)-l-alaninate was polymerized to obtain a polysoap. The average molecular weight of the polysoap was determined by gel permeation chromatography. Rheological measurements suggested that the aqueous solution of the polysoap behaves as a non-Newtonian fluid. Fluorescence probe studies using pyrene as probe molecule indicated hydrophobic domain(s) (intra-chain aggregate) formation within a polymer chain. It has been found that the vesicular structure formed by surfactant monomers are retained after polymerization. The polymer forms inter-chain aggregates in concentrated solution. The dependence of fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene on temperature, pH, and urea concentration suggested strong inter-chain interactions of the polysoap. The pK_a of the surfactant units of the polymer chain and the phase transition temperature were determined. Dynamic light scattering measurements were performed to determine the mean size of the aggregates. The size of the aggregates was found to increase with the increase in polymer concentration also suggesting formation of inter-chain aggregates. The transmission electron micrographs revealed closed vesicular structures in water.     

Polymerization of micelle-forming monomers: Mechanistic study and characterization of the systems before and after polymerization

Cationic surfactants bearing a polymerizable styryl headgroup and a variable alkyl chain with 8–16 carbon atoms have been synthesized. Their aqueous solutions have been characterized by the surfactant critical micellar concentration (CMC) and aggregation number using electrical conductivity, spectrofluorimetry and time-resolved fluorescence quenching. The photoinitiated polymerization of these surfactants in the micellar state led to stable and transparent or slightly bluish systems. The kinetics of polymerization were measured by dilatometry and were found to be close to those obtained for styrene emulsion polymerization. A mechanism of polymerization is proposed and discussed in terms of micellar dynamics. The polymerized systems, p(Cn-STY), and the recovered polymers were characterized by means of several complementary techniques. The polymers have high molecular weights (3 × 10⁵-3 × 10⁶), which indicates that the initial micellar structure is not preserved upon polymerization. The structure of the polymerized systems depends on the alkyl chain length of the surfactant. The p(C16-STY) systems exhibit a structure similar to that of a polysoap with intramolecular hydrophobic microdomains whereas the p(C8-STY) systems behave like classical polyelectrolytes.     

Higher aluminum trialkyls and magnesium aluminum alkyls as components of zioegler–natta catalysts

Magnesium aluminum alkyls containing higher (C₄–C₁₀) radical swere studied as components of Ziegler–Natta catalysts in styrene polymerization. The effects of alkyl radical length and MgR² contents in the components mentioned on the degree of TiCl₄ reduction and sterospecific activity of the catalysts were investigated. The components studied exdhibited high reducing (for TiCl4) and catalytic a tivities. Moleculear weight of the synthesized isotactic polystyrene was abnormally high.     

Absolute rate constants for radical-monomer reactions

Summary A method is described for determining the absolute rate constants for the first few propagation steps in radical polymerization. The procedure involves a product analysis of the oligomeric alkoxyamines formed when an initiator is decomposed in monomer containing a very low concentration of a nitroxide radical scavenger. The method is illustrated with analysis of data for methyl acrylate. The rate constants for the first two propagation steps for polymerization of this monomer,k _p(1) andk _p(2), are at least an order of magnitude greater thank _p(average). Values of the absolute rate constants for reactions of phenyl and primary alkyl radicals with methyl acrylate are also estimated.     

High molecular weight poly(methyl alkyl fumarates): radical high polymerization of methyl alkyl fumarates and monomer-isomerization radical polymerization of methyl alkyl maleates

Summary High molecular weight poly(methyl alkyl fumarate) were prepared through radical polymerization of methyl alkyl fumarates(MRF) and monomer-isomerization radical polymerization of methyl alkyl maleates(MRM). The polymerization reactivities(yield and viscosity) of MRFs and MRMs were found to increase with increasing of the bulkiness of the ester alkyl substituents, but MRFs showed generally higher reactivities than MRMs. These polymers were also observed to consist of less- or non-flexible rod-like poly(methoxy-carbonylmethylene-alt-alkoxycarbonylmethylene) structure depending on their bulkiness. The MtBF polymer did not melt, which showed somewhat decreased thermal stability.Polymers from 1,2-Disubstituted Ethylenic Monomers. VIII.     

Synthesis and homopolymerization studies of vinylimidazolium salts

The preparations and characterizations of several monomeric vinylimidazolium salts are presented from the quaternizations of 1-vinylimidazole and 2-methyl-1-vinylimidazole with n-alkyl iodides and with dimethyl sulphate. Although vinylimidazolium salts have been reported in the patent literature, many of these salts were not isolated and characterized prior to their polymerization. From the reactions of 1-vinylimidazole with n-alkyl iodides, a homologous series of 3-n-alkyl-1-vinylimidazolium iodides were prepared in which the longer chain derivatives appeared to form micelles in aqueous solution. Dicationic crosslinking agents were also prepared through similar quaternization reactions. All the cationic vinyl monomers were homopolymerized in aqueous solution by free radical initiation. The solution behaviour of the resulting polyions indicated that the longer side-chain polyions had polysoap properties.     

Photo‐mediated metal free atom transfer radical polymerization of acrylamide in water

Photo‐mediated metal free atom transfer radical polymerization of acrylamide was conducted at 25 °C in water under visible light irradiation with water soluble 2‐hydroxy‐3‐(4‐benzoylphenoxy)‐N,N,N‐trimethyl‐1‐propaminium chloride (HBTPC) as photoredox catalyst and 2‐hydroxyethyl 2‐bromoisobutyrate as alkyl halide. The polymerization followed first‐order reaction kinetics. The living character of photo‐mediated atom transfer radical polymerization of acrylamide was verified by the linear development of the polymer number average molar mass (M_n,GPC) with monomer conversion and narrow molecular weight distributions (?). The effects of acrylamide concentration, light intensity, amount of HBTPC, and tris(2‐dimethylaminoethyl)amine on polymerization were investigated. Increasing monomer concentration led to a higher M_n,GPC values with narrow ?. The polymerization rate increased with increasing the amount of monomer, light intensity, HBTPC and tris(2‐dimethylaminoethyl)amine. The polymerization was monitored by the periodic light on/off. The structure of polyacrylamide was analyzed by proton nuclear magnetic resonance spectrometer and gel permeation chromatography. Successful chain extension experiments show the controlled nature of the polymerization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46567.     

Surface rearrangement of vinyl acetate and acrylate terpolymer adhesives investigated by dynamic contact angles

Terpolymer solution-based adhesives of vinyl acetate and acrylates with different long alkyl side chains were prepared by radical polymerization. Dynamic contact angles of the adhesives-coated films measured by the Wilhelmy plate technique indicated that the reorientation of the adhesive surface varied with the length of the alkyl side chain. It was found that the changes of advancing contact angles (θ_a) and receding contact angles (θ_r) were relatively great within the range of lower immersion speeds at various temperatures, but approaching a certain velocity the contact angles became stable. The lower activation energies of the change in contact angles revealed that the rearrangement of surface groups can be achieved by small-scale secondary transitions. In addition, the activation energies required for rearrangement from apolar to polar medium and the reverse process were different. ©1997 SCI     

Control of molecular weight distribution for polypropylene obtained by a commercial Ziegler–Natta catalyst: Effect of a cocatalyst and hydrogen

The polymerization of propylene was carried out with an MgCl₂‐supported TiCl₄ catalyst (with diisobutyl phthalate as an internal donor) in the absence and presence of hydrogen (H₂) as a chain‐transfer agent. Different structures of alkylaluminum were used as cocatalysts. The effects of the alkyl group size of the cocatalyst, H₂ feed, and feed time on the propylene polymerization behaviors were investigated. The catalyst activity significantly decreased with increasing alkyl group size in the cocatalyst. The molecular weight and polydispersity index (PDI) increased with increasing alkyl group size. With the introduction of H₂, the catalyst activity increased significantly, whereas the molecular weight and PDI of polypropylene (PP) decreased. Additionally, the effect of the polymerization time in the presence of H₂ on the propylene polymerization was studied. The molecular weight distribution curve was bimodal at short polymerization times in the presence of H₂, and we could control the molecular weight distribution of PP by changing the polymerization time in the presence of H₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Properties of new cationic amphiphilic polymers in hydro‐alcoholic media

BACKGROUND: Following our recent synthesis and characterization of three new families of cationic amphiphilic polymers with great structural variability, this paper reports their physical chemical properties in aqueous media in relation to their chemical structure. These amphiphilic polymers are comb poly(meth)acrylamides laterally substituted by groups containing a quaternary ammonium site and hydrophobic n‐alkyl side chains with variable lengths. RESULTS: Viscometry first showed that these polymers display typical polysoap behaviour in hydro‐alcoholic mixtures. Fluorescence spectrometry was then used to characterize the corresponding intramolecular association with two complementary fluorescent probes. In addition to confirming macromolecular folding, pyrene provided information about the probe local environment polarity whereas a molecular rotor gave interesting complementary information about the compactness of the corresponding nano‐domains. CONCLUSION: It was shown that increasing the length of the n‐alkyl side chain induced much better polysoap properties whereas increasing the size of the spacer between the two polar amide and ammonium groups and the presence of a methyl side group had the greatest impact on the nano‐domain characteristics. Copyright © 2009 Society of Chemical Industry     

Solvent effects on polymerization of functionalized monomers in presence of alkyl halide/CuBr without a ligand

A modified system of atom transfer radical polymerization was used to perform polymerization of sodium o-methacryloylaminophenylarsonate (o-MAPHA-Na). The reaction was carried out without ligand at 48 °C for 45 h with methyl 2-chloro-propionate (MCP) as the initiator, copper bromide (CuBr) as the metal, and different mixtures of polar solvents, including: dimethylformamide (DMF):H₂O (60:40), dimethylsulfoxide (DMSO):H₂O (20:80), and DMSO. The ¹H NMR spectra showed that MCP was covalently attached as end group of the resulting polymers. Unexpectedly, we found that o- and p-MAPHA-Na could polymerize in the presence of alkyl halides without any initiation method to produce free radicals from alkyl halide. Further experiments suggested that radicals could be generated from the used monomer by initiation methods such ultraviolet radiation of environmental light or temperature. Thus, it was possible that the monomer generated phenyl radicals by breaking its C-As bond. Reactions of o-MAPHA-Na and o-MAPHA with MCP and different ratios of H₂O:DMF and H₂O:Metanol (MeOH) showed that water was necessary for polymerization to proceed. Finally, we found that o-MAPHA underwent self-initiated polymerization when water was present in the reaction media.     

Photomediated atom transfer radical polymerization of MMA under long-wavelength light irradiation

In this study, a novel photocatalyst, pentarylenebis(dicarboximide) dye: (1,6,13,18-tetra(4-(2,3,3-trimethylbut-2-yl)phenoxy)-N,N’-(2,6-diisopropylphenyl)-pentarylene-3,4,15,16-tetracarboxidiimide) (TTPDPT), was first used in metal-free photoinduced atom transfer radical polymerization (ATRP) of methyl methacrylates (MMA). The initiator was methyl α-bromoisobutyrate (MBI) and the light source was mild near-infrared (NIR) light irradiation (λ_max?≈?870 nm). The TTPDPT-mediated ATRP relies on in situ photoreduction of a MBI through an electron transfer process to generate the desired alkyl radical, which could induce polymerization of the monomer. The photoinduced metal-free ATRP of MMA shows typical characteristics of controlled free radical polymerization, showing the linear evolution of number-average molecular weight (M_n,GPC) with monomer conversion, where polymers with predetermined degree of polymerization have well-controlled molecular weights and narrow molecular weight distribution (M_w/M_n). The photoinduced metal-free ATRP of MMA can be carried out with just ppm level of TTPDPT. The polymerization initiation and propagation can be operated by the aid of pulsed light sequences while NIR light source was used to promote carbon–carbon bond formation and to produce poly(methyl methacrylate) (PMMA) with M_w/M_n as low as 1.5. The synthesized PMMA was characterized by ¹H nuclear magnetic resonance (¹H NMR). The resultant PMMA contained a bromide end group that can be employed to reinitiate styrene polymerization to produce block copolymers through chain extension experiments.     

Kinetic study on free radical polymerization of alkyl acylamidoacrylates by pulsed laser polymerization using nitrogen laser

Radical polymerization of captodatively substituted alkyl acylamidoacrylates was studied by pulsed laser polymerization using a N₂ laser. Propagation rate coefficient of the acrylates was varied with solvents used in spite of a radical mechanism, but little varied with methyl, n-propyl, and isopropyl substituents on the acrylates. Arrhenius parameters for the propagation indicated that a solvent affected mostly on a frequency factor rather than a activation energy. In addition, it was suggested that these captodatively substituted propagating radicals were thermodynamically persistent but kinetically active in propagation, which resulted in rather smooth propagation in spite of bulky 1,1-disubstituted olefins. The mechanism of the polymerizations was discussed in detail on the basis of the kinetic studies and ESR spectroscopy.     

Effect of Polysoap on the Physical and Tribological Properties of Soybean Oil‐Based Grease

Soybean oil (SBO)‐based grease, containing polysoaps synthesized from polymeric epoxidized soybean oil (PESO), were investigated. Greases were prepared using a mixture of lithium soap and triethanolammonium polysoap. Grease properties investigated were hardness, using the cone penetration procedure (ASTM D217); oxidation stability, using the pressurized differential scanning calorimetry (PDSC) method (ASTM D‐5483); and friction and wear, using a four‐ball tribometer (ASTM D‐2266). Penetration data showed that grease formulated in the presence of polysoap was harder than that without polysoap, and this was attributed to the cross‐linking in the polysoap structure, which was expected to provide higher resistance to deformation. The PDSC results indicated that the onset temperature of grease formulated with 3.8 and 7.3 wt% polysoap increased by 8 and 12°C, respectively, compared to grease without polysoap. The coefficient of friction of grease formulated with polysoap was much lower (0.015) than grease without polysoap (0.034).     

Mechanistic investigation of 9-bromoanthracene photodimers as initiators in atom transfer radical polymerization

Mechanistic pathways accounting for the lack of control in polymerizations employing photodimers of 9-bromoanthracene as alkyl halide initiators in atom transfer radical polymerization (ATRP) reactions are presented. Converting the aryl bromide on the anthracene moiety into an alkyl bromide via a [4+4] cycloaddition reaction effectively generated the photodimer with two alkyl halide sites, which were investigated as potential initiating sites for the ATRP of styrene and n-butyl acrylate. Polymers synthesized using these photodimers as initiators possessed relatively broad polydispersity index (PDI) values and displayed a non-linear relationship between their number average molecular weights (M_n) and monomer consumption, consistent with slow initiation from the bridgehead alkyl halide. Reactions performed at 80 °C in bulk or THF generated polystyrene with M_n values 3-5 times higher than calculated based on monomer-to-initiator ratios. UV-vis spectrometry of the products demonstrated absorbance bands indicative of polymer-bound anthracene, caused by thermal degradation of the photodimer during the polymerization. When the initiator was introduced last into the reaction mixture in an attempt to suppress photodimer cleavage prior to initiation, PDI values and M_n values were generally lowered with the resulting polymers showing similarly high anthracene content. Composition of polystyrene and poly(n-butyl acrylate) products was also studied as a function of reaction temperature, with decreased anthracene labeling observed at lower temperatures (40 and 60 °C), further validating a model of heat-induced cleavage of the photodimer.     

Dependence of ESR spectra of poly(fumaric ester) radicals on temperature and ester alkyl group

Summary ESR spectra of polymer radical from fumaric esters bearing different ester alkyl groups were recorded at room temperature and 120°C. Simulation for the spectra with much better resolution at 120°C revealed that the spectra consist of three components differentiated by molecular weight of the polymer radical and that the component corresponding to the highest molecular weight radical increased with increasing total bulkiness of the ester alkyl groups. Gel permeation chromatography of the polymerization mixture exhibited that the radicals corresponding to the respective spectral components repeat propagation to reach high molecular weight prior to termination.     

Emulsion polymerization of styrene in the presence of carbohydrate-based amphiphiles

Summary Novel amphiphilic N-alkyl-, N-decenyl-, and N-alkyl-N'-methyl-semicarbazones of maltose and maltotriose with C_nH_2n+1 alkyl chains and n=8,9,10,11,12,16 were applied as emulsifiers in styrene emulsion polymerization. Surfactant properties, emulsion polymerization, and rheology were examined as a function of amphiphile molecular architectures. Both critical micelle concentration and average polystyrene particle size increased with decreasing alkyl chain length. Using N-methyl-N-[11-(acryloylamino)-undecanoyl]-glucamine comonomer in a starved feed emulsion polymerization process, it was possible to prepare uniform polystyrene latex with glucamide surface.     

Polymerization of propylene with TiCl3–AlEt2Cl–trilauryltrithiophosphite catalyst

AlEt₃Cl was modified with TLTTP (trilauryltrithiophosphite) in the catalyst system consisting of TiCl₃ and AlEt₂Cl. The effects of TLTTP on the polymerization of propylene were studied in comparison with those of alkyl homologues of TLTTP. The catalytic behavior of the TiCl₃–AlEt₂Cl-TLTTP catalyst system in the polymerization of propylene was also studied in comparison with that of the TiCl₃–AlEt₂Cl catalyst system. In the study of the effect of various alkylthiophosphites added, it is found that the bulkiness of the alkyl group affects the rate of propylene polymerization and the stereoregularity of the resultant polymers. The TiCl₃–AlEt₂Cl–TLTTP catalyst system gave different catalytic behavior in the propylene polymerization from that of the unmodified conventional catalyst system (TiCl₃–AlEt₂Cl). These effects of TLTTP were considered to be due to the bulkiness of the alkyl groups attached to the phosphorous atom and the higher reactivity to TiCl₃ of the modified AlEt₂Cl than of the unmodified AlEt₂Cl.     

Rapid solid‐state photopolymerization of octadecyl acrylate: low shrinkage and insensitivity to oxygen

Mobility restrictions in solid‐state photopolymerization give extremely poor polymerization kinetics, but octadecyl acrylate can be rapidly photopolymerized in the solid state. The XRD, real‐time Fourier transform IR and DSC analyses prove that the hexagonal packing of monomer molecules is favorable for UV‐initiated solid‐state polymerization, and crystalline long alkyl chains of monomers were preserved as the crystalline long alkyl side‐chains of polymers. More importantly, octadecyl acrylate provides a chance to investigate the shrinkage and oxygen inhibition of UV‐induced solid‐state polymerization. This novel radical‐mediated solid‐state photopolymerization is insensitive to oxygen and lowers the volume shrinkage (1.48%). © 2013 Society of Chemical Industry     

Study of microwave irradiation polymerization mechanism in the presence of carriers

Microwave irradiation polymerization was studied in the presence of a carrier. The influence of different carriers, such as Al₂O₃, SiO₂, and MgO on the microwave irradiation polymerization mechanism of acrylamide and 2‐ethylhexyl acrylate was studied by adopting polymerization inhibitors such as an anionic inhibitor, cationic inhibitor, and radical inhibitor hydroquinone. When the system contains the carriers Al₂O₃ and SiO₂, the polymerization mechanism occurs according to a radical mechanism, but when the system contains MgO, the polymerization mechanism occurs according to not only a radical mechanism but also an anionic polymerization mechanism with superficial grafting occurring. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1519–1524, 2004