Characterization limits of a polymer adsorbed under a monolayer by GIXD measurements

The study of interactions between a polyelectrolyte (sodium polystyrene sulfonate, PSSt) or its water-soluble monomer (SSt) at different concentrations and a monolayer of dioctadecyldimethylammonium bromide (DODA) has been investigated. The monolayer phase behavior and structure at the air-water interface were studied by surface pressure-area isotherms and grazing incidence X-ray diffraction measurements. DODA molecules organize following a rectangular unit cell in all three subphases (pure water, water containing SSt or PSSt). The presence of polyelectrolytes in the subphase decreases, on one hand, the tilt angle and the mean area per molecule in the condensed phase, revealing a higher 2D density in this state, and, on the other hand, the amount of organized matter.     

Polyreactions in ordered systems: Polymerization of octadecyl methacrylate in monolayers at the gas–water interface

The ultraviolet-initiated polymerization of octadecyl methacrylate (ODMA, octadecyl 2-methyl-2-propenoate) as a monomolecular layer at the gas-water interface was studied. The polymerization was carried out at 27°C at the nitrogen-water interface; air inhibits the polymerization. At 27°C the ODMA monolayer exhibits three different states which were characterized by surface pressure-area diagrams and by surface potential measurements. The ODMA monolayer was polymerized under constant surface pressure in the range between 0 and 10 dyne/cm. The polymerization was followed by recording the contraction of the film. The conversion was determined by comparison of the area per monomer unit during polymerization with the area of mixed monolayers formed from ODMA and poly-ODMA as well as by infrared spectroscopy. The polymerization in the condensed state of the monolayer (at high surface pressure) is considerably faster than in the expanded state (at low surface pressure). As the polymer has a condensing effect on the monomer in the mixed monolayer, autocatalysis is suggested at low surface pressures. The resulting polymer was studied by x-ray diffraction. The structure of the freshly collapsed film is determined by the conformation of the polymer at the interface; the data after crystallizing the same sample from the melt point to higher tacticity of the poly-ODMA prepared in monolayers than that of poly-ODMA prepared by normal radical polymerization in solution.     

Synthesis of ionic polymers by free radical polymerization using aprotic trimethylsilylmethyl-substituted monomers

Aprotic ionic polymers containing trimethylsilylmethyl-substituted imidazolium structures are synthesized using free radical polymerization of monomers comprising a vinyl group either at the cation or at the anion. Bulk polymerization is used for the room temperature ionic liquid monomer 1-trimethylsilylmethyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide. In contrast to this, solution polymerization is applied for 1-trimethylsilylmethyl-3-methylimidazolium p-styrene sulfonate because this monomer undergoes self-polymerization during melting at a higher temperature than selected for bulk polymerization. Glass transition temperature (T _g) of the ionic polymers and intrinsic viscosity measurements indicate differences between these polymers, which are composed either of a polycation with a trimethylsilylmethyl substituent at each vinylimidazolium segment of the polymer chain and mobile bis(trifluoromethylsulfonyl)imide (NTf₂⁻) anions or a polyanion containing p-styrene sulfonate segments and mobile 1-trimethylsilylmethyl-3-methylimidazolium cations. The new aprotic ionic polymers containing trimethylsilylmethyl substituents may be interesting for application in adhesive, interlayer and membrane manufacturing.     

Synthesis and characterization of a new benzofulvene polymer showing a thermoreversible polymerization behavior

A new polymer based on a functionalized benzofulvene moiety has been synthesized by spontaneous polymerization of the monomer in the solid state. This polymer shows a very high molar mass, high solubility in the most common organic solvents, and thermoreversible polymerization properties. An interesting application in synthesis is reported.     

The role of dislocations in the solid-state polymerization of monomers having conjugated triple bonds: A study of 2,4-hexadiyne-1,6-diol bis(p-toluene sulfonate)

The crystal structure of the monomer bis(p-toluene sulfonate) ester of 2,4-hexadiyne-1,6-diol (pT) is conducive from the viewpoint of both the separation distances and molecular configuration, to polymerization, irrespective of whether initiation is thermal, photochemical, or mechanical. The dislocations present in the monomer and polymer structures have been characterized by employing optical microscopic techniques. The slip system (102)[010] is found to be present in both monomer and polymer crystals but the (010)[001] system is found only in the monomer. On this basis a crystal structure for the monomer is proposed based on existing crystallographic information relating to the structure of the polymer. Dislocations are thought, on energetic grounds, to facilitate nucleation of product in the thermal polymerization but have no observable influence on the photoinduced reaction which proceeds homogeneously through the bulk.     

TRANSIMIDIZATION IN THERMOPLASTIC POLYIMIDES*

In order to improve the processibility in thermoplastic polyimides, a new method, termed the"reactive plasticizer" approach, has been proposed. This method uses a small amount (5～15 mol%) of a lessactivated, weak nucleophilic diamine co-monomer as a "reactive plasticizer" to obtain copolyimide resinswhich possess relatively low viscosity at low temperatures and can be readily processed through the autoclavecycle at low pressures. During a high temperature treatment, the reactive plasticizers join the reaction to formhigh molecular weight copolyimides, and the preferred material properties are thus achieved. The mosteffective reactive plasticizer is aromatic heterocyclic diamines, such as 2, 6-diaminopyridine diamine (DAP),and the transimidization involved with a reactive plasticizer has been proposed to play a major role for thesuccess of this approach. In order to understand the transimidization mechanism, three steps have been takenin this research: first, a copolyimide system of 50% of DAP and 50% 1, 4 -bis [4-aminophenoxy] benzenediamine (DODA) with 100% of 2, 2'-bis[4-(3, 4-dicarboxyphenoxy)phenyl] propane dianhydride (Ultem~(R)DA) is prepared. Second, several specifically designed polyimide mixture systems were used, and they consistof two homopolyimides: one is Ultem~(R) DA-DODA, and the other is Ultem~(R) DA-DAP. The third step is toinvestigate two mixture systems in which Ultem~(R) DA-DODA is mixed with DAP monomer solution andUltem~(R) DA-DAP is mixed with DODA monomer solution. For all systems, with increasing degree oftransimidization upon heat-treatment, the chain structures of the mixtures and their thermal and dynamicmechanical transition behaviors are investigated via one-dimensional and two-dimensional nuclear magneticresonance, differential scanning calorimetry, and dynamic mechanical analysis experiments. Experimentalresults indicate that in the mixture of two homopolyimides, transimidization takes place much moreefficiently in solution than in the melt. For the two mixtures with monomer solutions, the transimidizationcan only be found in the mixture of Ultem~(R) DAP/DODA system in p-chlorophenol, and this process does noteffectively occur in the Ultem~(R) DODA/DAP system in p-chlorophenol, indicating that free DODA canefficiently attack the imide linkage of Ultem~(R) DA-DAP. The final product resulting from the transimidizationin the mixtures is a random copolyimide with a major population of DAP as end groups for the copolymersystem.     

磺酸基甜菜碱共聚物的合成及其界面活性研究

以N-[3-(二甲氨基)丙基]丙烯酰胺与1,3-丙磺酸内酯为原料,制备了3-[(3-丙烯酰胺)丙基-二甲氨基]丙磺酸钠甜菜碱型单体,并将其与丙烯基聚乙二醇通过自由基聚合物反应合成了磺酸基甜菜碱和聚乙二醇的共聚物.利用红外光谱(FT-IR)和凝胶渗透色谱仪(GPC)对共聚物进行表征,并考察了在高浓度CaCl2条件下该共聚...     

水溶性聚合物和两亲聚合物:9.新型丙烯酰胺基两亲单体及其两亲聚合物的单层膜研究

本文对新型两亲单体,2-丙烯酰胺基十六烷磺酸(AMC_(16)S),及其两亲聚合物PAMC_(16)S在空气-水界面上形成单层膜的特点进行了研究。AMC_(16)S可通过在亚相中添加Ca~(2+)或Cd~(2+)等多价阳离子在界面上原位生成不溶性磺酸盐的方法获得满意的成膜行为。PAMC_(16)S不溶于水,可直接成膜。发现,PAMC_(16)S的成膜行为与亚相的性质明显相关。纯水亚相下PAMC_(16)S的极限单体链节面积较大,如亚相含有Ca~(2+)或Cd~(2+),极限面积明显缩小,说明烷基碳氢链的排列趋向紧密。     

Polymerization Kinetics of Water-Soluble N-Vinyl Monomers in Aqueous and Organic Solution

Summary: Free-radical batch polymerization (FRP) of N-vinyl pyrrolidone (NVP) and N-vinyl formamide (NVF) monomers in aqueous solution as well as NVP polymerization in organic (n-butanol) solution has been studied. The differences found in rate of monomer conversion with monomer and solvent choice correlates well with the differences in values of the propagation rate coefficients (k_p) and their variation with monomer concentration measured in independent pulsed-laser polymerization studies, a result demonstrating that a generalized understanding of water-soluble vinyl monomers can be obtained once their k_p differences have been accounted for. A reasonable representation of polymer molecular mass averages and the complete molecular mass distributions for the three systems was obtained by assuming that the rate coefficient for transfer to monomer, polymer, and organic solvent also vary as a function of monomer concentration.     

Dispersion polymerization of styrene in ethanol: Monomer partitioning behavior and locus of polymerization

A thermodynamic model has been proposed for the simulation of monomer partitioning behavior in the dispersion polymerization of styrene in ethanol. The monomer concentration in the polymer particles is very low (20 vol% at 5% conversion) and decreases further as the polymerization proceeds. It is independent of stabilizer concentration but is strongly dependent on initial monomer concentration. The partitio n coefficient ([M_p]/[M_c]) of styrene increases from 0.8 to 1.1 with incresing conversion. There are two polymerization loci in dispersion polymerization, namely the continuous and polymer phases. Competition between solution and heterogeneous polymerization has been observed in this system. The rate of dispersion polymerization is dependent on initial monomer concentration but is independent of initiator concentration at higher conversions. The molecular weight of the polymers produced by this process increases with increasing conversion and decreases with increasing initiator concentration.     

Effect of amount of monomer on radiation-induced polymerization of styrene adsorbed on silica gel

The effect of amount of monomer on radiation-induced polymerization of styrene adsorbed on silica gel was investigated with the monomer amounting from less than monolayer adsorption to more than the equilibrium adsorption. The rate of graft polymerization and the molecular weight of the polymer changed with the amount of monomer adsorbed on silica gel. Maximum grafting efficiency was obtained at monolayer adsorption. The molecular weight of graft polymer was higher than that of homopolymer in both radical and cationic polymerizations, and the ratio in molecular weight of graft polymer to that of homopolymer tends to be unity with increasing amount of adsorbed monomer. These results can mainly be explained in terms of the number of initiating species (radical and cation) that change in relation to the amount of adsorbed monomer. Propagation and termination change with amount of adsorbed monomer in relation to the molecular mobility of adsorbed monomer. A very high-molecular-weight graft polymer is formed only with a small amount of adsorbed monomer in the initial stage. The grafting percent with a large amount of adsorbed monomer increased after most of the monomer has been polymerized. Secondary effect of radiation on the graft and homopolymers due to energy transfer from silica gel is suggested from the complicated phenomena in the later stage of the reaction.     

Enzymatic polymerization of phenol catalyzed by horseradish peroxidase in aqueous micelle system

Enzymatic polymerization of phenol catalyzed by horseradish peroxidase (HRP) has been carried out in aqueous micelle system using sodium dodecyl benzene sulfonate (SDBS) as a surfactant. The addition of SDBS to buffer greatly enhances the polymer yield. With a usage of SDBS over 0.4 g for 5 mmol of phenol monomer, the polymer could be obtained almost quantitatively. The number-molecular weight of the THF-soluble part determined by GPC is increased from 1100 to 2000 with increasing the dosage of SDBS. The phenol polymerization maintains high yields in aqueous micelle system over a wide pH range from 4 to 10. The activity of enzyme in buffer is so high that the phenol polymerization in aqueous micelle system could be completed only in 2 h with high yield. The resulting polymer is a kind of powdery material, which is partly soluble in DMF, DMSO and THF. IR analysis showed that the polymer structure contained a mixture of phenylene and oxyphenylene units. From TG analysis, the polymer was found to possess high thermal stability.     

Synthesis and nanostructure of strong polyelectrolyte brushes in amphiphilic diblock copolymer monolayers on a water surface

We synthesized an ionic amphiphilic diblock copolymer, poly(hydrogenated isoprene)-b-poly(styrenesulfonic acid) (PIp-h2-b-PSS), by living anionic polymerization, and the nanostructure of its monolayer spread on a water surface was directly investigated by the in situ X-ray reflectivity technique. The monolayer of the diblock copolymer on a water surface had a smooth hydrophobic PIp-h2 layer on water and a "carpet"/polymer brush double layer in a hydrophilic sodium polystyrene sulfonate (PSSNa) layer under the water. The surface pressure dependence and PSSNa chain length dependence of the PIp-h2 layer thickness and the brush nanostructure were quantitatively studied. The effect of salt concentration in the subphase was also investigated in aqueous solutions containing 0-2 M NaCl. The salt effect on monolayer structure occurred at around 0.2 M. The thickness of the PSS brush layer decreased at salt concentrations above 0.2 M, while no structural change was observed below 0.2 M. This critical salt concentration is thought to be related to the balance of ionic concentrations inside the brush and in bulk solution.     

Synthesis and electric field actuation of an ionic liquid polymer

Polymerizable ionic liquids and their actuation in an electric field are a combination of material and properties with unique potential to display structural and fluid dynamics above that found in small molecule ionic liquids. In an effort to blend ionic liquid nature with actuation response, we have synthesized a new ionic liquid ammonium sulfonate monomer and polymer. The liquid temperature ranges of both the monomer and polymer ionic liquid systems are quite large extending from their respective glass transitions (Tg) of -57 and -49 degrees C to decomposition at approximately 200 degrees C. Particularly remarkable is the small Tg increment that accompanies the transformation from monomer to polymer. The electrowetting behavior of the polymer and of the monomer presents an interesting contrast. This communication will encompass the polymerization, characterization, and actuation of these new ionic liquids.     

Synthesis and characterization of a self-crosslinkable polymer from cardanol: Autooxidation of poly(cardanyl acrylate) to crosslinked film

Cardanyl acrylate (CA), a monomer that yields crosslinkable copolymers, was synthesized by the reaction of cardanol with acryloyl chloride. A linear polymer was obtained by solution polymerization of the monomer in toluene using 0.8% azobisisobutyronitrile as initiator. Upon removal of solvent, the polymer undergoes crosslinking on exposure to air (or UV light) to give an insoluble transparent film. However, in bulk and suspension polymerization the polymer undergoes in situ crosslinking in the absence of any crosslinking agent. The polymer was characterized by IR, NMR, DSC, and GPC. The crosslinking reaction of soluble polymer on exposure to air at ambient conditions was explained by the hydroperoxide theory. © 1993 John Wiley & Sons, Inc.     

具有聚集诱导发光效应的咔唑基三苯乙烯衍生物单体及聚合物

合成了一类新的咔唑基三苯乙烯衍生物单体及其聚合物.利用示差扫描量热法(DSC)、热重分析法(TGA)、紫外可见分光光度法和荧光分光光度法等对单体和聚合物的性能进行了初步的表征.实验结果表明,该单体和聚合物具有较高的玻璃化转变温度(Tg),分别为210℃和229℃;单体和聚合物均具有很高的热稳定性,热失重5%的温度分别为466℃和467℃;单体具有明显的聚集诱导发光性能(AIE),而聚合物则具有聚集诱导增强发光性能(AIEE);所合成的单体和聚合物有望在OLED器件以及化学传感器上得到应用.     

Preparation of highly sulfonated polystyrene model colloids

Previous attempts to prepare monodisperse styrene/sodium styrene sulfonate copolymer latexes by batch, seeded, and semicontinuous emulsion polymerization were unsuccessful at high concentrations of the functional comonomer. Broad, and sometimes bimodal, size distributions, and large amounts of water soluble homopolymer were obtained. After removal of free monomer, solute and adsorbed homopolymer and copolymer, the overall incorporation of the functional comonomer was found to be low. To overcome these problems, a two stage “shot-growth” or in situ seeding technique was developed. A first stage copolymerization was carried out with a low concentration of sodium styrene sulfonate: the purpose of the functional comonomer was to enhance the stability and regulate the size of the seed particles. When this reaction had reached high conversion (> 90%), a second stage monomer mixture was added. The ratio of styrene to sodium styrene sulfonate in this mixture determined the final surface charge density. The mechanism by which the NaSS is incorporated in the polymer particles is considered to be by solution copolymerization with solute styrene monomer to form surface active oligoradicals. These radicals adsorb on the particle surface, initiate polymerization and become inextricably bound, preventing their transfer back to the aqueous phase. By this means, it was possible to vary independently the particle size and surface charge density. High concentrations of functional comonomer could be polymerized without undue wastage (incorporations were only slightly less than 100%) or loss of monodispersity. In extreme cases, the area per functional group fell below the theoretical minimum, indicating considerable hydration of the surface layers.     

Polymerization of the 12-methacryloyloxydodecanoic acid and a corresponding phospholipid in monolayers at the liquid/gas interfaces

The following surface-active monomers with methacrylic group at the end of hydrophobic tail: 12-methacryloyloxydodecanoic acid (12-MAODA) and 12-(methacryloyloxydodecanoyl)-glycerophosphatidylcholine 12-MAODPC) were synthesized and investigated. Both monomers are forming monolayers at the liquid/gas interfaces with liquid-expanded and liquid-condensed states at low and high surface pressures, respectively. These monomers have been polymerized in the monolayers just by soft UV-irradiation (254 nm). Dependences of polymerization rate vs. surface pressure for both monomers have maxima (3.33^*10⁻⁴ s⁻¹ for 12-MAODPC and 4.89^*10⁻⁴ s⁻¹ for 12-MAODA) at about 8–10 mN/m. The higher polymerization rate of 12-MAODA polymerization as compared to 12-MAODPC is due to the more dense packing of the acid molecules in monolayers as compared to the lipid. Areas per monomer unit in the obtained polymeric monolayers are much smaller than those for the monomer one. The collapse pressures increase after monomer polymerization that evidences the increase of the monolayer stability in case of polymer as compared to monomer.     

[Hydroxy(tosyloxy)iodo]benzene as Thermal initiator for the Radical Polymerization of Methyl Methacrylate

Abstract

The thermal polymerization of methyl methacrylate in a solution of N,N-dimethylacetamide has been studied using [hydroxy(tosyloxy)- iodo]benzene (HTIB) as the initiator. The rate of polymerization was a direct function of the monomer and initiator concentrations. The initiator and monomer exponent values expressing this dependence were found to be 1.0 and 0.8, respectively. The overall activation energy of polymerization was estimated to be 45 kJ·mol^?-1. The polymerization was inhibited in the presence of hydroquinone. The effect of various solvents on the polymerization rate was studied. The polymer prepared with HTIB (0.47 × 10^?3 mol·L^?-1) had a number-average molecular weight of 138,000 and a glass transition temperature of 106°C. The polymer showed good thermal stability as determined by thermogravimetric analysis.     

Formation of flat, homogeneous surfaces of organized molecular films of three-armed polymerizable amphiphiles with metal-scavenging properties

Surface complexing (i.e., metal-bridged polymerization in this study) of a three-armed amphiphilic compound with metal-scavenging properties has been investigated using the surface pressure-area (π-A) isotherms of a Langmuir monolayer from the subphase. Inductively coupled plasma mass spectrometry (ICP-MS) was also carried out on eluted solutions from corresponding multilayers of the solid. Furthermore, the molecular arrangement and surface morphology of organized molecular films of the resultant comb polymer were estimated by in-plane and out-of-plane X-ray diffraction (XRD) and by atomic force microscopy. From an analysis of the wide-angle X-ray diffraction of the corresponding monomer in the bulk, the long hydrocarbon chains are observed to pack hexagonally in the solid state. Compared to their monolayer on distilled water as the subphase, a polymerized monolayer on a buffer solution containing Cd(2+) ions is remarkably expanded at 15 °C. From ICP-MS and IR measurements, it is found that this monolayer stoichiometrically contains Cd(2+) ions on the -SH group. It is found by XRD that highly ordered layer structures and regular 2D lattices are constructed in the organized molecular films of the Cd-bridged comb polymer. Furthermore, the surface morphology of Langmuir-Blodgett films fabricated from the monolayers on a buffer solution containing Cd(2+) and Pd(2+) shows flat and smooth domains upon metal scavenging and polymerization.