Ring-opening metathesis polymerization of new α-norbornenyl poly(ε-caprolactone) macromonomers

Poly(ε-caprolactone) (PCL) macromonomers capped by a polymerizable norbornene end-group have been synthesized and (co)polymerized by ring-opening metathesis with formation of graft copolymers and polymacromonomers. α-Norbornenyl PCL macromonomers have been synthesized by ring opening polymerization (ROP) of ε-caprolactone (εCL) initiated by 2-diethylaluminoxymethyl-5-norbornene. Copolymerization of these PCL macromonomers with norbornene and polymerizable derivatives has been catalyzed by the [RuCl₂(p-cymene)]₂ PCy₃/(trimethylsilyl)diazomethane complex yielding a series of poly(norbornene)-graft-poly(ε-caprolactone) copolymers. These new graft copolymers have been characterized by a set of analytical methods, i.e., SEC, ¹H-NMR, FTIR, DSC, and TGA. Furthermore, PCL macromonomers have been polymerized into high molecular weight comb chains of narrow molecular weight distribution (M_w/M_n = 1.10) within high yields (90%). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2447–2455, 1999     

Effect of polymerization of synthetic glycolipids on their supramolecular assemblies

Sugar-derived surfactants bearing a polymerizable acryloyl moiety on one of the branches of the double-chain hydrophobic tail were prepared. The non–ionic hydrophilic head and the biantennary hydrophobic tail were built on, respectively, an aspartic acid and a tris(hydroxymethyl)aminomethane core. Ultraviolet irradiation of aqueous dispersions of these surfactants above their transition phase temperature (T_c) was achieved. The morphology of self-assemblies produced in such a way were investigated by transmission electron microscopy. TEM photographs revealed that irradiation leads to the formation of unilamellar vesicles. Neither fibers nor tubules were detected in contrast to what was observed before polymerization.     

Synthesis and palladium‐catalyzed addition polymerization of norbornene carrying epoxy moiety

A norbornene monomer carrying epoxy moiety 1 was successfully synthesized from 5‐norbornene‐2‐carbardehyde by treating it with thioylide. With using a catalytic system consisted of palladium (II) acetate/tricyclohexylphosphine/triphenylcarbenium tetrakis(pentafluorophenyl)borate, homopolymerizations and copolymerization of 1 and 5‐butyl‐2‐norbornene (BNB) were examined. The homopolymerization of 1 was slower than that of BNB presumably due to coordination of the epoxy moiety to the palladium‐center in competition with the C? C double bond of norbornene. This deceleration became less significant in the copolymerizations with low initial feed ratios [ 1 ]₀/[BNB]₀, leading to successful formation of the corresponding copolymers having a rigid poly(norbornene) main chain and epoxy moiety in the side chains, of which composition ratios agreed with the feed ratios. Influence of the epoxy moiety of 1 on its Pd‐catalyzed addition polymerization was elucidated by studying the homopolymerization of BNB in the presence of 1,2‐epoxyhexane. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3982–3989, 2009     

Synthesis and vesicular polymerization of novel counter‐ion polymerizable/crosslinkable surfactants

Two novel two‐tail surfactants, dicetyldimethylammonium 4‐vinyl benzoate (DDVB) and dicetyldimethylammonium 3,5‐divinyl benzoate (DDDB), were synthesized by neutralizing the corresponding quaternary ammonium hydroxide with the appropriate benzoic acid. As expected, these surfactants formed both homo and mixed‐vesicles, which were readily polymerized with a suitable radical photo‐initiator. The polymerization process was followed by UV–vis spectroscopy and also reconfirmed by NMR and IR spectroscopy. Polymerization of vesicles prepared from DDVB, unlike the more commonly polymerized vesicles, in which the polymerizable group forms an integral part of the surfactant, leads to the formation of a linear polyelectrolyte chain that is only electrostatically bound to the lipid bilayer. On the other hand, polymerization of DDDB vesicles leads to the formation of a crosslinked shell (or net) that encases the vesicle bilayer. Such counterion crosslinked vesicles were shown to be resistant to destabilization both by lysis as well as in the presence of a fairly high volume fraction of an organic solvent, such as ethanol. However, although the simple polymerized (linearly) vesicles, formed from DDVB, exhibit enhanced stability toward lysis when compared to their unpolymerized counterparts, they are readily destabilized in the presence of ethanol, leading to precipitation. This sharp contrast in the behavior of linearly polymerized and crosslinked systems suggests that crosslinking is essential to arrest conformational reorganization of the polyelectrolyte chains induced by a change in the solvent medium, which in turn leads to precipitation. Such counterion crosslinked vesicular systems also have an added advantage; they may retain the fluidityof the lipid bilayer while at the same time possess enhanced stability. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5271–5283, 2004     

Interpenetrating polymer networks templated on bicontinuous microemulsions containing silicone oil, methacrylic acid, and hydroxyethyl methacrylate

Polydimethylsiloxane-poly(methacrylic acid—hydroxyethyl methacrylate) interpenetrating polymer networks (PDMS-P(MAA–HEMA) IPN) were formulated and polymerized simultaneously from bicontinuous microemulsion templates. Microemulsions containing reactive silicone oils and MAA/HEMA in aqueous solution were stabilized with silicone surfactants, and were then reacted at 50 °C for 3 h under an N₂ atmosphere. The formation of bicontinuous morphology was confirmed by laser scanning confocal microscopy, reversible swelling behavior, differential scanning calorimetry, texture analysis, and permeability to vitamin B₁₂ in aqueous solution. Incorporating polymerizable surfactants into the microemulsion aided in stabilizing the initial microemulsion structure during polymerization, yielding a more uniform IPN morphology with domain sizes of <200 nm at equilibrium swelling. The process developed here demonstrates a simple, single-step polymerization approach to forming IPNs from low viscosity microemulsion templates, and could potentially be extended to a variety of hydrophilic and hydrophobic monomers.     

Vesicle-micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

The vesicle-micelle transition in aqueous mixtures of dioctadecyldimethylammonium and octadecyltrimethylammonium bromide (DODAB and C(18)TAB) cationic surfactants, having respectively double and single chain, was investigated by differential scanning calorimetry (DSC), steady-state fluorescence, dynamic light scattering (DLS) and surface tension. The experiments performed at constant total surfactant concentration, up to 1.0 mM, reveal that these homologous surfactants mix together to form mixed vesicles and/or micelles, depending on the relative amount of the surfactants. The melting temperature T(m) of the mixed DODAB-C(18)TAB vesicles is larger than that for the neat DODAB in water owing to the incorporation of C(18)TAB in the vesicle bilayer. The surface tension decreases sigmoidally with C(18)TAB concentration and the inflection point lies around x(DODAB) approximately 0.4, indicating the onset of micelle formation owing to saturation of DODAB vesicles by C(18)TAB molecules. When x(DODAB)>0.5 C(18)TAB molecules are mainly solubilised by the vesicles, but when x(DODAB)<0.25 micelles are dominant. Fluorescence data of the Nile Red probe incorporated in the system at different surfactant molar fractions indicate the formation of micelle and vesicle structures. These structures have apparent hydrodynamic radius R(H) of about 180 and 500-800 nm, respectively, as obtained by DLS measurements.     

Spontaneous Formation of Biocompatible Vesicles in Aqueous Mixtures of Amino Acid‐Based Cationic Surfactants and SDS/SDBS

The spontaneous formation of vesicles by six amino acid‐based cationic surfactants and two anionic surfactants (sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS)) is reported. The head‐group structure of the cationic surfactants is minutely altered to understand their effect on vesicle formation. To establish the regulatory role of the aromatic group in self‐aggregation, both aliphatic and aromatic side‐chain‐substituted amino acid‐based cationic surfactants are used. The presence of aromaticity in any one of the constituents favors the formation of vesicles by cationic/anionic surfactant mixtures. The formation of vesicles is primarily dependent on the balance between the hydrophobicity and hydrophilicity of both cationic and anionic surfactants. Vesicle formation is characterized by surface tension, fluorescence anisotropy, transmission electron microscopy, dynamic light scattering, and phase diagrams. These vesicles are thermally stable up to 65 °C, determined by temperature‐dependent fluorescence anisotropy. According to the MTT assay, these catanionic vesicles are nontoxic to NIH3T3 cells, thus indicating their wider applicability as delivery vehicles to cells. Among the six cationic surfactants examined, tryptophan‐ and tyrosine‐based surfactants have the ability to reduce HAuCl₄ to gold nanoparticles (GNPs), which is utilized to obtain in‐situ‐synthesized GNPs entrapped in vesicles without the need for any external reducing agent.     

Novel doubly polymerizable functional norbornene: Its synthesis,reactivity, and macromolecular architectures from a dual cure via ring‐opening metathesis polymerization and radical photopolymerization

A novel doubly polymerizable functional norbornene, 5‐(methacryloyloxyethylamino carboxylmethyl)bicyclo[2.2.1]hept‐2‐ene (NBMOACM), was prepared. The ring‐opening metathesis polymerization (ROMP) of NBMOACM was carried out to prepare polymers with crosslinkable side chains with the Grubbs catalyst. No gel formation occurred during the ROMP of NBMOACM. The ¹H NMR spectrum of poly(NBMOACM) showed broad signals between 5.10 and 5.40 ppm, corresponding to the vinyl protons of the cis and trans double bonds of the ring‐opened polymer. Increasing the ratio of the monomer concentration to the catalyst concentration resulted in the formation of higher molecular weight polymers. Poly(NBMOACM) was incorporated into poly(methyl methacrylate) [poly(MMA)] to produce AB crosslinked materials. These crosslinked materials [1 wt % poly(NBMOACM), 10% weight loss temperature = 300 °C in air] had higher thermal stability than pure poly(MMA) (10% weight loss temperature = 276 °C in air). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6287–6298, 2006     

Surface Activity of Novel Polymerizable Anionic Polyoxyethylene 4-Nonyl-2-Prpylene-Phenyl Ether Ammonium Sulfate Succinate Surfactants

Novel polymerizable surface-active monomers were synthesized by successive treatment of polyoxyethylene 4-nonyl-2-prpylene-phenyl ether ammonium sulfate with maleic anhydride in the presence of hydroquinone at temperature of 180°C. The molecular structures of the polymerizable surfactants were confirmed by ¹H and ¹³C NMR spectroscopy. The surface tension isotherms on the air-water solution interface were obtained. The critical micelle concentrations (cmc) as well as the surface tension at the cmc were determined for these substances. The micellization and adsorption of the prepared anionic surfactants have been investigated by surface tension, and cloud point measurements. Surface parameters such as surface excess concentration (Γ _max), the area per molecule at interface (A _min) and the effectiveness of surface tension reduction (π_CMC) were determined from the adsorption isotherms of the prepared surfactants.      

SYNTHESIS CHARACTERIZATION AND REMEDIATION POTENTIAL OF POLYMERIZABLE SURFACTANT MONOMERS OF N,N-DIALLYL-N,N-DIALKYL AMMONIUM CHLORIDE

The amphiphilic polymerizable surfactants N,N-diallyl-N,N-dioctylammonium chloride, N,N-diallyl-N,N-didecylammonium chloride and N,N-diallyl-N,N-didodecylammonium chloride have been synthesized. Experimental techniques including dynamic light scattering, fluorescence spectroscopy, nuclear magnetic resonance, and atomic force microscopy indicate the monomers form large, well-organized structures similar to vesicles of naturally occurring lipids. Studies of the sequestration of a model foulant by the didodecyl monomer revealed a strong interaction with a high degree of binding. The loading of higher amounts of cresol causes a change in the properties of the monomer assemblies indicating the formation of mixed micellar aggregates. The large monomer aggregates are retained by the dialysis membrane and present a potential alternative to small micellar assemblies.     

Synthesis of silica hollow spheres assisted by ultrasound

A simple and effective method for synthesizing silica hollow spheres is presented. The synthesis utilizes vesicles from oppositely charged surfactants sodium dodecyl sulfate (SDS) and tetrapropylammonium bromide (TPAB) aqueous solution as template for the silica growth. Tetraethyl orthosilicate (TEOS) is added to the vesicular template as a precursor for the silica formation. Ultrasound was employed to accelerate the formation of vesicles template. The morphology of the silica spheres is uniform and well-defined (diameter: 200 nm-5 microm, wall thickness: 50 nm). The product was also characterized by FTIR, TG-DTA, N2 adsorption. TEM images reveal that the spheres have structure stability after calcinations at 550 degrees C.     

Nonionic reactive surfactants. I. Synthesis and characterization

A procedure to prepare nonionic reactive surfactants with different polymerizable groups is described. The synthesis involves the initiation of living anionic ring-opening polymerization of ethylene oxide and propylene oxide (for the hydrophilic part and the hydrophobic part, respectively) by a potassium salt prepared from the stoichiometric reaction of potassium hydride and diethylene glycol monomethyl ether. The resulting anion is reacted with chloride compounds (methacryloyl, allyl, vinylacetoyl) and maleic anhydride, as well as with isobutanoyl chloride, leading to a nonpolymerizable compound having a similar structure. Then, it was possible to produce a range of reactive surfactants more or less reactive with the monomers. These surfactants are expected to be used further in emulsion polymerization processes (styrene and butyl acrylate). This procedure gives good control of both hydrophobic and hydrophilic parts, and the end reaction for the different functionality of surfmers is quite quantitative. All the surfactants were characterized by size-exclusion chromatography and ¹H NMR. Physicochemical properties, such as the critical micellar concentration and the specific area, were also measured.     

Cosolvent effects on the spontaneous formation of vesicles from 1:1 anionic and cationic surfactant mixtures

This paper aims to provide a practical catanionic vesicle-boosting method by means of cosolvent addition in water and to propose a theoretical explanation which can delineate the general trend of cosolvent effects and elucidate the possible role of cosolvent in the formation of catanionic vesicles. Effects of four homologous cosolvents (methanol, ethanol, 1-propanol, and 1-butanol) on the spontaneous formation of vesicles from eight 1:1 anionic-cationic mixed surfactant systems, sodium alkyl sulfates-alkyltrimethylammonium bromides (C(n)SO4Na-C(m)N(CH3)3Br; n = 12, 14; m = 8, 10, 12, 14), at a total surfactant concentration of 10 mM were systematically studied. The experimental results revealed that varied changes in vesicle formability of different mixed surfactant systems may result from various kinds and amounts of cosolvent. Four types of cosolvent effects, however, can be classified. Among them, cosolvent effects type 2 and type 3 would serve the purpose and were exemplified by C12SO4Na-C10N(CH3)3Br, C14SO4Na-C10N(CH3)3Br, and C12SO4Na-C12N(CH3)3Br mixed surfactants. Furthermore, the effectiveness of vesicle boosting increases in the order 1-butanol > 1-propanol > ethanol > methanol. An explanation of cosolvent effects based on the medium dielectric constant was then proposed.     

Synthesis of acrylate and norbornene polymers with pendant 2,7-bis(diarylamino)fluorene hole-transport groups

New hole-transport monomers have been synthesized in which a 2,7-(diarylamino)fluorene hole-transport functionality is linked through the 9-position of the fluorene bridge to a polymerizable acrylate or norbornene group; these monomers have been polymerized under free-radical and ring-opening metathesis polymerization (ROMP) conditions, respectively. The norbornene monomer has also been copolymerized with a cinnamate-functionalized norbornene; this copolymer can be rendered insoluble through photo-crosslinking of the cinnamate groups under UV irradiation, thus permitting the use of the polymer in organic electronic devices based upon multiple polymer layers. The norbornene monomer has also been copolymerized with dicyclopentadiene to afford insoluble crosslinked films. Time-of-flight studies indicate that the norbornene polymer has a higher hole mobility than the analogous acrylate material, consistent with the predictions of the disorder formalism.     

The effect of polymerizable surfactants on morphology and electro-optical of PDLCs films based on epoxy acrylate system

Polymer dispersed liquid crystals (PDLCs) have been extensively studied for various excellent electro-optical applications. The anchoring interaction of liquid crystals (LCs) molecules on the surface of the polymer cavity surrounding an LCs droplet has a crucial effect on the electro-optical performance of the PDLCs. The effect of polymerizable surfactants on the electro-optical properties of PDLCs films was studied in detail. The active double bonds were polymerized with prepolymer to stabilize the performance of polymer matrix. The experimental results showed that polymerizable surfactants could effectively reduce the driving voltage. The speed of polymerization was monitored by real-time transmittance. The electro-optical properties of PDLC films were measured by Polarimeter (PerkinElmer Model 341). The driving electric field was reduced from 3.9 V/μm to about 2.8 V/μm for doping undec-10-enoic acid at curing temperature 80?°C. The surfactants containing polymerizable functional groups, polarity, and alkyl chain weakened the surface anchoring between LCs droplets and polymer interface. The morphologies of PDLCs films were also investigated by polarizing optical microscopy (POM) and Fourier transform infrared (FTIR) images. The LC droplets were encapsulated by polymerizable surfactant according to FTIR images.     

Chemically Locked Bicelles with High Thermal and Kinetic Stability

In situ polymerization of a bicellar mixture composed of a phospholipid and polymerizable surfactants afforded unprecedented stable bicelles. The polymerized composite showed an aligned phase over a wide thermal range (25 to >90 °C) with excellent ²H quadrupole splitting of the solvent signal, thus implying versatility as an alignment medium for NMR studies. Crosslinking of the surfactants also brought favorable effects on the kinetic stability and alignment morphology of the bicelles. This system could thus offer a new class of scaffolds for biomembrane models.     

Synthesis of reactive poly(norbornene): Ring‐opening metathesis polymerization of norbornene monomer bearing cyclic dithiocarbonate moiety

A norbornene monomer bearing cyclic dithiocarbonate moiety (NB‐DTC) was successfully synthesized from the corresponding precursor having epoxy moiety by its reaction with carbon disulfide. NB‐DTC underwent the ring‐opening metathesis polymerization (ROMP) catalyzed by a ruthenium carbene complex to give the corresponding poly(norbornene). The dithiocarbonate moiety incorporated into the side chain of the obtained poly(norbornene) reacted with amine to afford the corresponding thiourethane moiety with thiol group, which underwent oxidative S‐S coupling and/or addition reaction to the C‐C double bond in the main chain, leading to formation of a cross‐linked polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

膜表面具有2-羟基-3-氯丙基或环氧丙基的对pH和离子强度敏感的新型磷酸酯囊泡

近年来,囊泡已被广泛应用于药物基因传导、人工模拟酶和纳米分子器件等研究领域,在对囊泡研究中,需要对囊泡进行某种包结或化学修饰,并对囊泡的稳定性及对物质的包结与释放进行可控操作．囊泡状态下使囊泡分子间聚合是提高囊泡稳定性的有效方法之一,苯乙烯等一些可进行聚合反应的基团已被导入囊泡中,我们曾在单长链烷基磷酸酯的亲水头部引入2-羟基3-氯丙基,进而将其转变成化学活性的环氧丙基.     

Preparation of water-in-diesel oil nano-emulsion using nonionic surfactants with enhanced stability and flow properties

Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants (T6?+?S8) have been tested and the best possible combination of mixed surfactants is found at a surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB)?=?8.01, which resulted in smaller droplet size of 44.87?nm. A phase diagram study is performed to identify the zones of formation of transparent, translucent, and opaque emulsions (44?nm??27?m³?·?s^?1. Comparison of Ostwald ripening rate with other sets of surfactants obtained by different authors showed the lowest rate among them, indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the Newtonian behavior (1.0371?≤?n?≤?1.0826) over a wider range of shear rates (10–1000?s^?1) at different temperatures (25–40°C).     

可聚合囊泡体系(烯丙基-二甲基-十二烷基溴化胺和十二烷基硫酸钠)在溶液中的盐效应

高稳定的囊泡广泛用于制作生物模型、药物输送以及合成纳米材料的模板。获得高稳定囊泡结构的重要方法之一是用聚合反应固定囊泡结构。作为可聚合囊泡制备的前期基础工作,研究了一种可聚合的囊泡体系：1-丙烯基－2,2,二甲基－十二烷基溴化胺（ADDB）和ADDB与十二烷基磺酸钠（SDS）的等摩尔比混合体系。该囊泡体系即使在高浓度盐水中也能够自发地形成均相的囊泡溶液。在聚合之前,采用动态激光光散射（DLS）、冷冻蚀刻透射电镜（FF-TEM）技术研究了可聚合囊泡的盐效应。DLS测试发现没有盐存在时,囊泡大小为83 nm,盐的浓度增加到250 mmol/L时,囊泡尺寸增大到250 nm。然而继续增大盐浓度到1000 mmol/L, 囊泡尺寸减小到180nm. FF-TEM结果发现盐浓度小于150 mM时, 单个囊泡为70 nm左右,然而明显存在囊泡的絮凝与融合;当盐浓度增加到400 mM时,单个囊泡尺寸减小到20 nm. 因此DLS 观测到囊泡尺寸增大的原因是由于囊泡的絮凝与融合;而尺寸减小的原因是由于在高盐浓度下,盐屏蔽了带电颗粒之间的静电相互作用,在熵增的驱使下,大囊泡变成小囊泡。