Development of porous polymer monolith by photoinitiated polymerization

Porous polymer monoliths have been successfully prepared by photoinitiated polymerization of butyl methacrylate (BMA) and ethylene glycol dimethacrylate (EDMA) monomers in porogenic solvent of methanol. Mercury intrusion porosimetry and scanning electron microscope are used to characterize the porous properties; nevertheless, the pore size obtained from both techniques is not comparable. The porous structure of the porous polymers is controlled by the phase separation during the polymerization and crosslinking. By varying the composition of the starting solution such as initiator fraction, BMA/EDMA ratio, porogen fraction, and UV intensity, porous polymers with median pore size from about 140 nm to 3 μm can be obtained, and the pore size distribution for majority of the porous polymers is also narrow. The results present a very positive prospect to microfluidic applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymer phase transition in n‐lauryl methacrylate monoliths

Monolithic materials prepared from a mixture of n‐lauryl methacrylate (LMA) and ethylene glycol dimethacrylate (EGDMA) dedicated to nano‐liquid chromatography separation were synthesized using in situ UV polymerization in 75 µm inner diameter capillary tubing. A mixture of cyclohexanol and ethylene glycol was used as a porogen to control porosity. While the preparation conditions yielded satisfactory analytical results, values of pertinent parameters turned out to be critical for obtaining columns with efficient separation. In particular, the impact of two key parameters was studied here in an attempt to identify optimal preparation conditions: (a) different concentrations of the crosslinker EGDMA and (b) different porogen compositions while the monomer to porogen ratio was kept constant. Resulting monolithic phases were characterized in terms of permeability, mean pore diameter and swelling using three different eluents (water, acetonitrile and a mixture at maximum viscosity). First, the LMA/EGDMA monolithic phases present peculiar morphology and hydrodynamic properties for 37% by weight of EGDMA, as reflected by the peak observed for their permeability and mean pore diameter. Swelling experiments revealed the coexistence of two phases in the monolithic structure: a highly crosslinked rigid phase which was insensitive to swelling in the presence of solvent and a weakly crosslinked flexible phase exhibiting significant swelling, with a transition to such a biphasic behavior taking place at 37% by weight of EGDMA. The effects of porogen composition and network swelling properties are presented based on a combination of the Flory ? Huggins theory of isotropic mixing in polymer solutions and the Flory ? Rehner theory of rubber elasticity in the affine network approximation. © 2016 Society of Chemical Industry     

Synthesis and characterization of reactive macroporous poly(glycidyl methacrylate‐triallyl isocyanurate‐ethylene glycol dimethacrylate) microspheres by suspension polymerization: Effect of synthesis variables on surface area and porosity

A novel macroporous poly(glycidyl methacrylate‐triallyl isocyanurate‐ethyleneglycol dimethacrylate) copolymer, hereinafter P_{GMA‐TAIC‐EGDMA}, of controlled bead size was prepared via free radical suspension copolymerization. The effects of varying the concentration of crosslinking agents and porogenic diluent on the average pore diameter, pore size distributions, specific surface area, and pore volume of the copolymer matrix were thoroughly investigated. The spherical beads were characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The specific pore volume, average pore diameter, pore size distribution, and the specific surface area were measured by Mercury intrusion porosimetry and BET adsorption method, respectively. The porous properties of the polymer matrix are a direct consequence of the amount and quality of the porogenic solvent, the percentage of crosslinking monomers, and the ratio between the monomers and porogen phases. When the polymer was prepared at 30 and 40% crosslinking density, and 75 and 100% diluents, respectively, it showed a fine beads morphology, mechanical stability and pore size distributions. By comparing the copolymers P_{GMA‐TAIC‐EGDMA} and P_GMA‐EGDMA, it was found that the former is more stable both thermally and mechanically than its predecessor. The presence of epoxide functionalities of macroporous P_{GMA‐TAIC‐EGDMA} beads makes it a versatile carrier. The resulting polymers have the potential for wide applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Simple synthesis of polymeric primary aromatic amines

Summary A new simple and versatile method of obtaining polymers bearing aromatic primary amino groups was developed. The method consists in the reaction of an alkylating polymer with sodium 4-acetylaminobenzenesulfinate and subsequent deacetylation of the intermediate polymer by acid hydrolysis. Alkylating polymers such as chloromethylated polystyrene resin, tosylated macroporous poly (2-hydroxyethyl methacrylate), macroporous poly(glycidyl methacrylate) and PVC were used in the alkylation performed either in an organic swelling solvent or in an aqueous suspension under phase transfer catalysis conditions. Yields in the alkylation step depend largely on the type of the alkylating group, hydrolysis yields are essentially quantitative.     

Combined experimental and computer simulation study of the kinetics of solute release from a relaxing swellable polymer matrix. II. Release of an osmotically active solute

The performance of a model monolithic controlled release device, consisting of a swellable polymeric matrix subject to structural relaxation (cellulose acetate), loaded with a simple osmotically active solute (NaCl) and activated by the ingress of solvent (water), was studied experimentally and by computer simulation. The former study involved detailed monitoring of the kinetics of both solute release and solvent absorption (followed in due course by desorption of osmotically imbibed excess solvent). The computer simulation study was based on extensive previous modeling work. Values of the relevant input model parameters were derived from independent experimental measurements of the sorption and diffusion properties of solvent (cf. Part I) and solute (reported in the present article). The resulting simulation was highly successful, considering that it proved possible to simulate closely and consistently the kinetics of both solute release (over practically the whole experimental range) and concurrent solvent absorption (including correct prediction of the magnitude of the osmotically induced excess swelling of the polymeric matrix). Simulation of the final desorption of osmotically imbibed water was facilitated by the realization that this process actually reflects the kinetics of a long‐term deswelling relaxation of the polymer structure back to the state of normal hydration, the rate of which could be measured to a good approximation on the pure deswelling polymer. The results presented here are of obvious practical significance in relation to progress toward computer‐assisted design of monolithic controlled release devices exhibiting relatively complex kinetic behavior. They should also prove useful by calling attention to an important caveat when desorption into water is used as a method for the straightforward determination of solute diffusivity in hydrated polymers, in cases of osmotically active solutes diffusing in nonhydrophilic polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2468–2479, 2004     

复乳法制备大孔聚合物微球

研究在不使用乳化剂和致孔剂的条件下采用两亲性聚合物单甲氧基聚乙二醇聚乳酸共聚物制备大孔微球,确定了形成大孔结构的必要条件及孔径的控制方法,并对大孔微球的形成机理进行了探讨. 结果表明,两亲性聚合物单甲氧基聚乙二醇聚乳酸共聚物能较好地稳定乳液进而形成贯穿孔结构,而选用疏水性聚合物聚乳酸和聚(乳酸-羟基乙酸)时只能制备出单腔室结构的微球;当内水相与油相体积比在1:4~1:2、油相溶剂去除分两步时,能形成孔径在100 nm以上的大孔聚合物微球,大孔微球的孔径随着初乳化速率的增大而减小.     

Role of water as a coporogen in the synthesis of mesoporous poly(divinylbenzenes)

The morphology of mesoporous poly(divinylbenzenes) prepared under so called “hydrothermal” conditions and with the monomers diluted in 10 times as much porogen solvent (tetrahydrofuran with 0–20% water) was studied in both dry and swollen states, with nitrogen adsorption/desorption and inverse steric exclusion chromatography, respectively. It was found that the pore volume in the polymer examined just after preparation corresponded to the volume of the porogen used. Such a high porosity can be explained only on the basis of pore formation through microsyneresis rather than the macrosyneresis mechanism that is common in the synthesis of conventional porous polymer materials. Naturally, drying induces a pore collapse and the addition of water to the porogen influences the ability of the polymer to regain the original pore volume by reswelling in tetrahydrofuran. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41198.     

Preparation and morphology study of microporous poly(HEMA–MMA) particles

Porous poly(2‐hydroxyethyl methacrylate‐methyl methacrylate) particles crosslinked with ethylene glycol dimethacrylate were synthesized by free‐radical suspension copolymerization in an aqueous phase initiated by an oil‐soluble initiator, 2,2‐azobisisobutyronitrile. 1‐octanol was used as a pore forming agent (porogen). The porous structures, the particle morphology, and the swelling capacity of the resultant polymer in water at room temperature were studied at different crosslink densities and under various porogen concentrations. The analysis via Scanning Electronic Microscopy (SEM) indicated that permanent pores remained in the dried polymeric particles prepared in the presence of the porogen at certain crosslink densities. According to the studies via the SEM pictures and the pore size distributions, higher porogen concentration promotes the formation of more pores, and higher crosslink density results in narrower pore size distribution. The swelling capacity of the particles in water at room temperature decreases with an increase in the crosslink density, and the existence of the highly porous structures enhances the swelling capacity of the porous particles of poly(2‐hydroxyethyl methacrylate‐methyl methacrylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 707–715, 2007     

复乳法制备大孔琼脂糖分离介质与疫苗结合性能研究

大孔分离介质在分离纯化特别是超大生物分子分离纯化领域具有十分重要的应用意义。受材料性质和制备技术所限制,大孔分离介质以聚合物材料最为常见,针对琼脂糖的大孔分离介质较为少见。通过复乳法制备大孔琼脂糖微球,研究制备条件对微球形貌与成孔情况以及粒径与分布等的影响,发现该微球具备微米级超大孔结构,且制备条件对孔道结构的影响呈现一定规律,琼脂糖溶液浓度、内/外油相与水相比例、初乳转速和成球转速等都对成孔性至关重要。激光共聚焦显微镜实验结果表明,衍生后的大孔琼脂糖分离介质对乙肝表面抗原具有良好的结合能力,使其能够完全进入微球内部。与传统琼脂糖介质相比,大孔琼脂糖介质能够更快速、充分结合大分子疫苗,在超大分子分离纯化领域应用前景广阔。     

New method for fabricating an α‐fetoprotein affinity monolithic polymer array

Bisphenol A based epoxy acrylate (BABEA), a commercial UV‐curable material, was introduced as a crosslinker for the fabrication of an epoxy‐functionalized monolithic polymer array through UV‐initiated copolymerization with glycidyl methacrylate as the functional monomer and poly(ethylene glycol) 200 as the porogen. Scanning electron microscopy images showed that the monolithic poly(bisphenol A based epoxy acrylate‐co‐glycidyl methacrylate) [poly(BABEA‐co‐GMA)] exhibited a well‐controlled skeletal and well‐distributed porous structure. The α‐fetoprotein (AFP) immunoaffinity monolithic polymer array prepared by the immobilization of AFP on epoxy‐functionalized monolithic arrays was used as an immunosensor for chemiluminescent AFP detection. X‐ray photoelectron spectroscopy results indicate that the AFP antibody was successfully immobilized on the monolithic poly(BABEA‐co‐GMA) array. With a noncompetitive immune‐response format, the proposed AFP immunoaffinity array was demonstrated as a low‐cost, flexible, homogeneous, and stable array for AFP detection. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41792.     

Synthesis and properties of solvent absorptive methyl methacrylate‐divinylbenzene copolymer beads

Methyl methacrylate‐divinylbenzene copolymer beads were synthesized by radical suspension polymerization. The effects of the divinylbenzene concentration and the composition of the toluene/heptane diluent were studied with regard to the polymer bead formation, surface morphology, solvent swelling ratio, and absorption kinetics. The crosslinking density and diluent composition were responsible for solvent swelling. The interaction between the polymer and the diluents is attributed to phase separation, which controls the formation of a network‐type or pore‐type polymer, or a combination. For the optimum bead swelling in toluene, a combined morphology of more flexible polymer networks and a small amount of pores is essential for the desired absorption–desorption behavior. Dynamic swelling behavior of the polymer beads was elucidated. The mechanism of toluene transport into the beads became more a relaxation control. POLYM. ENG. SCI., 47:447–459, 2007. © 2007 Society of Plastics Engineers.     

Interplay of kinetics and interfacial interactions in breath figure templating - A phenomenological interpretation

Breath Figure BF templating is an attractive technique for the production of polymer films with controlled porosity: upon the exposure to a moist airflow, monodisperse water droplets condense on the surface of evaporating polymer solution into ordered arrays, acting as a template for the final film structure.This work has been focused on polylactic acid (PDLLA), a biocompatible biodegradable polymer, and aims to provide a phenomenological interpretation of BF process based on the role of kinetics and the influence of interfacial tension. The effects of physical and chemical properties of solvents have been evaluated; the contribution of kinetics has been assessed by modifying the rate of film hardening from seconds to minutes, via different experimental set-up. Our experimental observations indicated that the interplay of kinetics and interfacial tension defines the structure of BF films: interfacial forces govern the physical interactions among water, solvent and polymer, but the dynamics of the process and thus the final pore structure is regulated by kinetics.     

Electron microscopic observation of uniform macroporous particles. I. effect of seed latex type and diluent

Uniform and macroporous polymer particles in the size range of 5–21 μm were prepared by a multistep seeded polymerization method. The uniform polystyrene particles in the size range of 1.9–7.5 μm were used as the seed particles in the preparation of macroporous beads. The seed particles with different sizes and molecular weights were produced by dispersion polymerization, by changing the type of dispersion medium and the initiator concentration. In the synthesis of macroporous particles, a two‐step swelling procedure was employed. The seed latexes were first swollen by a low molecular‐weight organic agent (i.e., dibutyl phthalate, DBP), then by a divinylbenzene–ethylvinylbenzene isomer mixture including an oil phase soluble initiator (i.e., benzoyl peroxide). The porous structure in the final beads was achieved by the polymerization of the monomer phase within the swollen seed particles including a mixture of linear polystyrene and DBP. The initiator concentration in the repolymerization step, the seed latex type (i.e., the diameter and the molecular weight of seed latex), DBP/seed latex, and the monomer/seed latex ratios were changed to achieve uniform polymer beads with different average sizes and pore structures. The average size, the size distribution, and the surface morphology of final beads were analyzed by Scanning Electron Microscopy. The internal structure of the beads were analyzed by Transmission Electron Microscopy. The results indicated that the average size of the final particles increased with increasing the seed latex diameter, DBP/seed latex, and monomer/seed latex ratios. The average pore size decreased with decreasing the molecular weight of the seed latex and increasing the DBP/seed latex and monomer/seed latex ratios. These tendencies were explained by the viscosity change of the porogen solution used in the repolymerization step. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2271–2290, 1999     

Controlled radical polymerization of N,N-dimethylaminoethyl methacrylate using triazolinyl as counter radical

Summary The role of the triazolinyl radical as additive for controlled radical polymerisation is investigated for N,N-dimethylaminoethyl methacrylate (DMAEMA) as polar monomer. A linear increase of the molecular weight with conversion and first-order kinetics are observed proving the controlled behaviour of the polymerization. The end-functionalisation of the obtained polymers was proven by both GPC und UV-spectroscopy. Furthermore, various amphiphilic block copolymers were obtained by chain extension with styrene, methyl methacrylate and ethyl methacrylate. In all cases monomodal GPC curves were obtained indicating an almost quantitative reinitiation.     

Reactive polymers. XII. Bead macroporous methacrylate terpolymers containing aldehyde groups

Bead macroporous terpolymers of methacrylaldehyde with methyl methacrylate and ethylene dimethacrylate were prepared. Preparation conditions (composition of the monomer mixture, of the inert components, concentration of the initiator and of the suspension stabilizer, and the rate of stirring) were discussed with respect to the properties of the terpolymers (porosity and concentration of reactive aldehyde groups). Concentration of reactive groups in the polymer was controlled by adding a third monomer. The analytically determined differences in the concentration of the reactive groups in the batch and in the polymer were interpreted (a) by the inaccessibility of the groups within the polymer bulk (for polymers with 30–50 mol-% of crosslinking agent), (b) by the presence of tetrahydropyran rings or acetate bonds between the chains, and (c) by the formation of extractable soluble polymers or copolymers, or by not reacting of parts of the monomers (observed predominantly with low-crosslinked polymers containing 10 mol-% of crosslinking agent).     

快速膜乳化法制备尺寸均一及结构可控聚苯乙烯微粒

以苯乙烯为单体、二乙烯基苯为交联剂,采用快速膜乳化法制备了聚苯乙烯微粒,对其粒径分布、制备重复性、颗粒结构进行了表征,并考察了致孔剂种类及用量对不同粒径颗粒形态结构的影响规律. 结果表明,聚苯乙烯颗粒粒径与所用膜孔径呈线性关系,最佳乳化压力与膜孔径呈反函数关系. 优化工艺条件下所制颗粒粒径为1~6 mm,粒径分布系数均小于0.8,批次相对标准偏差低于3%. 体积效应对小粒径颗粒的成型结构影响较大;粒径越小,颗粒成型时致孔剂与聚合物间的相分离程度越低,颗粒粒径小于2 mm时液体石蜡无法形成完整颗粒,颗粒粒径大于2 mm时十六烷用量在60%(w)以下才能形成大孔结构.     

Effects of solvent and concentration on scission of polymers with high-speed stirring

The effects of solvent and concentration on scission of polymers such as poly(methyl methacrylate) (PMMA) and polystyrene (PSt) in solution by high-speed stirring were investigated. Solvents were chloroform (good), benzene (intermediate), and ethyl acetate (poor) for PMMA and methyl ethyl ketone (good), toluene (intermediate) and dioxane (poor) for PSt, respectively. Concentration was varied from 0.04 to 2% w/v. The rate of scission of polymer chains was higher and the final molecular weight was lower in a good solvent than in a poor solvent at a low concentration for both polymers, but vice versa at a high concentration except for PSt in methyl ethyl ketone. Concentration dependence of the scission was large in a good solvent but small in a poor one. Polymer chains were ruptured to lower molecular weights with decreasing concentration, regardless of kind of polymer and solvent, showing that they were more easily broken in the isolated state.     

Controlling porous properties of polymer monoliths synthesized by photoinitiated polymerization

Porous monoliths have been successfully prepared by photoinitiated polymerization of hydroxyethyl methacrylate and ethylene glycol dimethacrylate monomers in a porogenic solvent. By varying the composition of the starting solutions such as initiator fraction, monomer ratio and pore generator (porogen) fraction and type, as well as UV intensity, monoliths have been obtained with narrow pore size distribution and median pore size from about a few nanometres to a few micrometres. © 2012 Society of Chemical Industry     

Macroporous polymers made from medium internal phase emulsion templates: Effect of emulsion formulation on the pore structure of polyMIPEs

Emulsion templating is an effective route to prepare low-density, interconnected macroporous polymers known as poly(merised)High and Medium Internal Phase (Ratio) Emulsions. Here, we provide evidence that the interconnectivity of polyMIPEs is strongly dependent on the initiator used for the polymerisation of the continuous phase of the template. The characteristic interconnected pore structure can be observed if an oil soluble initiator, we used α,α′-azoisobutyronitrile, is used irrespectively of the surfactant employed to stabilise the emulsion templates. However, polymerisation of the continuous emulsion phase initiated by water-soluble initiators such as redox initiators or potassium peroxodisulfate results in low pore interconnectivity or even closed celled polyMIPEs.     

Synthesis of highly efficient D‐naproxen imprinted polymer and investigation of their specific performance

D‐naproxen was selected as the imprinted molecule. An original ultraviolet spectrum analysis method based on proof of solvent effects was designed to verify the realization of the noncovalent self‐assembly between naproxen and functional monomers under the influence of the solvents with different nature. The facts proved that it is a more scientific way to effectively implement the pre‐selection of functional monomer. Then, a series of molecular imprinted polymers (MIPs) were synthesized by different ratios of raw materials. These products were detected by infrared spectroscopy as well as adsorption experimentation to analyze their structure and performance. Meanwhile, the transmission electron microscopy (TEM) was first used to observe the morphology of MIPs, by which the pore‐forming mechanism and the effect of the solvent (porogen) were investigated. The MIPs with morphology of different structure were also tested in the adsorption kinetics experiments to testify the influence of morphology factors on the materials' adsorption properties. Through the evaluation of the imprinting efficiency, the best condition accessing to the preparation of highly efficient D‐naproxen imprinted polymer was obtained. The apparent imprinting efficiency of the ultimate product was as high as 90.39%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009