Facile Visible-Light-Induced Preparation and Hydrophobization of Porous polyEGDMA and polyTEGDMA Thick Monoliths

The simple low-cost method for synthesis and post-functionalization of thick macroporous polymer monoliths was proposed and realized by example of obtaining and hydrophobization of monoliths based on mono- and triethylene glycol dimethacrylates. Described procedures comprise using of ubiquitous visible-light projection system and single photoinitiator (9,10-phenanthrenequinone) in both cases. This approach eliminates the need in “material” photomasks and permit to operate with computer generated virtual photomask to form the pattern of functionalization. Macroporous polymer monoliths of 2 and 4 mm in thickness with a system of interconnected pores were synthesized and hydrophobized. The thick layers of functionalized porous polymer with wetting pattern through the entire sample thickness with the water contact angle for hydrophobic parts reaching120–125° were obtained. POLYM. ENG. SCI., 60:682–689, 2020. © 2020 Society of Plastics Engineers     

Adsorption of indomethacin onto chemically modified chitosan beads

Macroporous chitosan beads used for the immobilization of an anti-inflammatory drug were prepared by the wet phase-inversion method. There are two stages of phase-inversion observed from the cast of chitosan droplet in tripolyphosphate (TPP) aqueous solution. The first stage of phase-inversion is dominated by liquid-liquid demixing and the morphology of the freeze-dried chitosan bead shows a bundle-like porous structure. The following stage of phase-inversion is attributed to the solid-liquid demixing and the morphology of the freeze-dried chitosan bead changes to an interconnected porous structure comprising particulates around the pores. The pore size and porosity of the bead can be varied by altering synthesis conditions, such as initial polymer concentration, and the pH value and concentration of the casting agent (TPP aqueous solution). Quaternary ammonium, and aliphatic and aromatic acyl groups were introduced into the porous chitosan beads to interact with an anti-inflammatory drug, indomethacin, through the electrostatic interaction and hydrophobic interaction. The results indicated that chemical modification of the porous chitosan beads have obvious effect on the adsorption of indomethacin.     

New platforms for 3-D microarrays: Synthesis of hydrophilic polymethacrylate monoliths using macromolecular porogens

Hydrophilic macroporous monolithic material based on poly(glycidyl methacrylate-co-glycerol dimethacrylate) was synthesized by photo-initiated free-radical polymerization. Different pore-forming agents, including low molecular mass cyclohexanol and dodecanol, as well as the solutions of hydrophobic polymers, namely, polystyrene in toluene and poly(dimethyl siloxane) in hexane, were used to obtain the macroporous polymer platforms intended for new type of 3-D microarrays (biochips). The porous characteristics of functional copolymers obtained were investigated by mercury intrusion porosimetry and scanning electron microscopy. Some of developed materials were tested for protein microarray construction. Demonstration of potential of suggested materials, as well as optimization of protein covalent immobilization conditions, were realized using model mouse IgG – goat anti-mouse IgG affinity pair.     

Immobilization of enzymes onto modified polyacrylonitrile membranes: Application of the acyl azide method

Chemical reactions toward acyl azide activated polyacrylonitrile (PAN) and conditions for membrane surface modifications are described. Ultrafiltration (UF) membranes were prepared from PAN homopolymer and copolymer with methyl acrylate. Besides hydrazide formation and nitrosation, a new method to introduce acyl azide groups into carboxyl modified PAN, using azido transfer with diphenyl phosphoryl azide, was developed. Chemical conversions were characterized, especially with Fourier transform infrared spectroscopy. The heterogeneous modifications are not chemically selective due to side reactions and/or incomplete conversion. The pore structure is altered predominately via modified polymer swelling causing changed UF fluxes and selectivities. However, for the modification via PAN reaction with hydroxyl amine, acid hydrolysis, and azido transfer, the initial membrane separations performance is qualitatively preserved. Using the acyl azide ḿethod, amylo-glucosidase (AG) (EC 3.2.1.3) was immobilized onto the modified PAN UF membranes, enabling hydrolysis of starch or maltose to glucose. Enzyme activity was assayed depending on previous chemical modification (azide content) and immobilization (pH) conditions as well as hydrolysis parameters (substrate, conversion during diffusion or UF). The best results (up to 600 mU/cm² at 40°C and pH 5.0) were obtained after modification of PAN membranes via carboxyl creation and azido transfer. AG convalently bound to PAN is not influenced much in its catalytic properties (K_m = 3.48 and 3.1 mmol/L for free and bound AG, respectively, with maltose at 40°C and pH 5.0). Under UF conditions, AG effective activity can be improved by the convective flow through the membrane. UF selectivity for the polymer starch determines effective substrate concentrations in the membrane, thus affecting observed activities and product purities in the filtrate. © 1996 John Wiley & Sons, Inc.     

Energetic polyurethanes from branched glycidyl azide polymer and copolymer

Branched glycidyl azide polymer (GAP) and glycidyl azide–ethylene oxide copolymer (GEC) have been prepared by a degradation process using different polyols in the synthesis reaction. The azido homopolymers and copolymers were characterized by gel permeation chromatography and viscometry techniques. Energetic polyurethanes were then obtained from the curing of branched glycidyl azide polymers and copolymers using isophorone diisocyanate as a curing agent. The polyurethanes were characterized using thermomechanical analysis and tensile testing. The polyurethane copolymers have generally a higher elongation at break and a lower glass transition temperature than their GAP homopolymer counterparts. The polyol reactant used in the synthesis of GAP and GEC had an effect on the mechanical properties of the polyurethanes obtained from these polymers. © 1996 John Wiley & Sons, Inc.     

The application of Langmuir–Blodgett technique in preparation of the macroporous titania coatings

The aim of this work was preparation of the macroporous titania coatings with the use of the sol–gel process and poly(methylmetacrylate) beads as a template. The effectiveness of the Langmuir–Blodgett (LB) and dip-coating (DC) methods in deposition of polymer beads on the silicon wafers was compared. Resulted polymer layers and final porous titania coatings were analyzed with the use of the atomic force microscope. It was found, that application of the LB is possible only when arachidic acid is present in the subphase. It should be highlighted, that the application of the LB method is the novelty between the methods of the polymer beads arrangement having the diameter of 200–300 nm. Main factors which influence the structure and the arrangement of polymer templates were the concentration of the polymer suspension and the rate of the substrate immersion/withdrawal from the suspension. We established, that the optimal concentrations for preparation of polymer templates, exhibiting good arrangement of individual beads, were 0.5 and 6 % for LB and DC methods, respectively. The size of pores of the obtained macroporous titania (200–330 nm) corresponds well with the size of the polymer beads used as the template (200–235 nm).     

软、硬模板合成多孔氧化镁、氧化钙和碳酸钙

总结了以软、硬模板辅助法合成多孔氧化镁、氧化钙和碳酸钙的研究进展。分别以三嵌段共聚物F127(PEO₁₀₆PPO₇₀PEO₁₀₆)和规整排列的聚甲基丙烯酸甲酯微球为软、硬模板,可制得孔壁为蠕虫状介孔的三维有序大孔多晶氧化镁;采用以三嵌段共聚物P123(PEO₂₀PPO₇₀PEO₂₀)、十六烷基三甲基溴化铵和聚乙二醇为软模板的水热法可获得具有长方状和六方状介孔多晶碳酸钙和单晶氧化镁和氧化钙,水热温度和表面活性剂性质对产物粒子形貌、孔道结构和比表面积有重要影响。所得多孔氧化镁、氧化钙和碳酸钙的比表面积最高可分别达到298、257、134 m²/g。     

Synthesis and characterization of energetic GAP‐b‐PAEMA block copolymer

Energetic block copolymer of polyglycidylazide‐b‐poly (azidoethyl methacrylate) (GAP‐b‐PAEMA) was synthesized and characterized. Macroinitiator PECH‐Br prepared via the reaction of 2‐bromoisobutyryl bromide with hydroxyl‐terminated polyepichlorohydrin (PECH‐OH) was used to initiate the atom transfer radical polymerization (ATRP) of chloroethyl methacrylate (CEMA). After azidation of the resulting copolymer, energetic copolymer GAP‐b‐PAEMA was obtained. Increase in the molecular weight determined by gel permeation chromatograph (GPC) is in agreement with the formation of block copolymer. Fourier transform infrared spectroscopy (FTIR) shows that the chlorine groups in the block copolymer can be substituted by azide group easily. Thermogravimetric analysis (TGA) shows that degradation of GAP‐b‐PAEMA involves two steps: the instantaneous decomposition of the azide groups followed by progressive scission of the polymer backbone. From differential scanning calorimetry (DSC) analysis, the GAP‐b‐PAEMA copolymer exhibits two glass transition temperatures (T_g) at ?18 and 36°C, suggesting that the synthesized copolymer is a thermoplastic elastomer. This research provides a new method for the synthesis of energetic polymer. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Preparation of porous thin films of a partially aliphatic polyimide

A thermally labile polymer, poly(propylene glycol), was modified to obtain PPG having an amino end group. PPG was incorporated into a partially aliphatic polyimide based on an alicyclic dianhydride, and this afforded triblock copolymers containing various amounts of PPG blocks. The thermal properties of the copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry. The thermal decomposition of the PPG block in the copolymers was carried out at 240°C under various pressures to obtain porous polyimide films. The pores remained during the thermolysis under a reduced pressure of 710 mmHg, whereas they collapsed under (near) atmospheric pressure. The pore size increased as the amount of the PPG block in the copolymers increased. The dielectric constants of the porous polyimides varied from 2.60 to 2.42 with the original copolymer composition. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 532–538, 2006     

Preparation of Polyglycidylmethacrylate Macropore Beads and Application in Candida species 99–125 Lipase Immobilization

Polyglycidylmethacrylate beads with macroporous structure were synthesized by suspension polymerization and directly used for Candida species 99–125 lipase immobilization because of their rich surface epoxy groups. The properties of the synthesized polymer beads were characterized by scanning electron microscopy and FT‐IR spectroscopy. To increase the enzyme activity, divinyl benzene and toluene/heptane were used as cross‐linker and porogen, respectively, and the effects of cross‐linker content and porogen content on lipase immobilization were studied. After optimizing the synthesis conditions, the optimum lipase concentration for immobilization was determined as 10 mg mL^–1. The immobilized lipase showed a broader pH stability and higher temperature stability. The immobilized enzyme could be reused for ten batches with 62 % of residual activity.     

超临界CO_2中CTFE和BVE的共聚合研究

以超临界CO2为反应介质,制备得到三氟氯乙烯(CTFE)和乙烯基正丁基醚(BVE)共聚物,研究了单体配比、反应温度、引发剂用量、单体浓度对聚合反应及聚合物的结构与性能的影响情况。结果表明:通过控制单体配比及其他实验条件,可以得到不同结构、不同氟含量的含氟聚合物;当单体配比中CTFE的比例增大到一定程度(BVE/CTFE质量比<6/10),实验得到的聚合物是交替共聚物。同时实验发现,聚合反应过程中压力的变化与反应的进程是同步的。     

Improvement of mechanical properties of macroporous β-tricalcium phosphate bioceramic scaffolds with uniform and interconnected pore structures

The biocompatible and degradable macroporous bioceramic scaffolds with high mechanical properties and interconnected porous structures play an important role in hard tissue regeneration and bone tissue engineering applications. In this study, the improvement of mechanical properties of macroporous β-tricalcium phosphate [β-Ca₃(PO₄)₂, β-TCP] bioceramic scaffolds with uniform macropore size and interconnected pores were fabricated by impregnation of the synthesized β-TCP nano-powder slurry into polymeric frames. The microstructures, mechanical properties and in vitro degradation of the fabricated samples were investigated. For a comparison, β-TCP scaffolds were also fabricated from commercial micro-size powders under the same conditions. The resultant scaffolds showed porosities ∼65% with uniform macropore size ranging from 400 to 550 μm and interconnected pore size ∼100 μm. The compressive strength of the samples fabricated from nano-size powders reached 10.87 MPa, which was almost twice as high as those fabricated from commercial micro-size powders, and was comparable to the high-end value (2–10 MPa) of human cancellous bone. Furthermore, the degradation of the β-TCP bioceramics fabricated from nano-size powders was apparently lower than those fabricated from commercial micro-size powders, suggesting the possible control of the degradation of the scaffolds by regulating initial powder size. Regarding the excellent mechanical properties and porous structures, the obtained macroporous β-TCP bioceramic scaffolds can be used in hard tissue regeneration and bone tissue engineering applications.     

Preparation and application of fluorocarbon polymer/SiO2 hybrid materials,part 1: Preparation and properties of hybrid materials

For this study, we first prepared a fluorocarbon polymer and its hybrid materials. We found that fluorocarbon copolymers can produce hydrogen bonds with SiO₂ to form hybrid materials. We also used thermogravimetric analyzer and tested the thermostabilities of the four products, which were ranked as follows: fluorocarbon copolymer/SiO₂ hybrid material > fluorocarbon polymer/SiO₂ hybrid material > fluorocarbon copolymer > fluorocarbon polymer. In addition, we found that, due to the inorganic SiO₂ used, the number of pores and the specific surface areas of the hybrid materials both increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1140–1145, 2007     

Influence of urethane group on properties of crosslinked polyurethane elastomers

Three series of weakly crosslinked polyurethanes based on a hydroxyterminated polybutadiene, hydroxyterminated butadiene–acrylonitrile copolymer, and hydroxyterminated ethylene–adipate–maleate–fumarate copolymer were prepared while varying the hard segment content between 1.72 and 2.36 mol ? NH? COO? /1000 g polymer. Information on the microphase structure and the properties of the synthesized polyurethanes was obtained by differential scanning calorimetry, wide‐angle X‐ray scattering, and mechanical studies. Up to a urethane concentration of around 2 mol ? NH? COO? /1000 g polymer, there is a mixture of hard–hard and hard–soft segments. Above this concentration a large part of the hard–soft segments passes into hard–hard crystallites, liberating the soft segments. The best mechanical properties of the studied polyurethanes were found for a urethane concentration of around 2 mol ? NH? COO? /1000 g polymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1858–1867, 2003     

Porous structure and swelling properties of styrene–divinylbenzene copolymers for size exclusion chromatography

Small spherical particles of styrene–divinylbenzene copolymers have been synthesized by modified suspension polymerization. The effects of divinylbenzene (DVB) contents, dilution degree of the monomers and diluent composition on the porous structure and swelling properties of the copolymers were investigated. Toluene uptakes of macroporous copolymers were considered as a result of three contributions: filling of the fixed pores, expansion of the fixed or collapsed pores, and nuclei swelling and heptane uptakes as a result of the two first contributions. The increase of DVB content in the copolymers synthesized in presence of a solvating diluent (toluene) provoked a decrease on the nuclei swelling. The increase of dilution degree with solvating diluents changed the toluene and heptane uptakes, and when the diluent–copolymer affinity was reduced, the fixed pore volume increased. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1257–1262, 1997     

New poly(acrylic acid) containing segmented copolymer structures by combination of “click” chemistry and atom transfer radical polymerization

In this paper, the combination of atom transfer radical polymerization (ATRP) of 1-ethoxyethyl acrylate (EEA) and the copper(I) catalyzed “click” 1,3-dipolar cycloaddition reaction of azides and terminal alkynes was evaluated as a method to synthesize diverse amphiphilic copolymer structures. Using the 1-ethoxyethyl protecting group strategy, the application field was broadened with the synthesis of complex polymer structures containing poly(acrylic acid) (PAA) segments. A modular approach has been used: polymers with alkyne functionalities as well as azide functionalities have been synthesized. These polymers were subsequently “clicked” together to yield block copolymers. Furthermore, graft copolymers were synthesized by grafting alkyne-containing polymers onto a polymer backbone with multiple azide functions using the combination of ATRP and “click” reactions.     

Preparation of highly dispersed gold nanoparticles inside the porous support assisted by amphiphilic vinyl maleate copolymer

An amphiphilic copolymer composed of maleic acid and alkyl (C₁₈) vinyl monomer was encapsulated into the porous support. A series of colloidal gold nanoparticles of known size was substantially immobilized in the composite porous supports based on cross-linked polyacrylate ester and cross-linked polystyrene resin. Maleic acid moiety of the amphiphilic copolymer can act as a stabilizer for gold nanoparticles in analogy to citric acid, whereas alkyl chains play a role for the stable accommodation of the amphiphilic copolymer. Maleic acid stabilizes the gold nanoparticles by flexing the geometrical arrangement of the linear polymer. Presence of C₁₈ alkyl chain in the poly(C₁₈-vinyl maleate) is indispensable to act as spacing group that prevents mutual aggregation of gold nanoparticles. On the other hand, gold nanoparticles with average diameter of less than 8 nm were spontaneously formed by treatment of the composite resin beads with aqueous HAuCl₄ solution, subsequently dispersed inside the pores of resin beads as observed by TEM. We have also elucidated the catalytic activity of the material with the hydrogenation of cinnamaldehyde in supercritical carbon dioxide. Notably, apparent size effect of gold was observed in the selectivity of the reaction.     

Electrochemical copolymerization of pyrrole and thiophene nanofibrils using template‐synthesis method

Copolymer nanofibrils composed of pyrrole and thiophene were prepared by synthesizing the desired polymer within the pores of microporous anodic aluminum oxide (AAO) template membranes. The copolymer nanofibrils were photographed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for microstructure analyses. The results of the SEM and TEM revealed that the copolymer nanofibrils obtained had uniform and well‐aligned arrays and their diameter and length could be controlled by changing the aspect ratios of the AAO membrane. The results of cyclic voltammetry and IR spectrometry indicated that polypyrrole and polythiophene were both involved in the copolymer. The nanofibrils that were obtained were identified as copolymers rather than composites. The influence of the applied polymerization potential on the synthesis of copolymer nanofibrils was investigated. The higher potential favored the incorporation of thiophene units into the copolymer nanofibrils. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2403–2407, 2002     

Porous carbon material based on petroleum pitch

The samples of granulated (2–4 mm) porous carbon material with unimodal and bimodal poresize distributions were prepared. The sample with a unimodal porous structure was prepared via the mixing of soot and petroleum pitch followed by carbonization (the first stage). At the second stage, the carbon material obtained was ground to a particle size smaller than 0.2 mm, mixed with petroleum pitch, and also subjected to carbonization. The porous structures of these materials were studied by scanning electron microscopy and mercury porosimetry. It was established that the predominant pore size (20–1000 nm) of the samples with the unimodal structure depends on the used soot grade. At the second stage of the process, a considerable volume of pores in a range of 4–12 μm is formed in the production of bidisperse material. As compared with a sample with the monodisperse structure, porous carbon material with a bimodal distribution of pores was characterized by a lower crushing strength of granules and comparable specific surface areas, total pore volumes, and ash contents.     

Sol-gel and SPS combined synthesis of highly porous wollastonite ceramic materials with immobilized Au-NPs

Here we present a prospective method of sol-gel synthesis of highly porous wollastonite ceramic powders with controlled macroporous structure (mean pore size ~160 nm) and immobilized gold nanoparticles (particle size is less than 50 nm). The method's distinction is based on using the colloidal template (micelles of "core-shell" polymer latex) both as a poreforming agent and as nanoreactors for nanoparticle synthesis in the system wollastonite/Au-NPs. We revealed the impact of template thermal removal on the morphology of nanostructured wollastonite. We also optimized thermal treatment to obtain defect-free macroporous calcium silicates. Template functionalization by size stabilized gold nanoparticles with their following immobilization into the porous volume of synthesized wollastonite has been described. Besides, an original nonstandard method of combined sol-gel (template) synthesis and spark plasma sintering (SPS) is suggested to obtain the wollastonite ceramic compounds with bimodal pore size distribution (100–500 nm and not less than 1 µm), high mechanical strength (compressive strength limit ~120 MPa) and containing immobilized Au-NPs. Peculiarities of biporous silicate framework formation has been studied using two types of poreforming agents (templates) of various origin, shape and size, introduced during different stages of sol-gel and SPS processes. These templates are organoelemental polymer latex of “core-shell” type and nonorganic carbon filler. Developed approaches are innovative and provide to make new materials with unique characteristics and functional properties as bone-like structure, mechanical stability, antibacterial and anti-inflammatory effects and etc. The materials meet all the biomaterials requirements and are in high demand by modern medicine.