Imprinted microspheres doped with carbon nanotubes as novel electroresponsive drug‐delivery systems

Novel molecularly imprinted polymers (MIPs) suitable for the electroresponsive release of diclofenac were synthesized by precipitation polymerization in the presence of carbon nanotubes (CNTs). Both conventional and electroresponsive imprinted polymers were synthesized with methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. Preliminary experiments were performed to fully characterize the conventional MIPs and composite materials in terms of their morphological properties, recognition behavior, and electric resistivity. In vitro release experiments were performed in aqueous media to elucidate the ability of the MIPs and spherical imprinted polymers doped with CNTs to release the loaded template in a sustained manner over time in comparison to the that of the corresponding nonimprinted materials. Furthermore, a 20‐V direct‐current voltage was applied through the releasing media to evaluate how the electric field influenced the drug release to demonstrate the suitability of the proposed macromolecular system as an electroresponsive drug‐delivery device. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 829‐834, 2013     

Novel approach to fabricate polycarbonate antibacterial superhydrophobic surfaces

A novel approach to fabricate a stable polycarbonate (PC) surface with superhydrophobicity and antibacterial properties obtained by use the phase separation and solvent/non-solvent selected method without any use to surface chemical modification materials, with high chemical stability. At the same time a systematic study of dependence surface morphology on the acetone/DMF solvent mixture treatment. In medical devices, the bacterial attachment onto the surface of polymers such as a PC is influenced by the physicochemical properties of the polymers, including surface roughness and hydrophobicity. The resulting surfaces demonstrated that the water CA of the PC surface was 154 ± 2° with excellent inhibition percentage of two bacteria. FESEM showed that the surface structure comprised branches or petals outside the ‘plant seabeds’ with a hierarchical micro-/nano-binary formation, in addition to related AgNps with a rough surface. In order to test the stability and properties of the PC surfaces, Pseudomonas aeruginosa and Acinetobacter baumannii suspensions in ‘Amide Organic’ was poured above the surface and allowed to settle on top of the surface for several minutes, then, the Anti-adhesive effect of colonies bacteria was evaluated and the results showed the very small percentage of bacteria was adhesive on surfaces.     

Fabrication and superhydrophobicity of fluorinated carbon fabrics with micro/nanoscaled two-tier roughness

Superhydrophobic carbon fabric with micro/nanoscaled two-tier roughness was fabricated by decorating carbon nanotubes (CNTs) onto microsized carbon fibers, using a catalytic chemical vapor deposition and subsequent fluorination surface treatment. The superhydrophobic surfaces are based on the regularly ordered carbon fibers (8-10 μm in diameter) that are decorated by CNTs with an average size of 20-40 nm. The contact angle of water significantly increases from 148.2 ± 2.1° to 169.7 ± 2.2° through the introduction of CNTs. This confirms that the wettability of carbon fabric changes from hydrophobicity to superhydrophobicity due to structural transformation. This finding sheds light on how the two-tier roughness surface induces superhydrophobicity of rough surfaces, and how the presence of CNTs reduces the area fraction of a water droplet in contact with the carbon surface with two-tier roughness.     

Synthesis,Characterization, Antimicrobial Activity,and Adhesive Property of Amino Benzyl Group Substituted Acrylic/Methacrylic Polymers and Their Copolymers

The monomers 2-aminobenzylacrylate (2-ABA) and 2-aminobenzyl methacrylate (2-ABMA) were synthesized. The homopolymers and various compositions of copolymers with ethoxylated bisphenol-A-dimethacrylate (EBPADMA) were synthesized using free radical polymerization. The polymers were characterized by FT-IR, ¹H NMR, and ¹³C NMR spectral techniques. The thermal property of the polymers was determined by thermogravimetric analysis and differential scanning calorimeter. The prepared adhesives were tested on leather and metal surfaces using single-lap-joint shear test method. The antimicrobial activity of polymers and copolymers has been studied using Mueller Hinton Broth method.     

Surface Modification of Carbon Fibers by Free Radical Graft‐Polymerization of 2‐Hydroxyethyl Methacrylate for High Mechanical Strength Fiber–Matrix Composites

Free radical polymerization of vinylic monomers in the presence of carbon fibers results in the grafting of polymers onto the carbon fiber surface. Graft polymers cannot be removed by intense washing with good polymer solvents. The density and size of these structures are successfully controlled by reaction conditions. Grafting of the carbon fiber surface with hydroxyethyl methacrylate allows for introducing functional groups suitable for the reaction with an epoxy‐based resin. The resulting fiber‐reinforced composites show enhanced mechanical properties compared to samples prepared from carbon fibers equipped with a standard sizing for epoxy resins. Thus, tensile strength increases by 10%, while interlaminar shear strength improves by 20%.     

Preparation of molecularly imprinted polymers in supercritical carbon dioxide

Molecularly imprinted polymer nanoparticles were prepared in supercritical carbon dioxide using a noncovalent imprinting approach. In the present work, propranolol was used as a model template, methacrylic acid as a functional monomer, and divinylbenzene as a crosslinker. Under a high dilution condition, the heterogeneous polymerization resulted in discrete crosslinked polymer nanoparticles. Compared with the nonimprinted polymers, the imprinted nanoparticles displayed much higher propranolol uptake in a low polarity organic solvent. The use of a single enantiomer (S)‐propranolol as the template clearly demonstrated that the imprinted binding sites are chiral‐selective, with a cross‐reactivity towards (R)‐propranolol of less than 5%. The overall binding performance of the imprinted nanoparticles was comparable to imprinted polymers prepared in conventional organic solvents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2863–2867, 2006     

Synthesis and properties of new photosensitive and chiral poly(amide‐imide)s based on bicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic diimide and dibenzalacetone moieties in the main chain

Aromatic poly(amide‐imide)s (PAIs) are high‐performance materials with a good compromise between thermal stability and processability when compared with polyamides or polyimides of analogous structures. In addition, the incorporation of photosensitive functional groups and chiral segments into the polymer backbone can lead to interesting polymers for various applications. In this work, six new photosensitive and chiral PAIs were synthesized from the direct polycondensation reaction of novel N,N′‐(bicyclo[2,2,2]oct‐7‐ene‐tetracarboxylic)‐bis‐L ‐amino acids with 2,5‐bis(4‐aminobenzylidene)cyclopentanone as dibenzalacetone moiety using two different methods. The polymerization reactions produced a series of photosensitive and optically active PAIs in high yields and with good inherent viscosities. The resulting polymers were characterized using Fourier transform infrared and ¹H NMR spectroscopy, elemental analysis, inherent viscosity, specific rotation, solubility tests and UV‐visible spectroscopy. The thermal properties of the PAIs were investigated using thermogravimetric analysis. Due to the presence of the dibenzalacetone moiety in the polymer chain, the PAIs have photosensitive properties. Also, these PAIs are optically active and soluble in various organic solvents. These resulting new polymers have the potential to be used in column chromatography for the separation of enantiomeric mixtures. Copyright © 2009 Society of Chemical Industry     

Electrospinning of Fluorinated Polymers: Formation of Superhydrophobic Surfaces

Summary: Superhydrophobic surfaces are generated by a simple one‐step method of electrospinning of fluorinated homopolymers and copolymers of PFS. The hydrophobicity and superhydrophobicity can be changed by simply changing the surface morphology, which is possible by changing the electrospinning conditions. The appropriate combination of surface morphology and fluorinated materials led to the formation of super‐water‐resistant coatings showing the ‘water‐roll’ effect at an angle of 0°, i.e. placement of water droplets on such surfaces was not possible as they immediately rolled away. The effect is compared with the corresponding nonfluorinated PS and found to be clearly distinct in terms of water‐roll effect. Incorporation of about 30 mol‐% PFS onto the PS backbone could also convert hydrophobic PS surfaces to superhydrophobic surfaces. The effect is generalized by also using a new fluorinated poly(p‐xylylene) derivative. The molecular weight of the polymers has no noticeable effect on hydrophobicity/superhydrophobicity behavior.

SEM micrographs PFS–styrene copolymer, 10% solution in THF:DMF (1:1 v/v); 5% solution in THF:DMF (1:1 v/v) and homo‐PPFS < 2% solution in THF:DMF (1:1 v/v).     

Low‐molecular‐weight polytetrafluoroethylene bearing thermally stable perfluoroalkyl end‐groups prepared in supercritical carbon dioxide

Low‐molecular‐weight (M_n) polytetrafluoroethylene (PTFE) homopolymers were successfully prepared using a perfluorodiacyl initiator, bis(perfluoro‐2‐n‐propoxypropionyl) peroxide, in supercritical carbon dioxide. Solid‐state ¹⁹F NMR and Fourier transform infrared spectral analyses show that perfluoroalkyl end‐groups are present in the resultant PTFEs. Thermogravimetric analysis suggests all polymers with various M_n have outstanding thermal stability. Differential scanning calorimetry measurements indicate that both melting and crystallization transitions of PTFE shift to lower temperatures when M_n decreases, because shorter polymer chains can move more easily at lower temperatures. Investigation of polymerization kinetics suggests that the rate law for the polymerization has kinetic orders of 0.5 and 1.0 with respect to initiator and monomer concentrations, indicating that termination occurs through coupling of propagating chains. Melt fusion crystallinity of as‐polymerized PTFE can be as high as 86%, and the polymerization rate does not seem to be obviously affected by the total interphase area of the polymer phase, implying polymerization mainly occurs in the carbon dioxide‐rich fluid phase; meanwhile, the low viscosity and high diffusivity of supercritical carbon dioxide mean that propagating chains have more opportunities to meet, thus yielding low‐M_n PTFEs. Copyright © 2012 Society of Chemical Industry     

有机硅合成革涂层的原位构建及其性能

为实现合成革涂层材料的以“硅”代“碳”，以端乙烯基硅油（ViPDMSVi）、侧含氢硅油（PMHS）、侧乙烯基硅油（ViPMVSVi）、白炭黑等为原料，在热诱导下原位聚合制备了有机硅（PDMS）聚合物涂膜。通过力学性能、DSC、耐曲挠、耐磨、疏水防污等测试对PDMS聚合物涂膜的性能进行了表征，探究了ViPDMSVi、PMHS活性氢、双键与活性氢物质的量比、ViPMVSVi及白炭黑对PDMS聚合物涂膜的拉伸强度、断裂伸长率及硬度的影响。结果表明，侧乙烯基硅油和白炭黑的质量分数分别为7%和40%时对PDMS聚合物涂膜力学性能的提升最为显著，优化条件下制得的PDMS聚合物涂膜拉伸强度为5.96 MPa，断裂伸长率为481%，合成革涂层表现出优异的低温曲挠性、耐磨性、疏水及防污性。     

Wettability of conducting polymers: From superhydrophilicity to superoleophobicity

The review reports most of the works realized in the field of the surface wettability based on conducting polymers. The surface wettability is highly depending on the intrinsic hydrophobicity of materials and the roughness geometry. Conducting polymers have unique properties allowing to tune the surface wettability, for example, by reversibly incorporating various hydrophobic/hydrophilic doping ions, by changing the nature of the polymerizable core or by functionalization with various hydrophobic/hydrophilic substituents. Conducting polymers are obtained by monomer oxidation using various strategies such as the chemical oxidative polymerization in solution, the electrochemical polymerization on conductive substrates or the vapor-phase polymerization, leading to have an easy control of the surface morphology at micro- or a nanoscale with a surface wettability going from superhydrophilicity to superoleophobicity.     

炭黑表面接枝聚合改性进展

从炭黑粒子表面性质及表面化学基团出发 ,并结合聚合反应理论 ,介绍了将单体接枝聚合或将聚合物直接接枝到炭黑表面的自由基接枝、正离子接枝、负离子接枝及其他功能化接枝改性方法。论述了实现这些过程的溶液法、熔融法及辐射法接枝等工艺方法及影响炭黑接枝改性的因素。炭黑表面接枝聚合改性能大大扩大炭黑的应用范围。     

Modifying and managing the surface properties of polymers

An ongoing challenge in polymer science is the preparation of materials with bespoke surface properties which differ from that of the bulk, for example hydrophobicity, wettability, chemical resistance, adhesion or biocompatibility. We highlight here recent efforts in the design, development and application of (multi)end‐functionalized polymers as additives for the efficient modification of polymer surface properties. Aryl‐ether moieties bearing up to eight functional groups have been used as initiators for the controlled polymerization of both styrene and methyl methacrylate by atom transfer radical polymerization (ATRP) and of lactide by ring opening polymerization (ROP). The resulting polymers have been used as additives to modify the surfaces of the corresponding bulk polymers. Fluorinated polymer surfaces are particularly appealing in terms of their liquid repellence, chemical inertness and low coefficient of friction. When an additive consisting of a low molecular weight polystyrene chain, end‐capped with four C₈F₁₇ groups, is present in a matrix of polystyrene at levels as low as 0.1%, near polytetrafluoroethylene‐like surface properties result. Copyright © 2007 Society of Chemical Industry     

Synthesis,characterization, and thermal behavior study of methyl methacrylate polymers containing 4‐carbazole substitutes

A new polymerizable monomer, [4‐(9‐ethyl)carbazolyl]methyl methacrylate ( 2 ), was synthesized by reacting of methacrylic acid and 4‐hydroxymethyl‐9‐ethyl carbazole ( 1 ) by esterification procedure in the presence of N,N′‐dicyclohexylcarbodiimide. The resulting monomer was then polymerized free‐radically to form the poly(methyl methacrylate) containing 4‐(9‐ethyl)carbazolyl pend ent groups. Also, copolymerization of monomer 2 with various acrylic monomers such as methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, and n‐butyl acrylate by azobisisobutyronitrile as a free radical polymerization initiator gave the related copolymers in high yields. The structure of all the resulted compounds was characterized and confirmed by FTIR and ¹H NMR spectroscopic techniques. The average molecular weight of the obtained polymers was determined by gel permeation chromatography using tetrahydrofurane as the solvent. The thermal gravimetric analysis and differential scanning calorimeter instruments were used for studying of thermal properties of polymers. It was found that, with the incorporation of bulky 4‐(9‐ethyl)carbazolyl substitutes in side chains of methyl methacrylate polymers, thermal stability and glass transition temperature of polymers are increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4989–4995, 2006     

Surface characteristics of poly(γ‐alkyl α l‐glutamate)s with different alkyl groups

A series of poly(γ‐alkyl α L ‐glutamate)s with different alkyl groups were synthesized by the ring opening polymerization of corresponding α‐amino acid N‐carboxyanhydrides. The characteristics of these polyglutamate surfaces were evaluated by attenuated total reflectance Fourier transform infrared spectroscopy spectra, water contact angle, water absorption, protein adsorption, and platelet adhesion measurements. Changing the length of the alkyl side chain provides a unique opportunity to study the influence of carbon number in the alkyl group on the surface properties of the polyglutamates. Water contact angle and water absorption data show that the hydrophilicity of these polyglutamate surfaces decreases with the increasing of methylene in the alkyl group. Protein adsorption on these polyglutamate surfaces increases with the enhancing of surface hydrophobicity. However, the changes in platelets adhesion could be attributed to the hydrophilicity/hydrophobicity of the polyglutamates and the specific effect of alkyl group. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymer–leather composites. III. Morphology and water absorptivities of selected acrylic polymer–leather composite materials

The morphology of composite materials made by polymerizing methyl methacrylate into chrome-tanned cattlehide was examined by both light and scanning electron microscopy. The composites were selected from a series previously prepared and characterized, and their kinetics were reported. Micrographs of the polymer phase of the composites, prepared by preferential removal of collageneous material with 6N hydrochloric acid, yielded negative replicas of the fiber conformations. These provided evidence in support of proposed mechanisms of polymer deposition for two different methods of composite preparation. One method involved emulsion polymerization of monomer into hydrated leather and the other, preferentially filling leather free space. Both light and scanning electron microscopy of all composites and replicas revealed poly(methyl methacrylate) deposited largely in coarse aggregates around individual fibers. In emulsion systems, fiber bundles expanded with continuous deposition. No difference was observed in the morphology of bound and deposited polymers. However, high magnification of bound-polymer replicas exposed polymer surrounding some fibril traces. Deposition of polymer in the fine structure of bulk or solution prepared composites was not found; instead, all free space was occupied. A theory specifying polymer location in previous publications of this series, and extended here to define replica parameters, was abundantly supported by measured physical properties. A dominant grafting mechanism was precluded because the large domains limited points of possible attachment. Water absorptivities of emulsion prepared composites and controls were identical when the data were corrected to neat leather, although the rates were slightly perturbed. In contrast, both rate and equilibrium absorption data of the bulk and solution composites were retarded by polymer presence.     

Azide-Modified Poly(diethyl vinylphosphonate) for Straightforward Graft-to Carbon Nanotube Functionalization

Rare-earth metal-mediated group-transfer polymerization (REM-GTP) offers distinctive features over common polymerization techniques, such as living character, a broad scope of functional monomers, high activity, excellent control of the polymeric parameters as well as inherent chain-end functionalization. Through the latter, polymers with reactive end-groups become feasible, opening the pathway for further post-polymerization functionalization. In this study, a straightforward graft-to immobilization of the Michael-type polymer poly(diethyl vinylphosphonate) (PDEVP) on multi-walled carbon nanotubes (MWCNT) is reported. Hence, a customized azide initiator is synthesized and studied in the C H bond activation with various lanthanide-based catalysts and the subsequent polymerization of diethyl vinylphosphonate (DEVP). The successful attachment of the azide end-group is demonstrated via electrospray ionization mass spectrometry (ESI-MS) and the synthesized polymers are subjected to immobilization on multi-walled carbon nanotubes in a graft-to approach. The prepared MWCNT:PDEVP composites are analyzed via thermogravimetric analysis (TGA), elemental analysis (EA), Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and the versatility of this approach is shown via the stabilization of MWCNT dispersions in water.     

Fettpolymere – Herstellverfahren und Eigenschaften

The radical polymerization of esters of acrylic, methacrylic or crotonic acid with fatty alcohols proved to be an efficient method for production of polymers with hydrophobic moieties. By co-polymerisation with hydrophilic co-monomers - such as maleic anhydride - copolymers with a broad spectrum of properties can be designed. As an example the copolymerisation of fatty crotonates with maleic anhydride was studied in detail. The reaction was carried out as bulk polymerisation in a semi-batch process. By this method the compatibility problems of the two monomers, which have very different hydrophilicities could be overcome. The product acts as a very effective fat liquoring agent in leather treatment: the maleic moieties cause an outstanding fixing of the agent on the leather and the fatty crotonate moieties create a very smooth leather. Terpolymers of fatty acrylates, hydrophilic monomers and terpenes could also be synthesized in a similar way. These terpolymers proved to be useful as dispersing agents for pigments in paints and varnishes.     

Multi‐walled carbon nanotubes as unexpected accelerators of chemical reactions

The influence of carbon nanotubes on various chemical reactions has been examined. These reactions include epoxy crosslinking, in situ polymerization of copolymers in the presence of carbon nanotubes and thermal degradation of a thermoplastic matrix. The various characterizations were based on different types of analyses, including differential scanning calorimetry, proton nuclear magnetic resonance, size exclusion chromatography and thermogravimetric analysis. In each case, we show that the presence of multi‐walled carbon nanotubes accelerates the process. © 2012 Society of Chemical Industry     

Development of nanocomposites of bentonite with polyaniline and poly(methacrylic acid)

Nanocomposites of bentonite with polyaniline (PANI), poly(methacrylic acid) (PMAA), and poly(aniline‐co‐methacrylic acid) (PANI‐co‐PMAA) were prepared by in situ intercalative polymerization technique. The nanocomposites were characterized by FTIR and UV–visible spectroscopies, XRD, SEM, TEM, as well as TG‐DTA studies. The in situ intercalative polymerization of PANI, PMAA, and PANI‐co‐PMAA within bentonite layers was confirmed by FTIR, XRD, SEM, as well as TEM studies. XRD confirmed the intercalation of polymers and copolymer in bentonite. The average particle size of the nanocomposites was found to be in the range of 250–500 nm. The thermal stability was found be the highest for PANI‐co‐PMAA‐bentonite. The swelling behavior studies suggest that these nanocomposites hold potential for their utilization in absorption of toxic materials from waste water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3299–3306, 2007