Transparent hydrophobic and superhydrophobic coatings fabricated using polyamide 12–SiO2 nanocomposite

Optically transparent hydrophobic and superhydrophobic coatings have been prepared using polyamide 12–SiO₂ nanocomposite (NC) on glass substrates by the spin‐coating method. The coatings have been optimized for their hydrophobicity and transparency. The transformation from hydrophobic to superhydrophobic is achieved with increase in roughness (R_a) which increases with SiO₂ content. These coatings are highly transparent in the entire visible region (400–800 nm). The influence of layer thickness on water contact angle (WCA) and optical transmittance of the coatings has been studied. Field emission scanning electron micrograph (FESEM) shows the presence of SiO₂ nanoparticles covered with polyamide homogenously on the surface and the particles are aggregated to form a rough structure. X‐ray diffraction (XRD) patterns show that the polyamide losses its crystalline structure in the composite. The preparation procedure reported here is simple and eco‐friendly. The dual nature of the coatings, that is, high transparency and superhydrophobicity in the entire visible region suggests for its potential usage in self‐cleanings, wind screen and optoelectronic applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of polystyrene‐b‐poly(ethylene oxide) on self‐assembly of polystyrene‐b‐poly(N‐isopropylacrylamide) in aqueous solution

Mixed micelles of polystyrene‐b‐poly(N‐isopropylacrylamide) (PS‐b‐PNIPAM) and two polystyrene‐b‐poly(ethylene oxide) diblock copolymers (PS‐b‐PEO) with different chain lengths of polystyrene in aqueous solution were prepared by adding the tetrahydrofuran solutions dropwise into an excess of water. The formation and stabilization of the resultant mixed micelles were characterized by using a combination of static and dynamic light scattering. Increasing the initial concentration of PS‐b‐PEO in THF led to a decrease in the size and the weight average molar mass (〈M_w〉) of the mixed micelles when the initial concentration of PS‐b‐ PNIPAM was kept as 1 × 10^?3 g/mL. The PS‐b‐PEO with shorter PS block has a more pronounced effect on the change of the size and 〈M_w〉 than that with longer PS block. The number of PS‐b‐PNIPAM in each mixed micelle decreased with the addition of PS‐b‐PEO. The average hydrodynamic radius 〈R_h〉 and average radius of gyration 〈R_g〉 of pure PS‐b‐PNIPAM and mixed micelles gradually decreased with the increase in the temperature. Both the pure micelles and mixed micelles were stable in the temperature range of 18 °C–39 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1168–1174, 2010     

喷涂法制备功能性超疏水复合涂层及其性能研究

以常用工程材料硅树脂BP与St(o)ber法合成的二氧化硅(SiO2)分散液为原料,运用喷涂法(spray-coating)制备出了功能性微/纳粗糙(MNR)结构的超疏水涂层,其接触角可以达到146.5°,滚动角小于1°(测试液滴量为15μL).通过分析喷涂法制备复合涂层所需的条件,得出喷涂液pH＝7.7-8.0时,在...     

Multi‐Walled Carbon Nanotubes (MWCNT)‐Ionic Liquid‐Modified Carbon Paste Electrode: Probing FurazolidoneDNA Interactions and DNA Determination

The interactions of furazolidone (Fu) with double‐stranded calf thymus DNA (dsDNA) on the multi‐walled carbon nanotubes‐ionic liquid‐modified carbon paste electrode (MWCNT‐IL‐CPE) have been studied by cyclic voltammetry. In the presence of DNA, the cathodic peak current of Fu decreased and the peak potential shifted to a positive potential, indicating the intercalative interaction of Fu with DNA. The binding constant of Fu with DNA and stoichiometric coefficient has been determined according to the Hill's model. This electrochemical method was further applied to the determination of DNA. Two linear calibration curves were obtained for DNA detection in the concentration ranges of 0.03–0.10 and 0.10–4.0 μg l^?1 with a detection limit of 0.027 μg l^?1. The method was successfully applied to analyze Fu in serum samples.     

Investigating properties of poly (ether‐amide)/MWCNT nanocomposite films containing 2,7‐bis(4‐aminophenoxy)naphthalene and isophthalic segments

Three nanocomposite films based on aramid (poly (ether‐amide), PEA) and multiwall carbon nanotubes (MWCNT) were prepared via solution casting method using 2,7‐bis(4‐aminophenoxy)naphthalene (4) and isophthalic acid (5) containing various amounts of MWCNT (2, 3, 5 wt.%). To comprehensively analyze the properties of the cast films as well as the monomers, different techniques were employed, namely FT‐IR, ¹H NMR, X‐ray diffraction, and field emission scanning electron microscopy. Also, thermal and tensile properties of PEA (6) and nanocomposite films were investigated using thermogravimetric analysis and mechanical analysis, respectively. The morphology, thermal, and mechanical properties of nanocomposite films approved that MWCNT had well dispersion in the PEA matrix and showed a synergistic effect on improving all of the investigated properties. Based on the thermogravimetric analysis results, employing MWCNT caused to increase in the char yields from 61 (in the neat PEA) to 66 (in the PEA /MWCNT nanocomposite 5 wt.%) under the nitrogen atmosphere. In comparison to the pristine PEA (426°C), the temperature at 10 losses mass % (T₁₀) was increased from 530°C to 576°C, with 2 to 5 wt.% of MWCNT. Mechanical analysis revealed that the tensile strength and initial modulus were improved by incorporating MWCNT into PEA (81.70–93.40 MPa and 2.10–2.22 GPa, respectively). Electrical conductivity of the PEA/MWCNT nanocomposites was displayed maximum value in the 5 wt.%, showing satisfactory value in many application areas. The X‐ray diffraction technique was employed to study the crystalline structure of the prepared nanocomposite films as well as PEA. In addition, the electrochemical impedance spectroscopy study demonstrated that the prepared nanocomposites had significant impedance improvement in the presence of MWCNTs.     

Angle‐resolved XPS of fluorinated and semi‐fluorinated side‐chain polymers

Angle‐resolved XPS data (elemental quantification and high‐energy‐resolution C 1s) are presented for ten polymers with side‐chains of the form ? OCO(CF₂)_yF, ? COO(CH₂)₂OCO(CF₂)_yF (y = 1, 2, 3) and ? COO(CH₂)_x(CF₂)_yF (x = 1, y = 1, 2, 3; x = 2, y = 8). Particular attention was paid to charge compensation and speed of data acquisition, with co‐addition from multiple fresh samples to give spectra with good energy resolution and good signal‐to‐noise ratio free from the effects of x‐ray‐induced degradation. Water contact angles for the polymers are also reported. The XPS data demonstrate preferential surface segregation of fluorine‐containing groups for all but the shortest side‐chain polymer, where the ? OCOCF₃ side‐chain either does not surface segregate or is too short for surface segregation to be detectable by angle‐resolved XPS. In the other polymers studied the relative positions of functional groups in the side‐chains correlate with the angle‐resolved behaviour of the corresponding C 1s components. This shows that the surface side‐chains are oriented towards the polymer surface. For the ? COO(CH₂)₂OCO(CF₂)_yF (y = 1) side‐chain, the angle‐resolved C 1s data suggest reduced ordering and linearity compared with y = 2 and 3. For any particular series of polymers, e.g. ? COO(CH₂)_x(CF₂)_yF, the water contact angles increase with y, consistent with burying of the hydrophilic ester groups as y increases. For any particular value of y the sequence of water contact angles is ? COO(CH₂)_x(CF₂)_yF > ? OCO(CF₂)_yF ～ ? COO(CH₂)₂OCO(CF₂)_yF, suggesting greater ordering and density of fluorocarbon species at the surface of the ? COO(CH₂)_x(CF₂)_yF side‐chain polymers compared with the other polymers studied. For the ? COO(CH₂)₂(CF₂)₈F polymer a water contact angle of 124° is measured, which is greater than that of poly(tetrafluoroethene). The ? COO(CH₂)₂OCO(CF₂)F polymer is unusual in that it shows a particularly low water contact angle (83° ), suggesting that the probe fluid is able to sense both ester groups, consistent with the reduced ordering of the side‐chain detected by angle‐resolved XPS. Copyright © 2004 John Wiley & Sons, Ltd.     

Dispersion of polystyrene inside polystyrene‐b‐poly(N‐isopropylacrylamide) micelles in water

The addition of mixture of polystyrene‐b‐poly(N‐isopropylacrylamide) (PS‐b‐PNIPAM) and polystyrene homopolymer (h‐PS) in tetrahydrofuran dropwise into water leads to nanoparticles with a PS core and a thermally sensitive PNIPAM shell. The effects of the ratio of the homopolymer to copolymer and temperature on the formation and stabilization of the dispersion were investigated by using a combination of static and dynamic laser light scattering. PNIPAM shell continuously collapses as temperature increases in the range 20–40 °C. Such formed particles are stable even at temperatures much higher than lower critical solution temperature (LCST ～ 32 °C) of PNIPAM. Our results reveal that the area occupied per hydrophilic PNIPAM chain on the hydrophobic PS core remains nearly a constant regardless of the amount of h‐PS in the polymer mixture. This clearly indicates that the surface area occupied per hydrophilic group is a critical parameter for stabilizing particles dispersed in water. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 749–755, 2010     

Synthesis and self‐assembly of polystyrene‐grafted multiwalled carbon nanotubes with a hairy‐rod nanostructure

Polystyrene‐grafted multiwalled carbon nanotubes (PS‐g‐MWNTs) with a hairy‐rod nanostructure were synthesized by the in situ free‐radical polymerization of styrene in the presence of multiwalled carbon nanotubes (MWNTs) terminated with vinyl groups. To quantitatively study the molecular weight and composition of polystyrene (PS) chains in PS‐g‐MWNTs, PS‐g‐MWNTs were fully defunctionalized by hydrolysis. The results showed that 1 of every 100 carbon atoms in MWNTs was functionalized at the tips and outer walls of the carbon nanotubes and grafted by PS with a weight‐average molecular weight of 9800 g/mol; therefore, a uniform thin layer (ca. 8–10 nm) of a PS shell was formed on the outer wall of MWNTs. PS‐g‐MWNTs were soluble in dimethylformamide and tetrahydrofuran. The thermal stability and glass‐transition temperature of PS in PS‐g‐MWNTs were obviously increased. Nanopins were formed on the glass substrates by the self‐assembly of PS‐g‐MWNTs, and the dewetting effect between the glass substrate and PS chains covered MWNTs during the evaporation of the solution. Both the length and diameter of the nanopins increased with the solution concentration. When PS‐g‐MWNTs were compression‐molded, MWNTs were dispersed uniformly in the PS matrix and formed good networks, such as circlelike and starlike structures, because of the entanglements of hairy PS chains on MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3869–3881, 2006     

Surface modification of polystyrene biochip for biotin‐labelled protein/streptavidin or neutravidin coupling used in fluorescence assay

A polystyrene biosensing chip to be used as a medical diagnostic tool has been developed. Its surface functionalization is optimized to bind the bioanalytes with high efficiency. Coatings of allyldextran monolayers were carried out on polystyrene chips activated with γ‐irradiation. The effect of the concentration of allyldextran solution on the coating efficiency was studied by surface‐sensitive x‐ray photoelectron spectroscopy (XPS) and contact‐angle measurements. In a second step, sodium periodate chemistry was applied to functionalize the dextran layer, followed by coupling with streptavidin or neutravidin. Copyright © 2004 John Wiley & Sons, Ltd.     

Core–shell functionalized MWCNT/poly(m‐aminophenol) nanocomposite with large dielectric permittivity and low dielectric loss

Core–shell carboxyl‐functionalized multiwall carbon nanotube (c‐MWCNT)/poly(m‐aminophenol) (PmAP) nanocomposite were prepared through in‐situ polymerization of m‐aminophenol (m‐AP) in the presence of MWCNTs, and explicated as a dielectric material for electronic applications. The formation of thin PmAP layer on individual c‐MWCNT with excellent molecular level interactions at interfaces was confirmed by morphological and spectroscopic analyses. Here we conducted a comparative study of the dielectric performances of PmAP based nanocomposite films with pristine MWCNTs and c‐MWCNTs as fillers. Compared to PmAP/MWCNT nanocomposites, the PmAP/c‐MWCNT nanocomposites exhibited higher dielectric permittivity and lower dielectric loss. The well dispersed c‐MWCNTs in PmAP/c‐MWCNT nanocomposite produce huge interfacial area together with numerous active polarized centers (crystallographic defects), which in turn intensified the Maxwell‐Wagner‐Sillars (MWS) effect based on excellent molecular level interactions and thus, produce large dielectric permittivity (8810 at 1 kHz). The percolation threshold of PmAP/c‐MWCNT nanocomposites is found lower than that of the PmAP/MWCNT nanocomposites, which could be attributed to homogeneous distribution of c‐MWCNTs and strong c‐MWCNT//PmAP interfacial interactions in the nanocomposites. Copyright © 2016 John Wiley & Sons, Ltd.     

Graft copolymers having hydrophobic backbone and hydrophilic branches. XXX. Preparation of polystyrene‐core nanospheres having a poly(2‐methacryloyloxyethyl phosphorylcholine) corona

Polystyrene core nanosphere particles possessing 2‐methacryloyloxyethyl phosphorylcholine (MPC) polymers on the corona were prepared by the free radical polymerization of hydrophilic polyMPC macromonomer and hydrophobic styrene with AIBN as a radical initiator in ethanol as a polar solvent. The morphology of the nanospheres was observed by transmission electron micrograph (TEM). The nanospheres were spherical in form and have a narrow size distribution. Their sizes could be controlled by varying the molecular weight of the macromonomer and the amount of it in feed. Electron spectroscopy for chemical analysis (ESCA) of the nanosphere surfaces suggested that polyMPC chains were located favorably on the surface of the nanosphere. The nanospheres having the polyMPC chains on their surfaces can be significant and useful materials in technological and medical fields. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3052–3058, 2000     

Stabilization of a cocontinuous phase morphology by a tapered diblock or triblock copolymer in polystyrene‐rich low‐density polyethylene/polystyrene blends

The stability against the thermal annealing of a cocontinuous two‐phase morphology developed in polystyrene (PS)/low‐density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends containing 1, 5, and 10 wt % of a tapered diblock poly(styrene‐block‐hydrogenated butadiene) (P(S‐b‐hB)) or triblock poly(styrene‐block‐hydrogenated butadiene‐block‐styrene) (P(S‐hB‐S)) copolymer were melt‐blended with roll‐mill mixing equipment. The efficiency of each of the two copolymers in stabilizing against coalescence the cocontinuous morphology was examined. The tensile properties of the resulting blends, annealed and nonannealed, were also examined in relation to the morphology induced by thermal annealing. The phase morphology was studied by optical and scanning electron microscopy. With computer‐aided image analysis, it was possible to obtain a measurable characteristic parameter to quantify the cocontinuous phase morphology. When it was necessary, the extraction of one phase with a selective solvent was performed. Although the observed differences were subtle, the tapered diblock exhibited a more efficient compatibilizing activity than the triblock copolymer, particularly at a low concentration of about 2 wt %. The superiority of the tapered diblock over the triblock might be due to its ability to quantitatively locate at the LDPE/PS interface and consequently form a more efficient barrier against the subsequent breakup of the elongated structures of the cocontinuous phase morphology. The tensile properties of the triblock‐modified blends were more sensitive to thermal annealing than the tapered‐modified ones. This deficiency was ascribed to the phase morphology coarsening of the dispersed polyethylene phase. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 202–216, 2003     

Arborescent polystyrene‐graft‐poly(tert‐butyl methacrylate) copolymers: Synthesis and enhanced polyelectrolyte effect in solution

A technique is described for the preparation of arborescent graft copolymers containing poly(tert‐butyl methacrylate) (PtBMA) segments. For this purpose, tert‐butyl methacrylate is first polymerized with 1,1‐diphenyl‐2‐methylpentyllithium in tetrahydrofuran. The graft copolymers are obtained by addition of a solution of a bromomethylated polystyrene substrate to the living PtBMA macroanion solution. Copolymers incorporating either short (M_w ≈ 5000) or long (M_w ≈ 30,000) PtBMA side chains were prepared by grafting onto linear, comb‐branched (G0), G1, and G2 bromomethylated arborescent polystyrenes. Branching functionalities ranging from 9 to 4500 and molecular weights ranging from 8.8 × 10⁴ to 6.3 × 10⁷ were obtained for the copolymers, while maintaining a low apparent polydispersity index (M_w/M_n ≈ 1.14–1.25). Arborescent polystyrene‐graft‐poly(methacrylic acid) (PMAA) copolymers were obtained by hydrolysis of the tert‐butyl methacrylate units. Dynamic light scattering measurements showed that the arborescent PMAA copolymers are more expanded than their linear PMAA analogues when neutralized with NaOH. This effect is attributed to the higher charge density in the branched arborescent copolymer structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2335–2346, 2008     

Surface study of sintered alumina substrates using solution‐processed ZnO nanorods as a microscopic wettability indicator

Wettability and its distribution are crucial factors that indicate the surface conditions of substrates. We report a surface study of sintered alumina substrates using solution‐processed ZnO nanorods as a microscopic wettability indicator. The alumina substrates comprising of micrometer‐sized sintered grains were treated separately with ultraviolet/ozone (dry process) or ozone water (wet process), and their surface conditions were characterized by conventional surface analysis methods, such as water contact angle, X‐ray photoelectron spectroscopy and grazing angle attenuated total reflection Fourier transform infrared spectroscopy. The results showed that the alumina substrates treated with ultraviolet/ozone and ozone water had distinct clean surfaces compared to those without treatments, but no significant differences were noted between these two ozone‐based treatments. Then, as a wettability‐sensitive deposition technique, Pd‐catalyzed chemical deposition of ZnO nanorods was performed on the alumina substrates, which involved dip coating of Pd nanoparticles on the substrates in aqueous solutions, followed by the chemical solution growth of ZnO. Vertically aligned ZnO nanorods of ~85 nm in diameter were densely formed along a rough surface of the substrates. Morphological uniformity of the nanorods varied depending on the treatment condition; local surfaces with sufficient wettability provided uniform nanorods but those with insufficient wettability gave irregular nanorods, making the visualization of the microscopic surface wettability possible. Copyright © 2016 John Wiley & Sons, Ltd.     

ToF‐SIMS and computation analysis: Fragmentation mechanisms of polystyrene,polystyrene‐d5, and polypentafluorostyrene

We studied the time‐of‐flight secondary ion mass spectrometry fragmentation mechanisms of polystyrenes—phenyl‐fluorinated polystyrene (5FPS), phenyl‐deuterated polystyrene (5DPS), and hydrogenated polystyrene (PS). From the positive ion spectra of 5FPS, we identified some characteristic molecular ion structures with isomeric geometries such as benzylic, benzocyclobutene, benzocyclopentene, cyclopentane, and tropylium systems. These structures were evaluated by the B3LYP‐D/jun‐cc‐pVDZ computation method. The intensities of the C₇H₂F₅⁺ (m/z = 181), CyPent‐C₉H₃F₄⁺ (m/z = 187), CyPent‐C₉H₄F₅⁺ (m/z = 207), and CyPent‐C₉H₂F₅⁺ (m/z = 205) ions were enhanced by resonance stabilization. The positive fluorinated ions from 5FPS tended to rearrange and produce fewer fluorine‐containing molecular ions through the loss of F (m/z = 19), CF (m/z = 31), and CF₂ (m/z = 50) ion fragments. Consequently, the fluorine‐containing polycyclic aromatic ions had much lower intensities than their hydrocarbon counterparts. We propose the fragmentation mechanisms for the formation of C₅H₅⁺, C₆H₅⁺, and C₇H₇⁺ ion fragments, substantiated with detailed analyses of the negative ion spectra. These ions were created through elimination of a pentafluoro‐phenyl anion (C₆F₅⁻) and H⁺, followed by a 1‐electron‐transfer process and then cyclization of the newly generated polyene with carbon‐carbon bond formation. The pendant groups with elements of different electronegativities exerted strong influences on the intensities and fragmentation processes of their corresponding ions.     

Synthesis and characterization of well‐defined [polystyrene‐b‐poly(2‐vinylpyridine)]n star‐block copolymers with poly(2‐vinylpyridine) corona blocks

This article describes the synthesis and characterization of [polystyrene‐b‐poly(2‐vinylpyridine)]_n star‐block copolymers with the poly(2‐vinylpyridine) blocks at the periphery. A two‐step living anionic polymerization method was used. Firstly, oligo(styryl)lithium grafted poly(divinylbenzene) cores were used as multifunctional initiators to initiate living anionic polymerization of styrene in benzene at room temperature. Secondly, vinylpyridine was polymerized at the periphery of these living (polystyrene)_n stars in tetrahydrofuran at ?78 °C. The resulting copolymers were characterized using size exclusion chromatography, multiangle laser light scattering, ¹H NMR, elemental analysis, and intrinsic viscosity measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3949–3955, 2007     

Preparing a polystyrene‐functionalized multiple‐walled carbon nanotubes via covalently linking acyl chloride functionalities with living polystyryllithium

A new method was developed for preparing polystyrene‐functionalized multiple‐walled carbon nanotubes (MWNTs) through the termination of anionically synthesized living polystyryllithium with the acyl chloride functionalities on the MWNTs. The acyl chloride functionalities on the MWNTs were in turn obtained by the formation of carboxyls via chemical oxidation and their conversion into acyl chlorides. The polystyrene‐functionalized MWNTs had good dispersion in common organic solvents, and this indicated good compatibility for the preparation of styrenic nanocomposite materials. The synthesis results and characterization data for the functionalized MWNTs, collected via Fourier transform infrared, thermogravimetric analysis, solid‐state NMR, and electron microscopy, are presented and discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5802–5810, 2004     

Synthesis,surface properties,and morphologies of poly[methyl(3,3,3‐trifluoropropyl)siloxane]‐b‐polystyrene‐b‐poly(tert‐butyl acrylate) triblock copolymers by a combination of anionic ROP and ATRP

A series of well‐defined poly[methyl(3,3,3‐trifluoropropyl)siloxane]‐b‐polystyrene‐b‐poly(tert‐butyl acrylate) (PMTFPS‐b‐PS‐b‐PtBA) triblock copolymers were prepared by a combination of anionic ring‐opening polymerization of 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane (F₃), and atom transfer radical polymerization (ATRP) of styrene (St) and tert‐butyl acrylate (tBA), using the obtained α‐bromoisobutyryl‐terminal PMTFPS (PMTFPS‐Br) as the macroinitiators. The ATRP of St from PMTFPS‐Br, as well as the ATRP of tBA from the obtained PMTFPS‐b‐PS‐Br macroinitiators, has typical characteristic of controlled/living polymerization. The results of contact angle measurements for the films of PMTFPS‐b‐PS‐b‐PtBA triblock copolymers demonstrate that the compositions have an effect on the wetting behavior of the copolymer films. For the copolymer films with different compositions, there may be different macroscale or nanoscale structures on the outmost layer of the copolymer surfaces. The films with high content of PtBA blocks exhibit almost no ordered microstructures on the outmost layer of the copolymer surfaces, even though they have microphase‐separated structures in bulk. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Luminescent polymeric ruthenium complexes with polystyrene‐b‐poly(methyl methacrylate) macroligands: The sequential activation of initiator sites for blocks generated by parallel polymerization mechanisms

The synthesis of polystyrene‐b‐poly(methyl methacrylate) diblock copolymers with a luminescent ruthenium(II) tris(bipyridine) [Ru(bpy)₃] complex at the block junction is described. The macroligand precursor, polystyrene bipyridine‐poly(methyl methacrylate) [bpy(PS–H)(PMMA)], was synthesized via the atom transfer radical polymerization of styrene and methyl methacrylate from two independent, sequentially activated initiating sites. Both polymerization steps resulted in the growth of blocks with sizes consistent with monomer loading and narrow molecular weight distributions (i.e., polydispersity index < 1.3). Subsequent reactions with ruthenium(II) bis(bipyridine) dichloride [Ru(bpy)₂Cl₂] in the presence of Ag⁺ generated the ruthenium tris(bipyridine)‐centered diblock, which is of interest for the imaging of block copolymer microstructures and for incorporation into new photonic materials. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4250–4255, 2002     

Surface characterization and radical decay studies of oxygen plasma‐treated PMMA films

Polymethylmethacrylate (PMMA) films were modified by RF oxygen plasma with various powers applied for different periods, and the effects of these parameters on the surface properties such as hydrophilicity, surface free energy (SFE), chemistry, and topography were investigated by water contact angle, goniometer, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy, and the types of the created free radicals and their decay were detected by electron spin resonance spectroscopy (ESR). SFE and contact angle results varied depending on the plasma parameters. Oxygen plasma treatment (100 W–30 min) enhanced the hydrophilicity of PMMA surface as shown by decreasing the water contact angle from 70° to 26°. XPS analysis showed the change in the amounts of the present functionalities as well as formation of new groups as free carbonyl and carbonate groups. The roughness of the surface increased considerably from ~2 nm to ~75 nm after 100 W–30 min oxygen plasma treatment. ESR analysis indicated the introduction of peroxy radicals by oxygen plasma treatment, and the intensity of the radicals increased with increasing the applied power. Significant decrease in radical concentration was observed especially for the samples treated with higher powers when the samples were kept under the atmospheric conditions. As a conclusion, RF plasma, causes changes in the chemical and physical properties of the materials depending on the applied parameters, and can be used for the creation of specific groups or radicals to link or immobilize active molecules onto the surface of a material. Copyright © 2012 John Wiley & Sons, Ltd.