Surface modification of polyurethane by plasma-induced graft polymerization of poly(ethylene glycol) methacrylate

A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to proceed in deaerated aqueous solutions of PEGMA at 60°C. The virgin, plasma-treated, and grafted films were characterized comparatively by means of attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, measurement of contact angle, and protein adsorption. The Tecoflex film undergoes etching during argon plasma treatment, surface oxidation when exposed to air after plasma treatment, and surface restructuring in response to environment upon storage in air. The plasma-induced graft polymerization of PEGMA proved to be successful in introducing PEG graft chains with reactive hydroxyl end groups onto the surface. Grafted films with different surface grafting density of PEG were prepared. Grafted films with higher PEG content exhibit higher hydrophilicity, smoother topography, and lower fibrinogen adsorption. The hydroxyl end groups built onto the surface offer further possibilities of improving its biocompatibility by immobilizing bioactive molecules. © 1996 John Wiley & Sons, Inc.     

超细CaCO3的聚合物胶囊化研究

先通过乳液聚合制备了粒径约为100nm带正电荷的聚苯乙烯PS纳球,再利用异相凝集,使正电性的PS吸附在带负电荷的超细碳酸钙（CaCO3）表面,后在高于PS玻璃化温度（Tg)下,进行热处理,形成胶囊化复合粒子,用Zeta电势,扫描电镜和粒径分布对复合前后的粒子进行了表征。     

Cell Adhesion and Proliferation on Plasma-Treated and Poly(ethylene glycol)-Grafted Polyethylene

Polyethylene (PE) was modified by an Ar plasma. The plasma-activated PE surface was grafted with poly(ethylene glycol) (PEG, molecular weight 300 and 20 000). The depth profiles of the oxygen in the modified PE samples were determined using Rutherford Backscattering Spectroscopy (RBS). The changes in the surface wettability were examined by goniometry, and Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology. The modified PE samples were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation was studied. The plasma treatment and the subsequent PEG grafting leads to dramatic changes in the PE surface morphology, roughness and wettability. The PEG grafting of the plasma-treated PE does not increase VSMC adhesion but it results in dramatic increase of VSMC proliferation.     

Encapsulation of fillers with grafted polymers for model composites

Glass beads were encapsulated by grafted polymers: polybutylacrylate and polystyrene. Grafting was performed by the polymerization initiated from the particle surface with preliminary adsorbed polyperoxide initiator. Grafting procedure and properties of grafted film were studied using model substrates: powders, plates, and wafers by wetting technique and SEM. Conditions of grafting affect the film structure. They are porous, and due to some sort of pores the wetting liquid is able to penetrate into covering and reach the substrate. Model epoxy composites were prepared with covered glass beads. The coverings allowed a decrease of adhesion between the matrix and bead surface to detect acoustic emission caused by the debonding process. The dependence of debonding stress from covering the structure and nature was studied. © 1996 John Wiley & Sons, Inc.     

Viscoelastic properties and morphological characterization of silica/polystyrene nanocomposites synthesized by nitroxide-mediated polymerization

Polystyrene (PS) chains with molecular weights comprised between 15,000 and 60,000 g/mol and narrow polydispersities were successfully grown from the surface of silica nanoparticles by nitroxide-mediated polymerization (NMP). Small angle X-ray scattering was used to characterize the structure of the interface layer formed around the silica particles, and at a larger scale, dynamic light scattering was used to determine the hydrodynamic diameter of the functionalized silica suspension. In a second part, blends of PS-grafted silica particles and pure polystyrene were prepared to evaluate the influence of the length of the grafted PS segments on the viscoelastic behavior of the so-produced nanocomposites in the linear viscoelasticity domain.Combination of all these techniques shows that the morphology of the nanocomposite materials is controlled by grafting. The steric hindrance generated by the grafted polymer chains enables partial destruction of the agglomerates that compose the original silica particles when the latter are dispersed either in a solvent or in a polymeric matrix.     

原位无皂乳液聚合硅灰石接枝PMMA反应机理及表征

以甲基丙基酸甲酯(MMA)为反应单体,采用无皂乳液聚合方法制备了硅灰石接枝PMMA。探讨了PMMA接枝聚合硅灰石的反应机理,并借助于FTIR、SEM、接触角测定仪对硅灰石接枝PMMA的结构及亲水性等进行分析表征。结果表明:PMMA通过化学键接枝在硅灰石表面,使其粒径变大,形成中心为硅灰石,外围为PMMA的"核-壳"结构,硅灰石的疏水性和亲油性得到明显提高。     

微乳液法腈纶接枝聚苯胺及其性能研究

采用低温等离子体技术对腈纶纤维表面进行处理,使用苯胺微乳液在腈纶表面进行接枝聚合,对腈纶进行改性处理,通过增重率、导电率测试、接枝聚合的因素和接枝聚合对腈纶纤维结构、导电性能和强力进行分析评价;扫描电镜和红外测试显示聚苯胺成功接枝上腈纶表面;腈纶接枝聚苯胺后,导电性能增加,强力变化不大,但伸长率略有降低。     

Surface‐initiated atom transfer radical polymerization (ATRP) of styrene from silica nanoparticles under UV irradiation

Diethyldithiocarbamyl‐modified silica nanoparticles were prepared and used as macroinitiator for the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of styrene under UV irradiation. Well‐defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well‐defined, densely grafted outer PS layer with a mass ratio of styrene to silica, or percentage grafting, of 276.3% after an UV irradiation time of 5 h. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of polystyrene‐grafted attapulgite via surface‐initiated redox polymerization

Polystyrene‐grafted attapulgite (ATP‐g‐PS) was prepared using surface‐initiated redox initiation via graft from approach. ATP was modified with (3‐ aminopropyl) triethoxysilane (APTES) to anchor amine on the surface (ATP‐NH₂), and then ATP‐NH₂ was further treated with 4‐(diethylamino) salicylaldehyde (DEAS) to give aromatic tertiary amine groups functional ATP (ATP‐ATA). Subsequently, the surface‐initiated redox polymerization of styrene in the presence of ATP‐ATA and benzoyl peroxide (BPO) was performed to afford ATP‐g‐PS . The chemical grafting of PS on the surface of ATP was confirmed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis . The crystal structure of PS‐grafted ATP was characterized by X‐ray diffraction (XRD) analysis. The morphology of ATP‐g‐PS was observed by scanning electron microscopy (SEM) . POLYM. ENG. SCI., 55:889–895, 2015. © 2014 Society of Plastics Engineers     

Preparation of monodispersed and lipophilic attapulgite and polystyrene nanorods via surface‐initiated atom transfer radical polymerization

A new kind of initiator, 3‐(2‐bromo‐2‐methylacryloxy)propyltriethysiliane (MPTS‐Br), was prepared with a simply hydrobrominated commercial silane coupling agent (3‐methacryloxy‐proplytriethysilane, MPTS). It has been one‐step self‐assemble onto the surface of attapulgite (ATP) nanorods in the dispersion system, and by using this initiator‐modified nanorod (MPTS‐Br‐modified ATP nanoparticles, ATP‐MPTS‐Br) as macroinitiator for atom transfer radical polymerization (ATRP). Structurally well‐defined homopolymer polystyrene (PS) and block polymer poly(styrene‐b‐methyl methacrylate) (PS‐b‐PMMA) chains were then grown from the needle‐shaped nanorods surface to yield monodispersed nanorods composed of ATP core and thick‐coated polymer shell (ATP and PS). The graft polymerization parameters exhibited the characteristics of a controlled/”living” polymerization. The PS‐grafted ATP nanorods could be dispersed well in organic solvent with nanoscale. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cationic polystyrene spheres for removal of anionic contaminants in white water of papermaking

In a paper mill's water circuit, normal runnability of the paper machine is often disturbed due to the buildup of dissolved and colloidal substances (DCS). Contaminant adsorption on a solid adsorbent in a fluidized bed reactor has been applied for white water treatment. In the present study, polystyrene (PS) spheres were firstly acylated by acryloyl chloride, then poly(methacryloxyethyltrimethyl ammonium chloride) (PMAC) was grafted onto the acylated PS spheres, induced by surface‐initiated free‐radical polymerization. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and scanning electron microscopy were used to characterize the changes of PS spheres in chemical structures and surface morphology. The results showed that acylated PS spheres could be easily grafted with PMAC in 53.83% weight increase. Polyelectrolyte loading of PS spheres reached up to 1.72 mmol/g. The resulted cationic modified PS spheres could effectively decrease the cationic demand in white water and it still maintained high performance after operating repeatedly for 10 batches. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 10.1002/app.41379.     

Mesoporous silica particles grafted with polystyrene brushes as a nucleation agent for polystyrene supercritical carbon dioxide foaming

In this study, spherical ordered mesoporous silica (s‐OMS) was applied as a new type of nucleating agent in polystyrene (PS) foaming with supercritical CO₂ as a blowing agent. These s‐OMS particles were modified by the selective grafting of PS brushes on the outside surface, by which the mesoporous structure inside particles could be maintained. Transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis were used to characterize the structure of the original and modified particles; these indicated that the PS brushes were grafted on the outside surface and the inside porous structure were maintained. PS/s‐OMS–PS composites were prepared by a solution blending method, and the s‐OMS–PS particles could have been well dispersed in the PS matrix because of the surface modification. Subsequently, PS and composite microcellular foams were prepared by a batch foaming process, and the morphology characterization on these foams showed that the s‐OMS particles exhibited an excellent heterogeneous effect on PS foaming. The heterogeneous effect became more significant when the foaming temperature or saturation pressure was low. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4308–4317, 2013     

Preparation and characterization of composite resin by vinyl chloride grafted onto poly(BA-EHA)/poly(MMA-St)

Crosslinked poly(butyl acrylate-co-2-ethylhexyl acrylate)/poly(methyl methacrylate-co-styrene) (ACR I) latex was synthesized by multi-stage emulsion polymerization. A series of grafting vinyl chloride (VC) composite latices were prepared by emulsion copolymerization in the presence of core-shell ACR I latex. The effects of ACR I amount and its core/shell ratio on particle diameters of the composite latices and mechanical properties of the prepared materials were investigated. The grafting efficiency (GE) of VC grafted onto ACR I increases with an increasing ACR I content. Transmission electron microscope (TEM) study indicates that ACR I latex particles have a regular core-shell structure obviously. However, when styrene content in the shell of ACR I is more than 70 percent of the shell by weight, ACR I latex particles have an irregular core-shell morphology like sandwich. The composite latex particles synthesized by core-shell ACR I latex grafting VC have a clear three-layered core-shell structure. Dynamic mechanical analysis (DMA) study reveals that the compatibility between ACR I and PVC is well improved. With increasing ACR I content, the loss peak in low temperature range for every composite sample becomes stronger and stronger and gradually shifts to a higher temperature. Scanning electron microscope (SEM) graphs showed that the fractured surface of the composite sample exhibited better toughness of the material. TEM graphs showed that ACR I was uniformly dispersed in the PVC matrix.     

聚乙二醇接枝聚醋酸乙烯酯的聚合动力学研究

以过氧-2-乙基己酸叔丁酯为引发剂,进行了聚乙二醇(PEG)存在下的醋酸乙烯酯(VAc)本体接枝聚合,考察了各VAc:PEG配比下聚合速率、PEG上PVAc的接枝率、PVAc的接枝效率、PEG的被接枝效率以及接枝共聚物的分子量随聚合时间的变化规律.结果发现,随配方中VAc配比的增加,聚合速率与极限转化率明显增加,聚合反应出现明显的自动加速现象;当VAc:PEG配比较大时,综合速率参数K随聚合时间不断上升,当VAc:PEG配比较低时,K随聚合时间呈下降趋势.各VAc:PEG配比下PVAc的接枝率几乎都随转化率的增大而线性地增加,接枝效率则几乎不随聚合时间而变;接枝率的大小正比于VAc:PEG配比,接枝效率则普遍较高,低VAc:PEG配比时,接枝效率可达95%以上;PEG的被接枝效率虽随转化率和VAc:PEG配比的增加而明显增加,但总体仍较低,表明聚合体系中有相当多一部分PEG未被接枝.高的VAc接枝效率和低的PEG被接枝效率表明,该Graft From接枝聚合体系中,可能存在着Graft Onto的接枝聚合机理.根据定义用来计算PEG-g-PVAc的数均分子量,发现随聚合转化率的增大而减小,并逐渐趋于常数,配方中VAc浓度越大越大;由GPC测试、PVAc普适校正计算发现,接枝聚合产物的分子量分布指数在1.5～2.5 之间,且随单体浓度和转化率的增加而增大.这些均与聚合体系的凝胶效应有关.     

Preparation and characterization of poly (ethylene glycol) grafted Ca-alginate fibers by γ-irradiation for biomedical applications

Radiation processing, being a physical process, is an environmentally friendly alternative to chemical modifications. It is economically viable, safe, and possesses several advantages over other conventional methods employed for modification and grafting. To improve the physico-mechanical properties of Ca-alginate fiber (CaAF), poly (ethylene glycol) (PEG) was grafted by applying γ-radiation of different intensities. The effect of γ-irradiation on the physico-mechanical, thermal, morphological, thermal and water aging, water, and simulated body fluid (SBF) uptake were evaluated. FT-IR results confirmed that PEG was successfully grafted onto Ca-alginate fibers by γ-irradiation. From the detailed experimental results, irradiation doses and PEG concentration were optimized for grafting processes. The results showed that 50% PEG and 2.5?kGy irradiation dose yielded the highest tensile strength. Differential scanning calorimetric (DSC) analysis showed that with increasing γ-intensity a decrease of dehydration temperature of the fibers had occurred. On the other hand, the glass transition temperature (T _g) increased with increasing irradiation dose. The tensile cracked surfaces of the grafted alginate fibers were analyzed by scanning electron microscope (SEM) in order to monitor their surface morphologies. The SEM images of the cracked surfaces demonstrated that spherical shape rods were present for irradiated fiber sample while no such rods were observed for non-irradiated fibers. The characteristic data obtained from SBF and water uptake, and water and thermal aging experiments indicated that CaAF grafted with 50% PEG by applying 2.5?kGy γ-irradiation can be potentially employed for biomedical purposes, such as surgical suture.     

Synthesis of controlled thermoresponsive PET track‐etched membranes by ATRP method

Controlled thermoresponsive PET track‐etched membranes were synthesized by grafting N‐isopropylacrylamide (NIPAAm) onto the membrane surface via atom transfer radical polymerization (ATRP). The initial measurements were made to determine the anchoring of ATRP initiator on PET membrane surface. Thereafter, polymerization was carried out to control the mass of polymer by controlling reaction time grafted from the membrane surface and, ATR‐FTIR, grafting degree measurements, water contact angle measurements, TGA, and SEM were used to characterize changes in the chemical functionality, surface and pore morphology of membranes as a result of modification. Water flux measurements were used to evaluate the thermoresponsive capacity of grafted membranes. The results show the grafted PET track‐etched membranes exhibit rapid and reversible response of permeability to environmental temperature, and its permeability could be controlled by controlling polymerization time using ATRP method. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

等离子体引发微孔板接枝SMCC及蛋白吸附性能

用丙烯酰胺等离子体引发活化聚苯乙烯（PS）微孔板，接枝4-(N-马来酰亚胺基甲基)环己 烷-1-羧酸琥珀酰亚胺酯（SMCC）联接剂，制备了易于固定蛋白的PS-g-SMCC微孔板。利用FTIR、EDS、XPS、SEM、接触角测试仪和酶标仪对其表面组成、结构、形貌及蛋白吸附性能进行了表征。结果表明，PS微孔板表面成功接枝了丙烯酰胺与SMCC，当等离子体处理参数为500 W，300 s时，接枝丙烯酰胺的效果最好，PS-g-SMCC微孔板表面达到超亲水；当SMCC质量浓度为5 g/L 时，PS-g-SMCC微孔板对牛血清蛋白的吸附量最大，为903.08 ng/cm2，与未处理的PS微孔板相比，吸附量提高了2.93倍，有效提高了PS微孔板的检测灵敏性。     

Effect of annealing on poly(urethane‐siloxane) copolymers

The N‐substituted polyaniline (PANi) was synthesized by incorporation of bromine‐terminated polystyrene (PS‐Br) onto the emeraldine form of polyaniline. End brominated polystyrene was synthesized by atom transfer radical polymerization (ATRP) technique and then deprotonated polyaniline was reacted with PS‐Br to prepare PS‐grafted PANi (PS‐g‐PANi) copolymer through N‐grafting reaction. The degree of N‐grafting can be controlled by adjusting the molar feed ratio of PS‐Br to the number of repeat units of PANi. The microstructure and compositions of the PS‐g‐PANi copolymers with different degrees of N‐substitution were characterized by FT‐IR, elemental analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The cyclicvoltammetry shows that the electroactivity of N‐substituted PANi is strongly dependent on the degree of N‐grafting. The solubility of PS‐g‐PANi copolymers in common organic solvents such as tetrahydrofuran and chloroform was improved by increasing the degree of N‐grafting, and also the samples are partially soluble in xylene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Grafting of polystyrene and poly(p‐chlorostyrene) from the surface of ramie fiber via RAFT polymerization

Reversible addition‐fragmentation chain transfer (RAFT) radical polymerization was used for controlled grafting of styrene and p‐chlorostyrene from the surface of ramie fiber. The hydroxyl groups in ramie fiber were first converted to thiocarbonylthio groups as the RAFT chain transfer agent then used to mediate the RAFT polymerization of styrene, and p‐chlorostyrene in tetrahydrofuran using azobis (isobutyronitrile) as initiator at 60°C. The grafted copolymers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry, and contact angle measurements. The results confirmed that grafting occurred on the surface of the ramie fiber, substantially increasing the water contact angle from 75.31° to 147° for polystyrene grafted ramie fiber (cell‐PS) and 135° for poly(p‐chlorostyrene) (cell‐PSCl), and improving the hydrophobicity of the grafted fiber. The homopolymers formed in the polymerization were analyzed by size exclusion chromatography to estimate the molecular weights and polydispersity indices (PDIs) of chains grafted from the surface of the ramie fiber, as well as showed narrow chain length distributions with a PDI of 1.32–1.70. These materials possess potential applications in many advanced technologies. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Bioactivity evaluation of novel nanocomposite scaffolds for bone tissue engineering: The impact of hydroxyapatite

The objective of this study was to prepare scaffolds based on cellulose-graft-polyacrylamide composed of different contents of nano-hydroxyapatite (n-HAp). To this end, polyacrylamide was grafted onto cellulose in the presence of n-HAp through free radical polymerization. Then, the scaffolds of the dispersed grafted polymer nanocomposite powder were fabricated by the freeze-drying method. The grafted polymer nanocomposite scaffolds were tested and characterized using tensile test instrument, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Finally, bioactivity and apatite formation on the surface after immersion in a simulated body fluid (SBF) were determined by XRD and SEM analysis. According to the results, as the n-HAp content in the scaffold structure increased, the porosity, elastic modulus and compressive strength were increased. In addition, apatite was deposited very well on the interconnected irregular pores on the surface of the scaffolds after incubation in SBF, while the size of precipitated apatite was reduced by increasing the soaking time. The results indicated that the prepared grafted polymer nanocomposite scaffolds have a great potential as biocompatible materials for use in bone tissue engineering.