Effect of grafting of acrylic acid onto PET film surfaces by UV irradiation on the adhesion of PSAs

To improve the peel strength between a pressure-sensitive adhesive (PSA) and its substrate, grafting of acrylic acid (AA) onto the surface of poly(ethylene terephthalate) (PET) film was carried out. After AA was coated onto the surface of PET films using a spin coater, the coated PET films were irradiated by UV. To investigate the surface chemistry and topography of the PET-g-AA films, the grafted surface of the PET films was characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). From these investigations, the effects of grafting of AA at the surface of PET by UV irradiation were discussed. In addition, to determine the effect of grafting on the adhesion between PSA polymer and PET-g-AA films, peel strength was measured after the PSA/PET-g-AA system was cured at various temperatures. As the esterification between PSA polymer and PET-g-AA films occurred in the interfacial region, the peel strength of the PSA/PET-g-AA system generally increased with increasing curing temperature.     

Radiation grafting of acrylic acid/N‐vinyl pyrrolidone binary mixture onto poly(ethylene terephthalate) fabric and growth of human mesenchymal stem cell

Radiation grafting of acrylic acid (AA)/N‐vinyl pyrrolidone (NVP) binary mixture onto poly(ethylene terephthalate) (PET) knittings was investigated by preirradiation technique. The influence of the grafting conditions, such as monomer composition, reaction temperature, and the effect of storage time with temperature after irradiation on the degree of grafting was determined. ATR‐FTIR spectroscopy analysis of the grafted knittings confirmed the existence of amide group of NVP in the knittings. The concentration of peroxides and effect of storage time on peroxide concentration were also determined by 2,2‐Diphenyl‐1‐picrylhydrazyl at different temperatures. There was an increase in surface roughness of grafted PET in comparison to virgin PET as determined by atomic force microscopy and scanning electron microscopy. The grafted knittings were subsequently immobilized with collagen Type I which was further apt for the study of growth and morphology of human mesenchymal stem cell (hMSC). The immobilization of collagen on PET knittings has provided an excellent surface for the growth of hMSCs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of hydrophilic and antibacterial silver decorated silica-grafted-poly(vinylpyrrolidone) (Ag-SiO2-PVP) nanoparticles for polymeric nanocomposites

Hydrophilic antibacterial silver decorated silica-grafted-poly(vinylpyrrolidone) (Ag-SiO₂-PVP) nanoparticles were successfully synthesized in multiple steps. In this regard, silanization of the silica nanoparticles was performed with different concentrations of vinyltrimethoxysilane (VTS) to generate vinyl groups onto the nanoparticles surface. Obtained results showed that by increasing the VTS concentration the amount of vinyl groups on the surface of the silica nanoparticles increased while nanoparticles agglomeration did not occur. Then, poly(vinylpyrrolidone) PVP brushes were grafted onto the silanized silica nanoparticles (SiO₂-VTS) via grafting-through polymerization method to obtain PVP-grafted silica nanoparticles (SiO₂-PVP). Fourier transform infrared spectroscopy, thermal gravimetric analysis, and dynamic light scattering confirmed the successful generation of the vinyl groups and PVP brushes onto the silica nanoparticles. Finally, Ag-SiO₂-PVP nanoparticles were prepared by synthesizing silver nanoparticles onto the SiO₂-PVP nanoparticles to render them antibacterial. Energy dispersive X-ray spectroscopy showed that highest grafting of silver nanoparticles onto the SiO₂-PVP nanoparticles was obtained for the nanoparticles with highest content of vinyl groups. X-ray photoelectron spectroscopy was used to identify the elements and their chemical structure for the synthesized nanoparticles. Plate colony counting method was applied to assess the antibacterial effects of the Ag-SiO₂-PVP nanoparticles which revealed outstanding bactericidal properties of them.     

Small AgNP in the Biopolymer Nanocomposite System

In this work, ultra-small and stable silver nanoparticles (AgNP) on chitosan biopolymer (BP/AgP) were prepared by in situ reduction of the diamminesilver(I) complex ([Ag(NH₃)₂]⁺) to create a biostatic membrane system. The small AgNP (3 nm) as a stable source of silver ions, their crystal form, and homogeneous distribution in the whole solid membrane were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The X-ray photoelectron spectroscopy (XPS) and Auger analysis were applied to investigate the elemental composition, concentration, and chemical state of surface atoms. It was found that ultra-small metallic nanoparticles might form a steady source of silver ions and enhance the biostatic properties of solid membranes. Ultra-small AgNP with disturbed electronic structure and plasmonic properties may generate interaction between amine groups of the biopolymer for improving the homogeneity of the nanometallic layer. In this work, the significant differences between the typical way (deposition of ex-situ-prepared AgNP) and the proposed in-situ synthesis approach were determined. The improved thermal stability (by thermogravimetry and differential scanning calorimetry (TG/DSC) analysis) for BP/AgP was observed and explained by the presence of the protective layer of a low-molecular silver phase. Finally, the antibacterial activity of the BP/AgP nanocomposite was tested using selected bacteria biofilms. The grafted membrane showed clear inhibition properties by destruction and multiple damages of bacteria cells. The possible mechanisms of biocidal activity were discussed, and the investigation of the AgNP influence on the bacteria body was illustrated by AFM measurements. The results obtained concluded that the biopolymer membrane properties were significantly improved by the integration with ultra-small Ag nanoparticles, which added value to its applications as a biostatic membrane system for filtration and separation issues.     

PET/TiO2复合材料非等温结晶行为的研究

采用表面接枝和聚合改性的方法,分别以γ-缩水甘油醚氧丙基三甲基硅烷(GPS)和甲基丙烯酸甲酯(MMA)对纳米二氧化钛(TiO_2)进行表面修饰,通过熔融共混制得聚对苯二甲酸乙二醇酯(PET)/GPS- TiO_2和PET/聚甲基丙烯酸甲酯(PMMA)-TiO_2纳米复合材料,用差示扫描量热法研究了其复合材料的非等温结晶行为,利用不同动力学模型对其结晶过程进行处理。结果表明：未处理的纳米TiO_2提高了PET的熔融温度和结晶温度;而经表面接枝的GPS-TiO_2和PMMA-TiO_2对PET的熔融温度和结晶温度的影响并不显著;不同表面特性的纳米TiO_2降低了PET的结晶度,但经表面接枝后的纳米TiO_2其影响程度减弱;用Jezi- omy法和莫志深法处理PET/TiO_2纳米复合材料的非等温结晶过程比较理想,PET,PET/PMMA-TiO_2,PET/ TiO_2,PET/GPS-TiO_2复合材料的结晶速率依次减小。     

Surface grafting modification of fibrous silicates with polyvinylpyrrolidone and its application in nanocomposites

Chemical surface modification of fibrous silicate with polyvinylpyrrolidone (PVP) or its derivates via grafting‐from and grafting‐to methods was investigated. The grafting‐from method was based on the immobilization of reactive end functional groups of silane coupling agents on silicate surface, followed by chain growth via radical polymerization of N‐vinylpyrrolidone (NVP) to form grafted polymers with different molecular weight. In the grafting‐to method, a novel copolymer PVP‐171 with side functionalized groups and designed molecular weight was synthesized by radical polymerization of NVP and vinyltrimethoxysilane (DB171) and then bonded to the surface of fibrous silicates. Evidences from FTIR, XPS, TGA, and BET test indicate that there are ～ 68,000 reactive sites per square meters on the surface with the grafted vinyl concentration of 59 mequiv per 100 g of clay. XRD patterns and SEM images demonstrate that grafting modification was bound on the silicate surface and make the surface rough with the increase of graft‐loading quantity. In contrast with grafting‐to approach, grafting‐from approach facilitates the dispersion of silicates in PET composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型氨基化磁性纳米粒子的合成

通过嫁接方法在包有二氧化硅的纳米CoFe2O4磁粒表面进行氨基化修饰,制备出一种可用于生物医学领域的新型氨基化纳米磁粒,采用TGA-DTA,IR,VSM和Zeta-potential等测定方法,对氨基化和未氨基化的CoFe2O4纳米粒子进行了表征。元素分析结果显示,有0.98 mmol/g的有机分子固定在纳米粒子表面;红外和热分析数据显示,带氨基的有机分子嫁接到磁粒表面的二氧化硅壳层上;Zeta电位数据也显示,带氨基的有机分子嫁接到纳米磁粒表面;样品的磁性参数显示,氨基化纳米磁粒仍具有好的磁学性能。     

Grafting of polyacrylamide from poly(ethylene terephthalate) films

Poly(ethylene terephthalate) (PET) films were modified via the grafting of polyacrylamide (PAAM) onto the surface by surface‐initiated atom transfer radical polymerization and UV‐initiated grafting. The surface composition and morphology of the modified PET films were characterized by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy (SEM). The results show that the surface of the PET film was grafted by PAAM, with its own surface morphology different from that of PET. The properties of the modified PET films were studied by contact‐angle, peeling force, penetrability, haze, and friction factor measurements. The results indicate that the peeling force and friction factor of the modified PET films were higher than those of the unmodified PET film. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of Ni-g-polymer core–shell nanoparticles by surface-initiated atom transfer radical polymerization

Surface-initiated atom transfer radical polymerization (si-ATRP) technique was successfully employed to modify Ni nanoparticles with polymer shells. ATRP initiators were covalently bonded onto Ni nanoparticle surfaces by a combination of ligand exchange and condensation reactions. Various kinds of polymers including poly(methyl methacrylate) (PMMA) and poly(n-isopropylacrylamide) (PNIPAM) were grafted from the immobilized initiators. The grated polymer shells gave Ni nanoparticles exceptionally good dispersion and stability in solvents. Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and transmission electron spectroscopy (TEM) were employed to confirm the grafting and to characterize the nanoparticle core–shell structure. Gel permeation chromatography (GPC) studies of cleaved polymer chains revealed that the grafting polymerization was well controlled. The magnetic properties of Ni-g-polymer nanoparticles were also studied.     

Graft polymerization of vinyl acetate onto silica

The free‐radical graft polymerization of vinyl acetate onto nonporous silica particles was studied experimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free‐radical graft polymerization of vinyl acetate in ethyl acetate with 2,2′‐azobis(2,4‐dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by volume and the reaction was spanned from 50 to 70°C. The resulting grafted polymer, which was stable over a wide range of pH levels, consisted of polymer chains that are terminally and covalently bonded to the silica substrate. The experimental polymerization rate order, with respect to monomer concentration, ranged from 1.61 to 2.00, consistent with the kinetic order for the high polymerization regime. The corresponding rate order for polymer grafting varied from 1.24 to 1.43. The polymer graft yield increased with both initial monomer concentration and reaction temperature, and the polymer‐grafted surface became more hydrophobic with increasing polymer graft yield. The present study suggests that a denser grafted polymer phase of shorter chains was created upon increasing temperature. On the other hand, both polymer chain length and polymer graft density increased with initial monomer concentration. Atomic force microscopy–determined topology of the polymer‐grafted surface revealed a distribution of surface clusters and surface elevations consistent with the expected broad molecular‐weight distribution for free‐radical polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 300–310, 2003     

Synthesis of well‐defined responsive membranes with fixable solvent responsiveness

A versatile method is described to synthesize a new family of solvent‐responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2‐bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track‐etched membrane followed by room‐temperature ATRP grafting of poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxyethyl methacrylate‐co‐2‐(dimethylamino)ethyl methacrylate) (P(HEMA‐co‐DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo‐crosslinkable PET‐g‐PHEMA/CA membrane and PET‐g‐P(HEMA/CA‐co‐DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA‐co‐DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry     

Controllable surface modifications of polyamide by photo‐induced graft polymerization using immobilized photo‐initiators

A novel two‐step UV initiated grafting method has been developed and applied on surface modification of polyamide. Anthraquinone‐2‐sulfonate sodium, an acid dye, was chosen as the photo‐initiator. In the first step, photo‐initiators were ionically bonded onto polyamide through a normal acid dye dyeing process. Vinyl monomers such as acrylic acid were then grafted onto polyamide surface in the following step. During UVA irradiation, not only monomers were grafted onto polymer surface, photo‐initiator itself was also covalently bonded onto polymer. The grafted polymers were characterized by Fourier transform infrared spectrometer (FTIR), X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM).The degree of photo‐grafting can be controlled by adjusting concentrations of photo‐initiator and monomer, as well as UVA exposure time. This process demonstrated the feasibility of efficiently modifying polymer surface under low UV intensity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

"Soft and rigid" dithiols and Au nanoparticles grafting on plasma-treated polyethyleneterephthalate

ABSTRACT: Surface of polyethyleneterephthalate (PET) was modified by plasma discharge and subsequently grafted with dithiols (1, 2-ethanedithiol (ED) or 4, 4'-biphenyldithiol) to create the thiol (-SH) groups on polymer surface. This "short" dithiols are expected to be fixed via one of -SH groups to radicals created by the plasma treatment on the PET surface. "Free" -SH groups are allowed to interact with Au nanoparticles. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and electrokinetic analysis (EA, zeta potential) were used for the characterization of surface chemistry of the modified PET. Surface morphology and roughness of the modified PET were studied by atomic force microscopy (AFM). The results from XPS, FTIR, EA and AFM show that the Au nanoparticles are grafted on the modified surface only in the case of biphenyldithiol pretreatment. The possible explanation is that the "flexible" molecule of ethanedithiol is bounded to the activated PET surface with both -SH groups. On the contrary, the "rigid" molecule of biphenyldithiol is bounded via only one -SH group to the modified PET surface and the second one remains "free" for the consecutive chemical reaction with Au nanoparticle. The gold nanoparticles are distributed relatively homogenously over the polymer surface.     

Photoinduced grafting of vinyl benzyl trimethyl ammonium chloride on polyester nonwoven fabric with surfactant coating and its anion‐exchange properties

Vinyl benzyl trimethyl ammonium chloride (VBTAC) could be efficiently and stably grafted onto polyester fiber coated with a surfactant polyester (PET) by a photoirradiation‐induced graft polymerization with benzophenone as the photoinitiator without any cografting monomer required. The degree of VBTAC grafting could be controlled simply by the irradiation time and concentration of VBTAC in the monomer solution. The anion‐exchange capacity (AEC) of the PET‐g‐VBTAC fabrics increased with increasing degree of grafting up to 80 ± 5% and then leveled off. The maximum AEC of PET‐g‐VBTAC was 2.2 mequiv/g; this was similar to that of a commercial anion‐exchange resin (2.16 ± 0.04 mequiv/g) and much higher than those of nylon‐g‐VBTAC–2‐hydroxyethyl methacrylate fabrics (≤1.0 mequiv/g) prepared with a conventional cografting system. The grafted fabric was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy studies, and the sorption selectivity for anions and regeneration efficiency were estimated. The results suggest that the grafting system, in which VBTAC alone was grafted onto PET fiber coated with surfactant, was more practical and effective for the preparation of the VBTAC‐containing anion exchanger, and the resulting PET‐g‐VBTAC fabrics could be used as an effective anion exchanger. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41674.     

Lipases improve the grafting of poly(ethylene terephthalate) fabrics with acrylic acid

In this study, poly(ethylene terephthalate) (PET) fabrics were modified with two types of commercial lipases, namely, Lipex and Lipolase, and grafted with acrylic acid (AA) to improve their absorption properties. The effects of the enzyme concentration, reaction temperature, time, and pH on the grafting of AA onto PET were investigated. The pretreatment of PET with lipases increased the amount of AA that was introduced to the PET fibers, whereas AA grafting onto the untreated PET fabrics led to lower graft yields. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the AA‐grafted pretreated polyester fabrics. A new band appearing at 1546 cm^?1 in the Fourier transform infrared spectrum implied that AA was introduced onto the PET fabrics. The surfaces of the fabric fibers presented in scanning electron microscopy micrographs clearly indicated the formation of a layer of grafted poly (acrylic acid). The results show that the density of surface grafting was improved by the lipase pretreatment. The increase in grafting was higher for Lipex than for Lipolase. The highest graft yield was obtained with 1% Lipex and Lipolase for 30 min at pH values of 7 and 5, respectively. There were no significant changes in the tenacity or weight reduction of the fabrics. The moisture content of the samples increased linearly with increasing graft yield. This was higher for the pretreated fabrics grafted with Lipex. A higher color strength was obtained for grafted PET samples that were pretreated with Lipex when they were dyed in alkaline aqueous solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

接枝率对丙烯酰胺接枝涤纶的结构与性能的影响

用过氧化二苯甲酰（ＢＰＯ）作为引发剂,二甲基亚砜（ＤＭ ＳＯ）作为纤维溶胀剂,使丙烯酰胺和涤纶反应并形成不同接枝率的接枝共聚物,用扫描电镜和红外光谱对接枝纤维的结构进行了测试,结果表明,接枝先发生在纤维皮层,随接枝率提高,接枝层向中心发展;接枝后的纤维分子结构发生变化,接枝率越高,与丙烯酰胺有关的红外特征吸收越强。通过性能测试发现,接枝纤维的吸湿性和染色性明显提高,纤维强度随接枝率提高先降低后有所提高,断裂伸长和回弹率下降,３４．９０％ 接枝率的纤维既能得到较好改性又能基本保持原来纤维的性能。     

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.     

Atom transfer radical polymerization from silica nanoparticles using the ‘grafting from’ method and structural study via small-angle neutron scattering

Polymer chains were grafted from silica beads (colloidal sol in dimethylacetamide) by atom transfer radical polymerization (ATRP), via the ‘grafting from’ method. The grafting of the initiator onto the silica surface was done in two steps. First, thiol-functionalization of the surface was achieved via silanization with a mercaptopropyl triethoxysilane. Second, we performed an over-grafting of the surface by reacting the thiol with 2-bromoisobutyryl bromide to generate the halogen-functional ATRP initiator. The nanoparticles were kept in solution (in the same solvent) at each stage of the functionalization (even during the purification steps), as this is the only way to avoid irreversible aggregation. Then, the polymerization of styrene was conducted. Control of both the molecular weight and the density of grafted chains can be achieved by this method. Careful characterization such as gel permeation chromatography, ²⁹Si CP/MAS NMR, elemental analysis, infrared spectroscopy and thermo-gravimetric analysis is performed. The state of dispersion of the grafted nanoparticles is followed in details by small angle neutron scattering and results obtained from this technique are presented here as well as the way the SANS data can be treated. Connection is systematically done between the information provided by this technique and the improvement of the synthetic procedure.     

Synthesis of pH‐responsive polyethylene terephthalate track‐etched membranes by grafting hydroxyethyl‐methacrylate using atom‐transfer radical polymerization method

pH‐responsive polyethylene terephthalate (PET) track‐etched membranes were synthesized by grafting 2‐hydroxyethyl‐methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH‐responsive characteristics of PET‐g‐poly(2‐hydroxyethyl‐methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH‐response permeation to environmental pH values. Desired pH‐responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40912.     

Preparation and characterization of grafting polyacrylamide from PET films by SI‐ATRP via water‐borne system

The grafted homopolymer and comb‐shaped copolymer of polyacrylamide were prepared by combining the self‐assembly of initiator and water‐borne surface‐initiated atom transfer radical polymerization (SI‐ATRP). The structures, composition, properties, and surface morphology of the modified PET films were characterized by FTIR/ATR, X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by equable grafting polymer layer after grafted polyacrylamide (PAM). The amount of grafting polymer increased linearly with the polymerization time added. The GPC date show that the polymerization in the water‐borne medium at lower temperature (50°C) shows better “living” and control. After modified by comb‐shaped copolymer brushes, the modified PET film was completely covered with the second polymer layer (PAM) and water contact angle decreased to 13.6°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012