PERFORMANCE IMPROVEMENT OF POLYMERS BY THE ADDITION OF GRAFTED NANO-INORGANIC PARTICLES

An irradiation grafting method was applied for the modification of nanoparticles so that the latter can be added topolymeric materials for improving their mechanical performance using existing compounding techniques. The followingitems are discussed in this paper: (a) chemical interaction between the grafting monomers and the nanoparticles duringirradiation, (b) properties including modulus, yield strength, impact strength and fracture toughness of the resultantcomposites, and (c) possible morphological changes induced by the addition of nanoparticles. Though irradiation graftingpolymerization, nanoparticle agglomerates turn into a nano-composite microstructure (comprised of the nanoparticles and thegrafted, homopolymerized secondary polymer), which in turn builds up a strong interfacial interaction with the surrounding,primary polymeric matrix during the subsequent mixing procedure. Due to the fact that different grafting polymers broughtabout different nanoparticle/matrix interfacial features, microstructures and properties of the ultimate composites could thusbe tailored. It was found that the reinforcing and toughening effects of the nanoparticles on the polymer matrix can be fullybrought into play at a rather low filler loading in comparison to conventional particulate filled composites.

Preparation of Chelating Polymer Grafted Magnetic Adsorbent and Its Application for Removal of Pb(Ⅱ) Ions

A novel magnetic chelating adsorbent （CPMS） with iminodiacetate functionality was prepared by polymerization of glycidyl methacrylate-iminodiacetic acid （GMA-IDA） monomer with N, N-methylenebisacrylamide as crosslinker in the presence of monodisperse magnetic silica microspheres （MS）. CPMS was characterized by IR, SEM, VSM and TGA. The experimental results revealed that MS was embedded in the gel polymer, but the morphology of CPMS was irregular. The saturation magnetization for CPMS was found to be 28.4 emu/g, and the percentage of GMA-IDA polymer grafted on MS was about 46.5%. CPMS were shown to be efficient for the removal of Pb（II） ions at pH 3.0 - 6.0, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 54.4 mg？g？1 at pH 5.0. Moreover, the adsorption rate of CPMS was fast and it took about 5 minutes to achieve adsorption equilibrium in aqueous solution of lower lead ions concentration.

Superhydrophobic melamine sponge prepared by radiation-induced grafting technology for efficient oil-water separation

This paper presents a superhydrophobic melamine(ME)sponge(ME-g-PLMA)prepared via high-energy radiation-induced in situ covalent grafting of long-alkyl-chain dodecyl methacrylate(LMA)onto an ME sponge for efficient oil–water separation.The obtained ME-g-PLMA sponge had an excellent pore structure with superhydrophobic(water contact angle of 154°)and superoleophilic properties.It can absorb various types of oils up to 66–168 times its mass.The ME-g-PLMA sponge can continuously separate oil slicks in water by connecting a pump or separating oil underwater with a gravity-driven device.In addition,it maintained its highly hydrophobic properties even after long-term immersion in different corrosive solutions and repeated oil adsorption.The modified ME-g-PLMA sponge exhibited excellent separation properties and potential for oil spill cleanup.

Effect of Preparation Process of Functional Polymer Active Materials on Properties of Gadolinium Ion Selective Electrode

Recently we have studied the rare earth ion-selective electrodes with active materials of the func-tional polymers and found that the process chosen for the functional polymers had an effect on the propertiesof gadolinium ion selective electrode besides the effects of their structures.1.Effect of preparation process of the grafted polymers on the properties ofgadolinium ion selective electrodesThe electrode membranes which consist of functional polymers as active materials were prepared by re-action of gadolinium chloride with the radiation grafted clmer of acrlic acid and polystyrene of which

Anti-fouling ultrafiltration membrane prepared from polysulfone-graft-methyl acrylate copolymers by UV-induced grafting method

Membrane fouling is one of the most important challenges faced in membrane ultrafiltration operations. The copolymers of polysulfone-graft-methyl acrylate were synthesized by homogeneous photo-initiated graft copolymerization. The variables affecting the degree of grafting, such as the time of UV （Ultraviolet-visible） irradiation and the concentrations of the methyl acrylate and photoinitiator, were investigated. The graft copolymer membranes were prepared by the phase inversion method. The chemical and morphological changes were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （ATR/FT-IR）, scanning electron microscopy, and water contact angles measurements. Results revealed that methyl acrylate groups were present on the membranes and the graft degree of methyl acrylate had remarkable effect on the performance of membranes. Pure water contact angle on the membrane surface decreases with the increase of methyl acrylate graft degree, which indicated that the hydrophilicity of graft copolymer membranes was improved. The permeation fluxes of pure water and bovine serum albumin solution were measured to evaluate the antifouling property of graft copolymer membranes, the results of which have shown an enhancement of antifouling property for graft copolymer membranes.

UV-induced Self-initiated Graft Polymerization of Acrylamide onto Poly(ether ether ketone)

Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly（ether ether ketone） （PEEK） with the aim of extending its applications to biological fields. PEEK sheets were surface modified by grafting of acrylamide（AAm） with ultraviolet（UV） irradiation in the presence or absence of benzophenone（BP）. The effects of BP, irradiation time and monomer concentration on the surface wettability of PEEK were investigated. Characteriza tion of modified PEEK using scanning electron microscopy（SEM）, energy-disperse spectrometer（EDS） and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP. With the increase in irradiation time and monomer concentration, contact angles decrease to as low as 30°, demonstrating a significant improvement of surface hydrophilicity. In agreement with the decrease in contact angle, under identical conditions, the nitrogen concentration increases, suggesting the increase in grafting degree of the grafting polymerization. This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer. Though the graft polymerization proceeds more readily in the presence of BP, the self-initiated graft polymerization is clearly observed.

SURFACE MODIFICATION OF MICROPOROUS POLYPROPYLENE MEMBRANES BY GRAFT POLYMERIZATION OF N,N-DIMETHYLAMINOETHYL METHACRYLATE

Surface modification of microporous polypropylene hollow fiber membranes was performed by radical-induced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA). The influences of temperature, monomer concentration and pre-adsorbed amount of benzoyl peroxide on grafting degree were studied respectively. It was found that the appropriate graft temperature was 75 'C, at which the grafting degree was the highest and the hydrolytic decomposition of DMAEMA the lowest. Scanning electron photomicrography and the average pore diameters of the modified membranes demonstrated that part of the micropores on the membrane surface was plugged by the grafted polyDMAEMA chains, especially at high grafting degree. Contact angle and water swelling experiments showed that a moderate grafting degree could improve the hydrophilicity of the membranes. In the range of 11.3%-12.0% grafting degree, the water swelling percentage reached its maximum (51.1%) and the contact angle reached its minimum (74 degrees). The bovine serum albumin (BSA) adsorption experiment indicated that the grafted polyDMAEMA had a dual effect on protein adsorption. At the first stage, the BSA adsorption decreased with increasing of DMAEMA grafting degree. As the interaction between BSA and polyDMAEMA on membrane surface increased, the BSA adsorption increased with increasing of DMAEMA grafting degree.

PHOTO-INDUCED GRAFT POLYMERIZATION OF ACRYLAMIDE ON POLYPROPYLENE MEMBRANE SURFACE IN THE PRESENCE OF DIBENZYL TRITHIOCARBONATE

Ultraviolet （UV）-induced graft polymerization of acrylamide （AAm） on polypropylene substrates was successfully conducted using dibenzyl trithiocarbonate （DBTTC） as photoinitiator. It was confirmed by chemical analysis and surface morphology observation with attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. A possible mechanism for this graft process was presented, which suggested that, under UV irradiation, the C： S bond in DBTTC could split and abstract a hydrogen from the polypropylene surface and a surface free radical was then formed, and initiated the graft polymerization of AAm.

LAMINATION OF POLYMER FILMS BY BULK SURFACE PHOTOGRAFTING PROCESS AND PROPERTIES

A new process for lamination of polymer films by 'bulk surface photografting' has been developed. The chemical component of the invention is that the curing of reactive solution between two substrates is initiated by the surface free radicals produced by aromatic ketones and surface-hydrogen of substrates. Using the new approach, two or more polymer films are bonded together by a grafted polymer network which is grafted to adjacent substrate surfaces. The technique has been applied to film substrates of different polymers such as polyolefins, polyesters, and polyamides which have abstractable hydrogens at the surface. The photolaminated film composites containing carrier films and an intermediate functional film of low permeability give strong laminates with high barrier properties, e.g, for oxygen and air.

Ultravilolet-radiation-induced graft polymerization of acrylamide onto the melt-blown polypropylene filter element by dynamic method

By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.

Plasma-induced graft polymerization on the surface of aramid fabrics with improved omniphobicity and washing durability

Durable superomniphobic surfaces are desirable for their practical applications,including selfcleaning,non-fouling,protective clothing and the separation of liquids.The plasma-induced polymerization of environmentally friendly C6 from a perfluoralkyl methlacrylate copolymer emulsion,AG-E081,was performed and a durable omniphobic fabric was achieved.C6 is an ecological alternative to C8(eight CF2 groups)fluorinated compounds,and it was thereafter successfully incorporated into aramid fabric to achieve a durable superomniphobic surface.The fabric became water and oil repellent with an extremely high water contact angle of 180°.As tested by the water spray AATCC test and hydrocarbon resistance test,the as-prepared fabric gained 100°(ISO 5)and grade number 4 respectively.Furthermore,the fabrics also showed significantly improved washing durability after ten washing cycles.By scanning electron microscopy(SEM),Fourier-transform infrared spectroscopy(FTIR)and x-ray photoelectron spectroscopy(XPS)tests,it is indicated that the durable superomniphobicity can be attributed to the roughness and activation of the aramid surface by the plasma pre-treatment,which induces more adsorption and chemical graft of the C6 copolymer.

Graft Polymerization of Acrylic Acid and Acrylamide onto BOPET Corona Films

The graft polymerization of acrylic acid(A) and acrylamide(B) was carried out onto bi-oriented polyester BOPET corona film.The influence of monomer concentration,reducer concentration and reaction time on the graft polymerization was investigated.The surface tension of the films increased with an increase of monomer concentration,till the concentration of monomer A reached 1.5×10^(-2)g/mL and the concentration of monomer B reached 4.0×10^(-2)g/mL.The surface tension of the films reached a maximum value at 7×10^(-4)M of reducer concentration and subsequently decreased with further increase in reducer concentration.The surface tension of the films increased with the increase of the reaction time apparently within 50min.The grafted corona BOPET films were characterized with IR and XPS.The presence of graft on the film surface was confirmed.The attenuation experiments on grafted corona BOPET films in air at 50℃ and in water were carried out to investigate the persistence of graft polymerization of acrylic acid and arylamide onto BOPET corona films.

Synthesis of PGMA Microspheres with Amino Groups for High-capacity Adsorption of Cr(VI) by Cerium Initiated Graft Polymerization

Abstract A novel polyglycidylmethacrylate （PGMA） microspheres with high adsorption capacity of Cr（VI） was prepared by cerium（IV） initiated graft polymerization of tentacle-type polymer chains with amino group on polymer microspheres with hydroxyl groups. The micron-sized PGMA microspheres were prepared by a dispersion polym erization method and subsequently modified by ring-opening reaction to introduce functional hydroxyl groups. The polymer microspheres were characterized by scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The results indicated that the polymer microspheres had an average diameter of 5 m with uniform size distribution. The free amino group content was determined to be 5.13 mmol·g^-1 for g;PGMA-NH2 microspheres by potentiometric and conductometric titration methods. The Cr（VI） adsorption results indicated that the graft polymerization of tentacle-type polymer chains on the polymer microspheres could produce adsorbents with high adsorption capacity （500 mg-g-l）. The polymer microspheres with grafted tentacle polymer chains have potenial application in large-scale removal of Cr（VI） in aqueous solution.

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)microspheres were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as stabilizer.The surfaces of PDVB microspheres werechloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzeneinitiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system.Polystyrene was found to begrafted not only from the particle surfaces but also from within a thin shell layer,resulting in the formation of particles sizeincreased from 2.38-2.58 μm,which can further grow to 2.93 μm during secondary grafting polymerization of styrene.Thisdemonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature.All of the preparedmicrospheres have narrow particle size distribution with coefficient of variation around 10%.

GRAFT POLYMERIZATION OF ACRYLAMIDE ONTO HOMOPOLYMER OF 5-METHYL-5-HEXEN-2, 4-DIONE INITIATED BY CERIC ION

The homopolymerization of 5-methyl-5-hexen-2,4-dione (methacryloylacetone, MAA), a vinyl monomer having beta-diketone group, was carried out in the presence of benzophenone (BP)/N, N-dimenthyl-4-toluidine (DMT) system. Graft polymerization of acrylamide initiated by eerie ion onto the homopolymer film was investigated and the mechanism of the grafting reaction was proposed on the basis of ESR study. The grafted copolymer was characterized by means of grafting percentage, water absorption, XPS spectra and scanning electron photomicrographs.

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate)from narrow disperse polymer particles by surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)particles were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as the stabilizer.Chloromethylated PDVB was used as initiating coresites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system.It was found that poly(methylmethacrylate)was grafted not only from the particle surfaces but also from within a thin shell layer,leading to particles sizeincreases from 2.38-3.00 μm with a core-shell structure particles.The grafted core-shell particles were characterized withFTIR,SEM,DSC.

Radiation-Induced Graft Polymerization of Sodium 4-Styrene Sulfonate onto Multiwalled Carbon Nanotubes and Their Application as Electrogenerated Chemiluminescence Biosensors

Sulfonate groups were introduced to the surfaces of multiwalled carbon nanotubes by the radiation-induced graft polymerization of sodium 4-styrene sulfonate for the use as biosensor supports. Alcohol dehydrogenase was immobilized onto a sulfonated nanotube-supporting electrode with tris（2,2＇-bipyridyl） ruthenium（II） complex to form an electrogenerated chemilluminesce sensor of alcohol. When it was used to detect alcohol in cyclic voltammetric measurements, the sensor showed the linearity over the range of 1.0 × 10^-4 M-5.0 ×10^-2 M, with a correlation coefficient of 0.992 and a detection limit of 1.9 ×10^-6 M. In electrogenerated chemilluminesce detection, it showed linearity over 5.0 × 10^-4 M-1.0 × 10^-2 M, with a correlation coefficient of 0.986 and a detection limit of 1.0 × 10^-6 M. The sensor was demonstrated to be able to detect ethanol in commercial drinks.

Emulsion Graft Polymerization of Methyl Methacrylate onto Cellulose Nanofibers

Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-phenanthroline N1,N10)zinc(II) complex (Phen-DEZ) with oxygen as the radical initiator. The effects of reaction temperature, initiator concentration, and monomer content on the grafting reaction were investigated. The molecular weight of the non-grafted PMMA, which was produced during graft polymerization, was more than 1 million, as determined by size exclusion chromatography. The PMMA-grafted CNFs were analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, which confirmed the grafting of PMMA on the nanofiber surface. The study presents a strategy for the grafting of high-molecular weight PMMA onto CNFs in an emulsion system using Phen-DEZ and O2.

Tunable wavelength filters using polymer long-period waveguide gratings based on metal-cladding directly defined technique

In this work, long-period waveguide grating-based tunable wavelength filters using organic–inorganic grafting poly（methyl methacrylate）（PMMA） materials are designed and fabricated by metal-cladding directly defined technique.The thermal stabilities and optical properties of the organic–inorganic grafting PMMA core materials are analyzed. Structures and performance parameters of the waveguide gratings and self-electrode heaters are designed and simulated. The contrast of the filter is about 15 d B and the resonant wavelength can be tuned by different electric powers applied to the metal-cladding self-electrode heaters. The temperature sensitivity is 3.5 nm/℃ and the switching time is about 1 ms. The technique is very suitable for realizing the optoelectronic integrated wavelength-division-multiplexing systems.

Polycaprolactone (PCL) Chains Grafting on the Surface of Cellulose Nanocrystals (CNCs) during <i>In Situ</i>Polymerization of <i>ε</i>-Caprolactone at Room Temperature

This work aimed at investigating the feasibility of surface modification of cellulose nanocrystals (CNCs) using in situ ring opening polymerization of ε-caprolactone (ε-CL) at room temperature. Residues of flax and milkweed (Asclepias syriaca) stem fibers were used as a source of cellulose to obtain and isolate CNCs. The cationic ring opening polymerization (CROP) of the monomer ε-CL was used to covalently graft polycaprolactone (PCL) chains at the CNCs surface. Silver hexafluoroantimonate (AgSbF6) was used in combination with the extracted CNCs to initiate, at room temperature, the polymerization and the grafting reactions with no other stimulus. Fourier-Transform InfraRed (FTIR), X-ray Photoelectron Spectrometry (XPS), UV/visible absorption and Gel Permeation Chromatography (GPC) analyses evidenced the presence of PCL chains covalently grafted at CNCs surface, the formation of Ag(0) particles as well as low or moderate molecular weight free PCL chains.