UV-induced Graft Polymerization Research Articles

RETRACTED: Advanced multi-functional regenerative and self-healing tight ultrafiltration membrane for dye/salt wastewater efficient purification

Membrane fouling and membrane damage during membrane operation significantly reduce the permeate flux and separation efficiency, and the preparation of ultrafiltration membranes with renewable and self-healing properties is particularly critical for the sustainable recycling of water resources. Herein, we report a novel tight ultrafiltration membrane, which achieves self-healing properties by incorporating modified β-cyclodextrin (β-CD) monomers into the membrane, forming hydrogel by utilizing UV-induced graft polymerization and covalently binding to the membrane substrate, and then utilizing modified Azo to self-assemble into the hydrophobic cavities of the β-CD via host–guest interactions to construct host–guest chemistry to achieve regenerative anti-fouling properties. In addition, the chemical damage caused by UV-induced during the regeneration process is somewhat avoided by the modified azobenzene (Azo) and β-CD. Taking the renewing membrane as an example, the regeneration test shows that the membrane still has high flux recovery (FRR = 92.5 %) and stable separation performance after three regenerations. Physical self-healing tests showed that the dye/salt rejection recovery of the renewing membrane was greater than 95 % for all four common dyes and salts. In the case of chemical damage, a new peak appears in the XPS at 165.4 eV, demonstrating of the reliability of the actual self-healing of chemical damage. Meanwhile, the results of the mechanical properties of the renewing membrane before and after damage show that the membrane can still maintain high mechanical properties after physical self-healing has occurred. This novel anti-fouling and self-healing tight ultrafiltration membrane for practical high salinity textile wastewater separation has a broad application prospect.

Fabrication of a robust zwitterionic coating on glass with anti-fogging, anti-frosting, self-cleaning and antibacterial properties via UV-induced grafting polymerization

In this work, glass slides were separately silanized by silane coupling agents, 3-(trimethoxysilyl) propyl methacrylate (TPM) and 3-(mercaptopropyl) trimethoxysilane (MPS). Then, in presence of a photoinitiator, multifunctional hydrophilic coatings were fabricated facilely on these silanized glasses via UV-induced grafting polymerization of zwitterionic acrylic monomer methacryloxyethyl sulfobetaine (SBMA). The results showed that both TPM and MPS silanized glasses could participate in the UV-induced grafting polymerization of SBMA, while more SBMA could be grafted to the former glass to gain a little bit higher hydrophilicity. The structure, morphology and properties of the multifunctional glasses were investigated fully. As the hydrophilic polymer brushes poly(SBMA) (pSBMA) covalently attached to the glass surface, the glasses could render a series of excellent performances, including underwater superoleophobicity, anti-fogging, anti-frosting, abrasion resistance, self-cleaning and antibacterial adhesion, and especially high stability even after being immersed in water for 20 days. The strong interaction of pSBMA and water was confirmed via differential scanning calorimeter (DSC) and Raman spectrum analysis, to explicit the anti-fogging mechanism. Therefore, it is promising that the scalable multifunctional glass fabricated via UV-induced grafting polymerization could be potentially applied in the fields of automobile, bathroom, medical, etc.

UV-induced graft polymerization of polyamide-6 for electroless copper deposition

A simple and chromium-free method for the metallization on engineering plastic polyamide-6 (PA6) by UV irradiation is proposed in this article. The surface graft polymers with specific adsorption activity are developed through one-step UV exposure operation, which captures Pd2+ in the activation process. The chemisorption of Pd2+ is further reduced into catalytic Pd0 to enable the substrate with catalytic nucleus for conventional copper electroless deposition (ELD). The grafting layer and the deposited copper coating are characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle measurements, scanning electron microscopy, and X-ray diffraction. The results indicate that successful grafting occurs on PA6 after UV excitation. In addition, the as-deposited copper layer shows excellent conductive performance and high adhesion with the PA6 substrate. It’s expected that this emerging and feasible approach would have broad prospects for the metallization of plastic and offer significant value in the plating industry.

Terahertz Humidity Sensing Based on Surface-Modified Polymer Mesh Membranes with Photografting PEGMA Brush.

A simple and compact intensity-interrogated terahertz (THz) relative humidity (RH) sensing platform is successfully demonstrated in experiments on the basis of combining a porous polymer sensing membrane and a continuous THz electronic system. The RH-sensing membrane is fabricated by surface modification of a porous polymer substrate with hydrophilic and photosensitive copolymer brushes via a UV-induced graft-polymerization process. The intensity interrogation sensing scheme indicated that the power reduction of the 0.4 THz wave is dependent on the grafting density of the copolymer brushes and proportional to the RH percent levels in the humidity-controlled air-sealed chamber. This finding was verified by the water contact angle measurement. Based on the slope of the proportional relation, the best sensitivity of the hydrophilic surface-modified sensing membrane was demonstrated at 0.0423 mV/% RH at the copolymer brush density of 1.57 mg/mm3 grafted on the single side of the sensing membrane. The sensitivity corresponds to a detection limit of approximately 1% RH. The THz RH sensing membrane was proven to exhibit the advantages of low loss, low cost, flexibility, high sensitivity, high RH resolution, and a wide RH working range of 25-99%. Thus, it is a good candidate for novel applications of wearable electronics, water- or moisture-related industrial and bio-sensing.

Immobilization of chitosan on polyether ether ketone surface modified with acrylic acid by UV-induced graft polymerization

Immobilization of chitosan on polyether ether ketone surface modified with acrylic acid by UV-induced graft polymerization

3D-printed porous PEEK scaffold combined with CSMA/POSS bioactive surface: A strategy for enhancing osseointegration of PEEK implants

As an attractive biomaterial for orthopedic implants , polyetheretherketone (PEEK) has many prominent characteristics such as good biocompatibility and biomechanical properties , as well as natural radiolucency. However, the potential clinical application is limited due to its biologically inert surface and poor osseointegration . To solve this problem, we fabricate a macroporous PEEK scaffold modified with methacrylated chitosan/polyhedral oligomeric silsesquioxane (CSMA/POSS) nanocomposite through 3D printing , sulfonation and UV-induced graft polymerization. The water contact angle, protein adsorption ability and biomineralization study of the sulfonation-treated PEEK (SPEEK)-CSMA/POSS scaffolds were measured in order to evaluate the surface properties. The results indicated that CSMA/POSS as a bioactive microporous surface integrated with nanoparticles promoted the protein adsorption and apatite formation . For the in vitro and in vivo evaluation of the osteogenicity, rat bone marrow mesenchymal stem cells (rBMSCs) and rat calvaria defect repair model were used. Biological results showed that the 3D porous structure and bioactive surface of modified PEEK scaffolds provided a suitable condition for cell adhesion and proliferation, enhanced the osteogenic differentiation of rBMSCs and promoted osteogenesis in vivo compared to the untreated PEEK scaffold. Therefore, 3D-printed macroporous PEEK scaffold modified with CSMA/POSS bioactive microporous surface represents a promising modification strategy for enhancing osseointegration of PEEK implants.

Interfacial polymerization plus: A new strategy for membrane selective layer construction

Reverse osmosis membrane with high permselectivity and durability is highly desirable. Due to the self-limiting in interfacial polymerization process, existing strategies for membrane selective layer construction are constrained. Herein, a designable evolutionary strategy named interfacial polymerization plus, which combines interfacial polymerization and UV-induced graft polymerization, is proposed to construct the membrane selective layer. As a result, a sophisticated selective layer with rationally designed bulk and surface is obtained. The selective layer endows membrane with unprecedented improvement in permeability, chlorine-resistant and anti-fouling properties, while maintaining high rejection. Meanwhile, the long-term excellent performance under severe conditions indicates that the developed membrane has great potential in new and expanding applications.

Biofouling 방지를 위한 항균성 멤브레인 필터의 제조 : GMA의 그라프트 중합과 아민화/술폰화에 의한 표면개질

Biofouling is a major problem of membrane processes in water and wastewater treatment. One of the anti-biofouling strategies is to construct an antimicrobial membrane surface. In this study, polypropylene(PP) microfiltration membranes with antimicrobial property were fabricated by grafting glycidyl methacrylate(GMA), followed by amination or sulfonation with ethylenediamine or sodium sulfite solution. GMA was facilely grafted onto PP membrane by UV-induced graft polymerization, and the graft chains were easily aminated or sulfonated by a simple chemical reaction. The modified PP membranes were characterized by FT-IR, SEM, water permeability and antimicrobial tests. The PP membranes modified by grafting GMA improved the water permeability due to the hydrophilization of the surface, but the antimicrobial activity was too low. In contrast, aminated or sulfonated PP membranes exhibited high antimicrobial activity against both E. coli and S. aureus without a significant reduction in the water permeability.

Self-assembling of NCQDs-TiO2 nanocomposite on poly(acrylic acid)-grafted polyethersulfone membrane for photocatalytic removal and membrane filtration

Considering the tedious post-reaction recovery of nano-sized phototcatalysts and the critical fouling problem faced in membrane separation, incorporation of photocatalyst with polymeric membrane has been developed to alleviate these issues. In this study, polyethersulfone (PES) membrane was synthesized by phase inversion method and poly-acrylic acid (PAA) was later grafted onto the PES surface via UV-induced graft polymerization technique. The PAA film has introduced –COOH functional groups for the surface immobilization of green nitrogen-doped carbon quantum dots-titanium dioxide (NCQDs-TiO2) photocatalyst via a self-assembly approach. The PAA-modified supporting layer and the NCQDs-TiO2 functional layer were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). The characterization results evidenced that PAA chains were successfully polymerized on PES support while the nanocomposite was firmly deposited on the PAA-grafted membrane. The novel NCQDs-TiO2/PAA/PES composite membrane demonstrated excellent photocatalytic capability, wherein 94.41% of methylene blue (MB) was removed under 1 h of visible-light irradiation. The antifouling property of the modified membrane was proven by the rapid flux stabilization and the high flux recovery ratio of 83.92%. The current research work proposed the synergistic use of visible-light responsive photocatalytic membrane in the degradation and filtration of wastewater, which is more energy-efficient and could reduce secondary pollution.

HYDROPHOBIZATION OF PET TRACK-ETCHED MEMBRANES FOR DIRECT CONTACT MEMBRANE DISTILLATION OF LIQUID RADIOACTIVE WASTES

This article provides the results of liquid low-level radioactive wastes treatment by direct contact membrane distillation using polyethylene terephthalate hydrophobic track-etched membranes. The hydrophobization of track-etched membranes was carried out by UV-induced graft polymerization of triethoxyvinylsilane with styrene and coating with fluorine-containing silanes. Hydrophobic membranes were investigated by scanning electron microscope, Fourier-transform infrared spectroscopy, contact anglemeasurements, and liquid entry pressure analysis. Prepared membranes were tested in treatment of liquid low-level radioactive wastes by membrane distillation. The influence of pore sizes on water flux and rejection degree was studied. Rejection degree was evaluated by conductometry and atomic emission method. Decontamination factors evaluated by gamma-ray spectroscopy for 60Co, 137Cs, and 241Am are 85.4, 1900 and 5.4 for membranes modified with polystyrene and triethoxyvinylsilanewith pore diameters of 142 nm; 85.0, 1462 and 4 for membranes modified with perfluorododecyltrichlorosilanewith pore diameters of 150 nm respectively.

Polymer Membrane with Glycosylated Surface by a Chemo-Enzymatic Strategy for Protein Affinity Adsorption

Membranes with glycosylated surfaces are naturally biomimetic and not only have excellent surface hydrophilicity and biocompatibility, but have a specific recognition to target biomacromolecules due to the unique chemo-biological properties of their surface carbohydrates; however, they cannot be easily chemically produced on large scales due to the complex preparation process. This manuscript describes the fabrication of a polypropylene membrane with a glycosylated surface by a chemo-enzymatic strategy. First, hydroxyl (OH) groups were introduced onto the surface of microporous polypropylene membrane (MPPM) by UV-induced grafting polymerization of oligo(ethylene glycol) methacrylate (OEGMA). Then, glycosylation of the OH groups with galactose moieties was achieved via an enzymatic transglycosylation by β-galactosidase (Gal) recombinanted from E. coli. The fabricated glycosylated membrane showed surprisingly specific affinity adsorption to lectin ricinus communis agglutinin (RCA120). The chemo-enzymatic route is easy and green, and it would be expected to have wide applications for large-scale preparation of polymer membranes with glycosylated surfaces.

Bottlebrush-like highly efficient antibacterial coating constructed using α-helical peptide dendritic polymers on the poly(styrene-b-(ethylene-co-butylene)-b-styrene) surface.

Infectious diseases induced by pathogenic bacteria are the major causes for the failure of medical implants. Meanwhile, the drug-resistance is steadily developed because of the large and even inappropriate use of antibiotics. Therefore, the development of antibacterial coating with non-antibiotic-based agents on the surfaces of medical implants and devices has been an urgent need. Herein, we propose a bottlebrush-like antibacterial coating on a poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) triblock copolymer surface by UV-induced graft polymerization of poly(ethylene glycol) (PEG) acrylate terminated poly(lysine dendrimer). This PEG-conjugated antibacterial polymer possessed a substructure of α-helical backbone and cation dendrimer side chains stretching in the radial directions of the helix. The introduction of lysine peptide dendrimers endowed the prepared antibacterial polymer with precisely controlled characteristics of its local cation density, amphipathic composition as well as three-dimensional (3D) conformation to improve interactions with bacterial membranes. The antimicrobial assay and biocompatibility assay results showed that 96.83% of S. aureus and 99.99% of E. coli were killed after being in contact with the antibacterial coating, while no toxicity to mammalian cells or no hemolysis was detected. This antimicrobial activity was further confirmed by the molecular dynamics simulation results, which demonstrated that the employment of lysine peptide dendrimers enhanced the electrostatic interaction and hydrogen bonding between the brush and bacterial membranes remarkably. Such bottlebrush-like antibacterial coating constructed using α-helical peptide dendritic polymers may become an effective strategy for manufacturing antibacterial products for biomedical uses.

Functionalization of PET Track-Etched Membranes by UV-Induced Graft (co)Polymerization for Detection of Heavy Metal Ions in Water

Nowadays, water quality monitoring is an essential task since environmental contamination and human exposure to heavy metals increased. Sensors that are able to detect ever lower concentrations of heavy metal ions with greater accuracy and speed are needed to effectively monitor water quality and prevent poisoning. This article shows studies of the modification of flexible track-etched membranes as the basis for the sensor with various polymers and their influence on the accuracy of detection of copper, cadmium, and lead ions in water. We report the UV-induced graft (co)polymerization of acrylic acid (AA) and 4-vinylpyridine (4-VPy) on poly(ethylene terephthalate) track-etched membrane (PET TeMs) and use them after platinum layer sputtering in square wave anodic stripping voltammetry (SW-ASV) for detection of Cu2+, Cd2+, and Pb2+. Optimal conditions leading to functionalization of the surface and retention of the pore structure were found. Modified membranes were characterized by SEM, FTIR, X-ray photoelectron spectroscopy (XPS) and colorimetric analysis. The dependence of the modification method on the sensitivity of the sensor was shown. Membrane modified with polyacrylic acid (PET TeMs-g-PAA), poly(4-vinylpyridine) (PET TeMs-g-P4VPy), and their copolymer (PET TeMs-g-P4VPy/PAA) with average grafting yield of 3% have been found to be sensitive to µg/L concentration of copper, lead, and cadmium ions. Limits of detection (LOD) for sensors based on PET TeMs-g-PAA are 2.22, 1.05, and 2.53 µg/L for Cu2+, Pb2+, and Cd2+, respectively. LODs for sensors based on PET TeMs-g-P4VPy are 5.23 µg/L (Cu2+), 1.78 µg/L (Pb2+), and 3.64 µg/L (Cd2+) µg/L. PET TeMs-g-P4VPy/PAA electrodes are found to be sensitive with LODs of 0.74 µg/L(Cu2+), 1.13 µg/L (Pb2+), and 2.07 µg/L(Cd2+). Thus, it was shown that the modification of membranes by copolymers with carboxylic and amino groups leads to more accurate detection of heavy metal ions, associated with the formation of more stable complexes.

Fabrication of Chitosan-Based Intumescent Flame Retardant Coating for Improving Flame Retardancy of Polyacrylonitrile Fabric.

In order to improve the flame retardancy of polyacrylonitrile (PAN) fabrics, glycidyl methacrylate (GMA) was first grafted onto the surface of PAN fabric (PAN-g-GMA) by means of UV-induced photo grafting polymerization process. Then, PAN-g-GMA was chemically grafted with chitosan to obtain a bigrafted PAN fabric (PAN-g-GMA-g-CS). Finally, the flame-retardant PAN fabric (FR-PAN) was prepared by phosphorylation. The structure and elemental analysis of the samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal degradation properties and combustion characteristics of the fabrics were accessed by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and cone calorimeter (CC). The results show that the onset thermal decomposition temperature of FR-PAN fabric is lower than that of the control sample due to the degradation of the grafting groups. The combustion test indicates that the FR-PAN fabric has an excellent flame-retardant property and the combustion rate is significantly reduced. In addition, the char residue of the burned FR-PAN fabric is over 97%, indicating excellent char-forming ability.

Highly Transparent Cyclic Olefin Copolymer Film with a Nanotextured Surface Prepared by One-Step Photografting for High-Density DNA Immobilization.

Compared with conventional glass slides and two-dimensional (2D) planar microarrays, polymer-based support materials and three-dimensional (3D) surface structures have attracted increasing attention in the field of biochips because of their good processability in microfabrication and low cost in mass production, as well as their improved sensitivity and specificity for the detection of biomolecules. In the present study, UV-induced emulsion graft polymerization was carried out on a cyclic olefin copolymer (COC) surface to generate 3D nanotextures composed of loosely stacked nanoparticles with a diameter of approximately 50 nm. The introduction of a hierarchical nanostructure on a COC surface only resulted in a 5% decrease in its transparency at a wavelength of 550 nm but significantly increased the surface area, which markedly improved immobilization density and efficiency of an oligonucleotide probe compared with the functional group and polymer brush-modified substrates. The highest immobilization efficiency of the probes reached 93%, and a limit of detection of 75 pM could be obtained. The hybridization experiment demonstrated that the 3D gene chip exhibited excellent sensitivity for target DNA detection and single-nucleotide polymorphism discrimination. This one-step approach to the construction of nanotextured surfaces on the COC has promising applications in the fields of biochips and immunoassays.

Synthesis of Carboxyl-Rich Biosorbent by UV-Induced Graft Polymerization Method for High Efficiency Adsorption of Ce3+ from Aqueous Solution: Activation and Adsorption Mechanism

Developing a cost-effective and highly efficient sorbent for the recovery of rare-earth elements from aqueous solution is still an urgent need. In this study, a novel biosorbent, carboxyl-rich pine bark (CPB), was modified by UV-induced graft polymerization method to increase the carboxyl-containing functional groups and facilitate the adsorption of Ce3+. The grafting process was examined by Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM), indicating that high-density carboxyl functional groups are present on the surface of pine bark and the grafting yield of surface polymer brushes reaches up to 128%. Interestingly, the maximum adsorption capacity of Ce3+ on CPB could reach up to 256.5 mg/g. The adsorption mechanism of Ce3+ by CPB has been determined by the adsorption models and x-ray photoelectron spectroscopy (XPS), which can be inferred from these results that the high performance of CPB is attributed to the surface coordination between Ce3+ and hydroxyl or carbonyl groups. This work suggests that engineered surface functional groups of biomass could have an opportunity for the development of high performance rare-earth element adsorbents.

Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD.

Carboxymethyl chitosan (CMCS), acrylamide, and methacryloxyethyltrimethyl ammonium chloride were used as co-monomers to produce a sludge dewatering agent carboxymethyl chitosan-graft-poly(acrylamide-methacryloxyethyltrimethyl ammonium chloride) (CCPAD) by UV-induced graft polymerization. Single-factor experiments and response surface methodology were employed to investigate and optimize the grafting rate, grafting efficiency, and intrinsic viscosity influenced by the total monomer concentration, CMCS concentration, cationic degree, pH value, and illumination time. The structure, surface morphology, and thermal stability of CCPAD were characterized by infrared spectroscopy, hydrogen nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, and differential thermal-thermogravimetry. The raw sludge with 97.9% water content was sourced from the concentrated tank of a sewage treatment plant and used in the sludge condition experiments. In addition, CCPAD was applied as the sludge conditioner to investigate the effects of cationic degree, intrinsic viscosity, and pH on the supernatant turbidity, moisture content, specific resistance to filtration, and sludge settling ratio. Moreover, the mechanism of sludge conditioning by CCPAD was discussed by examining the zeta potential and extracellular polymeric substance (EPS) content of the supernatant. The sludge dewatering results confirmed that CCPAD had excellent performance for improving sludge dewaterability.

Synergistic effect of carboxylated-MWCNTs on the performance of acrylic acid UV-grafted polyamide nanofiltration membranes

Surface modification of a commercial polyamide nanofiltration membrane was achieved by UV induced graft polymerization of acrylic acid and incorporation of carboxylated-MWCNTs (COOH-MWCNTs). The grafting process was done under different monomer concentrations and UV exposure times. The modified membranes were characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle and zeta-potential analysis, and cross-flow filtration experiments. Changes in the surface hydrophilicity, negative charge and roughness of the modified membranes improved their permeability and fouling resistance significantly. The membrane grafted with 50 g/L acrylic acid under 5 min UV exposure showed the best filtration performance including pure water flux of 38.8 L/m2 h, salt rejections of 97.43% (Na2SO4) and 93.4% (NaCl), and flux recovery ratio (FRR) of 80.2% during bovine serum albumin (BSA) filtration. After optimizing grafting condition, different amounts of COOH-MWCNTs were dispersed in the monomer solution for embedding in the grafting layer. By adding 0.2 wt% COOH-MWCNTs to the grafting layer, a water flux improvement of around 30% was observed. But, excess loading of the COOH-MWCNTs led to compaction of the grafting layer and made it inflexible and subsequently, reduced the hydrophilicity and permeability of the membrane. Fouling tests with BSA aqueous solution showed that antifouling ability of the modified membranes was remarkably improved at all concentrations of the COOH-MWCNTs. Furthermore, salt rejection results displayed that simultaneous surface modification through grafting and COOH-MWCNTs embedding could effectively improve the nanofiltration performance of the membranes in the term of permeability, desalination and fouling resistance.

Photo-graft modification of fluoropolymer surface and its bonding properties with EVA hot melt adhesive

<p indent=0mm>As an important part of photovoltaic (PV) modules, backsheet materials play an important role in protecting solar cell from environmental degradation caused by moisture penetration. Fluoropolymers, which have excellent weatherability, UV radiation resistance and chemical stability, are widely used as the outer layer of the backsheet to ensure the long-term reliability and safety of PV modules. However, the low surface energy and poor adhesion to other materials of fluoropolymer markedly limits its practical application in encapsulation of solar cells which require the backsheet to be firmly bonded with PV modules by ethylene-vinyl acetate copolymer (EVA) hot melt adhesive. Although some methods such as corona discharge, plasma treatment, radiation grafting can effectively improve the surface properties of fluoropolymers, UV-induced graft polymerization is still considered as one of the most promising approach due to its advantages in fast reaction rate, low cost of processing, simple equipment, easy industrialization, and no damage to bulk property of materials. In this paper, different copolymers of acrylic acid-butyl acrylate (PAA-BA) or butyl acrylate-trimethylolpropane triacrylate (PBA-TMPTA) were introduced onto fluoropolymer film by photografting polymerization. The effects of UV irradiation time, monomer composition and monomer concentration on the graft efficiency were investigated. The chemical composition, surface morphology and chemical composition of the film were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and contact angle analysis (CA). The results showed that the UV-induced graft polymerization can be successfully performed on the fluoropolymer film and a dense graft layer could be introduced on the surface. The introduction of PAA-BA changed the surface property of fluoropolymer film and facilitated the spreading of EVA, while the adhesive strength of PAA-BA modified surface bonded with EVA film is only <sc>0.8–4.8 N/cm,</sc> which is almost same as the unmodified fluoropolymer film. Similarly, introducing functional groups such as hydroxyl and sulfate groups by confined photooxidation method did not improve the adhesion properties. When PBA-TMPTA copolymer was grafted on the fluoropolymer film, its laminate with EVA hot melt adhesive had a peeling strength up to <sc>17.6 N/cm</sc> (15 times of unmodified film). The remarkable increase in the adhesive property of modified fluoropolymer was believed to be attributed to the unreacted double bond of grafted PBA-TMPTA. During the melt of EVA, the peroxide additive in it decomposed to release radicals and resulted in the crosslinking of EVA film. Meanwhile, the chain radicals of EVA also reacted with double bond in the PBA-TMPTA layer, which could form covalent bond between the interfaces and improve the adhesive strength. Therefore, the improvement of interfacial adhesion performance is mainly due to chemical bond rather than physical interaction.

Polypropylene surface with antibacterial property by photografting 1-vinylimidazole and subsequent chemical modification

The surface of polypropylene (PP) fiber was modified by UV-induced graft polymerization of 1-vinylimidazole (Vim), followed by quaternization with iodomethane, sulfonation with chlorosulfonic acid, or loading of silver (Ag) nanoparticles to endow the surface with antibacterial properties. The modified PP fibers were characterized by FT-IR, SEM, and surface charge analyses. The antibacterial activity of the modified PP fibers was assessed against the Gram-negative and Gram-positive bacteria, Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus), respectively. The PP-g-Vim was greatly improved by loading of Ag nanoparticles (≥99.9%), quaternization (98.9–99.2%), or sulfonation (≥99.9%).