Enhancing the grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles (SiO2-g-PHEMA) by the sequential UV-induced graft polymerization with a multiple-UV irradiation

Grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles was accomplished via the sequential UV-induced graft polymerization. Under UV-irradiation, the silica was functionalized with the surface initiator, benzophenone (BP) and subsequently graft-polymerized with 2-hydroxyethyl methacrylate (HEMA). The grafting on the silica particles was confirmed by DSC analysis which revealed a shift of the glass transition temperature (T_g) of grafted PHEMA to higher temperature than T_g of ungrafted PHEMA. A significant improvement in the grafting efficiency and the grafting percentage was achieved when a sequential grafting approach was taken, employing multiple UV exposures. Using this approach, the efficient chain extension from the grafted-PHEMA was possible without producing significant amounts of ungrafted PHEMA when low HEMA concentrations were used during each UV-exposure.     

低温等离子体接枝改性PVDF膜

采用低温等离子体接枝技术改性聚偏氟乙烯膜(PVDF),在PVDF膜表面引入疏水性单体苯乙烯,达到改变膜表面孔径的大小和孔径分布的目的.通过傅立叶红外光谱仪(FTIR-ATR)对改性前后的PVDF膜表面进行了结构分析,考察了PVDF膜接枝前后官能团的变化.采用示差扫描量热仪(DSC)分析了PVDF改性前后膜的孔径分布,考察了改性条件对膜孔径大小和分布的影响.通过扫描电子显微镜(SEM)和原子力显微镜(AFM)观测了PVDF膜改性前后表面形貌的变化.研究了接枝温度、接枝时间等接枝条件对PVDF改性膜纯水通量的影响.结果表明,随着照射时间和接枝时间的延长,PVDF改性膜的孔径分布变窄,纯水通量下降,接枝率提高.     

原硅酸钠改性的聚偏氟乙烯接枝苯乙烯磺化膜接枝率的影响因素

以过氧化苯甲酰(BPO)作引发剂,通过溶液接枝聚合法把苯乙烯接枝到原硅酸钠改性的聚偏氟乙烯(PVDF)膜上,磺化后得到聚偏氟乙烯接枝苯乙烯磺酸(PVDF-g-PSSA)电解质膜。讨论了原硅酸钠的用量、接枝反应时间、反应温度、BPO浓度、苯乙烯单体浓度等对PVDF-g-PSSA膜接枝率的影响。结果表明,原硅酸钠用量为10%(质量分数,下同)、BPO浓度为0.016mol/L反应液、苯乙烯与四氢呋喃的比例为4∶1、在75℃水浴中,氮气保护下反应10h,可得到接枝率为16.1%、电导率为1.6×10-2S/cm的PVDF-g-PSSA电解质膜。     

Fabrication of polyacrylamide–carbon nanotubes by One-Step Radiation-Induced Graft Polymerization

A facile strategy for the preparation of organic nitrogen functional multi-walled carbon nanotubes (MWCNTs) in aqueous solution is proposed, where MWCNTs were functionalized by simultaneous radiation-induced graft polymerization of acrylamide under the γ-ray. The structure of the poly(acryl amide) grafted MWCNTs (denoted as MWCNT-g-PAM) is characterized by means of FT-IR, XPS spectroscopies, TGA analysis and TEM imaging. The degree of grafting dependent on the reaction conditions such as the monomer concentration was also discussed in this paper.     

Preparation of a reticulated polyurethane foam grafted with poly(acrylic acid) through atmospheric pressure plasma treatment and its lysozyme immobilization

We successfully introduced peroxide groups onto the surface of PU(Polyurethane) foam(10 PPI) through one atmospheric pressure plasma treatment and sequentially grafted PAAc(poly(acrylic acid)) on the surface of PU through radical copolymerization. The plasma treatment can generate large amount of peroxides on the surface of PU foam and the peroxide groups act as initiators for further grafting of PAAc in the monomer solution. To introduce large amount of peroxides on the surface of PU foam, we studied the effect of plasma rf-power and treatment time on the maximum grafting of PAAc. Through this study, we found that the optimum plasma treatment condition was the rf-power of 100 W and the treatment time of 100 s. On the other hand, we also studied the effect of graft reaction conditions such as temperature, monomer concentration and reaction time on the change of grafting degree (GD). The GD increased with increasing temperature and increased with reaction time before it leveled off at 3 h after reaction started. At low concentration of AAc, the GD was very low but it showed a maximum at the monomer concentration between 60 and 70%. The surface of the modified PU foam was qualitatively and quantitatively analyzed through the use of FT-IR and weight measurement, respectively. We also observed the surface change before and after plasma induced graft co-polymerization through photo and SEM analysis. Finally, we confirmed that the PU foams grafted with PAAc successfully immobilized lysozyme and other proteins from hen egg white.     

聚丙烯酸-g-聚(卤代)苯乙烯两亲性接枝共聚物的可控合成

以丙烯酸甲酯、(卤代)苯乙烯为原料,利用原子转移自由基聚合技术、从主干接枝的合成策略和聚丙烯酸甲酯的碱性水解,实现了两亲性接枝共聚物聚丙烯酸-g-聚(卤代)苯乙烯的可控合成.主链和侧链的分子量可分别通过调整单体与引发剂的投料比和反应时间进行控制.(卤代)苯乙烯单体接枝共聚时,采用单体过量的本体聚合且单体转化率控制在10...     

Influence of pre-irradiation atmosphere on the properties of polymer electrolyte membranes prepared using radiation grafting method

The influence of pre-irradiation atmosphere, argon and air, on radiation grafting of styrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and the properties of the ETFE-based radiation-grafted polymer electrolyte membranes were investigated. The preparation and properties of the membranes were found to be strongly influenced by the γ-ray pre-irradiation atmosphere. The proton conductivity was measured in its water-saturated state at 25 °C, and the membrane durability was tested in a 3% H₂O₂ aqueous solution at 60 °C. The proton conductivity of the membrane prepared by pre-irradiation under air was higher than that of the membrane prepared under argon with the same ion exchange capacity level. However, the durability of the former was considerably lower than that of the latter. For instance, the membrane with an ion exchange capacity of about 1.0 mmol g⁻¹ prepared under argon was twice as durable as that prepared under air. It was considered that the lower durability of the membrane prepared by pre-irradiation under air was because of the unstable ether bond introduced between the graft chains and the backbone chains.     

Synthesis and characterisation of styrene butadiene styrene-g-N-vinyl-2-pyrrolidinone for use in biomedical applications

The current contribution investigates the potential use of styrene butadiene styrene (SBS) block copolymer grafted with N-vinyl-2-pyrrolidinone (NVP) for use as a novel biomaterial. SBS-g-NVP was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic thermal mechanical analysis (DMTA) and goniometry were used to characterise the grafted copolymers. The ATR-FTIR spectrum for grafted SBS-g-NVP copolymer exhibits a shoulder at 1714 cm^?1, which is associated with carbonyl stretching of NVP. DSC analysis showed the grafted copolymers had broader thermographs within the butadiene rich domain resulting in increased T_g values, suggesting that grafting occurred. Confirmation of this was established by the use of DMTA, where the T_g (?90 °C) which represents the butadiene domain increased to ?76 °C, thus proving grafting. The surface chemistries of the grafted copolymers have also been altered which is reflected in the goniometry results which show a dramatic reduction in contact angles (113° to 7°), which is a desired property for biomedical polymers.     

Conducting poly(vinyl chloride)-<Emphasis Type="Italic">graft</Emphasis>-polythiophene: synthesis,characterization, and materials properties

A novel, and facile strategy for chemical, and electrochemical grafting of polythiophene onto poly(vinyl chloride) (PVC) is reported. For this purpose, a thiophene-functionalized PVC macromonomer was synthesized via a condensation reaction between phenylamine-functionalized PVC, and thiophene-2-carbaldehyde. The resultant macromonomer subsequently used in chemical, and electrochemical oxidation copolymerization with thiophene monomer to afford a poly(vinyl chloride)-graft-polythiophene (PVC-g-PTh) graft copolymer. The PVC-g-PTh obtained was characterized by means of Fourier transform infrared spectroscopy, and its electroactivity behavior was verified under cyclic voltammetric conditions. The electrical conductivities of the synthesized samples were measured using samples in which the conductive materials were sandwiched between two Ni electrodes at room temperature using the four probe technique. Moreover, thermal behaviors of the synthesized polymers were investigated by means of and thermogravimetric analysis.     

ABS接枝马来酸酐、苯乙烯双单体的研究

采用溶液法进行了ABS接枝马来酸酐、苯乙烯双单体的研究。本研究主要讨论了马来酸酐用量、苯乙烯用量、反应温度以及反应时间等因素对接枝率和接枝效率的影响 ,并用红外光谱法和热重法对接枝物进行了表征     

Modification of jute fibre through vinyl grafting aimed at improved rot resistance and dyeability

Raw, dewaxed and oxidized jute fibres and those chemically modified with phenol and formaldehyde (treatment done for 3 h at 95° C and pH 8) before or subsequent to oxidation, were subjected to graft copolymerization with methyl methacrylate (MMA) in the presence or absence of some other monomers such as maleic anhydride (MA) or methacrylic acid (MAA) in limited aqueous system using K₂S₂O₈ as the initiator under photoconditions with the objective of inducing improved rot resistance and dyeability without loss in tensile strength of the fibre. For preparing oxy-jute, dewaxed and preswollen (dewaxed jute fibre swollen with 10% aqueous urea at 90° C for 2h) jute fibre were separately subjected to mild oxidation or bleaching using aqueous H₂O₂ and NalO₄ and non-aqueous chlorine (Cl₂ in CCl₄) under specified conditions. Optimum conditions for graft copolymerization have been established by examination of the effect of such variables as monomer concentration, time of polymerization and nature of chemical modification of jute fibre prior to vinyl grafting. Percentage grafting, tenacity (g denier^–1), dye fixation (%) and rot resistance (expressed as percentage retention of tensile strength of the fibre after a standard soil burial test) were evaluated and analysed. High rot resistance (80–90% retention of tensile strength after soil burial test) and dye fixation (%) of as high as 86% were readily obtained for grafted jute fibres. Washing fastness and light fastness properties of the dyed fibres (grafted and ungrafted) were also examined and compared.     

Grafting polymers to titania nanoparticles by radical polymerization initiated by diazonium salt

The grafting of biocompatible poly(hydroxyethyl) methacrylate (PHEMA) by a very simple method onto titanium dioxide nanoparticles is reported. The selected grafting process is based on the chemical reduction of diazonium salts by reducing agents in presence of the vinylic monomer. As previously demonstrated on flat surfaces, it leads to strongly grafted and stable polymer films and has many advantages residing in a short one-step reaction occurring at atmospheric pressure, ambient air and room temperature in water. TiO₂ nanoparticles were synthesized by laser pyrolysis, giving nanoparticles with controlled size and composition. The coating, the composition, the chemical structure, and the grafted PHEMA quantities of the resulting products were investigated by Transmission electron microscopy, Infrared-attenuated total reflection, X-ray photoelectron spectroscopy, and Thermogravimetric analysis. It was demonstrated that the PHEMA shell was successfully chemically grafted onto the surface of the TiO₂ core without any significant influence on the morphology of the nanoparticles.     

Photoinitiator grafted styrene–butadiene–styrene triblock copolymer

Grafting of photoinitiator-4-maleimidobenzophenone (4-MBP) onto styrene–butadiene–styrene (SBS) triblock copolymer was carried out by free radical polymerization. The grafting ratio was evaluated by varying initiator concentrations, and the structure of grafted copolymer (SBS-g-MBP) was characterized by attenuated total reflectance infrared Fourier transform spectroscopy (ATR-FTIR), proton nuclear magnetic resonance (¹H NMR) and X-ray photoelectron spectroscopy (XPS). The results confirmed that 4-MBP was successfully grafted onto the SBS backbone. Thermal gravimetric analyzer (TGA), dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to study the thermal properties and morphology of the SBS-g-MBP. From the data of TGA, the SBS-g-MBP had better thermal stability compared with that of SBS. DMTA testing indicated that the glass transition temperature (T_g) of SBS-g-MBP was higher than that of SBS. With the aid of SEM and AFM, the structure of micro-phase separation can be observed obviously. What is more, the aggregates become smaller compared with those of pure SBS. The experiment of UV-crosslinked SBS-g-MBP revealed that the gel fraction could be facilely controlled by adjusting grafting ratio and exposure time. The results suggested that this novel grafted copolymer could be attractive for its application in biomedical materials such as medical pressure-sensitive adhesive.     

Modification in Surface Chemistry of the Polyetrafluoroethylene Through Chemical Graft Copolymerization for Potential Oil Contamination Control

In the present study, an attempt has been made to design an oleophobic surface through chemical graft copolymerization of methyl methacrylate (MMA) onto polytetrafluroethylene (PTFE) film. The PTFE films were grafted with MMA resulting in PTFE-g-MMA grafts using benzoyl peroxide (BPO) as initiator in aqueous media. Optimum conditions pertaining to maximum percentage of grafting were evaluated by varying time, temperature, initiator, and monomer concentration. The maximum graft yield 9.47% was obtained at [BPO] = 0.03 M, [MMA] = 10%V/V, [reaction temperature] = 50°C and [reaction time] = 120 min. Methyl iodide was used to measure the contact angle, which revealed the oleophobic nature of grafted PTFE-g-MMA film. Maximum contact angle 95.5° of PTFE-g-MMA film was observed at optimum grafting conditions. The surface morphology of PTFE-g-MMA films was studied by Field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD) analysis confirmed the change in structure of PTFE after MMA grafting.     

Amphiphilic Graft Copolymers as a Versatile Binder for Various Electrodes of High‐Performance Lithium‐Ion Batteries

It is known that grafting one polymer onto another polymer backbone is a powerful strategy capable of combining dual benefits from each parent polymer. Thus amphiphilic graft copolymer precursors (poly(vinylidene difluoride)‐graft‐poly(tert‐butylacrylate) (PVDF‐g‐PtBA)) have been developed via atom transfer radical polymerization, and demonstrated its outstanding properties as a promising binder for high‐performance lithium‐ion battery (LIB) by using in situ pyrolytic transformation of PtBA to poly(acrylic acid) segments. In addition to its superior mechanical properties and accommodation capability of volume expansion, the Si anode with PVDF‐g‐PtBA exhibits the excellent charge and discharge capacities of 2672 and 2958 mAh g^?1 with the capacity retention of 84% after 50 cycles. More meaningfully, the graft copolymer binder shows good operating characteristics in both LiN_0.5M_1.5O₄ cathode and neural graphite anode, respectively. By containing such diverse features, a graft copolymer‐loaded LiN_0.5M_1.5O₄/Si‐NG full cell has been successfully achieved, which delivers energy density as high as 546 Wh kg^?1 with cycle retention of ≈70% after 50 cycles (1 C). For the first time, this work sheds new light on the unique nature of the graft copolymer binders in LIB application, which will provide a practical solution for volume expansion and low efficiency problems, leading to a high‐energy‐density lithium‐ion chemistry.     

Synthesis,characterization and swelling properties of guar gum-g-poly(sodium acrylate-co-styrene)/muscovite superabsorbent composites

Abstract

A series of novel guar gum-g-poly(sodium acrylate-co-styrene)/muscovite (GG-g-P(NaA-co-St)/MVT) superabsorbent composites were prepared by free-radical grafting copolymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA), styrene (St) and muscovite (MVT) using ammonium persulfate (APS) as the initiator and N,N-methylene-bis-acrylamide (MBA) as the crosslinker. Optical absorption spectra confirmed that NaA and St had been grafted onto the GG main chain and MVT participated in the polymerization reaction. The simultaneous introduction of St and MVT into the GG-g-PNaA matrix could clearly improve the surface morphologies of the composites, and MVT led to better dispersion in the polymeric matrix without agglomeration, as revealed by electron microscopy. The effects of St and MVT on the water absorption and swelling behavior in various saline solutions, aqueous solutions of hydrophilic organic solvents and surfactant solutions were investigated. Results indicated that the swelling rate and capabilities of the composites were markedly enhanced by the incorporation of the hydrophobic monomer St and inorganic MVT clay mineral. The superabsorbent composite showed a clearer deswelling characteristic in solutions of multivalent saline, acetone and ethanol, and cationic surfactant than that in the solutions of multivalent saline, methanol and anionic surfactant.     

Synthesis and characterisation of styrene butadiene styrene-g-<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide via UV polymerisation for potential use in biomedical applications

The work undertaken investigates the mechanical and thermal properties of a styrene butadiene styrene (SBS) grafted with N-isopropylacrylamide (NIPAAm) for potential use in the field of biomaterials. SBS-g-NIPAAm was synthesised using UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform spectrometry (ATR-FTIR), dynamic mechanical thermal analysis (DMTA) and tensile tests were used to characterise the grafted copolymers. The ATR-FTIR spectrum for NIPAAm illustrates bands corresponding to C=O stretching and NH bending for secondary amides at 1655 and 1544 cm⁻¹, respectively. These bands are represented as shoulders in SBS-g-NIPAAm copolymers. In relation to the thermal analysis, the butadiene domain present in the SBS and the grafted SBS copolymers were analysed using DSC. It was evident that all of the grafted samples have a broad thermal transition when compared to the PB domain present in SBS, suggesting that grafting had occurred within each of the SBS-g-NIPAAm copolymers. This was confirmed by the use of DMTA, where the results showed an increase in T _g values from −92 to −74 °C for SBS-g-NIPAAm copolymers.     

Novel self-assembled amphiphilic poly(ε-caprolactone)-grafted-poly(vinyl alcohol) nanoparticles: hydrophobic and hydrophilic drugs carrier nanoparticles

In the present study, we have aimed to produce nanoparticles (NPs) possessing the capability of carrying both of the hydrophobic and hydrophilic drugs and reveal significant release for both drug types. Poly(ε-caprolactone) (PCL) grafted poly(vinyl alcohol) (PVA) copolymer (PCL-g-PVA) has been prepared and shaped in nano-particulate form to be adequate for carrying the drugs. Stannous octoate (Sn(II)Oct₂) was used to catalyze PVA and ε-caprolactone monomer to chemically bond. Moreover, this catalyst enhanced side chain polymerization reaction for the utilized ε-caprolactone monomer to form poly(ε-caprolactone) (PCL). The formed PCL was attached as branches with PVA backbone. ¹H NMR has confirmed formation of PCL and grafting of PVA by this new polymer. Moreover, the vibration modes in the functional groups of PCL-g-PVA have been detected by FT-IR. The thermal alteration in the grafted polymer was checked by TGA analysis. The successfully synthesized grafted copolymer was able to self-aggregate into NPs by direct dialysis method. The size, morphology and charges associated with the obtained NPs were analyzed by DLS, TEM and ELS, respectively. PCL-g-PVA NPs were investigated as drug carrier models for hydrophobic and hydrophilic anti cancer drugs; paclitaxel and doxorubicin. In vitro drug release experiments were conducted; the loaded NPs reveal continuous and sustained release form for both drugs, up to 20 and 15 days for paclitaxel and doxorubicin, respectively. However, in a case of using pure drugs only, both drugs completely released within 1–2 h. The overall obtained results strongly recommend the use these novel NPs in future drug delivery systems.     

新型室温酯化法制备纳米SiO2引发剂和原位引发聚合

提出了一种在室温、潮湿和大气环境等温和条件下,通过酯化反应在纳米SiO2微球表面接枝偶氮分子,合成纳米SiO2引发剂的新方法.使用这种纳米SiO2引发剂原位引发单体苯乙烯和甲基丙烯酸甲酯进行自由基聚合,在SiO2表面接枝聚苯乙烯或聚甲基丙烯酸甲酯.结果表明:用合成的纳米SiO2引发剂原位引发单体聚合后,在纳米SiO2表...     

Radiation grafting of hydrophilic monomers onto plasticized poly(vinyl chloride) sheets

Medical grade poly(vinyl chloride) (PVC) sheets were surface modified by grafting a combination of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP) or NVP alone using gamma radiation in an effort to retard the migration of the plasticizer from the PVC matrix. Presence of cupric ions at a concentration of 0.005m was found to be optimal in not only preventing the homopolymerization of the monomers but also producing the highest graft yield at all monomer concentrations used for grafting. The grafted PVC was characterized for its water absorption properties. Surface morphology of the grafted surface was examined using scanning electron microscopy (SEM). PVC sheets grafted on both sides as well as on one side were characterized for their physical and mechanical properties in order to assess their suitability in biomedical applications. While the tensile strength and percentage elongation values of PVC sheets grafted on both sides showed a downward trend with increasing graft yield, these properties were not drastically affected by surface modification on one side only at graft yields pertinent to prevent the migration of the plasticizer. Measurement of Shore A hardness and optical transparency of the migration resistant sheetings showed that such properties were not seriously affected by surface modification thus rendering them suitable for their intended applications.