Synthesis and characterization of radiopaque iodine-containing methacrylate-based polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization

The reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-(2′-iodobenzoyl) ethyl methacrylate (2-IEMA) was performed in benzene solution using 4-cyanopentanoic acid dithiobenzoate (CPADB) as chain transfer agent to yield well-defined iodine-containing methacrylate-based polymers. It is characteristic of a controlled/living polymerization, i.e., linear increase in M _n with conversion and narrow molecular distribution. Moreover, the block copolymerization of 2-IEMA with 2-(2′,3′,4′,6′-tetra-O-acetyl-β-Dglucosyloxy) ethyl methacrylate (AcGEMA) and 2-lactobionamidoethyl methacylate (LAMA) was also carried out to give radiopaque glycopolymers by using the same methodology, respectively. The radiopacity of these polymers was evidenced by a routine medical X-ray imaging technique. TEM and DLS analytical results showed that the selected PIEMA-b-PLAMA diblock copolymers can self-assemble in aqueous solution into nearly spherical aggregates of 60–86 nm in diameter.     

Synthesis of thermoresponsive poly(N-isopropylacrylamide) brush on silicon wafer surface via atom transfer radical polymerization

Thermoresponsive poly(N-isopropylacrylamide) [poly(NIPAM)] brush on silicon wafer surface was prepared by combining the self-assembled monolayer of initiator and atom transfer radical polymerization (ATRP). The resulting polymer brush was characterized by in situ reflectance Fourier transform infrared spectroscopy, atomic force microscopy and ellipsometry techniques. Gel permeation chromatography determination of the number-average molecular weight and polydispersity index of the brush detached from the silicon wafer surface suggested that the surface-initiated ATRP method can provide relatively homogeneous polymer brush. Contact angle measurements exhibited a two-stage increase upon heating over the board temperature range 25-45 °C, which is in contrast to the fact that free poly(NIPAM) homopolymer in aqueous solution exhibits a phase transition at ca. 34 °C within a narrow temperature range. The first de-wetting transition takes place at 27 °C, which can be tentatively attributed to the n-cluster induced collapse of the inner region of poly(NIPAM) brush close to the silicon surface; the second de-wetting transition occurs at 38 °C, which can be attributed to the outer region of poly(NIPAM) brush, possessing much lower chain density compared to that of the inner part.     

Preparation and characterization of optical-functional diblock copolymer brushes on hollow sphere surface via atom transfer radical polymerization

The optical-functional poly(methyl methacrylate)-block-Tb complex diblock copolymer brushes grafted from hollow sphere surface via atom transfer radical polymerization were investigated in this work. A sufficient amount of azo initiator was introduced onto hollow sphere surface firstly. Then the monomer methyl methacrylate was polymerized via surface-initiated reverse atom transfer radical polymerization using azo group modified hollow sphere as initiator. Following, the poly(methyl methacrylate) modified hollow sphere was used as maroinitiator for surface-initiated atom transfer radical polymerization of Tb complex. The samples were characterized by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, gel permeation chromatographer and transmission electron microscopy, respectively. The results indicated that the poly(methyl methacrylate) had grafted from hollow sphere surface and the average diameter of hollow core was about 1 μm. The optical properties of the poly(methyl methacrylate)-block-Tb copolymer modified hollow sphere were also reported.     

3D characterization of microstructured poly(methacrylic acid) thin films via Mach-Zehnder interference microscopy

We demonstrate the adaption of a further developed Mach-Zehnder interference (MZI) microscope for the rapid 3D characterization of transparent microstructured polymer thin films. In order to quantify the accuracy of the Mach-Zehnder interferometer, comparative film thickness measurements of photolithographically patterned poly(methacrylic acid) polymer brushes are performed employing two alternative techniques: white light profilometry (WIM) and atomic force microscopy (AFM). When the refractive index of the polymer brushes is calculated from MZI data, we obtain a good agreement with results received from an independent method (ellipsometry).In contrast to surface probing techniques such as AFM or WIM, Mach-Zehnder interferometry is a transmitted light method that measures both surface height profiles and refractive index distributions. MZI thus enables the quantification of film homogeneity with respect to height and density variations at the lateral resolution of a refraction limited microscope. We conclude that MZI is an adequate tool for the rapid and non-destructive characterization of structured polymer thin films. This method should be particularly useful for production quality control of microstructured polymer thin films which possess great potential in electronic device fabrication and biotechnology.     

Growing polystyrene chains from the surface of graphene layers via RAFT polymerization and the influence on their thermal properties

The polystyrene (PS) macromolecular chains were grafted on the surface of graphene layers by reversible addition-fragmentation chain transfer (RAFT) polymerization. In this procedure, a RAFT agent, 4-Cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid, was used to functionalize the thermal reduced graphene oxide (TRGO) to obtain the precursor (TRGO-RAFT). It can be calculated that the grafting density of PS/graphene (PRG) composites was about 0.18 chains per 100 carbons. Successful in-plain attachment of RAFT agent to TRGO and PS chain to TRGO-RAFT was shown an influence on the thermal property of the PRG composites. The thermal conductivity (λ) improved from 0.150 W m⁻¹ K⁻¹ of neat PS to 0.250 W m⁻¹ K⁻¹ of PRG composites with 10 wt% graphene sheets loading. The thermal property of PRG composites increased due to the homogeneous dispersion and ordered arrangement of graphene sheets in PS matrix and the formation of PRG composites.     

Synthesis and characterization of poly(ether sulfone ether ketone ketone) grafted poly(sulfopropyl methacrylate) for proton exchange membranes via atom transfer radical polymerization

A series of copolymers of poly(ether sulfone ether ketone ketone) grafted poly(sulfopropyl methacrylate) (PESEKK-g-PSPMA) were successfully synthesized by atom transfer radical polymerization (ATRP) of sulfopropyl methacrylate (SPMA) after chloromethylation of poly(ether sulfone ether ketone ketone) (PESEKK) backbone. The structure of the chloromethyl PESEKK and the copolymers were carefully investigated. Variation of the polymerization time leads to the formation of copolymers with different degree of sulfonation (DS). The properties of the proton exchange membranes such as water uptake, ion exchange capacity, proton conductivity, and methanol permeability are studied with compared to those of Nafion 117 membranes and could be modulated simply by control of the ATRP time. The copolymers exhibited much lower methanol permeability and higher proton conductivity as compared with Nafion 117.     

细乳液聚合法制备正十二醇/聚合物相变纳米胶囊及其性能研究

细乳液法制备了正十二醇/聚合物相变纳米胶囊（PCNs）,研究了乳化剂、共聚单体的用量以及正十二醇的投料量对纳米胶囊结构与性能的影响。采用DSC、TG、TEM以及激光粒度分析仪等手段分别对聚合物纳米微球的粒径大小及粒径分布、性能和微观形态等进行表征分析。研究表明亲水共聚单体的加入有助于对相变材料的包封,当AM用量为2%时,苯乙烯与正十二醇的投料比为1∶1时,制备的纳米胶囊相变潜热及相变材料包封效率分别为109.3J/g和92.1%。     

Synthesis and characterization of TiO2/poly(methyl methacrylate) nanocomposites via surface thiol-lactam initiated radical polymerization

An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.     

MBE growth and characterization of buried silicon oxide films on Si(100)

Silicon molecular beam epitaxy (Si-MBE) has been used to produce silicon oxide (SiO_x) films by evaporating Si on a heated Si(100) substrate in an ultra high vacuum system with an O₂ pressure of 10⁻⁶ to 10⁻⁴ mbar. Then the SiO_x films were overgrown with pure Si. The influence of the substrate temperature, the O₂ pressure and the Si deposition rate on the oxygen content in the SiO_x films and on the crystalline quality of the Si top-layer was investigated by Rutherford backscattering spectrometry and ion channeling. Epitaxial growth of the Si top-layer was observed up to a maximum concentration of ≈20 at.% oxygen content in the SiO_x film. Cross-sectional transmission electron microscopy shows that the structure of the SiO_x film changes duringa subsequent annealing procedure. Electron energy loss spectrometry proves that amorphous SiO₂ is formed and the development of holes indicates that the density of the as-grown SiO_x film is much lower than that of SiO₂. The specific for the as-grown SiO_x films was determined by I–V measurements.     

Preparation and characterization of poly(N-isopropylacrylamide) films on a modified glass surface via surface initiated redox polymerization

A functionalization with 3-aminopropyltriethoxysilane (APTES) monolayer of a hydroxylated glass surface, followed by the surface initiated graft radical polymerization of N-isopropylacrylamide (NIPAm) using amino groups of APTES monolayer chemical bonded with glass surface and Ce⁴⁺ as a redox initiating system. The microstructure of poly(N-isopropylacrylamide) (PNIPAm) film obtained from the redox graft polymerization on the modified glass surfaces was examined by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), and the results showed that about 60 nm thickness of thermosensitive polymer (PNIPAm) film successfully formed.     

含PCL和PBST链段聚酯聚氨酯的合成与表征

为提高PBS基脂肪族聚酯的综合性能,通过ε-己内酯的开环聚合制备了端羟基的聚己内酯(PCL-OH),再通过熔融缩聚法制备了端羟基的聚(丁二酸丁二醇酯对苯二甲酸丁二醇酯)无规共聚物(PBST-OH),用氢化MDI(H12MDI)作为扩链剂,制得了可生物降解的聚酯聚氧酯(PPCLBST).采用核磁共振谱和红外光谱确定了PP...     

Preparation of poly(N-isopropylacrylamide) brush grafted silica particles via surface-initiated atom transfer radical polymerization used for aqueous chromatography

Thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) brushes were densely grafted onto silica surface via surface-initiated atom transfer radical polymerization (SI-ATRP). The grafting reaction started from the surfaces of 2-bromoisobutyrate-functionalized silica particles in 2-propanol aqueous solution at ambient temperature using CuCl/CuCl₂/N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA) as the catalytic system. Based on thermogravimetric analysis (TGA) results, the grafting amount and grafting density of PNIPAM chains on the surface of silica were calculated to be 1.29 mg/m² and 0.0215 chains/nm², respectively. The gel permeation chromatography (GPC) result showed the relatively narrow molecular weight distribution (M_w/M_n=1.21) of the grafted PNIPAAm. The modified silica particles were applied as high-performance liquid chromatography (HPLC) packing materials to successfully separate three aromatic compounds using water as mobile phase by changing column temperature. Temperature-dependent hydrophilic/hydrophobic property alteration of PNIPAAm brushes grafted on silica particles was determined with chromatographic interaction between stationary phase and analytes. Retention time was prolonged and resolution was improved with increasing temperature. Baseline separation with high resolution at relatively low temperatures was observed, demonstrating dense PNIPAAm brushes were grafted on silica surfaces.     

Synthesis and characterization of polycationic chitosan-graft-poly (l-lysine)

A type of polysaccharide/polypeptide hydride material, chitosan derivatives with polypeptide side chains, was prepared via ring-opening polymerization of N_ε-carbobenzyloxy-l-lysine NCA initiated by water-soluble chitosan and followed by removing the side-chain protective groups. The graft polymer was investigated through FTIR spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray diffraction to confirm the structure. Furthermore, the results of the atomic force microscopy (AFM) measurement indicated the chitosan-graft-poly (l-lysine) was a kind of extraordinary polycation.     

Synthesis and electrochemical polymerization of 9,9-bis(carbazolylalkyl)fluorene and characterization of its conducting polymer film with high tensile strength

Free-standing poly(9,9-bis(carbazolylalkyl)fluorene) (P2Cz-A-F, alkyl = hexyl or dodecyl) films with high tensile strength (185–200 kg cm⁻²) were electrochemically synthesized by direct anodic oxidation of the monomer 9,9-bis(carbazolylalkyl)fluorene (2Cz-A-F) in a mixed electrolyte of boron trifluoride diethyl etherate containing 30% CH₂Cl₂ (by volume). The electrochemical and physical properties show that the quality of P2Cz-A-F films are much better than that of polycarbazole (PCz) and polyfluorene (PF) films due to the specially designed structure consisting of stiff bicarbazyl chromophores linked by a flexible long alkyl spacer at the fluorene unit. The structure of free-standing P2Cz-A-F films was investigated by UV–visible and infrared spectroscopy. Thermal analysis shows that the polymer films have good thermal stability. Fluorescent spectral studies indicate that polymer films in the solid state are blue-light emitters, which may meet potential applications in polymer light-emitting diodes.     

Synthesis and characterization of poly(ionic liquid)-grafted silica hybrid materials through surface radical chain-transfer polymerization and aqueous anion-exchange

Poly(ionic liquid)-grafted silica materials were firstly synthesized by polymerization of 1-vinyl-3-butylimidazolium bromide as a new ionic liquid monomer on mercaptopropylated silica by surface radical chain-transfer polymerization. The bromide counterion was exchanged with three other inorganic anions including tetrafluoroborate, hexafluorophosphate, and trifuoromethanesulfonate through simple aqueous anion-exchange reaction. The obtained poly(ionic liquid)-grafted silica materials were characterized by elemental analysis, infrared spectra, thermogravimetric analysis, and X-ray fluorescence. The wettabilities of the materials with different counterions were verified by static water contact angle measurement. This kind of new materials may have some potential in applied fields such as used as a catalyst, an extractant, a chromatographic stationary phase, etc.     

Calcium oxyhydroxide (CaO/Ca(OH)2) nanoparticles: Synthesis,characterization and evaluation of their capacity to degrade glyphosate-based herbicides (GBH)

Nanometric calcium oxyhydroxides (CaO/Ca(OH)₂) were synthesized by two chemical routes, controlled precipitation and polymer complex (Pechini). The ceramic powders synthesized by the Pechini method were assessed for their ability to remove organic molecules of a glyphosate-based herbicide (GBH). The nanoparticles were characterized using ultraviolet–visible (UV–Vis) absorption, infrared (IR), and Raman spectroscopies, as well as with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Characterization revealed the synthesized particles to be nanometric in size (<100 nm), with an irregular morphology and a band gap of ~6.3 eV, evidencing a quantum confinement phenomenon. In testing for the removal of GBH with the CaO/Ca(OH)₂ synthesized by the Pechini method, a new product was formed by interaction with the organic molecules. The CaO/Ca(OH)₂-GBH interaction was so strong, at room temperature, that the solid completely dissolved, leaving no sediment. To determine the chemical nature of the resulting solution, aliquots were taken at the end of the test and analyzed by IR spectroscopy, revealing the existence in the system mainly of phosphate and phosphate-calcium groups, indicating that an important chemical reaction must have occurred between CaO/Ca(OH)₂ and HBG to modify the chemical structure of both compounds. The results obtained lead us to consider the synthesized CaO/Ca(OH)₂ nanoparticles as potential removers of agrochemical residues and other organic compounds that exist in water sources.     

Synthesis and properties of novel photosensitive poly(arylene ether sulfone) containing chalcone moiety in the main chain

A new series of photosensitive poly(arylene ether sulfone)s containing chalcone moiety in the main chain were synthesized from 4,4′-dihydroxychalcone (4DHC), 4,4′-difluorodiphenylsulfone (DFDPS) and bisphenol A (BPA). This series of polymers were characterized by ¹H NMR, FT-IR, UV spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymers were stable up to 400 °C, which indicates that the polymers possess good thermal properties. The polymers were found to be soluble in polar solvents and chlorinated solvents. However, the polymers were insoluble in hydrocarbons and in hydroxyl group-containing solvents. After the irradiation of UV light, the thin polymer film was crosslinked to give an insoluble film in the absence of a photoinitiator or sensitizers. The rate of photocrosslinking was also examined and discussed.     

Synthesis and characterization of poly(3-hexylthiophene)/poly(3-(trimethoxysilyl)propyl methacrylate) rod-coil block copolymers by using atom transfer radical polymerization

In this study, polythiophene based rod-coil block copolymers (P3HT)47-b-(PMSMA)34 are synthesized by atom transfer radical polymerization (ATRP). The effects of altering the mix of solvent and processing temperature on the morphologies and photophysical properties of the block copolymers in both solution and solid state are investigated. The chemical structure of the prepared block copolymers is confirmed by NMR and FTIR analysis. TEM results show that different morphologies of aggregates can be obtained by varying the toluene/methanol ratios. Such aggregation leads to a significant red shift on the optical absorption and photoluminescence spectra of the P3HT-b-PMSMA in mixed solvents. The results of AFM, UV-Vis, and PL show that the morphologies and photophysical properties of P3HT-b-PMSMA films are also significantly affected by the curing temperature. Blue shifts on the optical absorption and photoluminescence spectra are observed upon increasing the curing temperature.