Hydrophilic polystyrene/maleic anhydride ultrafine fibrous membranes

Polystyrene/maleic anhydride (PSMA) was synthesized to reach a viscosity‐average molecular weight of 700 kDa and fabricated into ultrafine fibrous membranes consisting of fibers with an average diameter of 300 nm. These ultrafine PSMA fibers were rendered insoluble in organic solvents by reactions with hydrazine and ethylenediamine (ED). The highly efficient incorporation of diamines into the fibrous membranes was easily achieved by brief immersions in either dilute (0.5 wt %) hydrazine for 1 min or ED ether solution for 2 min. Heating at 150°C for 5 min produced crosslinked PSMA with very little or no solubility in acetone with the retention of the fibrous membrane structure. The ED‐crosslinked membranes were particularly stable to both bases and acids as well as hydrophilic solvents, had a 46° water contact angle, and absorbed 22 times the amount of water as the as‐spun fibrous membrane. This post‐fiber‐formation crosslinking approach was robust, highly efficient, and fast and required very little crosslinking reagent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of PEGylated single wall carbon nanotubes by a photoinitiated graft from polymerization

A considerable amount of research has been devoted to carbon nanotubes because of their unique electrical, mechanical, optical, and chemical properties. Here, in this report, we introduce a novel, simple ultraviolet initiated “graft from” polymerization method to synthesize PEGylated carbon nanotubes. This grafting procedure significantly enhanced nanotube aqueous dispersibility and long term stability in solution. Mass of grafted polymer chains was easily modulated by adjusting polymerization reaction time, and nanomaterials containing up to 80% polymer by weight were synthesized. Nanotube morphology was characterized by SEM, TEM before and after the functionalization. In addition, the covalent bonding of polymer chains to the nanotubes structure was elucidated by Raman, ATR‐FTIR, and XPS spectroscopy. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

国外农用功能性聚烯烃覆盖材料的发展动态

分别就国外近年在耐老化棚膜、流滴棚膜、光选择性棚膜、各类地膜以及覆盖材料的回收方面所做的工作进行介绍。     

Inner surface modification of halloysite nanotubes and its influence on morphology and thermal properties of polystyrene/polyamide‐11 blends

The asymmetry of halloysite surface chemistry was used to perform a selective modification of its inner surface via grafting of a synthesized styrene/(methacryloyloxy)methyl phosphonic acid copolymer. Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and pyrolysis gas chromatography/mass spectrometry were used to evidence and quantify the grafting. Then, raw and hybrid nanoparticles were incorporated in polystyrene (PS)/polyamide‐11 (PA11) blends (80/20 and 60/40 wt%). Scanning electron micrographs showed differences in localization of the halloysite nanotubes (HNTs), since raw halloysite is concentrated in the PA11 phase while modified halloysite is also located at the PS/PA11 interface, leading to a better interfacial adhesion between PS and PA11. An inhibiting effect of modified halloysite on PA11 coalescence was evidenced by measuring the particle size distribution of the extracted nodules. Moreover, the presence of modified halloysite at the interface shows an improvement in terms of thermal stability as observed by TGA, but with no significant effects on PA11 crystallization behaviour as shown by differential scanning calorimetry results. Rheological measurements were carried out to study the influence of the surface modification of halloysite on the blend morphology. A gel‐like behaviour was observed for the (60/40 wt%) HNTs reinforced composition that was enhanced in the case of 10% functionalized halloysite. © 2016 Society of Chemical Industry     

Tuning Carbon Materials for Supercapacitors by Direct Pyrolysis of Seaweeds

The sea provides a large variety of seaweeds that, because of their chemical composition, are fantastic precursors of nanotextured carbons. The carbons are obtained by the simple pyrolysis of the seaweeds under a nitrogen atmosphere between 600 and 900 °C, followed by rinsing the product in slightly acidic water. Depending on the origin of the seaweed and on the pyrolysis conditions, the synthesis may be oriented to give an oxygen‐enriched carbon or to give a tuned micro/mesoporous carbon. The samples with a rich oxygenated surface functionality are excellent as supercapacitor electrodes in an aqueous medium whereas the perfectly tuned porous carbons are directly applicable for organic media. In both cases, the specific surface area of the attained carbons does not exceed 1300 m² g⁻¹, which results in high‐density materials. As a consequence, the volumetric capacitance is very high, making these materials more interesting than activated carbons from the point of view of developing small and compact electric power sources. Such versatile carbons, obtained by a simple, ecological, and cheap process, could be well used for environment remediation such as water and air treatment.     

Structure and mechanism of functional isotactic polypropylene via in situ chlorination graft copolymerization

This paper discusses the structure and mechanism of maleic anhydride (MAH) grafted onto isotactic polypropylene (iPP) via in situ chlorination graft copolymerization (ISCGC). The molecular structure of the grafted iPP was characterized using ¹H NMR and ¹³C NMR spectroscopy, viscosity‐average molecular weight and gel content. The structure of un‐grafted MAH present in the reaction system was investigated using Fourier transform infrared spectroscopy in order to explore the grafting of MAH on iPP. The main side‐reactions, including iPP chain scission and crosslinking, during the grafting reaction were explored. From the experimental results obtained, the reason for controlled macromolecular chain degradation and crosslinking of grafted iPP in ISCGC is proposed. Based on the structural characterization of the grafted polymer, the mechanism of grafting onto iPP obtained via ISCGC was deduced. Mechanical properties, both static and dynamic, of grafted iPP were also investigated and the results showed that the properties of the material changed due to grafted MAH. Copyright © 2011 Society of Chemical Industry     

Starch derivatives with high degree of functionalization. III. Influence of reaction conditions and starting materials on molecular structure of carboxymethyl starch

Carboxymethyl starch (CMS) was prepared in a completely heterogeneous procedure in a methanol/water slurry activated with aqueous sodium hydroxide (45%, w/v) using monochloroacetic acid as the etherifying agent. The influence of the reaction conditions and the type of starting starch (amylose content and preactivation) was evaluated in regard to the formation of the main repeating units (i.e., unfunctionalized and mono‐, di‐, tri‐, and tetra‐O‐carboxymethylated) and the pattern of functionalization within the anhydroglucose units (AGU). The reproducible synthesis gave products with a maximal degree of substitution of CM groups (DS_CM) of 0.66, which was reached in a one‐step synthesis. Repeated carboxymethylation led to products with a DS_CM of 0.88. As revealed by means of HPLC analysis after complete acidic depolymerization, in any sample the mono‐O‐carboxymethylated glucose (mono‐O‐CMglc) was preferably present while the di‐O‐CMglc was formed to a very low extent only. The tri‐O‐CMglc was found in some samples while tetra‐O‐CMglc was not detected. The mole fractions determined did not follow the simple Spurlin statistic as shown for CM cellulose synthesized under comparable conditions. Within the carboxymethylated AGUs a preferred functionalization at position 2 was analyzed by means of ¹H‐NMR spectroscopy after hydrolytic chain degradation. Consequently, the CMS samples synthesized contained mainly 2‐mono‐O‐CM‐AGU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2036–2044, 2001     

Preparation of Functionalized Polymersomes and the In Vivo Imaging

Recently, polymersomes self-assembled from amphiphilic block copolymers have attracted considerable interests with superior physicochemical properties. Here, the biotinylated block copolymers were blended with unmodified block copolymers to produce biotinylated polymersomes via film rehydration. Then, the avidin molecules were attached onto the biotin molecules covalently linked with block copolymers to form surface functionalized vesicles that are capable of carrying various biotinylated bioactive molecules, generating a relatively universal delivery platform. Hydrophobic fluorophores DAF and Nile Red were encapsulated respectively into hydrophobic membrane to prepare hydrophobic substances loaded polymersomes for investigating the nature of hydrophobic functionalization. Furthermore, the hydrophobic functionalized DiR-polymersomes were employed to perform in vivo imaging to survey the in vivo behavior for nano-polymersomes with hydrophobic functionalization.     

Hydroxyl‐decorated ammonium polyphosphate as flame retardant reinforcing agent in solvent‐free two‐component polyurethane

Despite being extensively implemented in research, it remains challenging but highly desirable to develop ammonium polyphosphate (APP)‐based polyurethane (PU) combining excellent flame retardancy and improved mechanical properties. Herein, hydroxyl‐decorated APP (OH‐APP) was successfully fabricated through a facile, green, yet efficient cation exchange reaction with N‐methylethanolamine, and utilized as a multifunctional reinforcing agent for solvent‐free two‐component PU in the curing process. Results demonstrate that the conjugation of OH‐APP imparts to the resultant cured PU samples (PU/OH‐APP) enhanced fire safety and smoke suppression performance, as evidenced by the considerable decrease in peak heat release rate, total heat release, peak smoke production rate and total smoke production by 75.4, 30.1, 64.3 and 14.4% over those of pure PU. Furthermore, the tensile strength of PU/OH‐APP is improved by 66.5%, while the ductility is well maintained, highlighting its promising potential in industrial applications. This work is aimed at opening a new avenue for the development of APP‐based PU with outstanding performances through covalent anchoring approaches. © 2017 Society of Chemical Industry     

Preparation and characterization of micron‐sized non‐porous magnetic polymer microspheres with immobilized metal affinity ligands by modified suspension polymerization

A novel preparation method of micron‐sized non‐porous magnetic polymer microspheres with immobilized metal affinity ligands was developed. A modified suspension polymerization of methacrylate (MA) and divinylbenzene (DVB) was performed in the presence of oleic acid‐coated magnetic Fe₃O₄ nanoparticles to obtain magnetic poly (methacrylate‐divinylbenzene) (mPMA‐DVB) microspheres. Through ammonolysis using ethylenediamine (EDA) and subsequent carboxymethylation with chloroacetic acid, magnetic polymer microspheres with chelate ligands of iminodiacetic acid (IDA) were obtained. Charging with copper ions resulted in magnetic polymer microspheres capable of binding proteins that display metal affinity. The morphology, magnetic properties, and composition of magnetic polymer microspheres were characterized with scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR), respectively. Bovine hemoglobin (BHb) was adopted as a model protein to investigate their affinity adsorption capacity. It was found that the adsorption capacity was as high as 168.2 mg/g microspheres and with rather low non‐specific adsorption. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2174–2180, 2005