Surface Behavior of Polyamide 6 Modified by Barrier Plasma in Oxygen and Nitrogen

Polyamide (PA) 6 was modified by diffuse coplanar surface barrier discharge (DCSBD) plasma in an atmosphere of nitrogen and oxygen. The surface roughness decrease of PA 6 was detected by AFM and nano-indentation after modification in DCSBD plasma. A significant increase in O/C and N/C ratios of plasma-modified PA 6 using XPS analysis was found. The results show the importance of introducing oxygenic polar functional groups on the polymeric surface in order to increase its surface energy during a short time of plasma activation. The modification of PA 6 by DCSBD oxygen plasma was more efficient than by nitrogen plasma.     

Surface modification of UV‐cured epoxy resins by click chemistry

A novel method for surface modification of UV‐cured epoxy network was described. Photoinitiated cationic copolymerization of a bisepoxide, namely 3,4‐epoxy cyclohexylmethyl 3,4‐epoxycyclohexanecarboxylate (EEC) with epibromohydrine (EBH) by using a cationic photoinitiator, [4‐(2‐methylpropyl)phenyl]4‐methylphenyl‐iodonium hexafluorophosphate, in propylene carbonate solution was studied. The real‐time Fourier transform infrared spectroscopic, gel content determination and thermal characterization studies revealed that both EEC and EBH monomers take part in the polymerization and epoxy network possessing bromomethyl functional groups was obtained. The bromine functions of the cured product formed on the glass surface were converted to azide functionalities with sodium azide. Independently prepared alkyne functional poly(ethylene glycol) (PEG) was subsequently anchored to azide‐modified epoxy surface by a “click” reaction. Surface modification of the network through incorporation of hydrophilic PEG chain was evidenced by contact angle measurements. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2862–2868, 2010     

Improving properties of natural rubber/polyamide 12 blends through grafting of diacetone acrylamide functional group

The aim of the present study was to improve the compatibility in blends of natural rubber (NR) and polyamide 12 (PA12) by grafting NR with hydrophilic monomer, diacetone acrylamide (DAAM), via seeded emulsion polymerization. The increase in polarity of NR after grafting modification was confirmed by a considerable increase in the polar component of its surface energy. Blends of graft copolymers of NR and poly(diacetone acrylamide) prepared using 10 wt% of DAAM (NR‐g‐PDAAM10) and PA12 were prepared at a 60/40 blend ratio (wt%) using simple blend and dynamic vulcanization techniques. The mechanical and rheological properties of the resulting blends were subsequently investigated and compared with those of the corresponding blends based on unmodified NR. The results show that dynamic vulcanization led to a significant increase in both mechanical and rheological properties of the blends. It was also observed that the dynamically cured NR‐g‐PDAAM10/PA12 blend had smaller particle size of vulcanized rubber dispersed in the PA12 matrix than observed for the dynamically cured NR/PA12 blend. This is due to the compatibilizing effect of DAAM groups present in NR‐g‐PDAAM10 molecule, which decreases the interfacial tension between the two polymeric phases. Therefore, it can be stated that the interfacial adhesion between NR and PA12 was improved by the presence of DAAM groups in NR molecule. This was reflected in the higher tensile properties observed in the dynamically cured NR‐g‐PDAAM10/PA12 blend. Copyright © 2017 John Wiley & Sons, Ltd.     

Specific properties of in situ ruthenium‐catalyzed polyamide 12/polydimethylsiloxane compatibilized blend

The main objective of this work focused on the chemical modification of polyamide 12 (PA12) properties through the reaction with a hydride‐terminated polydimethylsiloxane (PDMS‐SiH). The investigated PA12/PDMS‐SiH blend was compatibilized by ruthenium derivative catalyzed hydrosilylation reaction in molten state. This original route enhanced interfacial adhesion and avoid PDMS‐SiH leaching phenomenon between the two immiscible phases. More specifically, the size of PDMS‐SiH domains in the blend decreased from around 4 μm to 800 nm and from 30 to 1 μm after compatibilization with 10 and 20 wt % PDMS‐SiH, respectively. For the best compatibilized PA12/PDMS‐SiH blend, the introduction of PDMS lowered the surface free energy and the PA12‐based blend turned from hydrophilic to hydrophobic behavior, as evidenced by the water contact angle measurements. Gas permeability and CO₂/H₂ and CO₂/He gas selectivity were also improved with the increase in PDMS content. Besides, the mechanical properties were enhanced with 13% increase in Young's modulus after in situ compatibilization with 15 wt % PDMS‐SiH. Thermal stability was also improved after compatibilization as the initial degradation temperature of reactive blends obviously increased compared with nonreactive ones. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 978–988     

Aging of polyamide 12 in oil at different temperatures and pressures

Polyamide 12 (PA 12) is an alternative to steel in the manufacture of pipes for transporting oil and gas. However, polyamide pipes suffer degradation, triggered by factors such as temperature and exposure to chemicals. In this research, the authors studied the variation of mechanical and thermal properties and of structural characteristics of a PA 12 grade after aging in oil. The aging process lasted 3360 h. It was made at ambient temperature and at 70 °C, under pressures of 1 and 17 atm. At ambient temperature and atmospheric pressure, PA 12 increased in volume, weight and rigidity, and decreased in damping. At 70 °C and atmospheric pressure, there was a smaller increase in volume and weight. PA 12 samples also darkened, showed an increase in crystallinity and damping, and a decrease in rigidity. At 70 °C and 17 atm, a decrease in volume and weight was observed; the samples also darkened, increased in crystallinity and rigidity, and decreased in damping. In all aging conditions, the results of the thermal analysis and the analysis of functional groups showed that the chemical structure of the material was not significantly changed. According to the results, PA 12 has a good resistance to aging under these conditions. Copyright © 2017 John Wiley & Sons, Ltd.     

Adsorption of polyamides on SAMs: effect of SAM grafting density on polyamide morphology

In this paper we focus on the understanding of the morphological behaviour of Polyamide 66 (PA66) in a constrained geometry generated by adsorption onto chemically controlled interfaces such as thiol self‐assembled monolayers (SAMs) grafted on gold substrates. The latter are prepared under different experimental conditions to illustrate the mechanism of PA–SAM interaction. The crystalline morphology of polyamide nanofilms, analysed by atomic force microscopy, was found to be dependent directly on the surface chemistry that is controlled by the thiol functionality (e.g. NH₂‐ and COOH‐ terminated thiols) and by the density and the structural organization of the grafts. These two parameters depend on the immersion times of the gold substrate in the thiol solutions. Furthermore, a direct correlation is evidenced between the polyamide morphology in thin films and its crystalline amount, as calculated by polarization–modulation infrared reflection–absorption spectroscopy. Quantitative results propose an interfacial interaction mechanism between the polyamide chains and the surface grafts, and give information about the SAM formation kinetics and its organization during the grafting process. Copyright © 2003 John Wiley & Sons, Ltd.     

Adhesion Aspects of Plasma Polymerized Acetonitrile and Acrylonitrile on Polypropylene Surface

Acetonitrile and acrylonitrile were plasma polymerized on Polypropylene (PP) surface. Surface modifications were characterized by surface energy measurements and ATR-FTIR spectroscopy. Surface energy measurement showed incorporation of hydrophilic groups along with deposition of cross-linked network of plasma-polymerized product. ATR-FTIR analysis of modified films showed incorporation of conjugated imine and amine groups. Using change in the relative intensities of C—H stretch bands of polypropylene surface, site of attachment of hydrophilic group and most predominant surface chemical reaction could be inferred. Chemical nature of plasma polymerized product was studied using FTIR by KBr disc method. Adhesion test was performed on modified surface by peel test method. Surface energy and peel strength measurements were performed for the samples aged for 2 months in order to check the durability of surface modification.     

Surface Modulation of Iron-doped MoS2 Nanosheets by Phytic Acid for Enhanced Water Oxidation

Surface modulation and heteroatom doping are important approaches for boosting the electrocatalytic performances of MoS₂ nanosheets. As a molecular electrocatalyst, the natural organic phytic acid (PA) offer attractive intermediate for oxygen evolution reaction (OER). Here, a surface modulation strategy is demonstrated through the decoration of PA onto the basal plane of iron (Fe)-doped MoS₂ nanosheets supported on nickel foam (NF) for boosted OER activity. Experimental results indicate that the PA modification and Fe doping could effectively boost the charge transfer and mass transport during the OER process. Specially, PA2-Fe−MoS₂ grown on NF (PA2-Fe−MoS₂/NF) exhibits excellent OER activity (218 mV@20 mA cm⁻²) and durability, even superior to RuO₂ and many other previously reported OER catalysts. This natural organic molecule modification provides a facile strategy to designing low-cost and efficient electrocatalytic materials.     

Effect of POSS on crystalline transitions and physical properties of polyamide 12

Polyamide 12/Trisilanolphenyl‐POSS (PA 12/POSS) composites were prepared via melt‐compounding. The effect of polyhedral oligomeric silsesquioxane (POSS) on crystalline structure and crystalline transition of PA 12 was investigated by wide‐angle X‐ray diffraction (WAXD) and real time fourier transform infrared spectroscopy (FTIR). WAXD results indicated that PA 12 crystallized into γ‐form as slowly cooling from melt and the presence of POSS did not influence the crystalline structure of PA 12. Both PA 12 and PA 12/POSS composites underwent Brill transitions when they were heated from room temperature to melt point. Real time FTIR patterns showed that an absorption band at 697 cm^?1 ascribed to Amide V (α) mode was emerged along with the disappearance of Amide VI (γ) band at 628 cm^?1 with the increase of the temperature for PA 12 and PA 12/POSS composites, which suggested that the γ‐form crystalline has transformed into α form. The Brill bands were identified and the transformed mechanism was discussed based on the real FTIR results. The addition of POSS enhanced the tensile strength and thermal stability of PA 12. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 121–129, 2009     

Solid‐state bonding of silicone elastomer to glass by vacuum oxygen plasma,atmospheric plasma,and vacuum ultraviolet light treatment

We experimentally demonstrated that treating a silicone elastomer by a vacuum oxygen plasma, an atmospheric pressure plasma, and vacuum ultraviolet (VUV) radiation resulted in different surface modifications that gave different contact angles, contact angle aging, and bond strengths. The aim of this study was to assess whether high‐throughput surface modification techniques of atmospheric pressure plasma and VUV radiation have the potential to replace conventional oxygen plasma modification. Four silicone elastomers with different hardnesses were used as specimens. The surfaces of all four silicone elastomers were successfully modified from hydrophobic to hydrophilic and they were also bonded to glass surfaces by the three surface modification techniques, although considerable variations were observed in the surface hydrophobicity and the bonding properties. The results clearly reveal that atmospheric pressure plasma and VUV treatment have the potential to replace conventional oxygen plasma treatment. In particular, VUV irradiation produced the most hydrophilic surface that was preserved for a long time. Thus, VUV irradiation is the most promising technique for realizing high‐throughput surface modification and bonding of silicone elastomers. Copyright © 2012 John Wiley & Sons, Ltd.     

无烟煤型焦的成焦机理研究

研究了不同煤阶无烟煤添加粘结剂冷压成型的型焦质量及其与粘结剂的成焦机理。利用Ｘ射线衍射光谱（ＸＲＤ），电子顺磁共振（ＥＳＲ）、孔结构，扫描电镜（ＳＥＭ）等手段，对不同煤阶无工焦配料在加热过程中的微观结构变化进行了分析。     

Effect of surface chemical modification for aluminum hypophosphite with hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene on the fire retardancy,water resistance,and thermal properties for polyamide 6

The surface chemical modified aluminum hypophosphite (AHP) defined as MAHP was successful prepared through P–H bonds on AHP surface reacted with the aldehyde groups in hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene made in our lab. The wettability of the flame retardants was evaluated by water contact angle tests, and the water contact angle of the prepared MAHP dramatically increased from 0° for AHP to 145°, which indicated the surface modification made the superhydrophilic AHP into superior hydrophobic MAHP. The prepared MAHP and AHP, respectively, incorporated into polyamide 6 (PA6) matrix to prepare flame retardant PA6 composites and the fire retardancy and thermal degradation behavior of flame retardant PA6 composites were investigated by limiting oxygen index, vertical burning test (UL‐94), cone calorimeter, and thermogravimetric analysis tests. The morphologies and chemical compositions of the char residues for PA6 composites were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. The water resistant properties of flame retardant PA6 composites were evaluated by putting the samples into distilled water at 70°C for 168 hr, and the mechanical properties for flame retardant PA6 composites were investigated by the tensile, flexural, and Izod impact strength tests. The results demonstrated that the PA6/MAHP composites successfully passed UL‐94 V‐0 flammability rating, and the limiting oxygen index value was 27.6% when the loading amount of MAHP was 21 wt%. However, there is no rating in vertical burning tests for PA6/AHP composite with the same amount of AHP, which indicated the surface modification of AHP enhanced the flame retardancy efficiency for PA6 composites. The morphological structures and analysis of X‐ray photoelectron spectroscopy of char residues revealed that the surface modification of AHP benefited to the formation of a sufficient, flame retardant elements rich, more compact and homogeneous char layer on the materials surface during combustion, which prevented the heat transmission and diffusion, limit the production of combustible gases, inhibit the emission of smoke and then led to the reduction of the heat release rate and smoke produce rate. The mechanical properties results revealed that the surface modification of AHP enhanced the mechanical properties, especially the Izod impact strength comparing with that of PA6/AHP composites with the same amount of flame retardant. After water resistance tests, the PA6/MAHP composites remained superior flame retardancy and presented continuous and compact char layer after cone calorimeter tests; however, the fire retardancy for PA6/AHP composite obviously decreased, and the char layer was discontinuous with big hole caused by the extraction of AHP by water during water resistance tests. Copyright © 2017 John Wiley & Sons, Ltd.     

The addition of clay on the mechanical properties of surface‐treated CF‐filled PA66 composites

Polyamide 66 (PA66) composites filled with clay and carbon fiber (CF) were prepared by twin‐screw extruder in order to study the influence of nanoparticle reinforcing effect on the mechanical behavior of the PA66 composites (CF/PA66). The mechanical property tests of the composites with and without clay were performed, and the fracture surface morphology was analyzed. The results show that the fracture surface area of the clay‐filled CF/PA66 composite was far smoother than that of the CF/PA66 composite, and there formed a tense interface on the CF surface after the addition of clay. The tensile and flexural strength of CF/PA66 composites with clay was improved. The impact strength decreased because of the high interfacial adhesion. In conclusion, the addition of clay favored the improvement of the higher interface strength and so had good effect on improving the tensile and flexural properties of the composites. Copyright © 2017 John Wiley & Sons, Ltd.     

Atmospheric‐pressure spin plasma jets processing of polymethylmethacrylate surface using experimental design methodology

Atmospheric‐pressure spin plasma jets (APSPJs) have been developed to induce surface modifications on polymethylmethacrylate (PMMA). In this study, an experimental design methodology was used to investigate the influence of process parameters [such as radio frequency (RF) power, processing gap, and number of treatment cycles] on the characteristics of PMMA surface treated by APSPJs. It was observed from the atomic force microscope (AFM) and scanning electron microscope (SEM) results that the surface morphology of PMMA treated by direct plasma is much rougher than that treated by remote plasma. The direct plasma used in APSPJs processing created a substantial amount of nanostructure grains. Moreover, the measured XPS results showed that the O/C ratios of the PMMA surface were substantially increased and subsequently water contact angle decreased on direct plasma treatment. This decrease is due to an increase of oxygen‐containing functional groups on the PMMA surface by the APSPJs processing. From the statistical analysis, the RF power and the processing gap were found to play a major role in enhancing the hydrophilic properties of PMMA surface. In contrast, the number of treatment cycles played only a secondary role in this case. Finally, in this study the APSPJs processing was demonstrated to be an effective method for surface modification of PMMA by controlling processing parameters during the treatment process. Copyright © 2009 John Wiley & Sons, Ltd.     

One‐pot synthesis of polyamide 12,T–polyamide‐6 block copolymers

Polyamide 12,T–polyamide‐6 (PA‐12,T–PA‐6) block copolymers were synthesized by anionic polymerization of caprolactam using a PA‐12,T macrocoinitiator (McI). PA‐12,T McI and its precursors are soluble in molten caprolactam allowing for both the McI step‐growth polymerization and anionic polymerization to be performed in one‐pot. It was found that the competing reaction rates of caprolactam ring‐opening polymerization and McI transamidation are both deterred by a common ion effect using CaCl₂ and soluble materials were obtained using >1 mol % CaCl₂. Without CaCl₂, the reaction mixture solidifies in less than 30 s and produces crosslinked materials. To understand this effect, PA‐12,T McI reactions with caprolactam were performed with 1–10 mol % CaCl₂, and polymer structures were characterized using ¹³C NMR and dilute solution viscometry. These data were then correlated with unique thermal properties and swelling behavior of the block copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.     

Improving the flame retardancy of polyamide 6 by incorporating hexachlorocyclotriphosphazene modified MWNT

A nitrogen‐, phosphorus‐ and chlorine‐containing flame retardant, hexachlorocyclotriphosphazene (HCTP), has been covalently grafted onto the surface of multi‐wall carbon nanotubes (MWNT) to obtain MWNT‐HCTP. Polyamide 6 (PA6)/MWNT composites were then prepared via melt compounding. The flammability of PA6/MWNT composite was characterized by cone calorimetry, limiting oxygen index (LOI) and UL‐94 tests. The results showed that peak heat release rate of samples containing 3 wt% MWNT‐HCTP was only 460 kW/m², which decreased by 35.2% compared with that of a neat PA6 sample. The LOI value was increased from 22.7% to 26.5%, and UL‐94 test performance was also significantly improved by the presence of MWNT‐HCTP. Scanning electron microscope (SEM) and optical microscope analysis showed that modified MWNT had a better dispersion and compatibility in PA6 than unmodified MWNT. The composition of residue chars and volatile products was investigated by SEM/energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric‐FTIR, respectively. It was proposed that grafted HCTP was mainly functioned in the condensed phase, where P, N can synergistically promote char formation and Cl element can catch free radicals to terminate the chain reaction during combustion of the PA6 composite. Copyright © 2014 John Wiley & Sons, Ltd.     

芘分子共价修饰的硅纳米线制备及其发光性能表征

将功能分子共价链接于硅纳米线表面,是发展硅纳米线性能,获得新的硅纳米线器件材料的重要手段.但是对硅纳米线表面的修饰却存在产生不可控制的表面氧化层的缺点,因此有必要发展一种温和的新方法.本文通过羟基(—OH)与硅纳米线表面Si—H键反应生成Si—O—C键,从而在硅纳米线表面引入功能分子.并通过芘醇分子在硅纳米线表面的固定化,证明了这一方法能够温和地实现对硅纳米线表面的共价键修饰.     

The effect of hBN on the flame retardancy and thermal stability of P-N flame retardant PA6

A novel thermally conductive Polyamide 6 (PA6) with good fire resistance was prepared by introducing a phosphorous-nitrogen flame retardant (FR) and platelet-shaped hexagonal boron nitride (hBN) into the matrix. With high thermal conductivity and good flame retardancy, the material is suitable for applications in electronic and electrical devices. The limiting oxygen index (LOI) changes for various loadings content of FR. However this formulation still does not show an ideal fire resistance, due to the appearance of melt dripping behavior during the UL 94 test. With the extra introduction of 3 vol% and 5 vol% hBN, the melt dripping behavior during the burning process completely disappeared. The hBN also increased the thermal conductivity. Furthermore PA6 compounded with FR and hBN showed a better thermal stability than neat PA6. The morphology of the char residues was investigated by scanning electron microscopy (SEM). The flaky hBN acted as the framework in the char structure and the rigid hBN could effectively break the bubble-shaped char on the surface of the residues which resulted in the enhancement of the strength and compactness of the char.     

Region‐Selective Deposition of Core–Shell Nanoparticles for 3 D Hierarchical Assemblies by the Huisgen 1,3‐Dipolar Cycloaddition

A method for the region‐selective deposition of nanoparticles (NPs) by the Huisgen 1,3‐dipolar cycloaddition is presented. The approach enables defined stacking of various oxide NPs in any order with control over layer thickness. Thereby the reaction is performed between a substrate, functionalized with a self‐assembled monolayer of an azide‐bearing phosphonic acid (PA) and aluminum oxide (AlO_x) NPs functionalized with an alkyne bearing PA. The layer of alkyne functionalized AlO_x NPs is then used as substrate for the deposition of azide‐functionalized indium tin oxide (ITO) NPs to provide a binary stack. This progression is then conducted with alkyne‐functionalized CeO₂ NPs, yielding a ternary stack of NPs with three different NP cores. The stacks are characterized by AFM and SEM, defining the region‐selectivity of the deposition technique. Finally, these assemblies have been tested in devices as a dielectric to form a capacitor resulting in a dramatic increase in the measured capacitance.