Oxidative graft polymerization of aniline on Si(100) surface modified by plasma polymerization of glycidyl methacrylate

Modification of argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by reactive coupling of the epoxide groups of the plasma deposited GMA chains with aniline, and finally by oxidative graft polymerization of aniline was carried out. An alternative approach involved the modification of the argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by direct oxidative graft polymerization of aniline and thermal curing. The compositions and chemical states of the modified Si surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The two methods of surface modification of the Si(100) surfaces produced similar results. The protonation-deprotonation behavior, the interconvertible intrinsic redox states, and the metal reduction behavior (the electroless plating of Pd from the Pd(II) ion solution) of the grafted polyaniline (PANI) chains on the Si(100) surface were grossly similar to those of the PANI homopolymer. The coupling of PANI to the covalently tethered GMA chains on the Si(100) surface was suggested by the cohesive failure inside the epoxy adhesive that was applied to the modified Si surface in an attempt to peel off the PANI layer from the GMA plasma-polymerized Si (GMA-pp-Si) substrate.     

The study on the mechanical properties of PU/MF double shell selfhealing microcapsules

The self-healing microcapsules can be buried in the coating to improve the anticorrosive ability. In this paper,self-healing microcapsules of polyurea(PU)/melamine resin(MF) double shell were prepared by in-situ polymerization and interfacial polymerization with isocyanate as the core material. Scanning electron microscope was used to observe the microcapsule morphology. The structures of microcapsules prepared with different chain extenders were characterized by Fourier transform infrared spectroscopy. The micromanipulation system was used to loading–holding, loading–unloading and loading to rupture individual microcapsules, so as to explore the mechanical properties of microcapsules. The Young's modulus corresponding to microcapsules was calculated by mathematical model fitting. The self-healing properties of microcapsule coating were characterized by optical microscope. The experimental results showed that the microcapsule shell prepared under optimized conditions had a complete morphology and good mechanical properties. The microcapsule was in the elastic deformation stage under small deformation, and the plastic deformation stage under large deformation. The Young's modulus range of microcapsules was 9.29–14.51 MPa, and the corresponding Young's modulus could be prepared by adjusting the process. The surface crack of the coating containing microcapsule could heal itself after48 h in a humid environment.     

Self-healing linear polymers based on RAFT polymerization

Self-healing polystyrene (PS) composites were fabricated, in which glycidyl methacrylate (GMA)-loaded microcapsules were embedded. Because the matrix PS was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, it kept living characteristics and was able to resume the polymerization so long as monomers were available. Upon damage of the composites, the GMA released from the broken capsules infiltrated into the cracks and was copolymerized with the matrix PS according to the above mechanism. As a result, the cracked planes were covalently re-bonded, offering recovery of impact strength. Compared to the self-healing system based on atom transfer radical polymerization (ATRP), which is also an approach of living polymerization, the current one possesses robust vitality in air and eliminates the possibility of acceleration of matrix degradation aroused by metal ions. Additionally, the resultant self-healing PS composites have an advantage in coloration, which is important for satisfying esthetic requirement in practice.     

自修复聚脲甲醛微胶囊的制备及成囊机理研究

采用原位聚合法制备了自修复聚脲甲醛包覆环氧树脂微胶囊。考察了原料用量、反应温度、酸化值和固化时间等对微胶囊粒径分布和表面形态的影响,确定了微胶囊的最佳制备工艺。借助显微镜实时监测微胶囊化过程,探讨了微胶囊的成囊机理,并将微胶囊填充到脲醛树脂中。结果表明:采用最佳制备工艺制得的微胶囊包覆率较高、结构紧密、粒度均匀,室温下保存一周后没有出现团聚和破裂;将9%微胶囊添加到脲醛树脂中,微胶囊分散均匀,脲醛树脂复合材料的韧性得到提高。     

Preparation and evaluation of self-healing microcapsules for asphalt based on response surface optimization

The purpose of this study is to explore the best preparation process of asphalt self-healing microcapsules. Response surface design and single factor design were used to optimize the preparation process parameters of asphalt self-healing microcapsules, and the prediction model of core content was established. The optimal preparation process was determined. The results of response surface design showed that the interaction among emulsifier concentration/reaction temperature, core-shell ratio/reaction temperature, and pH/reaction temperature had significant effect on the core content of microcapsules; the microcapsules prepared by the optimal process were spherical with an average particle size of 90.19 μm. The results of thermogravimetric analysis (TGA) and heating simulation test showed that the microcapsule can delay the damage of the core in high temperature environment; the results of nanoindentation test showed that the young's modulus and hardness of the microcapsules were about 2.50 and 0.28 GPa, respectively. Finally, the improvement mechanism of self-healing performance of asphalt by microcapsules was revealed by fluorescence microscope.     

Adhesion enhancement of evaporated copper on HDPE surface modified by plasma polymerization of glycidyl methacrylate

Surface modification of high‐density polyethylene (HDPE) surfaces by plasma polymerization of glycidyl methacrylate (GMA) (the pp‐GMA‐HDPE surfaces), in the absence and presence of Ar plasma pre‐activation of the HDPE substrates, was carried out to enhance the adhesion of the polymer with evaporated copper. THe FTIR and X‐ray photoelectron spectroscopy (XPS) results suggested that the epoxide functional groups on the pp‐GMA‐HDPE surfaces had been preserved to various extents, depending on the RF power used during plasma polymerization. Ar plasma pre‐activation of the HDPE surface led to the strong interaction of the pp‐GMA layer with the HDPE substrate. GMA plasma polymerization at low RF powers and in the presence of Ar plasma pre‐activation was shown to be an effective method for enhancing the adhesion of HDPE with the evaporated Cu. An optimum adhesion strength of about 16 N/cm was achieved between the evaporated Cu and the pp‐GMA‐HDPE surface prepared by plasma polymerization of GMA at 5 W, 100 Pa, 20 sccm for 5 s on the HDPE surface pre‐activated by Ar plasma at 35 W, 100 Pa 20 sccm for 20 s. The adhesion enhancement of the Cu/pp‐GMA‐HDPE assemblies in the presence of Ar plasma pre‐activation of the HDPE substrate was attributed to the covalent bonding of the plasma‐polymerized GMA (pp‐GMA) layer with the HDPE surface, the preservation of the epoxide functional groups in the pp‐GMA layer, and the spatial interactions of pp‐GMA chains with the evaporated Cu matrix.     

脲醛树脂包覆双环戊二烯微胶囊的力学性能

包封活性物质的微胶囊与催化剂一起分散在树脂中能够制备出具有自修复功能的材料。自修复材料在外力作用下,内部出现裂缝时,具有自动修复并维持力学性能的功能。扩大自修复材料的应用,离不开对这种自修复用微胶囊力学性能优化的研究。在本研究中,使用三聚氰胺-甲醛树脂(MF)为壳材料,双环戊二烯(DCPD)为芯材料,采用原位乳液聚合法制备自修复用微胶囊。借助微操系统(micromanipulation),在探针移动速率为2μm.s-1,环境温度为(23±0.50)℃的条件下,对两种反应条件下得到的微胶囊用探针对单个微胶囊进行挤压-停留、挤压-释放和挤压至破裂等操作。结果表明,微胶囊在比较小的形变下(≤17.7%),体现的是弹性体的行为,在较大形变下(≥19.5%),体现的是黏弹性体的行为。     

Durable,hydrophilic surface modification of polypropylene films by plasma graft polymerization of glycidyl methacrylate

Summary The plasma graft polymerization of glycidyl methacrylate (GMA) was investigated to obtain hydrophilic surface. The combination of the argon plasma and GMA vapor exposures leaded to graft polymerization of GMA at the surface of polypropylene films. This graft polymerization was initiated by the argon plasma exposure for 2 min, and was accomplished with the GMA vapor exposure for 2 min. The GMA graft polymerization made polypropyrene surface hydrophilic. The surface energy was 55.8 mJ/m². The hydrophilicity introduced by the GMA graft polymerization remained for at least 3 weeks. The graft polymerization of hydrophilic monomers was a good means of hydrophilic surface modification.     

聚丙烯酸/氧化石墨烯自修复水凝胶的合成及性能

通过改进的Hummers方法成功制备了氧化石墨烯(GO)。以Fe3+为交联剂、丙烯酸(AA)为单体、GO为增强剂,采用原位聚合法制备了聚丙烯酸(PAA)/GO自修复水凝胶。考查了不同GO含量下,PAA/GO自修复水凝胶的溶胀性能,并探讨了GO含量、Fe3+含量和H2O含量对PAA/GO自修复水凝胶力学性能的影响,研究了PAA/GO自修复水凝胶的自修复性能。结果表明,Fe3+含量、GO含量和H2O单体含量分别为0.5 %（摩尔分数）、0.5 %（质量分数,下同）、80 %时,具有最佳力学性能（其拉伸强度为743.5 kPa,断裂伸长率为2940.5 %）;GO含量为0.25 %时,PAA/GO自修复水凝胶的吸水性能最大;PAA/GO自修复水凝胶具有优异的自修复性能。     

Preparation and Characterization of Microcapsules Containing Soybean Oil and Their Application in Self-Healing Anticorrosive Coatings

Synthetic self-healing materials are a new prototype in polymeric coatings. In the present investigation, soybean oil along with drier was encapsulated in urea–formaldehyde (UF) microcapsules, which were successfully prepared by in situ polymerization and their self-healing ability, the corrosion resistance, gloss, and adhesion strength of microcapsules were studied. The synthesized microcapsules were characterized by Fourier transform infrared spectrometer for identification of separated core and shell materials and their surface morphology was studied by scanning electron microscope. The particle size was checked under optical microscope and confirmed with particle size analyzer. Effectiveness of soybean oil-filled microcapsules was investigated for healing of cracks generated in anticorrosive coatings. Cracks in paint coatings were found to be healed when soybean oil was released from microcapsules under simulated mechanical action and the corrosion resistance of healed area was evaluated by immersion study.     

Controlled atom transfer radical polymerization of MMA onto the surface of high-density functionalized graphene oxide

We report on the grafting of poly(methyl methacrylate) (PMMA) onto the surface of high-density functionalized graphene oxides (GO) through controlled radical polymerization (CRP). To increase the density of surface grafting, GO was first diazotized (DGO), followed by esterification with 2-bromoisobutyryl bromide, which resulted in an atom transfer radical polymerization (ATRP) initiator-functionalized DGO-Br. The functionalized DGO-Br was characterized by X-ray photoelectron spectroscopy (XPS), Raman, and XRD patterns. PMMA chains were then grafted onto the DGO-Br surface through a ‘grafting from’ technique using ATRP. Gel permeation chromatography (GPC) results revealed that polymerization of methyl methacrylate (MMA) follows CRP. Thermal studies show that the resulting graphene-PMMA nanocomposites have higher thermal stability and glass transition temperatures (T_g) than those of pristine PMMA.     

Preparation of Tung Oil-Loaded PU/PANI Microcapsules and Synergetic Anti-Corrosion Properties of Self-Healing Epoxy Coatings

Tung oil is used as a catalyst-free repair agent. Tung oil-loaded polyurethane (PU) microcapsules are prepared by interfacial polymerization in a SiO₂-stabilized Pickering emulsion system, polyaniline (PANI) is deposited in situ on the PU microcapsule surface, and tung oil-loaded PU/PANI double-layer shell microcapsules are obtained. Synthesized PU/PANI microcapsules showed the characteristic dark-green color of conductive PANI. The average particle size is 31.1 ± 8.1 µm and the core content is 45.1 ± 4.3 wt%. The microcapsules have a good thermal stability, and the chemical structure of the PU/PANI wall and tung oil core is confirmed by Fourier transform infrared analysis. Self-healing anti-corrosion coatings are prepared by adding 10 wt% microcapsules into epoxy resin. The corrosion resistance properties of the self-healing coating are evaluated by immersing scratched coatings in 10 wt% NaCl solution for 15 days. The self-healing coating with 10 wt% tung oil-loaded PU/PANI microcapsules have the best anti-corrosion property, and slight corrosion do not occur until 15 days after immersion in salt solution. The self-healing and anti-corrosion mechanism are revealed. The tung oil core and the PANI wall of microcapsules contributed synergistically to the excellent self-healing and anti-corrosion properties of the coating through the formation of self-healing films and passivation layers.     

硅烷改性环氧树脂自修复微胶囊的制备及应用

采用硅烷偶联剂γ-（2,3-环氧丙氧基）丙基三甲氧基硅烷（KH-560）对环氧树脂E-51进行改性,并以此为芯材,三聚氰胺-脲醛树脂（MUF）为壁材,原位聚合法合成微胶囊,探讨了微胶囊制备工艺,并用光学显微镜（OM）、扫描电子显微镜（SEM）、红外光谱仪（FTIR）、热重分析仪（TGA）等对其表面形貌、化学结构及热性能等进行了表征和测试;之后将改性后的微胶囊应用到自修复环氧树脂涂层中,考察了自修复涂层的力学性能和电化学性能。结果表明,当芯壁比为1.5：1、乳化剂质量分数为1.4%时,微胶囊为规则球形,表面粗糙、致密,大小均匀,平均粒径约为100μm,具有良好的热稳定性。当涂层中改性微胶囊质量分数为3%时,涂层的拉伸强度、弯曲强度、黏结强度及冲击强度均较高,且其较未改性微胶囊自修复涂层分别提高了14.9%、14.3%、16.0%和9.6%;与未改性微胶囊自修复涂层相比,改性微胶囊自修复涂层的电化学性能增强,且电化学阻抗值显著提高。     

Molecular Self-Assembled Microcapsules Prepared by In Situ Polymerization Technology for Self-Healing Cement Materials

Monodisperse core–shell microcapsules have been widely used as self-healing cement materials and paid more attentions. A new series of self-assembled microcapsules containing poly(styrene-divinylbenzene) as shell material were prepared by in situ polymerization technology. The microencapsulating process of core material using mixture of epoxy resins and benzyl alcohol was monitored using optical microscopy (OM). Morphology and shell wall thickness of microcapsule were observed using scanning electron microscopy and OM, respectively. The effects of different weight ratios of core–shell and the agitation rates on the physical properties of microcapsules were investigated. The size and surface morphology of microcapsule can be controlled by selecting different processing parameters.     

沥青裂缝自修复微胶囊的制备与表征

为了提高沥青路面自修复性能,采用原位聚合法制备包裹沥青再生剂的脲醛树脂微胶囊,利用四因素三水平正交试验,研究了最佳芯壁比、终点pH、温度与乳化剂浓度对包裹沥青再生剂的脲醛树脂微胶囊形貌、粒径与包覆率的影响;对完整试样和断裂愈合后的试样分别进行延度试验,探究普通基质沥青和添加自修复微胶囊沥青的自修复能力。极差数值分析结果表明：pH和温度对微胶囊制备影响程度更大,制备微胶囊的最佳工艺是甲醛与脲的摩尔比为4：5,芯壁比为6：5,终点pH为4,反应最终温度为70℃,十二烷基苯磺酸钠的质量分数为0.5%,此条件下制备的微胶囊表面形貌致密,平均粒径为21.14μm,包覆率达到85%。在愈合试验中,微胶囊最优质量掺量为0.3%,此时愈合率为38.67%。     

Self-lubricating epoxy composite coating with linseed oil microcapsule self-healing functionality

Cured epoxy resins have poor abrasion resistance, which shortens the service life of the material. This work aims to improve the tribological properties of epoxy resins by coupling self-lubrication and auto-healing. In this study, linseed oil microcapsules with an average particle size of 38.57 μm and good thermal stability were successfully prepared by in situ polymerization. The effects of microcapsule content on the tribological, mechanical, and self-healing properties of the composite coatings were studied. It was demonstrated that the composite coating has outstanding self-lubricating properties. The coefficient of friction reduced from 0.634 (pure epoxy resin) to 0.0459 (epoxy resin with 10 wt.% linseed oil microcapsules). Wear rate reduced from 7.16 × 10⁻⁴ mm³/(N m) to 1.74 × 10⁻⁵ mm³/(N m). The self-lubricating mechanism of the coating was investigated by SEM and EDS, which indicated that the formation of uniform and continuous lubricating film on the surface of the friction pairs was the key to improving the wear resistance of the material. In addition, the linseed oil released after the microcapsules rupture can repair the abrasion marks by reacting with oxygen during the friction process. The dual-functional effect of linseed oil microcapsules prolongs the life of epoxy resin coating and expands its application range.     

Designing of polyamidoamine-based polyurea microcapsules containing tung oil for anticorrosive coating applications

A novel method for the fabrication of robust polyurea microcapsules containing tung oil as a core material was developed for self-healing anticorrosive coating application. Well-distinct microcapsules with polyurea as a shell were prepared by reacting hexamethylene diisocyanate trimer with 0.0 G polyamidoamine (PAMAM) via interfacial polymerization technique. Fourier transform infrared spectroscopic analysis was performed to elucidate the chemical structure of microcapsules as well as to confirm successful encapsulation of core by the polyurea shell. Surface morphology, particle size, distribution of particle size, thermal, and mechanical properties of the prepared PAMAM-based polyurea microcapsules were compared with microcapsules that were prepared using diethylenetriamine (DETA) and triethylenetetramine (TETA). The prepared microcapsules were embedded with acrylic polyol-based polyurethane (PU) coatings to ensure anticorrosive performance. The immersion study of self-healing PU coatings loaded with 5% PAMAM-based polyurea microcapsules possesses satisfactory anticorrosive property under an accelerated corrosion process in 5% NaCl salt solution.     

Chemical Functionalization of Graphene Oxide by Poly(styrene sulfonate) Using Atom Transfer Radical and Free Radical Polymerization: A Comparative Study

Poly(sodium styrenesulfonate)-functionalized graphene was prepared from graphene oxide, using atom transfer radical polymerization and free radical polymerization. In atom transfer radical polymerization route, the amine-functionalized GO was synthesized through hydroxyl group reaction of GO with 3-amino propyltriethoxysilane. Atom transfer radical polymerization initiator was grafted onto modified GO (GO-NH₂) by reaction of 2-bromo-2-methylpropionyl bromide with amine groups, then styrene sulfonate monomers were polymerized on the surface of GO sheets by in situ atom transfer radical polymerization. In free radical polymerization route, the poly(sodium 4-styrenesulfonate) chains were grafted on GO sheets in presence of Azobis-Isobutyronitrile as an initiator and styrene sulfonate monomer in water medium. The resulting modified GO was characterized using range of techniques. Thermal gravimetric analysis, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy results indicated the successful graft of polymer chains on GO sheets. Thermogravimetric analysis showed that the amount of grafted polymer was 22.5 and 31?wt% in the free radical polymerization and atom transfer radical polymerization methods, respectively. The thickness of polymer grafted on GO sheets was 2.1?nm (free radical polymerization method) and 6?nm (atom transfer radical polymerization method) that was measured by atomic force microscopy analysis. X-ray diffractometer and transmission electron microscopy indicated that after grafting of poly(sodium 4-styrenesulfonate), the modified GO sheets still retained isolated and exfoliated, and also the dispersibility was enhanced.     

Surface modification of poly(tetrafluoroethylene) films by plasma polymerization and UV-induced graft copolymerization for adhesion enhancement with electrolessly-deposited copper

Surface modification of H₂ plasma-pretreated poly(tetrafluoroethylene) (PTFE) films, either by plasma polymerization and deposition of GMA, or by UV-induced graft copolymerization with glycidyl methacrylate (GMA), was carried out for adhesion enhancement with the electrolesslydeposited copper. XPS and FTIR results revealed that the epoxide groups in the plasma-polymerized GMA (pp-GMA) layer had been preserved to various extents, depending on the glow discharge conditions. The T-peel adhesion test results showed that the adhesion strengths of the electrolesslydeposited copper on both the pp-GMA modified PTFE (pp-GMA-PTFE) film and the GMA graftcopolymerized PTFE (GMA-g-PTFE) film were much higher than that of the electrolessly-deposited copper on the pristine or the H₂ plasma-treated PTFE film. The high adhesion strength between the electrolessly-deposited copper and the surface-modified PTFE film was attributed to the fact that the plasma-polymerized and the UV graft-copolymerized GMA chains were covalently tethered on the H₂ plasma-pretreated PTFE surface, as well as the fact that these GMA chains were spatially and interactively distributed into the copper matrix.     

醇酸树脂微胶囊的制备及环氧涂层自修复性能

采用三聚氰胺-脲醛树脂（MUF）为壁材、合成的花椒籽油醇酸树脂为芯材,原位聚合法制备自修复微胶囊,探讨了微胶囊的制备工艺。并采用扫描电子显微镜（SEM）、红外光谱仪（FTIR）、热重分析仪（TGA）和粒径分析仪对微胶囊的表面形貌、化学结构、热稳定性及其粒径分布进行了测试表征。将醇酸树脂微胶囊分散到环氧基体中,研究了环氧涂层的力学性能和自修复性能。实验结果表明,当乳化剂浓度为2.0g/L、芯壁比为2∶1、终点pH为3.5时,微胶囊呈球形结构,无明显的缺陷和损伤,平均粒径为97.44μm,热稳定性良好。当添加质量分数5%的微胶囊时,与未添加微胶囊的自修复涂层相比,其弯曲强度、拉伸强度、黏结强度及其冲击强度分别提高了50.4%、50.0%、40.0%及25.2%,且涂层的自修复性能良好。