无溶剂型纳米SiO2/环氧树脂复合涂料的制备及性能

为了提高环氧树脂涂料的综合性能,以KH-560硅烷偶联剂对纳米SiO2进行原位改性,制备了无溶剂型纳米SiO2/环氧树脂复合涂料。用FT-IR及分散性试验研究了纳米SiO2原位改性的效果;探讨了改性纳米SiO2对复合涂层表面形貌、力学性能、耐紫外光老化性、耐蚀性能的影响。结果表明:KH-560硅烷偶联剂的有机分子链段成功地键合在纳米SiO2粒子表面,改性后的纳米SiO2粒子能均匀地分散在二甲苯中;纳米SiO2能够显著改善环氧树脂涂层的力学性能,当其含量为3%时最好;复合涂层耐紫外光老化及耐腐蚀性比环氧树脂涂层有较大的提高。本无溶剂型纳米SiO2/环氧树脂复合涂层对基材有良好的保护作用。     

聚苯乙烯/纳米SiO2复合颗粒制备与表征

为改善二氧化硅(SiO2)纳米粒子与聚合物基体间的亲和性,使SiO2表面功能化,将硅烷偶联剂KH-570引入C=C基团,采用乳液聚合方法在纳米SiO2粒子表面接枝苯乙烯(St)单体,实现了纳米二氧化硅表面的聚苯乙烯(PS)高分子包覆改性,制备了具有核/壳结构的SiO2-PS复合纳米粒子,产物的单体转化率和接枝效率在80%以上.研究了二氧化硅含量和偶联剂用量对聚合反应的单体转化率和接枝效率的影响,探讨了偶联剂的作用机理,利用FT-IR、TEM、TG对SiO2-PS复合粒子的表面结构进行了表征.结果表明,复合粒子具有明显的核壳结构,壳层厚度在20nm左右,乳液聚合过程可有效使二氧化硅的团聚体剥离呈纳米级颗粒.     

乙烯基三乙氧基硅烷表面改性纳米SiO2

采用硅烷偶联剂A-151处理的纳米二氧化硅(SiO2)粒子,具有良好的疏水性,并且反应副产物没有腐蚀性,有利于保护设备和环境.对改性前后纳米SiO2的表面进行研究,证明该工艺能够实现纳米SiO2的表面改性,能够有效分散纳米SiO2聚集体.红外光谱分析表明,A-151确实已经和纳米SiO2表明的羟基发生了化学反应.     

纳米粒子表面修饰与改性--SiO2纳米粒子表面接枝聚合

通过硅烷偶联剂处理SiO2纳米粒子并向其表面引入双键使其功能化，采用溶液聚合方法在SiO2纳米粒子表面进行接枝聚合实现高分子对SiO2纳米粒子的表面包覆处理，制得SiO2／PMMA复合纳米粒子，采用IR、XPS对SiO2纳米粒子表面结构进行了表征研究。     

纳米SiO2改性可生物降解材料研究进展

纳米SiO2无毒,无味,无污染,具有优异的纳米特性,与高分子聚合物具有良好的相容性,被广泛应用于改善可生物降解材料性能等领域。综述了纳米SiO2的分散稳定性能,以及纳米SiO2改性聚乳酸、聚乙烯醇等合成型生物降解材料与淀粉、纤维素、壳聚糖、蛋白质、木质素等天然高分子材料的研究进展,并从降低价格及增强性能方面,对其改性可生物降解材料替代某些通用塑料的应用前景进行了展望。     

季铵盐改性SiO_2纳米颗粒的制备及其抗菌性能

选用季铵盐作为抗菌剂,对纳米SiO2颗粒进行表面改性。对合成的季铵盐进行了FT-IR表征。通过FTIR、接触角、Zeta电位等手段研究了烷基链长度及纳米颗粒尺寸对改性纳米SiO2性能的影响,考察了改性纳米SiO2颗粒的抗菌性能。结果表明季铵盐接枝纳米SiO2颗粒表面带正电,随着烷基链的增长,疏水性渐强。抗菌测试表明,改性后的纳米SiO2对金黄色葡萄球菌有很好的抗菌性,24h可以全部杀死浓度为1.72×106 CFU/mL的金黄色葡萄球菌。     

纳米SiO_2/纤维素包装薄膜结构形态及性能研究

采用具有活性基团的硅烷偶联剂KH550(γ-氨丙基三乙氧基硅烷)对纳米SiO2粒子的表面进行改性。以NMMO为溶剂,以纤维素为原料,并向铸膜液中添加改性纳米SiO2,制备改性纳米SiO2/纤维素膜。采用原子力显微镜(AFM)观察了改性纳米SiO2/纤维素薄膜的表面形态,结合电子显微镜(SEM)观察其断面结构,并测定了薄膜的力学性能和透氧透湿性能。实验结果表明:改性后的SiO2较好的在铸膜液中分散,当SiO2粒径为30nm,添加量为2%,偶联剂用量为5%时,纳米复合纤维素膜的各项性能达到最佳。     

超声波无皂乳液制备BA/AM/纳米SiO2复合材料

将超声波辐照技术引入到聚合物纳米材料的制备过程,通过超声产生的分散、活化及引发等作用实现纳米粒子分散的同时进行无皂乳液聚合,制备了丙烯酸丁酯(BA)／丙烯酰胺(AM)／纳米SiO2复合材料。实验结果表明．采用经丙烯酸丁酯表面改性后的纳米SiO2粒子．生成的乳液分散稳定性好。FT-IR及TEM证实了聚合物对纳米粒子的包裹。研究了超声波强度、超声辐照时间、单体配比等因素对单体转化率和聚合速率的影响。结果表明,提高超声波强度,延长超声辐照时间以及提高丙烯酰胺在单体配比中的含量．均能提高单体转化率和聚合反应速度。     

光固化聚氨酯丙烯酸酯/SiO_2杂化涂层的制备及性能

以六亚甲基二异氰酸酯(HDI)或甲苯-2,4-二异氰酸酯(TDI)分别与不同相对分子质量的聚乙二醇(PEG)反应制备聚氨酯预聚体,再以预聚体对纳米SiO2进行表面接枝改性,将改性纳米SiO2分散到聚氨酯丙烯酸酯(PUA)中,光固化制备了PUA/SiO2纳米杂化涂层。场发射扫描电子显微镜和差示扫描量热法研究表明,与未改性的纳米SiO2相比,以聚氨酯分子链改性的纳米SiO2可显著提高与PUA树脂相容性及杂化涂层的热稳定性能。以摆杆阻尼试验仪及漆膜冲击器研究了杂化涂层的力学性能,研究表明通过调整预聚体的分子链结构可在提高杂化涂层硬度的同时,不损失涂层的冲击性能。     

一种抗紫外自清洁纳米涂料的制备及应用

采用硅烷偶联剂对纳米粒子(粒径30nm的TiO2、SiO2、ZnO)进行表面改性,并将改性后的纳米粒子用于氟碳涂料中,得到抗紫外自清洁纳米改性涂料。利用透射电镜TEM及沉降实验对纳米粒子的改性效果进行了表征,得到结果:改性后纳米粒子能均匀地分散到甲苯等有机溶剂中。通过紫外分光光度计和接触角测量仪分别对改性后的涂膜对紫外光的吸收及表面疏水的自清洁性能进行了表征,结果表明,改性后的涂膜能有效地吸收大气中的紫外光,并且测得纳米改性的涂膜比未改性的涂膜接触角明显增大,有较好的表面疏水自清洁功效。     

纳米粒子链/聚合物基复合体的界面形态及力学行为

介绍了纳米粒子链弹性力学属性，粒子链与高分子链缠结和吸附，以及界面形态和力学行为。同时研究原生粒子结合处的“脖颈”对增强高分子聚合物的作用。     

弹性体修饰纳米SiO2粒子改性PBT

选用乙烯-丙烯酸酯-甲基丙烯酸缩水甘油酯(E-MA-GMA)三元共聚物对纳米SiO₂表面进行修饰包覆改性,考察改性后纳米SiO₂在聚对苯二甲酸丁二醇酯(PBT)基体中的分散情况及对PBT复合材料力学性能的影响。FTIR、TEM、SEM结果表明,E-MA-GMA的环氧基团与纳米SiO₂的—OH 基团发生反应,破坏了SiO₂的链状团聚结构,降低了纳米粒子间氢键等作用力。质量分数为10%～20% E-MA-GMA 改性的纳米SiO₂在PBT基体中的分散性及其与基体的相容性均得到明显改善,从而提高了PBT基复合材料的弯曲和拉伸性能。与纯PBT相比,SiO₂/PBT复合材料的拉伸强度提高了9%,而弯曲强度和模量分别提高了14%和20%。     

纳米SiO2/纤维素复合材料的非均相制备及其性能

采用硅酸四乙酯(TEOS)作为无机前聚物,纤维素为有机组分,利用溶胶-凝胶法在非均相乙醇溶液中制备了纳米SiO₂/纤维素复合材料。通过傅里叶红外光谱(FTIR)、透射电镜(TEM)和热重分析(TGA)对复合材料的形貌、结构以及热稳定性进行表征。讨论了SiO₂含量对材料力学性能的影响。研究了主要因素碱催化剂氨水对纤维素与SiO₂复合效果的影响。结果表明,纳米复合材料的弹性模量、拉伸强度随SiO₂含量的增加先增加后减少,质量分数分别为3.1％、10.6％时弹性模量、拉伸强度达到最大。氨水加入量为3.70×10-4 mol/L时,纤维素与SiO₂的复合效果最佳。非均相制备的纳米SiO₂/纤维素复合材料同样也明显提高了纤维素材料的疏水性、热稳定性和力学性能。     

纳米SiO2对静电纺LA-PA/PET复合相变纤维形态和热学性能的影响

以月桂酸和棕榈酸二元低共熔混合物(LA-PA)、聚对苯二甲酸乙二酯(PET)和纳米二氧化硅(SiO2)为原料,通过静电纺丝的方法成功制备了新型的LA-PA/PET/SiO2定形相变复合纤维。分别采用扫描电子显微镜(SEM)和差示扫描量热仪(DSC)研究了纳米SiO2对静电纺LA-PA/PET/SiO2复合相变纤维的形貌结构和热学性能的影响。SEM观察结果显示,随着纳米SiO2的加入,复合相变纤维表面呈现出光滑的形态特点,纤维直径有所降低;且随着纳米SiO2含量的增加而逐渐减小。DSC分析结果表明纳米SiO2的含量对复合相变纤维的熔化焓值和结晶焓值有一定的影响,对相变温度没有显著性的影响。     

Effect of grafted polymer species on particle monolayer structure at the air-water interface

We have studied poly(methyl methacrylate)-grafted(PMMA) particle monolayer systems at the air-water interface. In previous papers, we reported that PMMA chains grafted from particles (silica particle and polystyrene latex) were extended on water surfaces. Through observing deposited particle monolayers on substrates using SEM, we have confirmed that PMMA of large molecular weights were either dispersed or arrayed in structure with long inter-particle distances approximately 500 nm. In contrast, low molecular weight PMMA were observed to aggregate upon deposition. We speculated that the difference in morphology in deposited particle monolayers would be attributed to the affinity between the grafted polymer and the substrate. To examine the effect of this affinity three new polymer-grafted silica particles were synthesized with a fairly high graft density of about 0.14 approximately 0.43 nm(-2). As well as PMMA-grafted silica particles (SiO2-PMMA), poly(2-hydroxyethyl methacrylate) and poly(t-butyl methacrylate)--grafted silica particles (SiO2-PHEMA and SiO2-PtBuMA) were also prepared and subjected to pi-A isotherm measurements and SEM observations. These pi-A isotherms indicated that polymer-grafted silica formed monolayer at the air-water interface, and the onset area of increasing surface pressure suggests that the polymer chains are extended on a water surface. However, the morphology of the deposited monolayer is highly dependent on polymer species: SiO2-PHEMA showed that the dispersed particle monolayer structure was independent of grafted molecular weight while SiO2-tBuMA showed an aggregated structure that was also independent of grafted moleculer weight. SiO2-PMMA showed intermediate tendencies: dispersed structure was observed with high grafted molecular weight and aggregated structure was observed with low grafted molecule weight. The morphology on glass substrate would be explaiened by hydrophilic interaction between grafted polymer and hydrophilic glass substrate.     

纳米SiO2表面改性研究

以乙醇为分散介质,用硅烷偶联剂γ-(2,3-环氧丙基)氧化丙基三甲氧基硅烷(KH-560)对纳米SiO2进行表面改性.讨论了偶联剂用量对SiO2改性的影响,并采用红外光谱、热失重、扫描电镜、表面羟基滴定等手段表征改性效果.结果表明,硅烷偶联剂与纳米SiO2发生化学反应并接到SiO2表面,改性后的SiO2在有机物中的分散性明显改善.     

Poly(L-lysine)-poly(ethylene glycol) layers with different structure and their influence on silica suspension stability

The effects of the structure of di- and triblock copolymers of poly(L-lysine) – LYS with poly(ethylene glycol) – PEG as well as the length of nonionic fragment in the LYS-PEG macromolecule on the copolymer chains conformation in the adsorption layer formed on the colloidal silica (SiO2) surface were examined. Spectrophotometry and turbidimetry were applied for the determination of copolymer adsorbed amounts and stability coefficients of silica aqueous suspensions. The electrokinetic parameters such as solid surface charge density and zeta potential were also estimated. The adsorption of LYS-PEG was proved to be the highest at pH 10 whereas the lowest adsorption on the solid surface was found for the triblock copolymer with long fragments of LYS at the same pH value.     

Quantitative mapping of surface elastic moduli in silica-reinforced rubbers and rubber blends across the length scales by AFM

The surface elastic moduli of silica-reinforced rubbers and rubber blends were investigated by atomic force microscopy (AFM)-based HarmoniX material mapping. Styrene–butadiene rubbers (SBR) and ethylene–propylene–diene rubbers (EPDM) and SBR/EPDM rubber blends with varying concentrations of silica nanoparticles (0, 5, 10, 20, 50 parts per hundred rubber, phr) were prepared to investigate the effect of different composition on the resulting morphology, filler distribution and elastic moduli of a specific rubber or rubber blend sample. For SBR, the elastic modulus values varied from 0.5 MPa for unfilled SBR to 5 MPa for 50 phr reinforced SBR with the increase in the concentration of filler. For EPDM, the corresponding values increased from 1.4 MPa for unfilled EPDM to 4.5 MPa for 50 phr reinforced EPDM. Local stiff and soft domains in silica-reinforced SBR and EPDM rubbers and rubber blends were identified by HarmoniX AFM imaging. While the stiff silica particles show modulus values as high as 2 GPa, the rubber matrix reveals modulus values in the range of ca. 30 MPa for the rubber blends to ca. 300 MPa for the unfilled rubbers. The lower value of elastic modulus of the EPDM phase in the blend, compared to the blank EPDM compound can be attributed to the presence of Sunpar oil in the compound which has a very good affinity with EPDM and decreases the rubber modulus. The elastic moduli maps revealed an increase of the areal fraction of silica particles showing an intrinsic surface modulus value with rising silica content in the compound preparation mixture. HarmoniX AFM measurements revealed the formation of larger silica aggregates in EPDM in contrast to SBR where isolated silica particles were observed. For silica-reinforced rubber blends a phase separation into a soft (ca. 40 MPa) and a significantly harder phase could be observed (ca. 500 MPa–1.5 GPa) indicating the incorporation of silica particles in the SBR phase. Using HarmoniX AFM imaging significantly higher surface elastic moduli were observed compared to those obtained by bulk tensile testing. Possible reasons for the observed differences between bulk modulus values and those measured by AFM are discussed in detail, including the aspect of different averaging procedures like inherent to surface probing by AFM versus bulk tensile testing, different filler distributions in SBR and EPDM and the AFM modulus calibration procedures.     

高镍三元正极材料的包覆与掺杂改性研究进展

随着新能源汽车的加速发展, 镍钴锰/铝酸锂三元正极材料、特别是高镍(镍含量大于50%)材料作为后起之秀, 由于其性能和成本的综合指标优于传统的钴酸锂和磷酸铁锂, 引起了学术界和产业界极大的研究兴趣。但是受其本身晶体结构和表面结构的限制, 三元正极材料也存在安全性较差、循环稳定性不足等缺点。近年来, 科研工作者为解决这些问题、并进一步提升三元材料的性能, 在材料改性技术方面开展了大量工作, 取得了令人瞩目的研究成果。本文从改性元素对三元正极材料结构以及对电化学性能改善的机理出发, 介绍了包覆和掺杂两种改性技术的研究进展, 并在此基础上对三元正极材料的发展方向做出展望。     

微粉增强水泥基复合材料的早期界面显微结构研究

介绍了粉煤灰、硅灰、纳米SiO₂与水泥水化反应产物的早期界面显微结构,探讨了三种微粉与水泥水化反应的机理及对改善界面结构的作用,并提出了"二级界面"的概念。研究表明,三种微粉对界面的改善呈递增趋势,单一微粉中纳米SiO₂的水化产物结构最致密、均匀,微粉复合有效改善二级界面显微结构,有效提高水泥基材料性能。