粒子-聚合物相互作用与粒子-粒子相互作用对聚合物基纳米复合物力学性能的影响

聚合物基纳米复合物(PNCs)具有比传统高分子材料更加优异的光学、力学、热力学等性能,广泛应用于各个工程领域.而纳米粒子(NPs)对材料性能提高的机理则是当前聚合物纳米复合物领域研究的重要问题,聚合物纳米复合体系相互作用的影响因素众多,至今尚未明确并完整建立复合体系相互作用与性能增强之间的关系.本文总结了近年来关于纳米粒子填充聚合物基体力学性能的研究,从粒子-聚合物相互作用和粒子-粒子相互作用角度阐述了聚合物纳米复合体系力学性能的增强机理,并根据体系中不同的结构关系分别总结了聚合物/未改性纳米粒子复合体系和聚合物/聚合物接枝纳米粒子复合体系中影响力学性能的因素.该部分内容具有重要的理论和实践意义,有助于构建复合体系微观结构与宏观性能之间的关系,进而对微观层面调控PNCs的力学性能提供指导.     

有机硅-丙烯酸酯聚合物乳液合成及粒径分析

通过种子乳液半连续法合成了有机硅改性丙烯酸酯聚合物乳液,并对其粒子形态及分布进行分析。结果表明:通过种子乳液半连续聚合工艺可制备出固含量42wt%,乳化剂含量4wt%(基于单体量)、窄分布纳米粒子的有机硅改性丙烯酸酯聚合物乳液。随反应进行,粒径分布变窄,平均粒径逐渐增大。随乳化剂中SDS与OP-10的摩尔比减少,粒径增大。     

胶原接枝改性用于制备红外低发射率涂层的研究

用甲基丙烯酸甲酯在硝酸铈铵和偶氮二异丁腈的联合引发下对胶原进行接枝共聚改性,并用制得的胶原接枝共聚物颗粒与氧化铟纳米粒子复合制成涂层.研究了接枝反应温度及萃取剂对胶原接枝共聚物及其复合物涂层的红外发射率的影响,同时对复合物涂层红外发射率的降低机理进行了初步探讨.结果表明,在反应温度为50～55℃时,先后用丙酮和水作为萃取剂,可制得粒径为40～80nm的胶原接枝共聚物颗粒,该颗粒与氧化铟纳米粒子复合后,涂层的红外发射率(8～14μm)较单一的胶原接枝共聚物和氧化铟纳米粒子的红外发射率明显降低,胶原接枝共聚物纳米颗粒和氧化铟纳米粒子之间显示出较强的复合协同效应.     

壳聚糖-聚丙烯酰胺接枝共聚物接枝率的测定

根据溶液的折光指数增量与溶液的组成间存在定量关系的原理提出了一种测定接枝聚合物接枝率的新方法, 并用此方法测定了壳聚糖-聚丙烯酰胺接枝共聚物的接枝率. 结果通过元素分析法测定样品中氮元素的百分含量, 以及运用折光指数增量法测定已知比例的壳聚糖与聚丙烯酰胺(PAM)混合物中二者的质量百分比进行佐证. 结果表明, 折光指数增量法测定接枝共聚物的接枝率也是可行的.     

PSI-g-PEG-DDA对油溶性超顺磁性氧化铁纳米粒子的包覆及对肿瘤核磁造影成像的研究

天冬氨酸(ASP)自身热缩聚产物聚琥珀酰亚胺(PSI)通过与氨基化聚乙二醇单甲醚(α-胺基-ω-甲氧基-聚乙二醇)和十二胺(DDA)进行连续两步开环反应,制备了双亲性蜈蚣形聚合物聚琥珀酰亚胺接枝聚乙二醇与十二胺(PSI-g-PEG-DDA).随着改变疏水链段DDA的接枝比例,通过胶束粒径的变化确定了最佳的接枝比例.核磁共振波谱(1H-NMR)及凝胶渗透色谱(GPC)对聚合物的性质进行了表征.通过相转移法,聚合物对油溶性超顺磁性氧化铁纳米粒子进行包覆,制备了新型的水溶性超顺磁性氧化铁纳米粒子(PSI-g-PEGDDA@IONPs).动态光散射(DLS)和透射电镜(TEM)对新型的水溶性氧化铁纳米粒子的粒径与形貌进行了表征.体外T2核磁造影成像(MRI in vitro)确定了制备的氧化铁纳米粒子的R2质子驰豫率.肝癌小鼠模型的体内核磁造影成像(MRI in vivo)结果表明新型氧化铁纳米粒子对肿瘤部位有明显的T2核磁造影增强效应,并有很长的体内循环半衰期.以上实验结果表明,新型的水溶性纳米氧化铁粒子可以作为一种潜在的用于肿瘤检测的核磁造影剂.     

原子转移自由基聚合接枝改性纳米SiO2的研究进展

纳米SiO2粒子极易团聚,在有机介质中难以均匀分散,从而大大地限制了其优异性能的发挥,有必要对其进行化学改性处理。原子转移自由基聚合(atom transfer radical polymerization,ATRP)是对纳米SiO2粒子进行接枝改性的一种有效途径,通过ATRP对纳米SiO2粒子进行表面改性,可以制备集无机纳米粒子和聚合物的优点于一身的SiO2-聚合物复合材料,且接枝链的长度及分子量分布可控,拓展了纳米SiO2的应用领域。本文主要综述了ATRP、RATRP(reverse ATRP)、AGET ATRP(activators generated by electron transferATRP)和ARGET ATRP(activators regenerated by electron transfer ATRP)方法对纳米SiO2接枝改性的研究现状。     

改性纳米炭黑/聚氨酯复合物的制备及表征

利用有机硅偶联剂改性的纳米炭黑和聚氨酯制备了纳米炭黑/聚氨酯复合物. 采用红外光谱、透射电镜、流变学及力学性能等测试方法对纳米粒子及其聚氨酯复合物进行了表征. 红外光谱表明, 纳米粒子的存在使聚氨酯的氢键结构发生了改变. 适量改性纳米炭黑粒子明显提高了聚氨酯的拉伸强度和断裂伸长率等力学性能. 流变学测试结果表明, 溶液中改性纳米炭黑粒子与聚氨酯分子间存在明显的相互作用.     

原位聚合法制备聚合物/纳米SiO_2复合材料的研究进展

纳米SiO_2改性聚合物制备的关键在于提高纳米粒子与聚合物基体的相容性及分散性;对纳米SiO_2进行不同的表面改性及选择合适的复合材料制备方法可以改变纳米粒子与聚合物基体的界面结合方式以及相容性和分散性,进而在不同程度上影响材料的性能.本文介绍了改性前后纳米SiO_2与聚合物基体的多种界面结合方式,对近年来利用原位聚合法制备聚合物/纳米SiO_2复合材料的研究现状和进展进行了综述.     

动脉粥样硬化造影剂PGMA-EDA-g-PEG-g-DS@IO的合成及性能

利用乙二胺(EDA)对聚甲基丙烯酸缩水甘油酯(PGMA)进行开环反应, 制备了侧链多氨基聚合物PGMA-EDA; 再利用聚乙二醇(PEG-COOH)和硫酸葡聚糖钠盐(DS)分别对PGMA-EDA上氨基进行酰胺化反应和还原胺化反应, 制备含动脉粥样硬化斑块靶向分子DS的双亲性接枝共聚物PGMA-EDA-g-PEG-g-DS. 通过核磁共振(¹H NMR)谱和红外光谱(FTIR)表征了聚合物的结构. 利用凝胶渗透色谱(GPC)表征了聚合物的数均分子量M_n=16255, 多分散性指数PDI=1.54. 采用配体交换法, 利用该聚合物对油胺配体超顺磁性氧化铁纳米粒子进行修饰, 制备了水溶性氧化铁纳米粒子PGMA-EDA-g-PEG-g-DS@IO. 通过透射电镜(TEM)和动态光散射(DLS)表征了纳米粒子的形貌和粒度, 采用热重分析(TGA)和振动样品磁强(VSM)仪表征了纳米粒子的包覆率和磁强度. 采用细胞计数试剂盒(CCK)测定了纳米粒子的细胞毒性, 结果表明, 水溶性纳米粒子的生物相容性较好, 可作为动脉粥样硬化斑块的特异性磁共振检测用造影剂.     

pH响应性树枝状聚合物-金纳米粒子复合药物载体的制备

以表面接枝聚乙二醇链的聚酰胺胺树枝状聚合物(PEG-PAMAM)为纳米载体, 在其内部空腔包覆金纳米粒子, 在金纳米粒子表面连接硫辛酸改性的阿霉素(LA-DOX), 从而间接实现了抗癌药物在PEG-PAMAM内的高效负载. 同时, LA-DOX中的酰腙键提供pH响应性, 实现了药物的pH响应性释放. 紫外-可见(UV-Vis)光谱表明, 包覆金纳米粒子的PEG-PAMAM纳米载体对LA-DOX的负载能力显著增强. 体外细胞实验表明, 负载LA-DOX的树枝状聚合物-金纳米粒子复合药物载体具有较强的抗肿瘤能力.     

Synthesis and nanoimprinting of high refractive index and highly transparent polythioethers based on thiol-ene click chemistry

This work demonstrates the UV nanoimprinting lithography (UV-NIL) of high refractive index and highly transparent polythioethers based on thiol-ene click chemistry. Herein, 9,9-bis(3-mercaptopropylphenylether)fluorene (BMPF) is designed as a new thiol monomer with a high refractive index, high transparency, and good processability for UV-NIL. Colorless polythioethers are synthesized from BMPF and ene monomers under mild thiol-ene click reaction conditions. Excellent transmittance (96%) of 400 nm light is observed in all the polymer films and high refractive index values of 1.5972–1.6382 are attained. UV-NIL using thiol-ene photopolymerization affords polymer nanoimprinting patterns with various features on the order of 100–500 nm without any fractures. To the best of our knowledge, this is the first report on UV-NIL of high refractive index and highly transparent polymers. Through proper monomer and polymer design, novel polythioethers with suitable glass transition temperature (T _g) values are developed with high refractive index, high transparency, and good UV-NIL processability. Furthermore, UV-NIL based on thiol-ene click chemistry is accomplished at the nanoscale. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2175–2182     

Preparation of styrene polymer/ZnO nanocomposite latex via miniemulsion polymerization and its antibacterial property

Styrene polymer/ZnO nanocomposite latex was fabricated using miniemulsion polymerization in the presence of coupling agent 3-aminopropyltriethoxysilane (APTES) and hexadecane as hydrophobe. The size distribution and morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron micrograph. X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer results demonstrate that ZnO nanoparticles were encapsulated into polymer phases. The coupling treatment of ZnO with APTES can improve the dynamic contact angles of ZnO nanoparticle with water to enhance its hydrophobicity. When 0.6% APTES to ZnO (wt/wt) is used to modify ZnO, the encapsulation efficiency of ZnO reaches to 95%. It shows that the high encapsulation efficiency improves dispersion of ZnO nanoparticles in polymer film by scanning electron microscope. The stable structural hybrid latex can adequately exert unique function of nanoparticles in coatings. It indicates that the coatings added the composite latex exhibits perfect antibacterial activity, which has a tremendous potentiality in the field of coating materials.     

Optical properties of polymer blends composed of poly(methyl methacrylate) and ethylene–vinyl acetate copolymer

Optical properties for immiscible polymer blends composed of poly(methyl methacrylate), PMMA, and ethylene–vinyl acetate copolymer (EVA) are studied employing various EVA samples with different vinyl acetate contents. PMMA/EVA shows transparency at room temperature when the difference in refractive index between both phases is small. The light transmittance, however, decreases with increasing the ambient temperature. This phenomenon is attributed to the difference in the volume expansion ratio, leading to the difference in refractive index, between PMMA and EVA. It is found that addition of tricresyl phosphate, TCP, improves the transparency and its temperature dependence. As a result, a ternary PMMA/EVA/TCP blend shows high level of transparency in the wide temperature range, although it has apparent phase separated morphology.     

Nanoparticle Dispersion and Glass Transition Behavior of Polyimide-grafted Silica Nanocomposites

How to control the spatial distribution of nanoparticles to meet different performance requirements is a constant challenge in the field of polymer nanocomposites.Current studies have been focused on the flexible polymer chain systems.In this study,the rigid polyimide(PI) chain grafted silica particles with different grafting chain lengths and grafting densities were prepared by "grafting to" method,and the influence of polymerization degree of grafted chains(N),matrix chains(P),and grafting density(a) on the spatial distribution of nanoparticles in the PI matrix was explored.The glass transition temperature(Tg) of PI composites was systematically investigated as well.The results show that silica particles are well dispersed in polyamic acid composite systems,while aggregation and small clusters appear in PI nanocomposites after thermal imidization.Besides,the particle size has no impact on the spatial distribution of nanoparticles.When σ·N0.5<<(N/P)2,the grafted and matrix chains interpenetrate,and the frictional resistance of the segment increases,resulting in restricted relaxation kinetics and Tg increase of the PI composite system.In addition,smaller particle size and longer grafted chains are beneficial to improving Tg of composites These results are all propitious to complete the microstructure control theory of nanocomposites and make a theoretical foundation for the high performance and multi-function of PI nanocomposites.     

Synthesis and characterization of functionalized carbon black/poly(vinyl alcohol) high refractive index nanocomposites

Carbon black(CB)/polymer composites with high refractive index(RI) were fabricated from poly(vinyl alcohol) (PVA) and covalently functionalized nano-CB(PVA-es-CB) by simple esterification reaction.Transmission electron microscopy showed that uniform aggregates of PVA-es-CB nanoparticles with a size smaller than 100 nm formed in the nanocomposite films.EUipsometric measurements indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.520-1.598 linearly increased with the PVA-es-CB volume content.Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values.The hybrid films also revealed relatively good surface planarity,thermal stability and optical transparency.     

Study on luminescence characteristic of the ZnO/polymer hybrid films

The cyclohexane solution of PS (polystyrene) and the ethyl acetate solution of PMMA (polymethyl methacrylate) were used as flowing liquid; the ZnO/polymer hybrid colloids were successively produced by focused pulsed laser ablation of ZnO target in interface of solid and flowing liquid. As solvent in the hybrid colloids has volatized, the ZnO/polymer hybrid films were obtained. The hybrid colloids were characterized by high-resolution transmission electron microscopy (HRTEM) and select-area electron diffraction (SEAD). The results show a good dispersion of the ZnO nanoparticles in the polymer matrix. The hybrid films were characterized by fluorescence spectrum, Fourier transform infrared spectroscopy (FTIR) spectroscopy, thermogravimetry with FTIR (TG/FTIR), and X-ray photoelectron spectrum. The results show the ZnO/polymer hybrid films can radiate strong blue light under ultraviolet. Meanwhile, the ZnO/polymer hybrid films have higher chemical stability than ZnO nanoparticles because nano-ZnO nanoparticles were enwrapped by polymers. In addition, the ZnO hybrid films have higher thermal stability then the related pure polymers because of strong interaction among ZnO nanoparticles and polymers.     

Graft polymerization of vinyl monomers onto nanosized alumina particles

To enhance the interfacial interaction in alumina nanoparticles filled polymer composites, an effective surface modification method was developed by grafting polystyrene and polyacrylamide onto the particles. That is, the alumina surface was firstly treated with silane, followed by radical grafting polymerization in aqueous or non-aqueous systems. Results of infrared spectroscopy and dispersiveness in solvents demonstrated that the desired polymer chains have been covalently bonded to the surface of the alumina particles. They also greatly changed their surface characteristics. In addition, effects of polymerization conditions, including ways of monomer feeding, concentrations of monomer and initiator, and reaction time, on the grafting reaction were presented. It was found that the growing polymer radicals and/or the grafted polymer chains had a blocking effect on the diffusion of radicals or monomers towards the surface of nanoalumina. This was due to the fact that the interaction between the solvent and the grafted polymers was weaker than that between the grafted polymers and the nanoparticles.     

Fabrication of Siloxane Hybrid Material With High Adhesion and High Refractive Index for Light Emitting Diodes (LEDs) Encapsulation

A novel inorganic-organic siloxane hybrid material with self-adhesion ability and high refractive index for high-power light emitting diodes (LEDs) encapsulation is introduced. Under the catalysis of an anion exchange resin, the hybrid material was synthesized by a sol-gel condensation process from methacryloxy propyl trimethoxyl silane (MPTS), γ-(2, 3-epoxypropoxy)propytrimethoxysilane (EPTS) and diphenylsilanediol (DPSD). This hybrid material was characterized by Fourier-transform infrared spectroscopy and ¹H-NMR. The resin-type encapsulation material was then prepared by hydrosilylation of the newly synthesized inorganic-organic siloxane hybrid material and methylphenyl hydrogen-containing silicone resin. The cured silicone resin-type encapsulation material can be used as a LEDs encapsulant, owing to high refractive index (n = 1.544), high transparency, appropriate hardness, and excellent thermal stability, as well as good adhesive strength between the encapsulating material and the substrate of LED lead frame.     

Preparation of ZrO2/silicone hybrid materials for LED encapsulation via in situ sol‐gel reaction

Organic silicones have been used as encapsulant materials for light‐emitting diodes (LEDs) for many years, while their performances need to be improved in order to satisfy the requirements of high‐power LEDs. A ZrO₂/silicone hybrid resin (ZHR) was synthesized for LEDs encapsulation by in situ sol‐gel reactions. The oligosiloxane was synthesized as polymeric matrix by nonaqueous sol‐gel condensation using diphenylsilanediol (DPSD), vinyltrimethoxysilane (VTMS), and 3‐methacryloxy propyl trimethoxysilane (MPTMS) as monomers. Then zirconium propoxide was added into this polymeric matrix to be hydrolyzed to obtain the hybrid resin with a uniform dispersion of ZrO₂ nanoparticles. The Si–O–Zr covalent bond was detected and benefited for excellent dispersibility of the ZrO₂ nanoparticles and the well compatibility between organic and inorganic phases. The cured ZHR with 5 wt% ZrO₂ content showed high light transmittance (greater than 80% in visible light range), high refractive index (=1.56), and high thermal stability (no yellowing at 150°C for 240 hours). The luminous flux of the LED chip with ZHR encapsulant was 10% higher than that of the pure silicone resin, suggesting that ZHR has great application potential in the field of LED packaging.     

Synthesis,thermal properties and crystalline morphology of poly(trimethylene terephthalate)/ZnO nanocomposites prepared by dual in situ polymerization

Poly(trimethylene terephthalate)/ZnO nanocomposites were successfully prepared by dual in situ polymerization. Firstly, ZnO nanoparticles were synthesized by a simple polyol method using 1,3‐propanediol (PDO) as solvent and stabilizer. Then, PTT/ZnO nanocomposites were prepared by in situ polymerization. The results of Fourier transform infrared spectra showed that PTT molecular chains were grafted to the surface of ZnO nanoparticles. The results of ¹H NMR spectra confirmed that propyl ester molecules (as reaction product) were incorporated into PTT molecular chains. It was found that the intrinsic viscosity and molecular weight of synthesized PTT decreased with the addition of ZnO nanoparticles and the incorporation of propyl ester molecules. TEM results showed that ZnO nanoparticles with particle size of 20 ~ 30 nm were well dispersed and fully distributed in the polymer matrix. Besides, the melting temperatures and crystallization temperature decreased gradually and then increased slightly with the increasing loading of ZnO nanoparticles. Because of the strong interaction between ZnO nanoparticles and PTT matrix, the thermal stability of PTT/ZnO nanocomposites was improved. Interestingly, the results of Polarized Optical Microscopy showed that banded spherulites morphology can be observed in all PTT/ZnO nanocomposite samples. However, at higher loading of ZnO nanoparticles, band spacing became larger and was finally disturbed. Copyright © 2016 John Wiley & Sons, Ltd.