液芯微囊的制备及其应用研究进展

近几年来,聚合物微囊被广泛应用于各行业中,其中液芯微囊因为其具有一般固体微球所不具备的特性,在食品行业,医药行业,纺织行业等进行了大量尝试与应用。本文旨在对液芯微囊的制备及其应用进行全面的阐述。目前有很多制备确切性质的聚合物微囊方法,包括胶体微囊制备法,聚合物沉淀相分离法,表面缩聚法,层-层聚电解质组装微囊,表面聚合共聚物微球,聚合物囊泡等方法。本文同时阐述了不同方法所制备微囊所具有的优缺点,以及使用不同方法制备的微囊在不同领域的应用。     

纳米磁性空心微球制备技术研究进展

纳米磁性空心微球由于其独特的结构和性质在国内外引起了越来越多的关注。本文综述了纳米磁性空心微球制备方法的最新研究进展。制备方法一般可分为模板法、非模板法、牺牲模板法、自催化还原法、置换反应法、溶胶-凝胶烧结法和化学镀法。同时,讨论了各种制备方法存在的问题及其优缺点。     

草莓型聚合物微囊的制备及表征

通过蒸馏沉淀聚合法制备的聚α-甲基丙烯酸核微球与St?ber法合成修饰氨基的二氧化硅冠微球,两者自组装得到草莓型核-冠微球。并以此为模板,制备草莓型聚合物微囊。通过傅里叶红外光谱、X射线光电子能谱研究了复合微球形成机理,通过透射电子显微镜分析了不同含量交联剂对聚合物微囊壁厚的影响。结果表明:复合微球形成机理是COO~-与NH_3~+间的静电作用;DVB加入量0.5 mL时,草莓型聚合物微囊壳层厚度及凸起明显度最为恰当。     

非金属超疏水材料的制备方法及研究进展

介绍了构造超疏水材料的基本原理,综述了近年来超疏水材料的制备方法,重点介绍了构造表面微纳米粗糙结构的方法（刻蚀法、相分离法、模板法、化学液相沉积法、溶胶凝胶法）,并讨论了不同制备方法的优缺点和应用前景。用激光辐照、等离子体刻蚀等方法处理非金属材料都能得到理想的微纳米结构;用激光刻蚀低表面自由能的聚合物材料,可以不用修饰直接得到超疏水表面;相分离法适用于制备超疏水聚合物薄膜,其优点是设备简单,成本低,适合大规模制造;利用模板压印法制备聚合物超疏水材料简单易行,利用剥离力和反模板的作用,可以形成理想的二阶微纳米粗糙结构。     

多孔空心纳米球材料制备研究进展

基于多孔空心纳米球材料的理化性质,对硬模板法、喷雾法、自组装法、微乳液法的制备方法进行了综述。结果表明:硬模板法可以有效的控制孔径大小,选择合适的模板去除方法可以有效避免材料的塌陷、破损;喷雾法可以实现连续操作和规模化生产,选择合适基质材料、浆液配方有利于提高纳米球的耐磨强度和反应性能;自组装法能够将构筑基元按照要求进行组装,选择合适的前体浓度、聚合物分子量有利于控制其尺寸和形态;微乳液法可以应用不同表面活性剂合成不同性质纳米球,选择合适的水/表面活性剂摩尔比、反应温度、时间有利于提高其反应性能。     

一种新型纳米二氧化硅微囊的制备

以正硅酸乙酯(TEOS)为硅源,Na_2HPO_4·12H_2O-Na OH碱性缓冲溶液为催化剂,采用溶胶-凝胶法制备纳米级单分散的SiO_2微囊。通过扫描电子显微镜、透射电子显微镜和傅里叶红外光谱仪等分析手段对所制备的纳米SiO_2微囊进行表征。结果表明,所制得的纳米SiO_2微囊形貌规整,具有较大的空腔结构,微囊的直径大小为250～400 nm,囊壁厚度为15～35 nm,分散性良好,具有单分散或窄分散性。     

基于纤维素模板的聚合物空心微球作为药物载体的性能研究及分析

以羟丙基纤维素为模板材料,分别采用不同的聚合方法制备了2种不同形态和结构的聚合物空心微球--聚N-异丙基丙烯酰胺-co-聚丙烯酸(PNIPAm-co-PAA)微凝胶和聚N-异丙基丙烯酰胺-聚丙烯酸(PNIPAm-PAA)水凝胶微囊。以盐酸阿霉素(Dox)作为模型药物,考察了聚合物空心微球作为药物载体的载药能力和体外释放性能。研究表明,PNIPAm-co-PAA微凝胶、PNIPAm-PAA水凝胶微囊和Dox分子能够通过正负电荷的相互吸引实现有效结合;载药微球具有良好的缓释性能,并对Dox的释放表现出明显的pH值敏感性和温度敏感性。体外细胞毒性实验表明,载药PNIPAm-co-PAA微凝胶、PNIPAm-PAA水凝胶微囊具有很高的抗肿瘤活性,细胞相对存活率均可达20%左右。PNIPAm-co-PAA微凝胶、PNIPAm-PAA水凝胶微囊在作为水溶性药物或蛋白类药物载体方面,具有潜在的应用价值,同时有望应用于木材胶黏剂防腐等。     

多功能性聚苯胺/聚合物纳米复合材料的制备及应用

基于国内外最新研究文献及本课题组的研究,综述了多功能性聚苯胺/聚合物纳米复合材料的制备方法、性能及应用前景。聚苯胺/聚合物纳米复合材料可以由机械共混法、涂布法和原位聚合法,如分散聚合法、模板诱导聚合法及电化学聚合法制备得到。聚苯胺/聚合物纳米复合材料在透明导电塑料薄膜、防静电涂料、导电纤维、电致发光器件、电磁屏蔽材料等领域有着广阔的应用前景。     

高分子微纳米球为模板制备磁性空心微纳米球的方法

本发明公开了一种微纳米材料技术领域的高分子微纳米球为模板制备磁性空心微纳米球的方法,即以表面带有负电荷的高分子微纳米球为模板,通过在微纳米球表面原位反应生成以磁性纳米粒子为壳,模板粒子为核的磁性复合微球,之后也可以在此微球表面包裹一层SiO2。进一步通过烧灼去除模板来获得空心磁性微纳米球。本发明易行、高效、容易规模化,制备的磁性空心微纳米球粒径可控性很好、且磁性壳层的厚度或磁响应强弱也可以根据要求进行调节。     

喷雾干燥法制备杨梅黄酮微囊

目的:喷雾干燥法考察杨梅黄酮微囊制备工艺。方法:以包封率为考察指标,对喷雾干燥工艺参数进行正交试验设计,并考察了囊芯囊材比对微囊性能的影响。结果:进风口温度140℃、进样速度7mL/min、囊芯囊材质量比2∶1,制得的微囊成型性好,包封率较高。结论:喷雾干燥法制备杨梅黄酮微囊,工艺简单可行,重现性高。     

A functional cross linked polymeric nanocapsule with pH-responsive brushes on its inner wall: Preparation,characterization and controlled release

Carboxyl-functionalized cross linked polymeric nanocapsules (PAA–CPS) with pH-responsive poly(acrylic acid) (PAA) brushes on the inner wall of the crosslinked polystyrene (CPS) shells have been prepared by the template-polymerization approach via combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and ultraviolet-irradiated crosslinking techniques. The hollow structure of the crosslinked nanocapsules with an inner diameter of about 30–40 nm was confirmed by transmission electron microscopy (TEM). The adsorption experiments showed that the PAA–CPS nanocapsules possess a higher adsorption capacity towards the basic dye methylene blue (MB) than the PtBA–CPS nanocapsules. Furthermore, the MB-loaded PAA–CPS nanocapsules release the dye more rapidly in acidic medium than in a neutral medium.     

Thermal and Structural Characterization of TiO2 and TiO2/Polymer Micro Hollow Spheres

Micro hollow spheres, synthesized by the coating of tetradecane filled microcapsules with titanium dioxide, are characterized using thermal gravimetry (TG), infrared spectroscopy (IR), Hg‐porosimetry and scanning electron microscopy (SEM). The investigations show a strong dependence of the coating efficiency on the initial pH (precipitation in water or dilute sulfuric acid) as well as the specific capsule surface present in solution. Since the process is dominated by heterogeneous precipitation, the coating efficiency is governed by the counteracting processes of capsule‐TiO₂ and TiO₂‐TiO₂ agglomeration. TG‐IR analysis of the capsules shows the vaporization of tetradecane prior to the decomposition of the polymeric wall to carbon monoxide, carbon dioxide and water. After the extraction or calcination of the core microcapsules, stable inorganic and organic‐inorganic hollow spheres are obtained.     

Macroporous polymers from particle-stabilized emulsions

Macroporous polymers are attractive materials due to their low density, low cost, recyclability and tunable mechanical and functional properties. Here, we report a new approach to prepare macroporous polymers from emulsions stabilized with colloidal polymeric particles in the absence of chemical reactions. Stable water-in-oil emulsions were prepared using poly(vinylidene difluoride) (PVDF), poly(tetrafluoroethylene) (PTFE), and poly(etheretherketone) (PEEK) as stabilizing polymeric particles in emulsions. The partial wetting of the polymeric particles by the two immiscible liquids drives particles at the water-oil interface during emulsification, leading to extremely stable water-in-oil emulsions. The particle-stabilized emulsions were processed into highly porous solid polymer components upon drying and sintering. The high stability of emulsions also allows for the preparation of hollow polymeric microcapsules. We describe the conditions required for the adsorption of particles at the liquid-liquid interface, we show the rheological behavior of the polymer-loaded wet emulsions and, we discuss the effect of the emulsions' initial compositions on the final sintered porous structures. This new approach for the fabrication of macroporous PVDF, PTFE, and PEEK polymers is particularly suited for the preparation of porous materials from intractable polymers but can also be easily applied to a variety of other polymeric particles.     

UV–Vis irradiation fatigue resistance improvement of azo photochromic compound using polyurethane‐chitosan double shell encapsulation

Double shell photochromic microcapsules were prepared by in situ polymerization with polyurethane and chitosan as inner and outer shell respectively. FT‐IR indicated that chitosan‐glutaraldehyde copolymer formed by imine and combined with polyurethane photochromic nanocapsules. The polyurethane‐chitosan microcapsules exhibited a near‐spherical shape, and the average particle size of nanocapsules was around 1.2 μm. The half‐life of azo compound increased from 135 to 340 min after encapsulated in polyurethane‐chitosan microcapsules. The polyurethane‐chitosan shell delayed the coloration process for 14 s compared with azo compound in ethanol, however, the absorbance of azo compound increased by 17.15% in polyurethane‐chitosan microcapsules. It decreased from 0.3486 to 0.1738 in ethanol during 20 s, however, it decreased from 0.4084 to 0.2625 in polyurethane‐chitosan microcapsules in 55 s when it reached steady state during decoloration process. Polyurethane‐chitosan double shell encapsulation is an effective route for improving the fatigue resistance, increasing the absorbance of azo compound. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40895.     

Safety profile and cellular uptake of biotemplated nanocapsules with nanometre-thin walls

Polymeric nanocapsules with nanometre-thin walls offer a promising platform for controlled cellular delivery of therapeutic or diagnostic agents. Therefore, their biocompatibility is crucial for future applications in the human body. However, there is little knowledge about their interaction with biological systems. In this study, polymeric nanocapsules containing different amounts of lipids and representing different scenarios for handling and storing nanocapsules are investigated. We find that all nanocapsules in our study can enter human cells and the presence of an outer lipid shell facilitates the process. These nanocapsules do not inhibit cell proliferation at concentrations up to 200 μg mL(-1) of nanocapsules. No cellular ROS, apoptosis or cell cycle perturbation is detected at this dose. These comprehensive examinations demonstrate that polymeric nanocapsules are promising nano-carriers for cellular delivery.     

Polymeric Nanocapsule from Silica Nanoparticle@Cross-linked Polymer Nanoparticles via One-Pot Approach

A facile strategy was developed here to prepare cross-linked polymeric nanocapsules (CP nanocapsules) with silica nanoparticles as templates. The silica nanoparticle@cross-linked polymer nanoparticles were prepared by the encapsulation of the silica nanoparticles by the one-pot approach via surface-initiated atom transfer radical polymerization of hydroxyethyl acrylate in the presence of N,N′-methylenebisacrylamide as a cross-linker from the initiator-modified silica nanoparticles. After the silica nanoparticle templates were etched with hydrofluoric acid, the CP nanocapsules with particle size of about 100 nm were obtained. The strategy developed was confirmed with Fourier transform infrared, thermogravimetric analysis and transmission electron microscopy.     

Facile Preparation of Crosslinked Polymeric Nanocapsules via Combination of Surface-Initiated Atom Transfer Radical Polymerization and Ultraviolet Irradiated Crosslinking Techniques

A facile approach for the preparation of crosslinked polymeric nanocapsules was developed by the combination of the surface-initiated atom transfer radical polymerization and ultraviolet irradiation crosslinking techniques. The well-defined polystyrene grafted silica nanoparticles were prepared via the SI-ATRP of styrene from functionalized silica nanoparticles. Then the grafted polystyrene chains were crosslinked with ultraviolet irradiation. The cross-linked polystyrene nanocapsules with diameter of 20–50 nm were achieved after the etching of the silica nanoparticle templates with hydrofluoric acid. The strategy developed was confirmed with Fourier transform infrared, thermogravimetric analysis, and transmission electron microscopy.     

Self-healing thermoset using encapsulated epoxy-amine healing chemistry

Self-healing was achieved with a dual-microcapsule epoxy-amine chemistry in thermoset epoxy. One capsule contained a modified aliphatic polyamine (EPIKURE 3274) while the second capsule contained a diluted epoxy monomer (EPON 815C). Amine microcapsules were prepared by vacuum infiltration of EPIKURE 3274 into hollow polymeric microcapsules. Epoxy microcapsules were prepared by an in situ polymerization method. Both types of capsules were incorporated into an epoxy matrix (EPON 828:DETA) and recovery of mode-I fracture toughness was measured using tapered-double-cantilever-beam (TDCB) specimens. The optimal mass ratio of amine: epoxy capsules was 4: 6 and an average healing efficiency of 91% was achieved with 7 wt% amine capsules and 10.5 wt% epoxy capsules. Long-term stability of the healing system was demonstrated for six months at ambient conditions. Thermal stability was investigated by post curing samples at 121 °C and assessing healing performance.     

Differential Interactions of Chiral Nanocapsules with DNA

(1) Background: Chiral nanoparticular systems have recently emerged as a compelling platform for investigating stereospecific behavior at the nanoscopic level. We describe chiroselective supramolecular interactions that occur between DNA oligonucleotides and chiral polyurea nanocapsules. (2) Methods: We employ interfacial polyaddition reactions between toluene 2,4-diisocyanate and lysine enantiomers that occur in volatile oil-in-water nanoemulsions to synthesize hollow, solvent-free capsules with average sizes of approximately 300 nm and neutral surface potential. (3) Results: The resultant nanocapsules exhibit chiroptical activity and interact differentially with single stranded DNA oligonucleotides despite the lack of surface charge and, thus, the absence of significant electrostatic interactions. Preferential binding of DNA on d-polyurea nanocapsules compared to their l-counterparts is demonstrated by a fourfold increase in capsule size, a 50% higher rise in the absolute value of negative zeta potential (ζ-potential), and a three times lower free DNA concentration after equilibration with the excess of DNA. (4) Conclusions: We infer that the chirality of the novel polymeric nanocapsules affects their supramolecular interactions with DNA, possibly through modification of the surface morphology. These interactions can be exploited when developing carriers for gene therapy and theranostics. The resultant constructs are expected to be highly biocompatible due to their neutral potential and biodegradability of polyurea shells.