复合玉米淀粉微球的合成与其性能研究

以复合淀粉(玉米淀粉和β-环糊精)为原料,N,N’-亚甲基双丙烯酰胺和环氧氯丙烷为交联剂,采用反相乳液聚合法,合成复合玉米淀粉微球。利用红外光谱、扫描电镜、差热分析等方法对微球进行了表征,并用溶胀度法测定微球交联程度,通过微球对无机金属粒子和有机色素吸附量测定微球的吸附性能。结果表明,制备的复合玉米淀粉微球外型规则,粒度均匀,分散性好。复合玉米淀粉微球的溶胀度比玉米淀粉降低,对无机物Ca2+、有机物胭脂红的吸附作用比玉米淀粉更强,可以作为良好的吸附剂。     

The surface modification of magnetic poly(methyl acrylate) microspheres with dendron and application in Au(III) adsorption

An improved suspension polymerization method for preparation of the magnetic poly(methyl acrylate) microspheres (mPMA‐DVB) was investigated. Through subsequent reaction with methyl acrylate (MA) and ethylenediamine (EDA), the magnetic poly(methyl acrylate) microspheres with dendron surface was obtained, and the magnetic poly(methyl acrylate) microspheres with dendron surface reacted with carbon bisulfide and sodium hydroxide to create sodium dithiocarbamate. Following, the resultant magnetic microspheres with dendron surface modification were used to adsorb Au(III) from aqueous solution. The result showed that the capacity of amino groups on the surface of the mPMA microspheres increased from 1.67 mmol/g for the magnetic polymer microspheres with G₀ dendron to 4.35 mmol/g with G₃ dendron, and the adsorption capacity rose from 0.1981 g/g with G₀ dendron to 0.7853 g/g with G₃ dendron. The effects of solution pH, the adsorption temperature, the adsorption time, and the initial concentration of Au(III) on the adsorption of Au(III) were studied, the optimum pH for Au(III) adsorption was found at pH = 1, the adsorption capacity achieved the maximum in 60 min, and the adsorption process was endothermic reaction and conformed to pseudo‐second‐order kinetic models. Furthermore, the adsorption process was in accordance with the Langmuir model. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of Polycarbonate Hollow Microspheres by Microencapsulation Method

For the purpose of recycling waste polycarbonate (PC) products, PC hollow microspheres were prepared using waste PC products via a microencapsulation method. In the microencapsulation process, dichloromethane was the suitable organic solvent of the oil phase, and the optimal adding amount of gelatin was 1.7 g in 70 g water. The size of the PC hollow microspheres was analyzed by scanning electron microscopy (SEM). The hollow microspheres with mean diameter from 19 to 645 µm could be obtained by varying the preparation factors. The tap density could be controlled through the manipulation of the weight ratio of W₁ and O phase and PC concentration.     

Effect of Basic Factors of Preparation on Characteristics,Hydrolytic Degradation,and Drug Release From Poly(ester-anhydride) Microspheres

Functional poly(ester-anhydride) microspheres were prepared using emulsion solvent evaporation (ESE) and phase inversion methods (PIM). The poly(ester-anhydride)s were obtained by polycondensation of sebacic acid (SBA) and oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl groups (OSAGE). The effects of various parameters, including: polymer and emulsifier concentrations, stirring speed and molecular weight of polyvinyl alcohol (PVA) used as emulsifier on size, size distribution and morphology of microspheres obtained by ESE technique were examined. The size of microspheres obtained was in the range 2–30 µm and depended mainly on the stirring rate in emulsion formulation process, as well as concentration of polymer solution used. Molecular weight of PVA, and its concentration in aqueous phase, significantly influenced tendency to agglomeration of microparticles formed, but only slightly changed the size of microspheres. The present study demonstrated that the ESE method can be useful to formulate, from functional poly(ester-anhydride)s, small (2–3 µm) or large (20–30 µm) microspheres with relatively narrow size distribution. Such microspheres were loaded with three model compounds (rhodamine B, p-nitroaniline, and piroxicam) with different water solubility and their release characteristics were examined. In the present study microparticles were also obtained by alternative phase inversion method to compare mainly stability of polymers during formulation of microspheres by both techniques.     

Study of Different Delivery Modes of Chondroitin Sulfate Using Microspheres and Cryogel Scaffold for Application in Cartilage Tissue Engineering

This study focuses on the development of an efficient delivery modes designed for chondroitin sulfate (CS) for application in cartilage tissue engineering. Novel three-dimensional (3-D) scaffold fabricated from natural polymers such as chitosan and gelatin blended with chondroitin sulfate (CGC) were synthesized using cryogelation technology. Other methods to deliver CS were also tried, which included incorporation into microparticles for sustained release and embedding the CS loaded microparticles in CG (chitosan-gelatin) cryogel scaffold. Novel CGC scaffolds were characterized by rheology, scanning electron microscopy (SEM), and mechanical assay. Scaffolds exhibited compression modulus of 50 KPa confirming the utility of these scaffolds for cartilage tissue engineering. Primary goat chondrocytes were used for the in vitro testing of all the delivery modes. So this study shows that CS microparticles when given freely with matrix (chitosan–gelatin) or embedded into scaffold has potential to enhance chondrocyte proliferation together with improved matrix production than in control without microspheres.     

Preparation of micron-scale monodisperse oil-in-water microspheres by microchannel emulsification

Micron-scale monodisperse oil-in-water (O/W) micropheres (MS) were prepared using a novel microchannel (MC) emulsification technique. The characteristics of the MS preparation and the O/W-MS prepared were studied. Soybean oil and medium-chain triacyglycerol (MCT) were used as the disprrsed phase, and physiological saline was used as the continuous phase. Silicon MC with 1 to 3μm-equivalent channel diameters were employed. A novel MC module was devised to easily recover the O/W-MS prepared. The effects of the channel shape on the behavior of MS formation, on the MS size, and on the distribution were investigated. An MC with a terrace at the MC outlet stably yielded micron-scale monodisperse O/W-MS; the MS had diameters of about 5 μm, and their coefficients of variation were below 9%. Monodisperse food-grade O/W-MS with diameters of about 4 μm could be obtained by using polyglycerol fatty acid ester as the surfactant. The size and size distribution of the recovered O/W-MS remained almost constant over 60 d, demonstrating their long-term stability.     

β-壳聚糖基体磁性微球的制备

实验通过化学沉淀法制备磁性氧化铁/羟基磷灰石(Fe3O4/HA),然后以β-壳聚糖(β-CS)为基体,利用原位沉析法将Fe3O4/HA与β-CS复合,制得磁性Fe3O4/HA/β-CS复合材料。考察了NaOH浓度、反应温度、反应时间三个主要因素对产率的影响,最佳工艺条件为:氢氧化钠浓度:2mol/L,反应温度为37℃,反应时间为6h。     

Characterization of macroporous 1‐vinyl‐2‐pyrrolidone copolymers obtained by suspension polymerization

Radical suspension copolymerization of 1‐vinyl‐2‐pyrrolidone (VP) with three different cross‐linkers: divinylbenzene (DVB), trimethylolpropane trimethacrylate (TRIM), and di(methacryloxymethyl) naphthalene (DMN) was used to prepare macroporous microspheres. During the copolymerization, the mixture of toluene and n‐dodecane as a pore‐forming diluent was used. All samples were characterized in terms of particle size and distribution, nitrogen content, specific surface area total pore volume, and pore size distribution. It was found that specific surface area of the obtained beads is strongly dependent on the diluent system and the type of cross‐linker and achieves value from 27 to 845 m²/g. To determine the influence of chemical structure of cross‐linkers on the selectivity and polarity of the copolymers, inverse gas chromatography was applied. In addition, VP–DVB and VP–DMN copolymers were modified by sulfonation into cation‐exchangers with cation exchange capacity equal 1.98 and 2.31 mmol/g, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sorption of Phthalates on Molecularly Imprinted Polymers

Porous beads of styrene divinylbenzene copolymer, S-co-DVB, imprinted with dimethyl phthalate, DMP, were obtained. Two solvents were applied for the formation of pores: n-hexane and n-octane. The sorbents were prepared by membrane emulsification of monomer mixtures containing DMP followed by suspension polymerization. The average diameters of the synthesized beads were 40 µm for beads obtained from mixtures with n-octane, and 30 µm for preparations with n-hexane as solvent. It was shown that almost all monodispersive sorbents were obtained; their SPAN parameter was as small as 0.7–0.9. Sorption properties of evaluated samples varied in relation to the kind of applied reaction mixture. Generally, imprinted materials showed higher sorption capacity towards DMP than their off-template analogues. For the sorbent obtained in the presence of n-octane and with 3 wt.% of DMP, sorption of dimethyl phthalate took the highest value - 89 mg/g. The sorbents imprinted with DMP were checked for sorption of diethyl phthalate, DEP, and dibuthyl phthalate, DBP also. It was shown that sorbability of synthesized materials towards other phthalates was much smaller than for DMP and was not related to the presence of dimethyl phthalate foot prints.     

Feasible Preparation of a Thin‐Film Composite Nanofiltration (TFC NF) Membrane with Enhanced Skin–Substrate Adhesion and Compaction Resistance: In Situ Construction of Rigid–Flexible Polymer Composited Microspheres (CPs) in the Casting Solution

Novel microspheres (CPs) composited by rigid and flexible polymers are synthesized and embedded in the supporting membranes to enhance both the skin–substrate adhesion and compaction resistance of the thin‐film composite (TFC) nanofiltration membranes. The CPs are in situ formed in the casting solution after the rigid poly(p‐phenylene terephthamide) (PPTA) is produced in the flexible poly(m‐phenylene isophthalamide) (PMIA) solution. Then the PPTA/PMIA in situ blending membranes are prepared by using the NIPs method, and the TFC NF membranes are fabricated via interfacial polymerization on them. The CPs are characterized via polarizing microscopy and TEM. The surface morphology and chemical composition of the blended membranes are characterized by using FESEM, AFM, FTIR, and WCA, respectively. As the results show, the supporting membrane with higher PPTA content exhibits higher permeability, thermal stability, and compaction resistance. Moreover, the adhesion strength between the TFC functional layer and the supporting membrane is improved significantly. It is proposed that this improvement can be attributed to the CPs that are exposed on the top surface of the supporting membrane, which leads to a great enhancement because of the anchoring effect between the functional layer and the CPs.