微米级单分散聚苯乙烯微球的制备

以苯乙烯(St)为单体、偶氮二异丁腈(AIBN)为引发剂、聚乙烯吡咯烷酮(PVP)为分散稳定剂,在乙醇-水反应介质中,采用分散聚合法制备了微米级单分散聚苯乙烯(PS)微球。分别用电镜扫描和激光粒度仪表征了PS微球表面形貌、粒径及粒度分布,探讨了影响PS微球粒径及粒度分布的诸多因素。结果表明,AIBN用量(以单体质量计,下同)大于5.0%或PVP用量(以单体质量计,下同)小于2%时,PS粒子间有聚并现象;当St浓度为10%、AIBN用量为2.5%、PVP用量为5.5%、醇水质量比为90∶10、聚合温度为70℃时,制备的PS微球粒径为1.612μm、粒度分散系数为0.357,微球单分散性及球形度最佳。     

Uniform Polystyrene Particles by Dispersion Polymerization in Different Dispersion Medium

Using PVP K-30 as steric stabilizer and AIBN as initiator, uniform polystyrene (PS) particles were prepared by dispersion polymerization of styrene in ethanol/water and isopropanol/ water media. The effects of initiator and stabilizer concentration, alcohol/water volume ratio on the average sizes and size range of PS particles were investigated. Unifrom PS particles in the size range of 0.7-1.7 μm were obtained. The results showed that higher stabilizer concentration led to PS particles with smaller average sizes, and higher initiator concentration caused greater average particle sizes. It was also found that the average sizes reduced and size ranges became narrow as the polarity (solubility parameter) of dispersion medium employed was increased.     

单分散微米级PMMA微球的制备

以聚乙烯吡咯烷酮(PVP)为分散剂,乙醇和水为反应介质,偶氮二异丁腈为引发剂,甲基丙烯酸甲酯(MMA)为单体,采用分散聚合工艺,制备了单分散微米级PMMA微球。研究了乙醇/水介质的配比、反应温度、分散剂用量、单体用量、引发剂用量对PMMA微球粒径和粒径分布的影响。结果表明,PMMA微球粒径随乙醇用量的增加先增大后减小;随反应温度的升高先增大后减小,粒径分布先变窄再变宽;随单体用量的增加先增大后减小,随引发剂用量的增加而增大;随PVP用量的增加而减小,粒径分布先变窄再变宽。     

原位聚合法制备纳米ATO/PMMA乙醇分散液的研究

将纳米掺锑二氧化锡(ATO)粒子经过超声分散和偶联剂处理后,以甲基丙烯酸甲酯(MMA)为单体,用原位聚合法制备了纳米ATO/PMMA乙醇分散液。讨论了偶联剂种类、MMA与ATO质量比值、引发剂偶氮二异丁腈(AIBN)用量对纳米ATO/PMMA乙醇分散液分散稳定性的影响。确定了合适的偶联剂为乙烯基三叔丁基过氧硅烷(VTPS),最优工艺参数为m(MMA)∶m(ATO)=2,w(AIBN)=1.5%。往聚丙烯酸酯树脂加入该纳米ATO/PMMA乙醇分散液所制得的涂料,其涂膜同时具有良好的可见光透过率和近红外光阻隔性能。     

Monosize polystyrene microbeads by dispersion polymerization

Monosize Polystyrene microbeads were prepared by dispersion polymerization in different alcohol/ water media. Azobisisobutyronitrile and polyacrylic acid were utilized as initiator and steric stabilizer, respectively. The polymerizations were performed in three kinds of dispersion media having different polarities: isopropanol/water, 1-butanol/water, and 2-butanol/water. The effects of initiator and stabilizer concentrations, alcohol/water ratio, and monomer/dispersion medium ratio on the size and monodispersity of the polymeric microbeads were investigated. By dispersion polymerization, polystyrene (PS) microbeads were obtained in the size range of 1.0–4.0 μm with narrow size distribution or in the monosize form. The average size and size distribution of microbeads with increasing polarity of the dispersion medium. The average size and size distribution increased with increasing initiator concentration in all dispersion media. The increase in the stabilizer concentration in homogeneous dispersion media resulted in a decrease in average size and size distribution of the microbeads. A clear increase was observed in the average size with increasing monomer/dispersion medium ratio. Isopropanol/water dispersion medium provided monosize microbeads with higher values of monomer/dispersion medium ratio. © 1993 John Wiley & Sons, Inc.     

非极性混合介质中分散聚合法制备聚乙烯基吡咯烷酮

以乙烯基吡咯烷酮(NVP)为单体,环己烷的混合溶剂为分散介质,AIBN为引发剂,SEBS为分散剂,采用分散聚合的方法制备了分散性能好、粒径为1μm左右、热稳定性较好的聚乙烯基吡咯烷酮。考察了单体含量、引发剂用量、分散剂用量对分散聚合反应的影响。结果表明,转化率和分子量均随单体含量增加而增大,随引发剂的量的增大而减小;且在单体含量为30%、AIBN的用量为0.5%,分散剂用量为10%时,所合成的聚合物分子量最大。     

One‐pot synthesis of self‐stabilized and carboxyl‐functionalized fluorescent poly(methyl methacrylate) microspheres covalently dyed with tris(8‐hydroquinolinato)aluminium by dispersion polymerization

The dispersion polymerization of methyl methacrylate (MMA) with fluorescent monomer tris[2‐((8‐hydroxyquinolin‐5‐yl)methoxy)ethyl methacrylate]aluminium (Al‐HQHEMA) was investigated to obtain fluorescent microspheres under varying conditions (such as composition of dispersion medium, and content of stabilizer polyvinylpyrrolidone (PVP) and Al‐HQHEMA) in methanol–water at 70 °C with 2,2′‐azoisobutyronitrile as the initiator. Fluorescent microspheres with particle size of 2.039 µm and uniformity of 0.171 were obtained under the following conditions: methanol–water, 7:3 (v/v); PVP, 15 wt% of MMA; Al‐HQHEMA solution, 1.5 mL. Maleic monoester of monomethoxyl poly(ethylene glycol) (Mal‐MPEG) was used as a comonomer to simultaneously incorporate carboxyl groups and PEG chains. With Mal‐MPEG, no aggregation was observed in the measurements of particle size and size distribution for the obtained microspheres after cleaning off PVP, indicating that self‐stabilized fluorescent microspheres were obtained. While without Mal‐MPEG, obvious aggregation was observed. The determination of surface carboxyl content using aqueous acid–base titration showed that most of the carboxyl groups of Mal‐MPEG were located on the surface of the microspheres. © 2015 Society of Chemical Industry     

Dispersion polymerization of n‐butyl acrylate

The dispersion polymerization of n‐butyl acrylate (BA) was investigated using alcohol/water mixtures as the dispersion medium, 4,4′ ‐azobis‐(4‐cyanopentanoic acid) as the initiator, and polyvinylpyrrolidone (PVP) as the stabilizer. The effects of polymerization parameters, such as the alcohol/water ratio in the medium and the type and concentration of the polymeric stabilizer, on the resulting particle size and size distribution were studied. The final particle size and the stability of the dispersion system were found to be greatly influenced by the type of alcohol used in the mixture; that is, methanol or ethanol, even though the apparent solubility parameters are almost the same for the two types of mixtures. Poly(butyl acrylate) particles with controlled size and size distribution (monodisperse), and gel content were successfully prepared in a 90/10 methanol/water medium. It was found that the particle size decreased with increasing initiator concentration. This is the opposite of what was previously reported in the dispersion polymerizations of styrene and methyl methacrylate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2692–2709, 2002     

Differential microemulsion polymerization as a new root for entrapment of drugs

Nanosized particles derived from poly(methyl methacrylate) as well as copolymer of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) were synthesized by differential microemulsion technique in the presence of ammonium persulfate as water‐soluble initiator. The polymerization was stabilized by adding biologically safe emulsifiers namely the sodium dodecyl sulfate (SDS) or polyvinyl pyrrolidone (PVP) either alone or in conjunction with polyethylene glycol. The turbidity measurements, surface tension, ζ potential, and morphological characterizations of the obtained nanosized poly MMA and its copolymer with HEMA in different monomer feed compositions were investigated. It is found that increasing HEMA content leads to increase in the particle size, turbidity measurements but the negatively charged ζ potential decreased. However, when SDS is used, the surface tension of the prepared lattices increased, whereas it is decreased by using PVP. Kinetic studies of (MMA/HEMA) in ratio of 95/5 wt % in the presence of SDS or PVP revealed that the emulsifier concentration has a considerable effect on the rate of polymerization and the power of the emulsifier. The entrapment of drug was investigated using two active molecules different in water solubility (sodium warfarin and ibuprofen). It is noted that entrapment efficiency is independent of HEMA content in the monomer feed composition but dependent on type of drug and the amount of drug introduced. Hence, higher entrapment efficiency was attained for sodium warfarin (more hydrophilic) than that of ibuprofen (more hydrophobic) and they were 95.5 and 85%, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

淀粉-MMA接枝共聚物的半干法合成新工艺

以硝酸铈铵(CAN)为引发剂,采用固相半干法合成了玉米淀粉(CS)接枝甲基丙烯酸甲酯(MMA)共聚物。考察了含水量、反应体系的酸性、反应时间与温度、MMA单体和引发剂CAN用量等因素对接枝共聚反应的影响。结果表明,体系含水质量分数为35%左右,CAN用量为CS质量的1.5%～3%,反应温度在40～50℃,反应时间为0.5h左右,可得到接枝率、接枝效率和单体转化率均较高的接枝共聚物。     

羧基聚苯乙烯微球的单分散性制备及表征

文章通过分散聚合法,以苯乙烯（St）为聚合单体,聚乙烯吡咯烷酮（PVP）为稳定剂,偶氮二异丁腈（AIBN）为引发剂,乙醇和水作为分散介质,合成微米级聚苯乙烯微球,并以此微球为种子,利用种子修饰法进一步合成羧基聚苯乙烯微球,并对合成的羧基微球单分散性、表面形貌及表面羧基密度进行表征。结果表明,在合成的聚苯乙烯微球表面成功连接上羧基基团,微球具有较高的羧基密度,并且保持良好的单分散性,适合下一步在其表面进行化学与生物活化以制备液相芯片的敏感元件。     

天然松香改性苯丙乳液的制备及其性能研究

以苯乙烯(St)、甲基丙烯酸甲酯(MMA)、丙烯酸-2-乙基己酯(2-EHA)、丙烯酸-2-羟基乙酯(HEA)和丙烯酸(AA)为反应单体,利用天然松香乳液作为改性剂,通过乳液聚合的方式制备了松香-苯丙复合乳液。研究了乳化剂用量、引发剂用量、松香乳液用量和单体配比对乳液性能的影响。并通过TGA、DLS、TEM对所制备的复合乳液进行了表征。结果表明:当乳化剂用量为单体质量的5%、引发剂用量为单体质量的0.8%、松香乳液用量为单体质量的30%、m(硬单体)∶m(软单体)=2.5∶1时,制得的乳液呈白色泛蓝光,粒径为131 nm。成膜后,漆膜光滑透明,硬度(1H)、耐水性(接触角97.05°)和附着力(1级)等性能良好。     

Dispersion Polymerization of Styrene by Initiation Within Monomer Phase with Lauroyl Peroxide

Dispersion polymerization kinetics of styrene was investigated in this study. A monomer phase soluble initiator, namely lauroyl peroxide, and a water phase soluble emulsifier, namely sodium dodecyl sulfate, were used. the polymerizations were carried out in a magnetic drive, sealed, cylindrical polymerization reactor, in nitrogen atmosphere. Two different fatty alcohols, cetyl and lauryl alcohols, were tried as particle size increasing agents. the effects of initiator, emulsifier concentrations, monomer/water ratio, and the weight ratio of particle size increasing agent to emulsifier on the total monomer conversion, average size, and size distribution of the large latex particles were studied. the agglomeration conditions were tested by changing the polymerization temperature, initiator, and emulsifier concentrations. the results indicated that the polymerization rate and the average size of the latex increased with increasing emulsifier concentration. the average size of the latex was also increased with increasing initiator concentration. the use of cetyl alcohol in the presence of emulsifier resulted in an appreciable increase in the polymerization rate and in the average size of the latex. the effect of fatty alcohols on the polymerization rate in the dispersion polymerization system was completely different than that in the swollen emulsion polymerization. the agglomeration of the large latex particles was increased with decreasing emulsifier and increasing initiator concentrations.     

2‐Hydroxypropylmethacrylate based mono‐ and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35–200 µm were prepared by suspension polymerization of 2‐hydroxypropylmethacrylate (HPMA). In the proposed method, a mixture of cyclohexanol and octanol was used as a diluent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organic phase including the monomer and the crosslinker (ethylene glycol dimethacrylate) by an oil soluble initiator benzoyl peroxide. Spherical and swellable gel beads carrying both hydroxyl and carboxyl functional groups were also prepared by suspension copolymerization of HPMA and a water soluble comonomer (methacrylic acid). For this purpose, the suspension polymerization method proposed for HPMA was modified by using poly(vinyl alcohol) as a stabilizer instead of PVP. The effect of initiator concentration, polymerization temperature, monomer/diluent ratio, crosslinker concentration, stirring rate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of the gel beads were defined. © 2000 Society of Chemical Industry     

Monodisperse poly(butadiene/styrene) particles by dispersion polymerization

Experimental conditions for preparing monodisperse, micron-size poly(butadiene/styrene) particles by dispersion polymerization were investigated. After some initial recipe development, the following variables were fixed: butadiene/styrene weight ratio (90/10), dispersion medium (ethanol), polymeric stabilizer [poly(vinyl pyrrohdone), K-30], costabilizer (sodium dioctyl sulfosuccinate), initiator (2,2′-azobisisobutryonitrile), and polymerization temperature (70°C). The primary process variables investigated were the monomer/ethanol ratio (M/S), the rpm of the bottle polymerizer, and the amount of free space (FS) in the polymerization bottles. The particle size varied from 0.77 to 1.8 μm and was found to increase with increasing M/S and rpm, and decreasing FS. © 1995 John Wiley & Sons, Inc.     

Hydrophobic magnesium hydroxide nanoparticles via oleic acid and poly(methyl methacrylate)-grafting surface modification

Hydrophobic magnesium hydroxide nanoparticles were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of nanoparticles after oleic acid (OA) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by OA modification, followed by dispersion polymerization on the particles surface in ethanol solution using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and polyvinylpyrrolidone (PVP) as stabilizer to graft PMMA on the surface of OA-modified magnesium hydroxide. The obtained composite particles were characterized by XRD, FTIR, TGA, FESEM-EDS, and the compatibility with organic solution was determined by sedimentation test. The results show that the organic macromolecule PMMA could be successfully grafted on the surface of OA-modified magnesium hydroxide nanoparticles, with the dispersibility and the compatibility of nanoparticles greatly improved in organic phase.     

Kinetic investigations of acrylic–polyurethane composite latex

The effect of various reaction parameters on the rate of polymerization, R_p, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, R_m, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/R_p = 1/K + 1/R_m. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002     

Preparation of raspberry‐like poly(methyl methacrylate) particles by seeded dispersion polymerization

The facile preparation of nonspherical raspberry‐like poly(methyl methacrylate) (PMMA) particles by seeded dispersion polymerization of methyl methacrylate (MMA) on micron‐sized PMMA seed particles was described. Various polymerization parameters influencing the particle morphology, as well as the polymerization kinetic and morphological stability, were investigated in detail. It was found that the following polymerization conditions were necessary to prepare this kind of nonspherical particles: a relatively low temperature, an appropriate ratio of seed/MMA, an initiator with a relatively low decomposition rate, and a relatively low initiator concentration. These particles showed very good morphological stability at room temperature, but they changed to the spherical ones when heat treated at 60°C in methanol solution of MMA. The experimental results suggest that the prepared PMMA particles were kinetically favored and the localized polymerization of the MMA monomer on PMMA seed particle surface was responsible for the formation of the raspberry‐like particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

超声-微波共辐射法合成纤维素-MMA接枝共聚物

引言纤维素作为一种天然的可再生高分子材料,存在于丰富的绿色植物中,是自然界取之不尽用之不竭的清洁资源。因此,在煤、石油、天然气的储量日益减少的今天,纤维素可作为一种可持续发展的绿色资源来研究和开发。而且天然植物纤维资源丰富、价格低廉,并且具有较好的生物可降解性,在     

分散聚合法合成含有环氧基的无孔超顺磁性微球及其表征

Non-porous superparamagnetic polymer microspheres with epoxy groups were prepared by dispersion polymerization of glycidyl methacrylate (GMA) in the presence of magnetic iron oxide (Fe3O4) nanoparticles coated with oleic acid. The polymerization was carried out in the ethanol/water medium using polyvinylpyrrolidone (PVP) and 2,2'-azobisisobutyronitrile (AIBN) as stabilizer and initiator, respectively. The magnetic microspheres obtained were characterized with scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the magnetic microspheres had an average size of 1μm with superparamagnetic characteristics. The saturation magnetization was found to be 4.5emu·g-1. There was abundance of epoxy groups with density of 0.028 mmol·g-1 in microspheres. The magnetic PGMA microspheres have extensive potential uses in magnetic bioseparation and biotechnology.