A Simple Method for Synthesizing Ultra-high-molecular-weight Polystyrene through Emulsion Polymerization Using Alkyl-9-BBN as an Initiator

Styrene emulsion polymerization using an alkyl-9-BBN, synthesized by reacting 9-BBN(9-borabicyclo-[3.3.1]-nonane) and styrene, in an aqueous sodium dodecyl sulfate(SDS) solution was studied. Ultra-high-molecular-weight( 1.0 × 10~7) polystyrene was synthesized using a radical initiator formed through the aerobic oxidation of this alkyl-9-BBN in a high yield( 80%). The kinetics of this emulsion polymerization of styrene with the alkyl-9-BBN was investigated. We confirmed that in the initial stage of the polymerization, the initial reaction rate followed first-order kinetics. The activation energy for this emulsion polymerization of styrene was approximately 56.2 kJ/mol.     

微乳液聚合制备多孔高吸油甲基丙烯酸酯类树脂的研究

研究了双连续相微乳液聚合制备多孔高吸油树脂,以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为共聚单体(油相),水(H2O)/乙醇(EtOH)为混合水相,2,2′-偶氮二异丁腈(AIBN)为引发剂,采用十二烷基硫酸钠(SDS)和复配十二烷基硫酸钠/吐温80(SDS/T80)两种乳化体系,调节油相和水相比例,配制出双连续相微乳液.聚合在无搅拌下进行.研究了乳化体系、混合水相含量、单体配比、交联剂和引发剂用量等因素对树脂吸油性能的影响.结果表明,多孔高吸油树脂比同系无孔树脂的吸油速率大大提高,最快可以在2min内达到吸油饱和.树脂对苯,四氢呋喃,四氯化碳的吸油倍率分别达到15.5g/g,15.5g/g,31.7g/g.     

Modified structural model for predicting particle size in the microemulsion and emulsion polymerization of styrene under microwave irradiation

In this study, the microemulsion and emulsion polymerization of styrene at 70 degrees C in the presence of sodium dodecyl sulfate (SDS, surfactant) and potassium persulfate (KPS, initiator) was conducted under microwave radiation. Laser light scattering was used to characterize the resultant polystyrene latex particles formed at different polymerization stages. The influence of the initial emulsion composition, that is, the SDS, KPS, and styrene concentrations, on the final particle size led us to a simple modified structural model in which we considered the stabilization effects of both the surfactant and the ionic end groups generated from the initiator. This model extended the application of the previous Wu plot from microemulsion polymerization to emulsion polymerization. Using this model, we were not only able to control the particle size but were also able to predict the monomer concentration dependence of the number of the resultant latex particles and the effect of diluting the reaction mixture on the resultant particle size.     

硅丙乳液的合成工艺研究

采用半连续种子乳液聚合工艺,以乙烯基三乙氧基硅烷(VTS)为改性剂、十二烷基硫酸钠(SDS)和烷基酚聚氧乙烯醚(OP-1O)为复合乳化体系,在引发剂过硫酸铵(APS)的作用下合成稳定的硅丙乳液.利用红外光谱(FTIR)和扫描电镜(SEM)对涂膜进行了表征.结果表明:单体转化率随乳化剂用量、引发剂用量、有机硅用量、聚合温...     

光致变色含氟丙烯酸酯涂层的制备及性能

选取十二烷基硫酸钠(SDS),辛基苯基聚氧乙烯醚(OP-10)为复合乳化剂,过硫酸钾(KPS)为引发剂,将2-(全氟己基)乙基甲基丙烯酸酯(PFM)与丙烯酸酯类单体采用预乳化-半连续种子乳液聚合法进行乳液共聚,再将羟基螺吡喃(SPOH)与乳液进行物理共混,制得光致变色含氟丙烯酸酯乳液。 通过多种表征手段研究丙烯酸正丁酯(n-BA)和甲基丙烯酸甲酯(MMA)软硬单体的质量比,SPOH的用量对聚合反应和乳胶膜性能的影响。 结果表明,加入含氟单体后乳胶膜与水、油的接触角提高,热稳定性提高;加入SPOH的质量分数为1.25%时,乳胶膜具有较好的光致变色性能。     

氧化-还原低温引发苯乙烯/丙烯酸丁酯细乳液共聚合动力学与成核机理的研究

详细讨论了 [(NH4 ) 2 S2 O8/NaHSO3 ]氧化 还原引发体系引发苯乙烯 (St)丙烯酸丁酯 (BuA)体系的细乳液共聚合的动力学特征及其与成核机理的关系 .细乳液的聚合速率比相同条件下的常规乳液聚合速率低 ,引发期长 .随聚合温度、引发剂浓度、乳化剂浓度的增加 ,聚合速率增大 .共乳化剂正十六烷 (HDE)的浓度在一定范围内增大 ,反应的速率增大 ,然后再增加HDE ,反应速率下降 .建立动力学曲线数学模型 ,并深入讨论了细乳液的聚合动力学特征 ,与常规乳液所得结果相比较 ,探讨了细乳液的单体液滴成核机理 .     

Synthesis of saccharidic polymer colloids via free radical mini‐emulsion polymerization

Polymer colloids based on 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG) and butyl acrylate (BA) were prepared via free radical mini‐emulsion polymerization. The kinetic and colloidal features of the copolymerization were investigated. The final particle size (D) of the sugar latexes is inversely proportional to the concentration of the anionic emulsifier (sodium dodecyl sulphate, SDS) and the non‐ionic one (alkyl polyglucoside, APG). It was also found that D is independent of the concentration of either the water‐soluble initiator (potassium persulfate, KPS), or the oil‐soluble initiator (2,2′‐azobisisobutyronitrile, AIBN). The rate of mini‐emulsion polymerization is lower in comparison with the conventional emulsion polymerization under the same conditions. The polymerization rate (R_p) and the total number of particles (N_p) are proportional to the 0.72th and 0.93th power of the SDS, and to the 1.40th and 2.22th of the APG concentration. Following reaction orders, 0.79/0.06 were obtained for R_p/N_p versus the concentration of KPS, and 0.22/?0.01 for AIBN, respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Emulsifier-free emulsion copolymerization of styrene and acrylamide using an amphoteric initiator

Emulsifier-free emulsion copolymerization of styrene (St) and acrylamide (AAm) has been investigated in the presence of an amphoteric water-soluble initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine]hydrate (VA057). The kinetics of polymerization and the colloidal properties of the resulting latices were studied and compared with the cases using ionic initiators. When adopting the amphoteric initiator at pHs lower than 10, stable amphoteric poly (St/AAm) latices, evidenced by the electrophoretic mobility, were prepared directly. Meanwhile, almost the same conversion versus time curves appeared and there were no apparent differences in the final particle sizes for those polymerizations, whereas in the polymerization at pH 10, a much lower rate of copolymerization and a larger size of particles were observed. The surface charge density and the growth rate of latex particles produced with VA057 at pH<10 were comparable to those of the particles with a cationic initiator, 2,2′-azobis(2-amidinopropane)dihydrochloride, but were apparently lower than those with an anionic initiator, potassium persulfate, when the polymerizations were carried out under corresponding conditions. The number of initiator fragments incorporated onto the particle surfaces was independent of polymerization pH, except for pH 10. The abnormal performance of VA057 at pH 10 was attributed to its degradation due to hydrolysis. Received: 14 December 1999 Accepted: 22 February 2000     

Kinetic and particle size studies of emulsion polymerization of methyl methacrylate and styrene with using polyamidoamine dendrimer as seed

The emulsion polymerization of methyl methacrylate (MMA) and styrene (St) were investigated with using polyamidoamine (PAMAM) dendrimer as seed, potassium persulfate as initiator and sodium dodecyl sulfate as emulsifier. The effects of 4.0GPAMAM dendrimer concentration, initiator concentration, emulsifier concentration, monomer concentration, and polymerization temperature on the monomer conversion and polymerization rate were investigated. At the same time, the influence of the generation of PAMAM dendrimer on latex particle size was studied also. The results showed that the monomer conversion and polymerization rate increased with increasing initiator concentration, emulsifier concentration, monomer concentration, and polymerization temperature. But polymerization rate increased firstly with an increase in the 4.0GPAMAM dendrimer from 0.03 g to 0.09 g and then decreased with further increase to 0.12 g. When the concentration of 4.0GPAMAM dendrimer less than 1.449 × 10^?4 mol/L, the kinetic equation can be expressed by Rp∝[4.0GPAMAM]^0.772[SDS]^0.562[KPS]^0.589[M]^0.697, and the activation energy (Ea) of emulsion polymerization is 62.56kJ/mol. In additional, the copolymer latex particle size decreased and possessed monodispersity with increasing the generation of PAMAM dendrimer. According to FT-IR spectrum analysis, PAMAM dendrimer is successfully incorporated into the poly(PAMAM-St–MMA) latex particles.     

Facile fabrication of monodisperse polymer hollow spheres

This article reports the facile synthesis of monodisperse polymer hollow spheres by seeded emulsion polymerization without additional treatment. In this method, P(St-MMA-MAA) copolymer latex particles were first prepared by emulsifier-free emulsion polymerization and then used as seeds to carry out emulsion polymerization of methyl methacrylate (MMA), divinyl benzene (DVB), and 2-hydroxyethyl methacrylate (HEMA) with potassium persulfate (KPS) as initiator at 80 degrees C. The void of hollow spheres was readily adjusted by changing the monomer/seed weight ratio, and it could be enlarged while the diameters of hollow spheres changed little after etching by dimethyl formamide (DMF). The effects of synthetic parameters including the monomer composition and the properties of seeds on the morphology of hollow spheres were investigated in detail. On the basis of the experimental results, it seemed reasonable to conclude that the formation of hollow spheres was due to the "dissolution" of seeds in monomers and phase separation between the constituent polymers. As a thermodynamic factor, sodium dodecyl sulfate (SDS) would allow the preparation of solid particles depending on its level.     

STUDY ON THE POLYMERIZATION KINETICS AND STABILITY OF P(UA)/MMA MICROEMULSION*

 Urethane acrylate anionomer (APUA) as a kind of new type polymerizable emulsifier was synthesized using 2,4-toluene diisocyanate (TDI), polypropylene glycol (PPG), 2-hydroxyethyl methacrylate (HEMA) and dimethylolpropionic acid (DMPA). The critical micelle concentration (CMC) of APUA was measured by the methods of conductance and surface tension. The comparative studies between polymerizable emulsifier AUPA and conventional emulsifier sodium dodecyl sulfate (SDS) were carried out in the emulsion polymerization of methyl methacrylate (MMA). Polymerization kinetics,stability, size and morphology of the latex particles were investigated. It was found that in APUA both water soluble initiator potassium persulfate (KPS) and oil soluble initiator 2,2'-azobisisobutyronitrile (AIBN) can start the reaction of MMA, and the polymerization rate and yield were very high. On using AIBN as an initiator, the conversion-time behavior of MMA with APUA as emulsifier was different to that of SDS as emulsifier, signifying a different nucleation mechanism of the polymer latex particle. The average size of the two kinds of particles is about 50 nm. The particle size decreases with increasing emulsifier concentration. On using KPS as the initiator, APUA as emulsifier, cross-linking hydrogel of PMMA would be formed, but SDS was used as emulsifier and the hydrogel of PMMA was not present.     

Solvent Effect in PLA-PEG Based Nanoparticles Synthesis through Surfactant Free Polymerization

Summary: In this work one-pot synthesis of PEGylated PLA-based nanoparticles (NPs) without using any surfactant has been performed. Adopting ring opening polymerization of L,L–Lactide and 2-hydroxyethyl methacrylate (HEMA), vinyl end functionalized poly(lactic acid) macromonomers (HEMA-LA_n) have been produced with tunable number of lactic acid units (larger than 5) and a low molecular weight distribution. Macromonomers have been further copolymerized with modified PEG chains (HEMA-PEG_m) through a monomer starved semi-batch emulsion polymerization performed without using any surfactant. In these conditions, small and monodispersed NPs of around 150 nm are obtained. Since macromonomers with n larger than 5 are highly viscous at room temperature, they have to be dissolved in a solvent before their injection in the reactor. In this work the effects in changing the solvent adopted in the starved process (water miscible or non-miscible) and its amount have been investigated. Moreover, the effect of both PEG chains concentration and MW on the final NPs properties has been elucidated. The colloidal stability of the NPs produced using different solvents has been verified in phosphate buffered saline (PBS) solution via dynamic light scattering measurements; in addition the critical coagulation concentration of these PEGylated NPs has been determined.     

Influence of surfactants on the morphologies of CaCO3 by carbonation route with compressed CO2

Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and polyoxyethylene-80-sorbitan monooleate (Tween 80), were used to control the growth of CaCO₃ crystals by carbonation route using Ca(OH)₂ and compressed CO₂. The obtained CaCO₃ particles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The effects of surfactants on the morphology of the particles were studied. It was demonstrated that Tween 80 and SDS have obvious effect on the morphology of CaCO₃ particles, while CTAB does not affect morphology considerably. The possible mechanism has been discussed on the basis of the binding of the surfactants to the certain face of the crystals.     

Synthesis of latex particles with surface amino groups

Monodisperse latex particles with surface amino groups were prepared by a two‐step emulsion polymerization. In the first step, the seeds were synthesized by batch emulsion polymerization of styrene; and in the second step, two different amino‐functionalized monomers [aminoethylmethacrylate hydrochloride (AEMH) and vinylbenzylamine hydrochloride (VBAH)], two different initiator systems (K₂S₂O₈ and K₂S₂O₈/Na₂S₂O₅) and mixtures of emulsifiers sodium dodecylsulfate (SDS) and Tween 21 were used to synthesize the final latexes. To characterize the final latexes, conversions were obtained gravimetrically and particle size distributions and average particle diameters were determined by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). The amount of amino groups was determined by the SPDP (N‐succinimidyl 3‐(2‐pyridyldithio)propionate) method. The influence of the different conditions used to synthesize the latexes on the colloidal stability of the particles was evaluated by measuring the diameters of the final latexes dispersed in solutions at different pHs and ionic strengths. The most stable latexes were obtained using the smallest seed, VBAH monomer, and the K₂S₂O₈/Na₂S₂O₅ initiator system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4230–4237, 2000     

Unseeded semibatch emulsion polymerization of butyl acrylate: Bimodal particle size distribution

Unseeded semibatch emulsion polymerization of butyl acrylate (BA) using sodium lauryl sulfate as emulsifier and potassium persulfate as initiator was carried out at the conditions where secondary nucleation was probable. This was achieved by using no emulsifier in the initial reactor charge. The effects of changes in monomer emulsion feed rate, initiator concentration and distribution, emulsifier concentration in the feed, and temperature on the evolution of particle size averages and distribution were investigated. Bimodal particle size distributions (PSD) were obtained for most of the latexes. Inhibition effects were found to be important in the development of PSD. Primary particle formation occurred through micellar nucleation, whereas secondary nucleation probably occurred through homogenous nucleation. The polydispersity index (PDI) of the latexes increased with the decreasing monomer emulsion feed rate. The application of a larger amount of initiator to the reactor charge or using a higher temperature, reduced the formation of secondary particles and resulted in a formation of an unimodal PSD. The overall steady‐state rate of polymerization was found to approach the rate of monomer addition (R_p ≈ R_a ), if the emulsifier concentration in the aqueous phase was appreciable. This is different from the correlation 1/R_p = 1/K + 1/R_a obtained for the BA semibatch process with neat monomer feed. This suggests that different rate expressions can be used for BA semibatch emulsion polymerization at different conditions. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 528–545, 2000     

The effect of cosurfactants and the initiator concentration on the polymer to surfactant concentration in nanolatexes

The effect of cosurfactant and initiator concentration on the ab initio production of nanolatexes using low surfactant levels was investigated. While the use of cosurfactants (acrylic acid and pentanol) increased the amount of monomer that can be used in styrene‐SDS microemulsion formulations to 13 wt %, high surfactant concentrations are still required, resulting in polymer‐to‐surfactant ratios (Pol/Surf) <1. Latexes with particle size of 30 ± 5 nm were produced upon polymerization of these microemulsions. The Pol/Surf can be significantly increased by increasing the initiator concentration of emulsion polymerization recipes. Particle sizes are comparable with microemulsion latexes, however, less surfactant is required. The reduction in the particle size with higher initiator concentration is attributed to a higher efficiency of particle nucleation and to a higher nucleation rate relative to the rate of monomer transfer. Nanolatexes (particle size < 30 nm) were obtained with 19 wt % solids content and Pol/Surf of 3.6 in ab initio. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Revisit to the formation mechanism of exfoliated montmorillonite/PMMA nanocomposite latex through soap‐free emulsion polymerization

Soap‐free emulsion polymerization of methyl methacrylate (MMA) in the aqueous suspension of montmorillonite (MMT) was able to fabricate the exfoliated MMT/PMMA nanocomposite latex. Because neither MMA nor substantial quantity of potassium persulfide (KPS) initiator could be individually absorbed into the interlayer region of MMT, the polymerizing ionic radicals in water phase were considered as a major component to diffuse into the gallery of MMT. They have been observed to organize into disk‐like micelles in the interlayer regions to exfoliate MMT. The diffusion of the polymerizing ionic radicals was further supported by using sodium dodecyl sulfate (SDS) surfactant as a model compound to diffuse into the gallery of MMT. The exfoliation of MMT was almost completed before micellization stage was over. After exfoliation, the disk‐like micelles became a polymerization loci for monomers. Because the disk‐like micelles in numbers were substantially over the commonly formed spherical micelles in the typical soap‐free emulsion polymerization, the conversion rate of MMA to MMT/PMMA nanocomposite latex was faster. Based on the above experimental observation, a justified exfoliation mechanism of MMT was proposed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 459–466, 2009     

氧化-还原引发剂引发苯乙烯超浓乳液聚合的研究

以过氧化羟基二异丙苯(CHPO)和四乙烯五胺(TEPA)为氧化-还原引发剂,以十二烷基硫酸钠(SDS)为乳化剂,十六醇(CA)为共乳化剂,通过超浓乳液聚合方法制备了聚苯乙烯乳胶粒子.探讨了乳化剂浓度及配比、分散相体积分数、引发剂种类、引发剂浓度及配比和温度等各因素对乳液稳定性、聚合速率、乳胶粒子大小、形态及分布的影响.用透射电子显微镜(TEM)观察了乳胶粒子的形态,用粘度法测定了聚苯乙烯的粘均分子量.考察了苯乙烯进行超浓乳液聚合的反应动力学,求得在30℃时聚合速率方程为Rp=K[M]^0.36[I]^0.49[E]^0.72,表观活化能为19.72kJ/mol.所得乳胶粒子的直径在0.1～0.3μm之间,粘均分子量在2×10⁶～4×10⁶之间.为低温下实现超浓乳液薄层聚合提供了参考数据.     

The Total Solubility of the Co-Solubilized PAHs with Similar Structures Indicated by NMR Chemical Shift

The synergism/inhibition level, solubilization sites and the total solubility (S_t) of co-solubilization systems of phenanthrene, anthracene and pyrene in Tween 80 and sodium dodecyl sulfate (SDS) are studied by ¹H-NMR, 2D nuclear overhauser effect spectroscopy (NOESY) and rotating frame overhauser effect spectroscopy (ROESY). In Tween 80, inhibition for phenanthrene, anthracene and pyrene is observed in most binary and ternary systems. However, in SDS, synergism is predominant. After analysis, we find that the different synergism or inhibition situation between Tween 80 and SDS is related to the different types of surfactants used and the resulting different co-solubilization mechanisms. In addition, we also find that three polycyclic aromatic hydrocarbons (PAHs) have similar solubilization sites in both Tween 80 and SDS, which are almost unchanged in co-solubilization systems. Due to the similar solubilization sites, the chemical shift changes of surfactant and PAH protons follow the same pattern in all solubilization systems, and the order of chemical shift changes is consistent with the order of changes in the St of PAHs. In this case, it is feasible to evaluate S_t of PAHs by chemical shift. In both Tween 80 and SDS solutions, the ternary solubilization system has relatively high S_t rankings. Therefore, in practical applications, a good overall solubilization effect can be expected.     

预聚物复合助稳定剂条件下含氟丙烯酸酯共聚物的细乳液聚合

以甲基丙烯酸三氟乙酯(TFMA)、苯乙烯(St)和丙烯酸丁酯(BA)为共聚单体,在十二烷基硫酸钠(SDS)/磺酸盐型阴离子氟表面活性剂(S100)/辛基苯基聚氧乙烯醚(OP-10)组成的乳化体系中,采用预聚物和十六醇(HDL)共同组成的复合助稳定剂,对细乳液聚合制备St/BA/TFMA三元共聚物的过程进行了研究.通过F...