反应性乳化剂存在下的五元苯丙乳液共聚合

采用反应性乳化剂SE-10N,通过正交实验及单因素实验确定了以苯乙烯、甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸和丙烯腈为单体的五元无皂苯丙共聚乳液的组成及聚合工艺。所制得的无皂乳液稳定,其乳胶粒大小均匀,粒径为50~60nm,比同组成的有皂乳液乳胶粒的粒径稍小。乳液涂膜透明、硬度达H级;其硬度、耐水性及钙离子稳定性均较同组成有皂乳液的好。     

On the emulsion polymerization of styrene in the presence of a nonionic emulsifier

The batch emulsion polymerization kinetics of styrene (St) initiated by a water-soluble peroxodisulfate in the presence of a nonionic emulsifier was investigated. The polymerization rate versus the conversion curves showed two nonstationary rate intervals, two rate maxima, and Smith–Ewart Interval 2 (nondistinct). The rate of polymerization and number of nucleated polymer particles were proportional to the 1.4th and 2.4th powers, respectively, of the emulsifier concentration. Deviation from the micellar nucleation model was attributed to the low water solubility of the emulsifier, the low level of the micellar emulsifier, and the mixed modes of particle nucleation. In emulsion polymerizations with a low emulsifier concentration, the number of radicals per particle and particle size increased with increasing conversion, and the increase was more pronounced at a low conversion. By contrast, in emulsion polymerizations with a high emulsifier concentration, the number of radicals per particle decreased with increasing conversion. This is discussed in terms of the mixed models of particle nucleation, the gel effect, and the pseudobulk kinetics. The formation of monodisperse latex particles was attributed to coagulative nucleation and droplet nucleation for the polymerizations with low and high emulsifier concentrations, respectively. The effects of the continuous release of the emulsifier from nonmicellar aggregates and monomer droplets, the close-packing structure of the droplet surface, and the hydrophobic nature of the emulsifier on the emulsion polymerization of St are discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4422–4431, 1999     

Emulsion copolymerization of styrene with a nonionic styrenic polymerizable surfactant

Among the variety of possible structures for polymerizable surfactants, it seems clear that the most interesting should be those with the reactive group located in the hydrophobic part of the molecule. We report here a study based on such a surfactant. Its general formula is A set of surfactants has been produced with m varying from 23 to 48 and n = 6 or 12. The compounds have been characterised by ¹H-NMR (nuclear magnetic resonance), size exclusion chromatography, surface tension measurements and turbidimetry. These surfactants have been copolymerized with styrene in emulsion polymerization. The coagulum is rather important, except if m is large enough. Although the incorporation of the surfactant in the latex is rather high. Most of the anchored surfactant remains at the surface and is not too buried inside. The particle size decreases with both the amount of surfactant and the length of its hydrophilic part. The use of these polymerizable surfactants leads to an excellent stability of the latex against the addition of electrolytes, and also against freeze-thawing constraints.     

Emulsion copolymerization of vinyl acetate and butyl acrylate in the presence of fluorescent dyes

This article describes our first experiments for preparing dye‐labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate‐butylacrylate (VAc‐BA). We discuss the synthesis of acrylate derivatives of phenanthrene, anthracene, and pyrene [9‐acryloxymethyl phenanthrene ( 7 ), 9‐acryloxymethyl‐10‐methyl anthracene ( 8 ), and 1‐acryloxymethyl pyrene ( 10 )] and an allyl ether derivative of anthracene [9‐allyoxymethyl‐10‐methyl anthracene ( 9 )]. Although the phenanthrene derivative 7 gave latex particles with high monomer conversion and good dye incorporation, the pyrene acrylate and both anthracene comonomers strongly inhibited the free‐radical reaction. To assist our search for a dye that would serve as a useful energy acceptor for phenanthrene and without suppressing VAc‐BA polymerization, we also examined batch emulsion polymerization in the presence of a variety of dye derivatives—substituted anthracenes, acridines, a coumarin, and two benzophenone derivatives. All of the anthracene derivatives, as well as acridine, strongly inhibited monomer polymerization. The coumarin dye 7‐hydroxy‐4‐methyl coumarin ( 22 ) that had only limited solubility allowed more than 90% monomer conversion. Most promising were 2‐hydroxy‐5‐methyl benzophenone ( 23 ) and 4‐N,N‐dimethylamino benzophenone ( 24 ) that at 1 mol % in the monomer mixture permitted virtually quantitative monomer conversion to latex. 4′‐Dimethylamino‐2‐acryloxy‐5‐methyl benzophenone ( 25 ) copolymerized well with the VAc‐BA mixture, yielding latex particles in high yield and with a narrow size distribution. These dyes appear to be useful acceptor dyes for energy‐transfer experiments with phenanthrene. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1594–1607, 2002     

反应性乳化剂存在下半连续苯丙乳液共聚合表观动力学

研究了在反应性乳化剂SE-10N存在下,采用半连续滴加工艺进行苯丙乳液共聚合的表观动力学.首先利用间歇法研究了引发剂、乳化剂用量、单体总量和温度对聚合反应速率的影响,得到了相应的聚合反应速率方程为Rp =k[M]0.30[I]0.18[E]0.97,并计算得到聚合反应的表观活化能为90.8 kJ·mol-1.然后采用半连续滴加法,讨论了不同滴加速率对聚合表观速率Rp的影响,结果表明,随滴加速率Ra 的增加,反应速率Rp也增加,但增加的幅度逐渐减少,且聚合过程的状态不断远离饥饿态.要使该聚合过程的状态保持在稳定的饥饿态,单体滴加时间应控制在140 min 以上.     

Emulsion copolymerization of butyl acrylate with cationic monomer using interfacial redox initiator system

The polymerization kinetics of butyl acrylate/[2‐(methacryloyoxy)ethyl]trimethyl ammonium chloride (BA/MAETAC) macroemulsion and miniemulsion copolymerizations was investigated with cumene hydroperoxide/tetraethylenepentamine as a redox initiator system. The postulate of an interfacial copolymerization with the two‐component redox initiator system (one hydrophobic and the other hydrophilic) was confirmed. Adding MAETAC had a complex effect on the polymerization kinetics of BA. The influence was ascribed to variations in the nucleation mechanism, which were dependent on the level of MAETAC, and the polymerization method (macroemulsion vs miniemulsion). It was proposed that at the beginning of a macroemulsion copolymerization with high MAETAC composition the micellar copolymerization occurred, which controlled the nucleation process. The hydration properties of the latex were used to characterize the copolymer composition. The composition of the copolymer from the interfacial polymerization was very heterogeneous. The copolymer composition was lower in BA when there was an increase in BA conversion or the particle size. Adding salt increased the MAETAC content and decreased the BA content in the copolymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2696–2709, 2001     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. I. Kinetic studies

A polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) and its nonpolymerizable counterpart were used in comparative studies of the emulsion polymerization of vinyl acetate. The conversion-time behavior differed for the two surfactants; the TREM LF-40 showed a decrease in the polymerization rate with increasing concentration while its hydrogenated derivative showed the opposite behavior, the rate increasing with increasing surfactant. Particle size analysis revealed a decreasing particle size with increasing surfactant concentration for both series of reactions. An explanation for the seemingly ambiguous results obtained for the polymerizable surfactant was sought by examining the reactivity of its vinyl group in copolymerization with vinyl acetate and its allylic group in a chain transfer reaction. The results suggest that both the copolymerization and chain transfer reactions can lead to the observed reduction in polymerization rate with increasing TREM LF-40 concentration. © 1992 John Wiley & Sons, Inc.     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. II. Polymerization mechanism

The mechanism of growth of latex particles in the emulsion polymerization of vinyl acetate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) was investigated. Both the aqueous phase and the particle/water interface were found to be loci for the copolymerization of TREM LF-40 with vinyl acetate. Competitive growth experiments using TREM LF-40 and its nonpolymerizable derivative were conducted to separate the effects of aqueous phase and particle surface. Particle size analysis of the seeded and unseeded polymerizations coupled with kinetic results suggested that the reactions at the particle/water interface are more important and that the particle size of the latexes is a key parameter controlling the polymerization rate through copolymerization and chain transfer to the polymerizable surfactant at the particle surface. A decrease in particle size lead to an increase in the amount of TREM LF-40 polymerized at the particle surface and to a decrease in polymerization rate. © 1992 John Wiley & Sons, Inc.     

乳化剂对聚硅氧烷乳液稳定性的影响

研究了乳化剂烷基酚聚氧乙烯醚(OP)、烷基聚氧乙烯醚和烷基季铵盐对聚硅氧烷乳液聚合的影响。采用复合乳化剂可以提高乳液稳定性。结果表明：①在以D4、N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷为原料的乳液聚合中。当非离子型乳化剂烷基聚氧乙烯醚和离子型乳化剂烷基季铵盐复合使用时,二者性能互补,产生协同效应,可使聚合物乳液具有很大的稳定性。②在实验选定的乳化剂中,非离子型烷基聚氧乙烯醚乳化剂用量为80mL(含量为0．05g／mL)、离子型烷基季铵盐乳化剂为60mL(浓度为0．05g／mL)时。其乳液的电解质稳定性、pH稳定性、冻融高温稳定性和离心稳定性等较好。     

Study of the mechanism of the emulsifier-free emulsion polymerization of the styrene/4-vinylpyridine system

For the emulsifier-free emulsion copolymerization of styrene with the water-soluble comonomer 4-vinylpyrindine (4VP), and using ammonium persulfate as an initiator, the kinetics, the content of 4VP, the molecular weight and the molecular weight distributions of the polymer at various conversions, and particle morphologies have been investigated. Based on the results obtained, the particle nucleation mechanism was discussed. Received: 9 September 1998 Accepted in revised form: 23 February 1999     

The dissolution of ionized water-insoluble carboxylated polymer particles in the nonionic emulsifier solution

It was found that 276 nm-sized styrene-butyl acrylate-methacrylic acid terpolymer (P(S-BA-MAA)) (50.4/40.9/8.7, molar ratio) particles produced by emulsifier-free emulsion polymerization dissolved in a polyoxyethylene nonylphenylether nonionic emulsifier aqueous solution at pH values above 11 and above 25°C resulted in polymer microemulsion. The weight-average diameter of P(S-BA-MAA) microparticles in the solution was 31 nm, which was measured by dynamic light scattering spectroscopy. Such a dissolution of the particles was not observed in the absence of the emulsifier.Part CXLI of the series Studies on Suspension and Emulsion.     

无皂乳液聚合法合成阴离子PS微球及粒径控制

以苯乙烯(St)和丙烯酸(AA)为单体,过硫酸钾(KPS)为引发剂,采用无皂乳液聚合法合成了单分散阴离子聚苯乙烯(PS)微球,并对微球结构和影响单分散性的因素进行了研究。结果表明,AA单体也已共聚到聚合物链上,AA的加入使PS微球粒径减小,并赋予PS微球表面负电性;聚合反应的活化能为42.95kJ/mol,升高聚合温度提高了反应速率;随着KPS用量的增加,PS微球粒径减小,在用量为0.6%时呈现最好单分散性;随着反应介质中丙酮含量增加,聚合物在介质中溶解度增加,使PS微球粒径有所减小,但微球粒径分布有所变宽。     

反应性乳化剂对有机硅-丙烯酸酯乳液共聚合的影响

有机硅改性丙烯酸酯;乳液聚合;反应性乳化剂对有机硅-丙烯酸酯乳液共聚合的影响     

无乳化剂乳液聚合制备高分子量聚乙烯醇

通过无乳化剂乳液聚合方法, 采用氧化还原引发体系制备了超高分子量的聚醋酸乙烯酯(PVAc), 继而醇解为超高分子量的聚乙烯醇(PVA). 研究了聚合温度、引发剂浓度、单体转化率对PVA的分子量和分子结构的影响. 探讨了线性高分子量PVA结构的控制方法. 结果表明, 利用无乳化剂乳液聚合可以实现在室温(14~20 ℃)制备出聚合度为9899的高分子量的PVA, 聚合过程对PVA的分子量和结构均有显著的影响. 在无乳化剂乳液聚合恒速聚合区得到的聚合物分子量较高, 分子量分布窄, 且结构比较规整, 而在加速区, PVAc的支化和交联现象显著, 最终会对PVA的线性程度产生很大影响. 因此, 可以通过聚合过程来控制PVA的分子量和链结构.     

Emulsion copolymerization of styrene with monomeric emulsifiers

Monomeric emulsifiers with different copolymerization reactivities were used as stabilizers in emulsion polymerization of styrene initiated by 2,2′ azobisisobutyronitrile (AIBN). A significant change in emulsifier function was observed between equal micellar concentrations of surface-active sodium sulfopropyl alkyl maleates and the corresponding sodium sulfopropyl dodecyl fumarate. In the presence of less reactive maleates, copolymerization mainly occurs in the interface of the monomer swollen particles, while copolymerization with the fumarate in the first period of emulsion polymerization leads to polyelectrolyte formation in the water phase.     

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     

Monosized cationic nanoparticles prepared by emulsifer-free emulsion polymerization

Monosized poly(styrene/N-[3-(dimethylamino)propyl]methacrylamide/poly(ethylene glycol) ethyl ether methacrylate) [poly(St/PEG-EEM/DMAPM)] cationic nanoparticles were synthesized by emulsifier-free emulsion polymerization conducted in the presence of a cationic initiator, 2,2-azobis(2-methylpropionamidine) dihydrochloride (APDH or V-50). Particle sizes and surface charge densities were measured with a Zeta Sizer. The structure of the terpolymers was determined by Fourier transform IR and ¹H NMR spectroscopies. The amounts of the main monomer (St), cationic comonomer (DMAPM), stabilizer (PEG-EEM), and initiator (APDH), and the water-to-monomer phase ratio were all effective on both the average size and the surface charge of the nanoparicles. The average particle size was in the range 75–400 nm depending on the recipe applied; it decreased on increasing the amount of DMAP or PEG-EEM or the water-to-monomer phase ratio in the feed, while it increased with increasing St or APDH content. These nanoparticles were quite monodisperse with a polydispersity index of 1.008–1.14.     

Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant

High polymer/surfactant weight ratios (up to about 15:1) of polystyrene microlatexes have been successfully produced by microemulsion polymerization using a small amount of polymerizable surfactant, ω-methoxypoly(ethylene oxide)₄₀ undecyl α-methacrylate macromonomer (PEO-R-MA-40), and cetyltrimethylammonium bromide (CTAB). After generating “seeding particles” in a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than 1 wt% PEO-R-MA-40 was added dropwise to the polymerized microemulsion for a period of about 4 h at room temperature. PEO-R-MA-40 copolymerized readily with styrene. The stable microlatexes were bluish-transparent at a lower polymer content and became bluish-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and their molar masses ranging from 0.6 to 1.6 × 10⁶ g/mol could be obtained by varying the polymerization conditions. The dependence of the number of particles per milliliter of microlatex, the latex particle size and the copolymer molar mass on the polymerization time is discussed in conjunction with the effect of the macromonomer concentration. Received: 25 October/2000 Accepted: 2 February 2001     

Radical copolymerization behavior of a highly fluorinated cyclic olefin with vinyl ether

The copolymerization of a highly fluorinated cyclic monomer, octafluorocyclopentene (OFCPE, M₁), with ethyl vinyl ether (EVE, M₂) was investigated with a radical initiator in bulk. Despite the poor homopolymerizability of each monomer, the copolymerization proceeded successfully, and the molecular weights of the copolymers reached up to more than 10,000. Incorporation of the OFCPE units into the copolymer led to an increase in the glass‐transition point. The copolymer composition was determined from ¹H NMR spectra and elemental analysis data. The molar fraction of the OFCPE unit in the copolymer increased and approached but did not exceed 0.5. The monomer reactivity ratios were estimated by the Yamada–Itahashi–Otsu nonlinear least‐squares procedure as r_1,OFCPE = ?0.008 ± 0.010 and r_2,EVE = 0.192 ± 0.015. The reactivity ratios clearly suggest that the copolymerization proceeds alternatively in the case of an excessive feed of OFCPE. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1151–1156, 2002     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. III. Mathematical model

A mathematical model was developed to aid in the further understanding of the growth of latex particles in the emulsion polymerization of vinyl acctate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40). The model incorporates the main features of the system observed experimentally: copolymerization in the aqueous phase, at the particle surface, and chain transfer to TREM LF-40. The reactions at the particle/water interface and, more specifically, the chain transfer to TREM LF-40 leading to a decrease in the average number of radicals per particle, was found to be the most significant mechanism for explaining the difference in kinetic results found for TREM LF-40 and its nonpolymerizable counterpart. The copolymerization of vinyl acetate with TREM LF-40 was also shown to slow the overall polymerization rate. However, the copolymerization alone was not sufficient to account for the decreased polymerization rates observed experimentally. A combination of copolymerization and chain transfer to TREM LF-40 was found to provide a good fit of the experimental results. © 1993 John Wiley & Sons, Inc.