微波辐照下P(St-MMA-AA)多孔乳胶粒的制备

在微波辐照条件下，通过间歇无皂种子乳液聚合，制得聚[苯乙烯(St)-甲基丙烯酸甲酯(MMA)-丙烯酸(AA)]复合乳液。将所得复合胶乳进行碱，冷却分段处理，得到具有多孔结构的乳胶粒。胶粒形态用透射电镜进行了表征。     

中空聚合物微球的制备Ⅰ．无胶束乳液聚合制种子乳胶粒

为了制得具有中空结构的聚合物微球，首先以十二烷基苯磺酸钠（SDBS）为乳化剂，在其用量低于CMC的条件下，进行甲基丙烯酸甲酯、甲基丙烯酸和丙烯酸丁酯的乳液聚合，制备了带羧基的种子乳液。以种子乳液为基础可通过核壳乳液聚合和适当的碱处理制得具有中空结构的聚合物微球。采用粒度仪和TEM测定了乳胶粒的直径及其分布，采用TEM和ESEM对乳胶粒结构形态进行了表征。研究了种子制备过程中单体加料方式、乳化剂用量及反应温度等对聚合稳定性、种子乳胶粒直径及其分布的影响，确定了制备种子乳胶粒的最佳工艺条件。当SDBS用量为单体总量的0．5％，采用一次性加入单体的进料工艺，反应温度为80℃时，可以得到粒径为140nm，且粒径呈单分散分布的种子乳胶粒。     

中空聚合物微球的制备——种子及核乳胶粒的制备

为了制得具有中空结构的聚合物微球,首先以十二烷基苯磺酸钠(SDBS)为乳化剂,在其用量低于CMC的条件下,进行甲基丙烯酸甲酯(MMA)、甲基丙烯酸(MAA)和丙烯酸丁酯(BA)的乳液聚合,制备了带羧基的种子乳胶粒.然后采用MMA、MAA和二乙烯基苯为单体进行种子乳液聚合,制备了轻度交联的带羧基的核乳胶粒.该核乳胶粒经过核-壳乳液聚合和适当的碱处理工艺就可成为具有中空结构的聚合物微球.采用粒度仪测定了乳胶粒的直径及其分布,采用TEM对乳胶粒结构形态进行了表征.研究了种子及核乳胶粒制备过程中单体加料方式、乳化剂用量及羧基单体种类等因素对聚合稳定性、乳胶粒直径及其分布以及最终的中空聚合物微球结构形态的影响,确定了制备种子及核乳胶粒的最佳工艺条件.在制备种子阶段,SDBS用量为单体总量的0.5%,采用一次性加入单体的进料工艺;在核乳胶粒制备阶段,以MAA为羧基单体,所有单体采用"饥饿式"加料,半连续补加乳化剂并使乳化剂用量为核单体总量的0.15%时可保持聚合稳定性并保证无新乳胶粒生成.     

乳液聚合法制备中空乳胶粒的研究

采用多段乳液聚合法制备了聚(甲基丙烯酸甲酯-丙烯酸正丁酯-甲基丙烯酸)/聚(苯乙烯-丙烯腈)核壳乳液,然后用碱溶胀处理得到了单分散性较好的中空聚合物微球.以透射电子显微镜(TEM)和扫描电子显微镜(SEM)对各阶段乳液聚合的胶粒大小和分布以及形貌行了表征.研究了种子乳液聚合反应时间、搅拌速度、单体滴加速度等因素对中空聚合物微球的形态及粒径分布的影响.结果表明:当单体的滴加速度控制在0.1～0.2g/min,搅拌速度控制在80～120 r/min时,可以制备中空形态较好的中空聚合物微球.     

苯丙乳液的粒径与形貌控制研究

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)和苯乙烯(St)为单体,采用半连续种子乳液聚合工艺,制备了苯丙聚合物乳液,研究了乳液聚合过程中的制备工艺、引发剂类型、乳化剂用量、种子乳液的乳化剂用量、预乳液和引发剂的滴加速率对不同阶段的乳胶粒粒径及其分布的影响。结果表明:半连续种子乳液聚合,单体滴加工艺制备的乳液粒径最小;引发剂种类对粒径无影响;乳化剂用量为10%时,乳液的粒径为96 nm,且分布宽度最窄,在种子乳液中乳化剂用量为40%时,乳液粒径最小,为104 nm;当预乳液滴加速度小于163 mg/s,引发剂滴加速率小于11.5 mg/s时,粒径未有变化。TEM测试表明了乳胶粒在整个乳液聚合过程中的成核长大的机理,并得到乳胶粒形貌可控的最佳方案。     

苯丙乳液最新研究进展

综述了具有高性价比的苯丙乳液研究现状,具体包括乳化剂体系、引发剂体系、聚合工艺、胶粒设计、新型乳液聚合技术等方面,为制备性能优异、用途广泛的苯丙乳液指明了方向。     

热敏乳液薄膜的制备及性能

本文介绍了一种可以通过三步法制得的具有亲油的核和亲水的壳的高分子微胶粒。首先,通过乳液聚合得到甲基丙烯酸正丁酯与甲基丙酸甲酯的共聚物乳液(p-(BMA-MMA));利用(p-(BMA-MMA)乳液作为种子,用一种氧化还原引发体系引发反应,通过控制反应条件,在乳胶粒表面包覆一层均匀的聚甲基丙烯酸缩水甘油酯(p-GMA)外壳,壳层聚合物的含量为5~15wt.%之间;最后,壳层表面的环氧基团与三乙醇胺盐酸盐反应,环氧基团转变为季铵盐,使外壳成为极性的亲水表面。核-壳型固体微胶粒可以在水中较好地分散并形成稳定的乳液。通过旋涂法将固体乳液颗粒和PVA的混合水溶液涂在铝版基上,室温下干燥,可得到乳液薄膜。实验发现,室温下核-壳乳液薄膜与水的接触角在16.1°-27.5°范围内,可经过150℃短时间的烤版处理后,接触角将超过87,°表明乳液薄膜通过加热后完全由亲水性转为亲油性。同时,该乳液薄膜在烤版前很容易用中性水由版基上冲洗掉,但烤版后不再能够被洗掉。当在乳液薄膜中加入一种红外染料(最大吸收波长在830nm)后,该薄膜变得对830nm的LD激光敏感,并通过LD激光曝光和中性水显影后,得到阴图型图像。     

有机——无机复合乳液研究（Ⅱ）

3 聚合方法及动力学研究 有机—无机复合高分子乳液采用不同的乳液聚合方法,所得乳液性质也有所不同,主要的乳液聚合方法有核壳乳液聚合（种子乳液聚合）、无皂乳液聚合和类乳液聚合（emulsion-likepolymerization）。3.1 核壳乳液聚合法（种子乳液聚合）制备有机—无机复合高分子乳液 采用种子乳液聚合反应得到的聚合物乳液,在材料的复合领域内占有一定的地位,控制不同聚合条件,可以获得形态结构完全不同的乳胶粒,乳胶粒的形态结构基本可以归结为两大类型,即正常型和异常型,具体形态如图11所示。其颗粒由核和壳两部分组成,这种复合的乳胶粒结构赋予乳液许多特殊功能     

核壳乳液聚合乳胶粒形态的研究（Ⅱ）乳胶粒达到平衡形态时间的预测

为了方便地进行核壳乳胶粒达到平衡形态的时间预测,提出了用简化的簇迁移动力学模拟方法进行反应过程中乳胶粒形态演化过程的模拟。以聚醋酸乙烯酯／丙烯酸丁酯体系2阶段种子乳液聚合为例,对指定实验条件下乳胶粒的形态进行预测,结果与实验相符。     

有机硅改性丙烯酸酯乳液的合成和形态分析

以过硫酸铵(APS)为引发剂、十二烷基苯磺酸钠(SDBS)/辛基酚聚氧乙烯醚马来酸酯钠(OP-10)为复合乳化剂,利用含乙烯基的有机硅单体与丙烯酸酯类单体进行乳液聚合制备了甲基丙烯酸甲酯(MMA)/丙烯酸丁酯(BA)/有机硅(Si-1800)交联聚合物乳液.通过透射电子显微镜(TEM)观察乳胶粒形态的最佳染色方法为pH...     

Effect of the Crosslinking Agent Content on the Emulsion Polymerization Process and Adhesive Properties of Poly(N-Butyl Acrylate-Co-Methacrylic Acid)

A series of poly(n-butyl acrylate-co-methacrylic acid) with different contents of acrylic crosslinking agent (1,4-butanediol dimethacrylate, BDDA) latexes, named as poly(BA-co-MAA-co-BDDA), PBMABD, were synthesized via a two-stage sequential emulsion polymerization. During the polymerization, the particle sizes of the PBMABD latexes and conversions including instantaneous conversion and overall conversion of monomers were monitored online by dynamic light scattering (DLS) technology and gravimetric analysis in half-hour intervals, respectively. The overall conversions at the end of emulsion polymerization with different crosslinking agent contents were high, and the latex particles grew in a spherical shape without secondary particles during the growth process. The adhesive properties, including loop tack force, peel force and shear resistance, were evaluated systematically according to Fédération Internationale des Fabricants et Transformateurs d'Adhésifs et Thermocollants sur Papiers et Autres Supports (FINAT) test methods. When the content of the crosslinking agent was 0.5?wt%, a best equilibrium among the adhesive properties could be achieved. The adhesive properties of the PBMABD polymer were closely related to its viscoelastic behaviour and molecular structure, such as gel content and various molecular weight parameters.     

Synthesis and characterization of latexes based on copolymers BA\MMA\DAAM and BA\MMA\VEOVA-10\DAAM and the corresponding 1K crosslinkable binder using the adipic acid dihydrazide as crosslinking agent

In this study stable latexes of butyl acrylate (BA)/methyl methacrylate (MMA)/diacetone acrylamide (DAAM) copolymers and BA/MMA/vinyl neo-decanoate (VeoVa-10)/DAAM copolymers were synthesized by a modified semi-continuous microemulsion copolymerization. Ammonium persulfate was used as initiator and a redox system for post-polymerization to reduce the free monomers content. Methacrylic acid (MMA), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), acrylic acid (AA) and various “green” industrial anionic, non-ionic and anionic polymerizable surfactants free of alkylphenol ethoxylates (APEO free) were tested as a stabilizing system. The resulting latexes, their corresponding self-1K crosslinkable binder using the adipic acid (ADH) dihydrazide as crosslinking agent and their films were characterized with rotational viscometer, dynamic light scattering, gloss, dynamic mechanical analysis, minimum film forming temperature (MFFT), water resistance and swelling in methyl ethyl ketone measurements. The experiments showed that BA\MMA\VEOVA-10\DAAM latexes prepared with methacrylic acid and a polymerizable surfactant showed zero coagulation during polymerization. Their corresponding 1K crosslinkable binder with ADH were stable over 6 months storage time and showed good all around properties that makes them suitable for use in friendly to the environment coatings.     

交联聚乙酸乙烯酯胶乳的合成

分别以二乙烯基苯、双甲基丙烯酸乙二醇酯和甲基丙烯酸烯丙基酯（ＡＭＡ）为交联剂，十二烷基硫酸钠（ＳＬＳ）为乳化剂，过硫酸铵为引发剂，合成了交联聚乙酸乙烯酯（ＰＶＡｃ）胶乳。结果表明，ＡＭＡ是乙酸乙烯酯乳液聚合最理想的交联剂，其用量为单体量的２％时，交联度可达到８５％以上。所用ＳＬＳ的浓度为１１．６ｍｍｏｌ／Ｌ时，合成了交联度为８７．４％、粒径为８４．５ｎｍ的交联ＰＶＡｃ胶乳。     

Effects of glycidyl methacrylate content and addition sequence on the acrylic latexes with carboxyl groups

Acrylic latexes with epoxy and carboxyl groups have been synthesized via a two-stage emulsion polymerization process. Different contents of glycidyl methacrylate (GMA) were introduced by three addition modes to copolymerize with methyl methacrylate, butyl acrylate, acrylic acid (AA) in the presence of K₂S₂O₈. To obtain stable latexes, NaHCO₃ was employed as a buffer to compensate for the acidity from the thermal dissociation of K₂S₂O₈, and triethylamine was used to neutralize the carboxyl acid from AA. The results showed that the stable latexes with core/shell structure were synthesized by this method, and higher GMA content or addition at earlier stage led to forming the latexes with higher content of coagulum and bigger sized particles. During the formation of films, the polymer epoxy groups underwent the crosslinking reaction with carboxyl acid. When the GMA content increased or GMA was introduced at a later stage, high crosslinking extent was formed in the films. As a result, the crosslinking provided the films with improved water resistance, chemical resistance, tensile strength, hardness, abrasion resistance, and thermal stability.     

Properties and anticorrosion application of acrylic ester/epoxy core–shell emulsions: effects of epoxy value and crosslinking monomer

We first prepared an unsaturated epoxy resin ester (EM) by addition–esterification reaction with acrylic acid and then synthesized a series of acrylic ester/epoxy hybrid latexes (AE) with core–shell structure by semicontinuous emulsion polymerization method. The resultant AE emulsions are utilized as anticorrosion coatings of metals. The influences of EM content and crosslinking agent (PEG(400)DA) content on the physicochemical properties of the resultant emulsions and anticorrosion coatings of metals are investigated in detail. The AE emulsion displays better anticorrosion properties when it is prepared under the following conditions: the EM content of 30 wt% and PEG(400)DA content of 2.0 wt%. The relationships between the AE structure and anticorrosion properties of AE coatings are clearly illustrated. The corrosion resistances of AE coatings are not only depend on the crosslinking density, hydrophilic, and polarity among the AE chains, but also rely on the stability of the emulsion and the integrality and homogeneity of the coatings.     

Control of adhesive properties through structured particle design of water-borne pressure-sensitive adhesives

The concept of using structured particles and the mechanism of film formation from latexes to produce pressure-sensitive adhesive (PSA) films with controlled sub-micron and nanometre scale morphology has been investigated with the objective of enhancing adhesive performance. Structured particle acrylate-based latexes were synthesised by seeded semi-continuous emulsion polymerisation procedures. Aliquots removed at intervals during the polymerisations were analysed for conversion and z-average particle diameter; the results confirm that the particles grew without secondary nucleation or coagulation. Three-layer particles were studied first and comprised a core whose composition was the same for all particles, an interlayer between core and shell which was crosslinked during synthesis (using 1,6-hexanediol diacrylate, HDDA) and a shell which contained diacetone acrylamide (DAAM) repeat units that provided for interfacial crosslinking between particles during film formation by reaction with post-added adipic acid dihydrazide (ADH). The three-layer latexes produced adhesive films with high shear resistance when ADH was added, but peel adhesion was generally low and further reduced by increasing either the thickness or HDDA concentration of the interlayer. Thus two-layer latexes with shell layers containing DAAM but no pre-crosslinked interlayer were the main focus of the study. The effects of core:shell ratio and amount of DAAM on adhesive performance were optimum with a core:shell ratio of 80:20 and 2 wt% DAAM in the shell copolymer, for which interfacial crosslinking using the stoichiometric amount of ADH led to a marked increase in shear resistance with only a slight reduction in peel adhesion. Increasing the level of n-dodecylmercaptan (DDM) chain transfer agent used in synthesis of the core increases peel adhesion and reduces shear resistance in the absence of ADH, but high shear resistance can be recovered through interfacial crosslinking with ADH. Adhesive performance can be optimised by using a high DDM level in the core and a low DDM level in the shell, a combination that enables both high peel adhesion and shear resistance to be achieved with the addition of ADH. The results from this study define guiding principles for development of commercial water-borne PSAs that can compete with solvent-borne PSAs in high-performance applications.     

Effects of three crosslinkers on colored pH‐responsive core–shell latexes

Environmentally responsive hydrogels have become attractive research subjects for many applications. In this work, a series of pH‐sensitive and color‐changing nanoparticles (nanogels) with core–shell structures were synthesized. The cores were blue latex particles synthesized by a miniemulsion technique with styrene and methacrylic acid as monomers and Neozapon Blue 807 as a dye. The shell was a pH‐sensitive polymer that was precipitation‐polymerized onto the core from 2‐(diethylamino) ethyl methacrylate with N,N′‐methylenebisacrylamide, poly(propylene glycol) diacrylate, and divinylbenzene as crosslinking agents. In the resultant latexes, the color was observed to change from deep blue to pale blue as the pH of the system was changed from a high of 10 to a low of 3. The synthesized latexes and particles (gels) were then characterized with an ultraviolet–visible spectrometer, dynamic light scattering, Fourier transform infrared, and nuclear magnetic resonance. Atomic force microscopy was also used to investigate the different morphologies of the particles after the synthesized latexes were dried at different pH values. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Investigation of the effect of precoalescence or postcoalescence crosslinking on film formation, properties, and latex morphology

Latexes have many product applications including functioning as a binder in coatings. For many years, coatings researchers in industry as well as in academe have been exploring various modes of crosslinking latexes. Quite often, the goal of preparing crosslinked latexes is to upgrade film properties relative to the film properties of uncrosslinked latexes. In the present report, the synthesis and properties of crosslinkable acrylic latexes prepared with either an internal crosslinker (1,3-butylene glycol dimethacrylate)—“precoalescence crosslinking”—or an external crosslinker (adipic dihydrazide)—“postcoalescence crosslinking”—at various levels of crosslinking were studied. For postcoalescence crosslinking, diacetone acrylamide was copolymerized into the latex to provide sites for subsequent reaction with adipic dihydrazide. Fundamental properties of films cast from the two types of latexes were systematically compared. These properties included gel content, dynamic mechanical properties, nano-indenter hardness and modulus, stress–strain properties as well as the characterization of latex morphology by atomic force microscopy (AFM). In addition, some specific end-use properties were determined. This study assesses the effect of type (precoalescence or postcoalescence) and level of crosslinking on the film formation process and the resulting fundamental and end-use properties as well as resulting latex film morphology. Presented at 2007 FutureCoat! Conference, sponsored by Federation of Societies for Coatings Technology, October 3–5, 2007, in Toronto, Ont., Canada.     

Control of pore generation and pore size in nanoparticles of poly(styrene‐methyl methacrylate‐acrylic acid)

Seeded emulsion polymerization of styrene‐methyl methacrylate‐acrylic acid onto seed latexes of monodisperse particles of poly(styrene‐methyl methacrylate) was conducted with or without divinyl benzene as a crosslinking agent. Experiments revealed that almost no new particles were formed during the second stage of polymerization, and that the seeded latex particles obtained were almost monodisperse. An alkali‐acid treatment was then applied to the seeded latex particles swollen in 2‐butanone. Experimental results indicated that: (1) for uncrosslinked particles, an optimum volume expansion of >50% is reached for a ratio of the swelling agent, 2‐butanone, to polymer (methyl‐ethyl‐ketone/polymer by weight) between 2.0 and 2.9; the volume expansion is much lower outside the above range. (2) For crosslinked particles, the particle volume expansion follows the same pattern, but with smaller values. (3) pH plays an important role in pore generation and volume expansion. Pore generation is optimized by decreasing pH to a value as low as 1.5 during acid treatment, and by keeping pH in the optimum range between 11.98 and 12.20 during alkali treatment. Based on the above observations, a discussion regarding the mechanism of pore generation and particle expansion is provided. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 419–426, 1999     

Morphology of poly(isoprene-co-styrene-co-methacrylic acid) latex prepared by two-stage seeded emulsion polymerization

Heterogeneous latexes were prepared by a two-stage seeded emulsion polymerization process at 80°C using potassium persulfate as the initiator and sodium dodecyl sulfate as the emulsifier. Poly(styrene-co-methacrylic acid) latexes containing varying amounts of methacrylic acid (MAA) were used as seeds. The second-stage polymer was poly(isoprene-co-styrene-co-methacrylic acid). By using different methods for the addition of the MAA and by varying the amount of MAA, the hydrophilicity of the polymer phases could be controlled. The morphologies and size distributions of the latex particles were examined by transmission electron microscopy. The latexes were in all cases unimodal, and had narrow particle size distributions. The particles displayed different morphologies depending on the polymerization conditions and monomer composition. The hydrophilic properties of the two phases in combination with the internal particle viscosity and crosslinking of the second phase during polymerization were found to be the major factors influencing the particle morphology. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1543–1555, 1997