无皂聚丙烯酸酯乳液的合成及稳定性研究

采用无皂乳液聚合技术合成了聚丙烯酸酯乳液。研究了单体配比、链转移剂十二烷基硫醇(DDM)、pH值对齐聚物P(MBA/AANa)聚合体系的影响,以及反应温度、单体配比、齐聚物用量、引发剂过硫酸铵对无皂乳液P(VAc/MBA)聚合体系及其稳定性的影响。     

AA—TFEMA—AC无皂含氟乳液共聚反应动力学的研究

采用无皂乳液聚合制备得到甲基丙烯酸三氟乙酯/丙烯酸/氯丙烯(TFEMA/AA/AC)含氟丙烯酸酯共聚物.考察了单体比例、引发剂、单体浓度、反应温度对亲水性单体AA、疏水性单体TFEMA和AC的无皂乳液共聚反应速率的影响,得到了相应的聚合速率方程:Rp=Kp[M]0.48[I]0.54,聚合反应表观活化能Ea=91.742 kJ/mol,由聚合速率方程可知引发剂用量对该体系的影响效果采用摄像显微技术对该共聚物的乳液形貌进行观察,结果表明:制备的含氟乳液的乳胶粒呈圆形,粒径分布窄.     

P(CTFE-BVE-SUA)含氟无皂乳液的制备

以无皂乳液聚合法合成了聚(三氟氯乙烯-乙烯基正丁基醚-十一烯酸钠)[P(CTFE-BVE-SUA)]含氟共聚物乳液,考察了单体配比对聚合反应的影响,同时对影响乳液粒径的因素进行了研究。结果表明:以无皂乳液聚合法制得的含氟乳液稳定性好、粒径分布均匀。通过控制单体配比可以得到不同结构、不同氟含量的乳液。聚合反应中过硫酸钾(KPS)的浓度、聚合温度以及SUA用量对乳液粒径的影响较大,试验中还发现,聚合反应过程中压力的变化与反应的进程是同步的。     

高固含量无皂丙醋乳液的制备

以P（VAc／AANa）两亲聚合物为乳化剂，对无皂聚丙烯酸丁酯／乙酸乙烯酯乳液的合成进行了研究，并对其性能进行了初步测试。得到的较佳合成工艺条件为：醋酸乙烯酯和丙烯酸丁酯的单体配比为70：30，引发剂为单体用量的0．5％，乳化剂为单体总质量的3％，反应温度为70℃，反应时间为3．5h，再保温1h。制得的无皂丙醋乳液各方面性能良好。     

甲基丙烯酸三氟乙酯/十一烯酸钠无皂乳液的制备与性能研究

对甲基丙烯酸三氟乙酯/十一烯酸钠（TFEMA/SU）无皂乳液聚合体系进行了研究。考察了单体配比对聚合反应及乳液性质的影响,研究了SU的用量对乳液稳定性、黏度、乳胶粒粒径大小及分布等的影响。实验发现：以TFEMA和SU为单体可制得稳定性较好的无皂乳液,SU的用量是影响乳液稳定性、乳液黏度及乳胶粒粒径大小的关键因素。配方中SU的质量分数控制在3%～9%,制得的乳液稳定性较好,低于或高于此添加量,稳定性较差;当SU的质量分数由3%增大到9%时,乳液的电解质稳定性由1.6 mL增大到2.2 mL,黏度由102 mPa.s增大到379 mPa.s,说明SU量的增大对乳液的电解质稳定性及黏度提高是有利的。     

聚丙烯酸酯微乳液平均粒径影响因素的研究

探讨了利用预乳化种子法合成聚丙烯酸酯微乳液的聚合过程中,去离子水用量、阴离子与非离子乳化剂配比及用量、聚合温度、功能性单体用量及混合单体配比对平均粒径的影响.结果表明,在反应过程中,控制去离子水用量为总质量的60%、乳化剂十二烷基硫酸钠(SDS)和壬基酚聚氧乙烯醚(OP-10)质量比为4:1及复合乳化剂的用量为总质量的3%～5%时,合成的微乳液粒径小、分布好;聚合温度对聚丙烯酸酯微乳液平均粒径的影响较小;随功能性单体甲基丙烯酸用量的增加,微乳液平均粒径增大明显,其加人量以不超过总质量的1.8%为宜;当甲基丙烯酸甲酯(MMA)的用量等于或大于丙烯酸丁酯(BA)的用量时,可得到纳米级微乳液.     

含氟无皂乳液P(CTFE-IBVE-SUA)的合成及性能研究

通过无皂乳液聚合法制备得到聚(三氟氯乙烯-乙烯基异丁基醚-十一烯酸钠)[P(CTFE-IBVE-SUA)]含氟乳液。考察了单体配比对聚合反应的影响,研究了SUA用量对乳液及聚合物性能的影响,并对聚合物的结构及乳胶粒的形貌进行了测定。结果表明:含氟无皂乳液P(CTFE-IBVE-SUA)的稳定性好、粒径分布均匀;改变单体配比中IBVE和CTFE的比例可以得到不同结构的含氟聚合物乳液;SUA用量对乳液的稳定性、乳胶粒的粒径大小及粒径分布、聚合物膜与水的接触角都有很大的影响;制得的乳液具有明显的核壳结构。     

AMPS作用下无皂醋丙乳液的合成

在不加入任何传统乳化剂的情况下,以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为表面活性功能单体(surfmer),作用于乙酸乙烯酯(VAc)与丙烯酸丁酯(BA)的共聚乳化体系中,成功制备了一种新型的P(VAc/BA/AMPS)三元无皂乳液,该乳化体系在聚合以及贮存过程中都表现出良好的稳定性。考查了单体配比、AMPS用量、引发剂用量、反应温度和反应时间等条件对乳液性能的影响。确定的最佳单体配比为mVAc:mBA=8:2,AMPS用量为单体质量的1.0%,引发剂过硫酸钾(KPS)用量为单体质量的0.6%,反应温度为80℃。所制得的乳液粒径约为144nm,且单分散性好,固含量在42%以上。     

聚(VAc/AA)的合成及在乳液聚合中的应用

采用无皂乳液聚合方法,合成聚(醋酸乙烯/丙烯酸)[P(VAc/AA)]共聚物,研究了加料方式、单体配比对乳液稳定性的影响.结果表明,mVAc:mAA=(0.5~2.5):1时,采用分段聚合工艺,共聚乳液性能良好;pH值越高,乳液越稳定.将P(VAc/AA)共聚乳液作为高分子乳化剂用于醋酸乙烯的乳液聚合,对乳液性能进行表征.结果表明,采用P(VAc/AA)为乳化体系,与传统的OP-10/SDS乳化体系相比,其稀释稳定性提高,胶膜的吸水性下降,粒径、黏度和压缩剪切强度均降低.     

阳离子型含氟聚丙烯酸酯无皂乳液的合成及性能

以可逆加成断裂链转移(RAFT)聚合合成的聚甲基丙烯酸-N,N-二甲氨基乙酯-b-聚丙烯酸六氟丁酯(PDMAEMA-b-PHFBA)为稳定剂,通过无皂乳液聚合技术合成了阳离子型含氟聚丙烯酸酯无皂乳液。用FTIR、1HNMR、TEM、DLS对乳胶粒子和聚合物的结构进行了表征。结果表明,当PDMAEMA-b-PHFBA的用量为总加料质量的2.4%时,乳液的稳定性好,Zeta电位达+57.8 m V,转化率达97.6%,乳胶粒具有明显的核壳结构,粒径分布指数为0.058。将阳离子型含氟聚丙烯酸酯无皂乳液用于皮革涂饰后,随着丙烯酸六氟丁酯用量的增加,涂饰后的皮革对水和二碘甲烷的接触角逐渐增加,当丙烯酸六氟丁酯用量为总单体质量的10%时,涂饰后的皮革对水的接触角为125°,对二碘甲烷的接触角为81.5°。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。