pH-温度双重敏感性水凝胶的制备及溶胀性能研究

制备具有pH及温度双重敏感性水凝胶。通过自由基聚合反应制备出NIPAM-co-PMAA水凝胶材料。考察不同单体甲基丙烯酸(MAA)和N-异丙基丙烯酰胺(NIPA)配比对pH和温度的响应能力,探究其溶胀性能。结果表明,不同配比的水凝胶具有双重敏感性。NIPA含量不同时,对于LSCT温度有影响,MAA含量不同时,在酸性条件下溶胀率较大。结论,NIPAM-co-PMAA水凝胶有望成为药物载体。     

粒状聚N-异丙基丙烯酰胺/壳聚糖水凝胶的制备、性能及其应用

用反相悬浮聚合法,合成了具有温度/pH敏感性的聚N-异丙基丙烯酰胺/壳聚糖粒状半互穿网络(PNIPA/CS semi-IPN)水凝胶,研究了该水凝胶在不同温度、不同pH介质以及不同组成下的溶胀率变化.结果表明:该水凝胶的最低临界溶液温度(LCST)与PNIPA水凝胶基本相同,均在33℃左右,pH=3时溶胀率达到最大,具有明显的温度和pH敏感性.壳聚糖(CS)的不同比例也对凝胶的溶胀率产生很大影响.振荡实验表明:凝胶粒子具有温度响应可逆性.同时进行了乳酸吸附与释放的初步研究,当PNIPA/CS质量比为10时,最大吸附达到168.29 mg(g dry gel)-1,释放率为31.74%.     

快速响应聚(N-异丙基丙烯酰胺)水凝胶的制备及性能

以N-异丙基丙烯酰胺为单体、N,N′-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂、N,N,N,′N′-四甲基乙二胺为加速剂,在不同浓度的羧甲基纤维素的水溶液中,在低温下聚合/交联制备了一系列快速响应的温度敏感性聚(N-异丙基丙烯酰胺)水凝胶。用SEM观察了其表面形态,测定了不同温度下达到平衡时水凝胶的溶胀比,研究了水凝胶的去溶胀动力学。结果表明,与传统水凝胶相比,该水凝胶的溶胀性能有所提高,并且对温度的变化具有较快的响应速率。以质量分数为0.75%的羧甲基纤维素水溶液中制备的水凝胶为例,该水凝胶在20℃时的溶胀比为21.4,而传统水凝胶在相同温度时的溶胀比仅为12.9;该水凝胶在1 m in内失去60%的水,在4 m in内失去约80%的水,而传统水凝胶在15 m in内仅失去66%左右的水。     

聚甲基丙烯酸/丙烯酰胺pH敏感凝胶的合成与溶胀行为研究

以单体丙烯酰胺(AM)、甲基丙烯酸(MAA),交联剂N-N'亚甲基双丙酰胺(BIS)为原料,通过自由基共聚合成了聚甲基丙烯酸/丙烯酰胺[P(MAA-co-AM)]水凝胶.研究了干凝胶在不同pH溶液中的溶胀动力学,结果表明不同AM、MAA单体配比的凝胶溶胀性具有很大差异,其溶胀率都随着溶液的pH增加而增大,在pH=12和pH=2溶液反复变换时显示可逆溶胀-退溶胀和快速响应特性,溶胀-退溶胀过程中搅拌作用对凝胶响应速率有显著影响.吸水平衡P(MAA-co-AM)水凝胶在酸性及碱性条件下均出现收缩,在pH=2下10 min之内凝胶收缩90%以上,随着pH增大逐渐减慢.通过不同浓度的NaCl与CaCl2溶液研究了溶液离子强度以及反离子的电荷数对凝胶溶胀性影响,在NaCl溶液和水中,呈现反复溶胀-退溶胀响应特性.     

温度和pH值对智能水凝胶溶胀行为的影响

以N-马来酰化壳聚糖(N-MACH)为交联剂,N-异丙基丙烯酰胺(NIPAAm)为单体,羧甲基纤维素钠(CMC)为半互穿材料,分别合成了PNIPAAm和PNIPAAm/CMC半互穿网络智能水凝胶,研究了两种水凝胶在不同温度的去离子水和不同pH值的缓冲溶液中的溶胀现象,结果表明介质温度和pH值对水凝胶的溶胀行为有显著影响。在温度和pH值一定时,水凝胶的溶胀率随着交联剂用量的增加而下降,随着CMC用量的增加而上升。     

温敏性聚(N-异丙基丙烯酰胺)/聚丙烯酰胺互穿网络水凝胶

采用紫外引发法制备了物理交联的聚(N-异丙基丙烯酰胺)和化学交联聚丙烯酰胺为组分的互穿网络水凝胶。利用FFIR对所得的凝胶进行了结构分析;测定了该水凝胶在20℃时的溶胀率和50℃时的水保持率;利用DMA和DSC分别研究了水凝胶的储能模量随温度的变化及相转变行为。结果表明:与聚(N-异丙基丙烯酰胺)水凝胶相比,该水凝胶有较好的溶胀率;且具有超快的响应速率,如10 min内失去90%的水;其储能模量增加;虽然其相转变行为变弱,但临界溶解温度(LCST)有所提高。     

含PEG组分的聚(N-异丙基丙烯酰胺)水凝胶的制备研究

首先合成了二丙烯酰基封端的聚乙二醇(PEG)大分子交联剂,然后使其与N,N-亚甲基双丙烯酰胺(BIS)和(N-异丙基丙烯酰胺)(NIPAM)单体进行交联反应,制备了PNIPAM-co-PEG-co-BIS水凝胶。与通常的PNIPAM-co-BIS凝胶比较,PNIPAM-co-PEG-co-BIS凝胶显示了明显加速的去溶胀动力学。这种加速的去溶胀性能归因于凝胶中的PEG组分为凝胶提供了亲水通道,在缩水过程中有利于凝胶的脱水。     

温敏型水凝胶的制备及溶胀特性

采用N-异丙基丙烯酰胺(NIPA)与N-乙烯基-2-吡咯烷酮(NVP)为共聚单体,以N,N-亚甲基双丙烯酰胺(BIS)为交联剂,过硫酸钾(KPS)为引发剂,通过化学交联的方法在水溶液中制备出P(NIPA-co-NVP)共聚物水凝胶。分别探讨了单体配比、交联剂用量等实验条件对水凝胶的温敏特性和溶胀性能的影响。利用傅里叶红外(FT-IR)对共聚物水凝胶的结构进行了表征。通过实验可知:当交联剂BIS和引发剂KPS分别为单体用量的5%和0.8%,制备的水凝胶具有较高的转化率、较好的机械强度和共聚性质。共聚物水凝胶中NVP含量越高,溶胀率越大,升温时溶胀率下降程度越大,自然条件下脱水速率越快;BIS用量越大,溶胀率越小,保水率越高,需要更长时间达到溶胀平衡。     

丙烯酰胺类共聚物水凝胶的合成及性能研究

用自由基聚合法合成了不同摩尔配比的HEMA／AM共聚物水凝胶材料。研究了单体组成、温度、pH值、离子强度等因素对凝胶溶胀性能的影响。结果表明：水凝胶的溶胀速度较快;水凝胶在pH值小于4及pH值大于9的酸、碱溶液中发生水解,导致水凝胶的饱和含水量大幅增加,而在弱酸性溶液中几乎没有变化;水凝胶的饱和含水量对离子强度的变化不够敏感;随着温度的升高水凝胶的饱和含水量略有减少,说明此类水凝胶对温度的敏感性也较弱。     

N-异丙基丙烯酰胺/N-羟甲基丙烯酰胺共聚物及其水凝胶的合成与温敏性研究

通过自由基聚合合成了N-异丙基丙烯酰胺(NIPAm)与-羟甲基丙烯酰胺(NHMPA)的共聚物及其水凝胶。研究发现,调节两单体的配比可得到不同的低临界溶液温度(LCST)值的共聚物及水凝胶。结果表明,NHMPA的加入不改变PNIPAm的温敏性,但可有效地调节其LCST值。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。