聚乳酸-聚乙二醇热致复合水凝胶的制备及性能

将疏水性不同的共聚物混合制备可注射水凝胶。通过先核后臂法分别制备出线型聚乳酸-聚乙二醇(PLLAPEG)共聚物和星型聚乳酸-聚乙二醇单甲醚(PLLA-mPEG)共聚物,将两者水溶液进行混合,采用试管翻转法测定混合溶液热致相转变行为。结果表明:线型PLLA-PEG_(600)溶液相转变范围15—42℃,星型PLLA-mPEG750溶液相转变范围52—68℃,当星型PLLA-mPEG750溶液与线型PLLA-PEG_(600)溶液混合,形成了以疏水性较强的线型共聚物为核,疏水性较差的星型共聚物为壳的核壳结构复合物,其相转变温度介于2种共聚物相转变温度之间,可作为注射水凝胶。体外药物释放结果表明:复合水凝胶对所包载的盐酸乌拉地尔具有良好的缓释作用,动力学释放符合一级动力学方程。     

聚乙烯醇基相变储能材料的制备与表征

相变储能材料能够解决能量储存和释放在时间和空间上的矛盾,被广泛应用于储热技术。以聚乙烯醇(PVA)和聚乙二醇单甲醚(mPEG)为原料,制备PVA/mPEG接枝聚合物和PVA+mPEG共混聚合物,并讨论不同相变剂mPEG分子量及添加量对PVA/mPEG接枝聚合物的化学结构及相变储能的影响。利用差示扫描量热仪(DSC)对PVA/mPEG接枝聚合物和PVA+mPEG共混聚合物进行表征。结果表明:随着mPEG含量的增加,PVA/mPEG接枝聚合物的相变焓和相变温度升高。随着mPEG分子量的增加,PVA/mPEG接枝聚合物的熔点和相变焓显著提高。PVA/mPEG接枝聚合物的稳定性优于PVA+mPEG共混聚合物。结合相变材料的力学性能,当mPEG的添加量为PVA的3%、mPEG分子量为1 000时,制备的PVA/mPEG接枝聚合物的性能较优异。     

聚乙二醇二元体系的相变特性研究

采用步冷曲线法和差示扫描量热法考察不同分子量聚乙二醇(PEG)及其二元相变体系的相变特性。结果表明,PEG分子质量和组分质量比对相变体系的相变温度和相变潜热有较大的影响,随着PEG分子量的增大,相变起始温度和相变峰温均呈升高趋势,相变潜热先升后降;二元相变体系PEG2000/PEG4000不同质量比步冷曲线均有明显的温度平台,结晶温度38.4~43.2℃,且变化趋势相近;DSC分析PEG2000/PEG4000相变温度和相变潜热均处于PEG2000和PEG4000单一组分范围之间,不同质量比时升温过程中双组分单独作用出现双峰,降温过程中双组分协同作用出现单峰。因此,将不同分子量PEG按一定质量比例共混可实现温度调控的相变材料。     

聚乙二醇二元体系的相变特性研究

采用步冷曲线法和差示扫描量热法考察不同分子量聚乙二醇(PEG)及其二元相变体系的相变特性。结果表明,PEG分子质量和组分质量比对相变体系的相变温度和相变潜热有较大的影响,随着PEG分子量的增大,相变起始温度和相变峰温均呈升高趋势,相变潜热先升后降;二元相变体系PEG2000/PEG4000不同质量比步冷曲线均有明显的温度平台,结晶温度38.4⁴3.2℃,且变化趋势相近;DSC分析PEG2000/PEG4000相变温度和相变潜热均处于PEG2000和PEG4000单一组分范围之间,不同质量比时升温过程中双组分单独作用出现双峰,降温过程中双组分协同作用出现单峰。因此,将不同分子量PEG按一定质量比例共混可实现温度调控的相变材料。     

立构嵌段聚乳酸的合成及结构性能表征

文章以左旋丙交酯(L-LA)为单体,以辛酸亚锡和月桂醇分别作为催化剂和引发剂,在二甲苯中开环聚合得到3种不同分子量的左旋聚乳酸(PLLA),然后以其作为大分子引发剂,在基本同样的条件下,继续引发右旋丙交酯(D-LA)开环聚合,期望获得PLLA和PDLA的立构嵌段共聚物(sb-PLA)。采用核磁共振谱、X射线衍射、红外光谱和凝胶渗透色谱等对产物的结构进行了表征。结果表明:产物为单一立构嵌段聚乳酸。结合差示扫描量热仪(DSC)、热失重(TGA)和偏光显微镜(POM)对产物热性能和结晶性能进行了研究。与PLLA相比,sb-PLA的冷结晶温度(T_(cc))下降25℃,但熔点(T_m)却高出50~60℃,这主要归因于PLLA-b-PDLA分子链中形成了更高紧密堆积的立构复合晶体,立体复合聚乳酸的结晶能力要明显强于PLLA或者PDLA。     

N-对甲苯基马来酰亚胺乳液共聚物性能表征

通过乳液聚合制得N-对甲苯基马来酰亚胺(NPTMI)、甲基丙烯酸甲酯、苯乙烯的三元共聚物．采用热重分析、维卡软化点测试、差示扫描量热分析等方法研究了不同单体配比共聚物的热性能及力学性能．用凝胶渗透色谱(GPC)测定了共聚物的分子量及其分布。结果表明：加入NPTMI可以有效地提高共聚物的热稳定性,NPTMI质量分数为20％的共聚物与不含NPTMI的共聚物相比．玻璃化转变温度、维卡软化点、热分解起始温度、分解50％时的温度分别提高了22．6,19．5,42．8,46．2℃．但力学性能有所下降。GPC测定结果表明,分子量在合适的单体配比下出现最大值。     

聚双甲基丙烯酸聚乙二醇酯固-固相变储能材料的制备

制备了以聚甲基丙烯酸为骨架、聚乙二醇(PEG)为工作物质的新型高分子固-固相变储能材料。对PEG和几种不同的相变材料分别进行DSC测试,对PEG分子量为4000的相变材料进行非等温DSC测试。结果表明,与纯PEG相比,相变材料的相转变温度降低12.3℃,相变焓降低45 J/g。随着聚乙二醇分子量由2000依次增加为4000,6000,10000,相变材料的相转变温度分别为44.8,52.9,63.8和74.3℃,相变焓分别为142.9,203.2,190.1,231.4 J/g,均有增加的趋势。随着升温速率增加,PEG分子量为4000的PCM的相变温度依次升高,分别为47.4,50.0和53.1℃。     

氮氧稳定自由基聚合与原子转移自由基聚合结合制备梳形支化聚苯乙烯的反应行为

为了实现对梳形支化聚苯乙烯结构的精确控制,采用核磁共振(1H-NMR)、多角度激光散射联用凝胶渗透色谱(GPC-MALLS)和气相色谱(GC)表征聚合物结构和观察反应动力学,研究了苯乙烯(St)与对氯甲基苯乙烯(p-CMS)氮氧稳定自由基共聚合(NMP)制备P(St-co-CMS)的反应行为以及以P(St-co-CMS)为大分子引发剂引发苯乙烯原子转移自由基聚合(ATRP)制备梳形支化聚苯乙烯的反应行为。结果表明,在反应温度为130℃,苯甲醚为溶剂,BPO/HTEMPO为引发体系引发St与p-CMS的氮氧稳定自由基共聚合过程中,St和p-CMS的转化速率接近,p-CMS按其在单体混合物中的比例均匀进入共聚物分子链,共聚物分子量随转化率增加线性增大,P(St-co-CMS)的组成和分子量可控。在反应温度为100℃,苯甲醚为溶剂,CuCl/PMDETA为催化体系,P(St-co-CMS)为引发剂引发St的ATRP反应体系中,氯甲基全部用于引发St聚合,形成梳形支链;低转化率阶段,聚合物分子量随转化率增加呈线性增长,分子量分布较窄;在较高转化率下,聚合体系发生交联,形成凝胶;P(St-co-CMS)中p-CMS含量越高,凝胶越早发生。通过选择不同p-CMS含量的P(St-co-CMS)为大分子引发剂以及将苯乙烯转化率控制在一定范围,制得了主链分子量在25000~30000、支链数目在6.3~42.6、支链分子量在6000~17000的一系列梳形支化PS。     

NVP-HEMA-AM三元共聚物水凝胶对氯霉素的缓释作用

采用本体共聚法制备了丙烯酰胺(AM)与甲基丙烯酸-2羟-基乙酯(HEMA)以及N-乙烯基吡咯烷酮(NVP)共聚物水凝胶,研究了AM-HEMA-NVP共聚物水凝胶对广谱抗菌药物氯霉素的缓释作用。结果表明,随氯霉素溶液浓度增大、NaC l浓度降低、温度升高以及NVP或者AM组分的含量增大,AM-HE-MA-NVP三元共聚物水凝胶对氯霉素的吸收量增大;随AM-HEMA-NVP三元共聚物水凝胶中NVP或者AM组分含量的增大,氯霉素的释放速度明显增大;氯霉素从水凝胶中缓释的动力学可采用Fick扩散动力学描述,其释放过程受水凝胶溶胀过程以及氯霉素扩散过程控制。     

交联三维网络结构PINPAm的制备及其性能研究

聚N-异丙基丙烯酰胺(PINPAm)水凝胶是一种亲水但不溶于水,具有交联三维网络结构的高分子聚合物,具有一定条件下的溶胀/退溶胀行为,同时具有输送和渗透性、能量转换、吸附分离、生物相容性等功能。本文研究了用不同量的引发剂过硫酸铵(APS)对水凝胶形成的影响;反应温度分别为低温(低于5℃、20℃、30℃、40℃对水凝胶形成的影响。所制备的PNIPAm水凝胶分别测定了相转变温度(LCST)和凝胶溶胀率(SR)。结果表明引发剂量用量增多时水凝胶形成反应时间变短;反应温度升高水凝胶外观出现由无色透明凝胶→乳白半透明凝胶→乳白色凝胶→乳白色且无固定形态凝胶的变化。低温生成的水凝胶相转变温度(LCST)在33~34℃之间,水凝胶体积发生不连续收缩现象;交联剂N,N-亚甲基双丙烯酞胺(BIS)使用量越多溶胀率越小。     

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。