简介:AtheoreticalinvestigationonthepH-inducedswitchingofmixedpolyelectrolytebrusheswasperformedbyusingamoleculartheory.TheresultsindicatethattheswitchingpropertiesofmixedpolyelectrolytebrushesaredependentonthepHvalues.AtlowpH,negativelychargedchainsadoptacompactconformationonthebottomofthebrushwhilepositivelychargedchainsarehighlystretchedawayfromthesurface.AthighpHvalues,theinversetransformationtakesplace.TheroleofpHdeterminingthepolymerchainsconformationandchargebehaviorofmixedpolyelectrolytebrusheswasanalyzed.Itisfoundthatthereexistsamechanismforreducingstrongelectrostaticrepulsions:stretchingofthechains.TheH+andOH-unitsplayamoreimportantroleascounterionsofthechargedpolymersdo.ThecollapseofthepolyelectrolytechainsfordifferentpHvaluescouldbeattributedtothescreeningoftheelectrostaticinteractionsandthecounterion-mediatedattractiveinteractionalongthechains.
简介:新奇tripyridylporphyrin单体,5-[4-[2-(acryloyloxy)ethoxy]苯基]-l0,l5,20-tris(4-pyridyl)porphyrin(TrPyP),被综合并且有acrylamide(AM)到的polymerized准备恐水病地联系水溶性的聚合物PAM-TrPyP。卟啉pendants的聚集行为被调查由紫外可见并且荧光系列。聚合物在甚至显示恐水病的协会的一个强壮的趋势冲淡解决方案。与增加集中,407nm的从416nm的Soret乐队变化的最大的吸收波长,和荧光为展览节制集中熄灭的内部过滤器效果改正了。所有结果显示那-卟啉pendants的相互作用在卟啉的PAM-TrPyP,和H总数的协会起一个关键作用主要在集中的答案被形成。在另一方面,散布的动态光(DLS)和传播电子显微镜学(TEM)被用来随集中增加在macromolecular集会的尺寸和结构跟随变化。聚合物聚集符合构造因此从松开的像泡的形态学改变到稳固的水珠。当答案的pH价值减少到4.3时,卟啉pendants上的pyridine一半能是protonated,在macromolecular矩阵形成的H总数被静电的排斥相互作用破坏。
简介:新pH应答的糖类hydrogels被设计并且准备了使用curdlan衍生物(curdlan-Boc-histidine,杂种狗--他的)。杂种狗--他的hydrogels拥有了高度多孔的结构。杂种狗的胀大的比率--他与Boc-histidine的替换的度增加的hydrogels组织。并且0.5mol/LNaCl的增加挑起了杂种狗的胀大的比率的锋利的减小--他的hydrogels。牛的浆液白朊(BSA)能高效地被包含进杂种狗--他的hydrogels。而且,在从杂种狗的不同pH价值的BSA的版本侧面--他的hydrogels是显著地不同的。这些hydrogels在cytotoxicity试金显示出好biocompatibility。杂种狗--他的hydrogels具有在象蛋白质交货系统那样的生物医学的应用的大潜力。
简介:Thecopolymerizationofp-diethynylbenzene(PDEB)withphenylacetylene(PhA),4,4’-diethynylbiphenyl(DEBP)orm-diethynylbenzene(MDEB)arestudiedbyvaryingmoleratiosofmonomers.WhenthemoleratiosofPDEB/PhAarelessorequalto1/5,thecopolymersaresolubleandfusible,buttheothercopolymersareinsolubleandinfusible.Theresultsshowthatthegoodsolventofcross-linkedcopolymersisbenzeneandtheirsolubilityparameteris9.15cal0.5.cm(-1.5).Andtheirswellability(θp),Hugginsparameter(χ),density(d425)andtheaveragemolecularweightsbetweencrosslinks(c)aremeasured.Itisfoundthatθpandcofcopolymersaregreaterbutd425islessthanthatofrespectivehomopolymers.IRspectrashowthatthecopolymershavetransoidconfigurationandsmallnumberofunreactedethynylgroupsexistinthecopolymers.Themechanismaboutthepolymerizationoracetylenicderivativesinitiatedby(Ph3P)2PdCl2isdiscussed.