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1.
两亲嵌段共聚物溶液内胶束形成的温度效应   总被引:2,自引:0,他引:2  
合成了一系列具有两亲嵌段结构的聚(乙二醇)(PEO)一聚(丙二醇)(PPO)共聚物.利用荧光探针及示差量热法测定了共聚物水溶液的临界胶束形成温度(CMT)值.发现二嵌段共聚物(PEO-PPO)和三嵌段共聚物(PEO-PPO-PEO)有着类似的变化规律,即随共聚物分子中疏水链(PPO)长度的增大,其CMT值降低.但三嵌段共聚(PPO-PEO-PPO)则因疏水链段处于共聚物分子的两端,因而在溶液中有可能形成立体网状交联结构.此外,利用探针分子在不同极性溶剂中荧光峰值波长发生位移的现象可以对形成胶束内核的组织程度、极性大小进行估测.  相似文献   

2.
合成了不同软链段长度和不同硬链段含量的系列对苯二甲酸乙二酯-环氧乙烷(PET-PEO)多嵌段共聚物,用NMR质子港测定了硬链段含量,对部分溶于氯仿的PET-PEO多嵌段共聚物进行了分离,并分别测定其氯仿可溶物和不溶物的硬链段含量、熔融热谱和热结晶谱.揭示了PET-PEO多嵌段共聚物的组成不均一性及其对软镇段长度和硬链段含量的依赖性,进而用DSC热谱证明了软链段和硬链段的结晶能力与PET-PEO多嵌段共聚物组成不均一性密切相关.  相似文献   

3.
两亲聚合物表面的反相气相色谱分析   总被引:3,自引:1,他引:3  
采用反相气相色谱探针技术研究了苯乙烯-氧乙烯-苯乙烯三嵌段两亲聚合物的表面物理化学性质。包括表面吸附热力学函数,表面能的色散分量以及表面分子链与探针的分子间相互作用,。探讨了共聚物中亲油性链段聚苯乙烯(PS)和亲水性链段聚氧乙烯(PEO)的组成比例与其表面性质的关系。结果表明共聚物表面组成中随PEO含量的增加,其表面能增大,表面分子链与探针分子的相互作用增强,表面吸附能力也增强。  相似文献   

4.
采用耗散粒子动力学方法(DPD),模拟了聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO—PPO—PEO)三嵌段共聚物在乙醇溶液中的自组装行为,考察了该共聚物的体积分数和聚氧乙烯(PEO)嵌段链长对介观形貌的影响。当F88(PEO104-PPO39-PEO104)体积分数为20%时,胶柬由初始的均衡分散态逐渐聚合,最终形成PPO为核、PEO为壳的平衡态柱状团聚体。改变共聚物的体积分数和PEO链的长度,会形成不同的介观结构,如:球状、柱状、立体网络、层状和穿孔状结构等。结果表明,DPD方法是研究三嵌段共聚物自组装行为和介观结构形成机理的有效工具,对合成具有特定结构性能的材料有一定的指导意义。  相似文献   

5.
本文采用可控聚合方法合成了一系列组成可控的由含端氨基的聚环氧乙烷(PEO)亲水链段和可生物降解的聚(ε-己内酯)(PCL)疏水链段组成的两亲性嵌段共聚物PCL-b-PEO-NH2.通过共聚物端氨基的反应活性,进一步合成了含有功能性基团的PCL-b-PEO-COOH和PCL-b-PEO-RGD两嵌段共聚物及含有温敏性组分的PCL-b-PEO-b-PNIPAAm三嵌段共聚物(PNIPAAm为聚异丙基丙烯酰胺).  相似文献   

6.
报导了系列聚四氢呋喃-聚甲基丙烯酸甲酯结晶-非晶(硬段型)两嵌段共聚物的结晶行为,结果表明,其微相分离和结晶规律与文献上唯一进行过系统研究的同类嵌段共聚物(PEO-b-PS)都有较大的差别;结晶段结晶能力的大小是制约这类体系微相分离和结晶规律的一个重要因素.  相似文献   

7.
在超声辐照作用下聚氧化乙烯和丙烯腈嵌段共聚的研究   总被引:2,自引:0,他引:2  
本文研究了聚氧化乙烯(PEO)和丙烯腈(AN)在水溶液中的超声共聚。共聚速率和AN浓度成正比,存在AN浓度最低限。PEO的降解速率常数越大,它所共聚的AN量越大,表明AN的聚合是由PEO降解生成的大自由基引发生成的。通过元素分析和IR测定证明产物为PEO-AN共聚物。通过POM、TEM、DSC和WAXD测定证实共聚物为结晶嵌段共聚物。  相似文献   

8.
报道用稀土化合物改性的钛系截体催化剂(SN催化剂)进行苯乙烯和丙烯顺序嵌段共聚合(Sequentialblockcopolymerization)的研究,通过对初生嵌段共聚产物进行溶剂萃取与分级,并用13C-NMR、WAXD.DSC,DMA和电子显微镜进行表征,推断共聚物为具有等规聚苯乙烯链和等规聚丙烯链段的A-B型二嵌段共聚物,且各段均能结晶。发现嵌段共聚物比相应的均聚物具有较好的综合力学性能和热性能,而且对iPS/iPP共混具有良好的增容作用。  相似文献   

9.
聚谷氨酸苄酯-聚乙二醇嵌段共聚物的合成和表征   总被引:11,自引:0,他引:11  
通过嵌段共聚技术,合成了聚γ-苄基L-谷氨酸(PBLG)作为疏水性链段-聚乙二醇(PEG)作为亲水性链段的嵌段共聚物。用对甲苯磺酸酯化-氨水皂化法合成带有端氨基的聚乙二醇(AT-PEG),光气-甲苯液相法制备谷氨酸苄酯-N-羟酸酐(BLG-NCA)。用AT-PEG引发BLG-NCA聚合制备PBLG-PEG或PBLG-PEG-PBLG,通过不同的单体、引发剂浓度比调节聚合物分子量。用GPC、^1HNMR、IR对聚合物的结构进行了表征。结果表明,带有端氨基的聚乙二醇确实能引发BLG-NCA生成PBLG和PEG的嵌段共聚物,产物中几乎没有残存的PEG,共聚物的分子量可控。  相似文献   

10.
用DSC法研究苯乙烯-丙烯嵌段共聚物(iPS-b-iPP)的等温结晶动力学,结果表明,在所选择的结晶温度(127-132℃)范围内,共聚物很好地符合Avrami动力学方程;共聚物结晶温度,结晶速率,结晶成和生长方式都与共聚物结构和组成比在关,随着嵌段共的中iPS段含量的增加,结晶速率和Avrami指数(n)明显降低。  相似文献   

11.
The novel biodegradable copolymer PDLLA-(MAH-Diol)_n-PDLLAwith unsaturated bond was synthesized by copolymerizing lactide and prepolymer, which was prepared by the polycondensation of maleic anhydride and poly(ethylene glycol), using p- toluene sulphonic acid as catalyst. The new copolymer has improved hydrophilicity and fexibility. The structure and properties of the novel polymers were studied by FTIR, NMR, GPC-MALLS and DSC.  相似文献   

12.
本文系统地研究了地超声波辐照下聚氧化乙烯(PEO)在其水溶液中与甲基丙烯酸己酯(HMA)的非均相共聚反应。结果表明,PEO超声降解产生的自由基可引发HMA聚合,形成PEO-HMA共聚物,该共聚物在超声波辐照下可进一步降解。通过红外光谱、裂解气相色谱及核磁共振分析表明,所得共聚物为嵌段共聚物。  相似文献   

13.
A new series of segmented copolymers were synthesized from poly(ethylene terephthalate) (PET) oligomers and poly(ethylene glycol) (PEG) by a two‐step solution polymerization reaction. PET oligomers were obtained by glycolysis depolymerization. Structural features were defined by infrared and nuclear magnetic resonance (NMR) spectroscopy. The copolymer composition was calculated via 1H NMR spectroscopy. The content of soft PEG segments was higher than that of hard PET segments. A single glass‐transition temperature was detected for all the synthesized segmented copolymers. This observation was found to be independent of the initial PET‐to‐PEG molar ratio. The molar masses of the copolymers were determined by gel permeation chromatography (GPC). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4448–4457, 2004  相似文献   

14.
四臂星形嵌段共聚物s-PDLLA-b-PEG的合成   总被引:1,自引:0,他引:1  
季戊四醇与D,L-丙交酯开环聚合制得末端为羟基的四臂星形聚乳酸(s-PDLLA);s-PDLLA与羧基封端的聚乙二醇单甲醚(CT-mPEG)完成酯化反应,合成了以季戊四醇为核,以聚乳酸为内部嵌段、聚乙二醇为外部嵌段的四臂星形聚(D,L-乳酸)-聚乙二醇嵌段共聚物(s-PDLLA-b-PEG),其结构经1H NMR,IR和GPC表征。  相似文献   

15.
用磺酸酯法制备单端氨基聚乙二醇引发剂,引发谷氨酸苄酯羧酸酐开环聚合,生成可生物降解的两亲嵌段共聚物聚乙二醇﹣聚谷氨酸苄酯(PEG-PBLG),用IR,NMR和GPC表征了共聚物。用超微透析法制备PEG-PBLG聚合物纳米粒,荧光芘探针法测定纳米粒的临界聚集浓度(cac)。紫外分光光度计考察纳米粒对疏水性药物的增溶作用,PEG-PBLG可作为亚微粒药物输送系统的载体。  相似文献   

16.
Catalytic copolymerization of styrene and ethylene by neutral nickel(II) complex has been performed in emulsion. The influences of the ratio of styrene to ethylene, polymerization temperature and time, ethylene pressure and polymerization procedure on the activity of catalyst and the composition of polymer were investigated in detail. The morphology of the polymer latex was observed by TEM, and the polymer was also characterized by NMR and GPC. The results showed that the latex particle was spherical, and the latex up to 10% solid content and the high-molecular-weight poly(styrene-b-ethylene) was obtained. The content of the ethylene in the copolymer was evidently enhanced by the addition of the styrene decreasing, addition of the toluene and introduction of the procedure without prepolymerization. The styrene incorporated in the copolymer were in the range of 72 mol% to 100 mol%.  相似文献   

17.
Polycaprolactone-poly(ethyleneglycol)(PCE)blockcopolymerisabiodegradablepolymer.ThebiodegradationcharacterisationinvitFoandinvivoofthePCEwasreported"'.ItwasfoundthatthedegradationrateofthePCEwasincreasedwithincreasingpoly(ethyleneglycol)content,temperature,acidityandalkalinityanditwasacceleratedbythepresenceofenzyme.Thefastestdegradationratewasobservedinthephysiologicalconditionofthesamplebeingimplantedinthebodyofanimals.SoPCEcopolymerpossessesagoodprospecttobebio-medicalmaterials3.Mostp…  相似文献   

18.
Poly(γ-benzyl-L-glutamate)-graft-poly(ethylene glycol) (PBLG-graft-PEG) copolymer was synthesized by the ester exchange reaction of PBLG with PEG. Nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM) were used to characterize the structure of PBLG-graft-PEG copolymer. The effects of reaction temperature, reaction time, and the chain length of PEG on the grafting ratio of PBLG-graft-PEG copolymer were investigated.  相似文献   

19.
采用大分子单体技术合成了一系列以聚乙二醇为支链、甲基丙烯酸六氟丁酯为主链的含氟两亲接枝共聚物(PHFMA-g-PSPEG)。用1HNMR和凝胶色谱(GPC)对制备的大分子单体和两亲接枝共聚物的结构进行了表征。利用示差扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(POM)测试技术对含氟两亲接枝共聚物的结晶行为进行了研究。DSC和XRD结果表明,随着共聚物中含氟链段质量分数的增加,其结晶温度(Tc)和结晶度(Xc)均降低,而结晶熔融温度(Tm)先减小后增加。POM发现,随着共聚物中含氟链段质量分数的增加,其结晶速度减慢,共聚物形成清晰球晶的能力减弱,当共聚物中含氟链段质量分数为57%时,含氟两亲接枝共聚物已不能形成清晰的球晶。  相似文献   

20.
Biodegradable, amphiphilic, four‐armed poly(?‐caprolactone)‐block‐poly(ethylene oxide) (PCL‐b‐PEO) copolymers were synthesized by ring‐opening polymerization of ethylene oxide in the presence of four‐armed poly(?‐caprolactone) (PCL) with terminal OH groups with diethylzinc (ZnEt2) as a catalyst. The chemical structure of PCL‐b‐PEO copolymer was confirmed by 1H NMR and 13C NMR. The hydroxyl end groups of the four‐armed PCL were successfully substituted by PEO blocks in the copolymer. The monomodal profile of molecular weight distribution by gel permeation chromatography provided further evidence for the four‐armed architecture of the copolymer. Physicochemical properties of the four‐armed block copolymers differed from their starting four‐armed PCL precursor. The melting points were between those of PCL precursor and linear poly(ethylene glycol). The length of the outer PEO blocks exhibited an obvious effect on the crystallizability of the block copolymer. The degree of swelling of the four‐armed block copolymer increased with PEO length and PEO content. The micelle formation of the four‐armed block copolymer was examined by a fluorescent probe technique, and the existence of the critical micelle concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. The cmc value increased with increasing PEO length. The absolute cmc values were higher than those for linear amphiphilic block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 950–959, 2004  相似文献   

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