Structure Changes of Silk Fibroin（SF） by Blending with Poly（ε-caprolactone）（PCL）：Characterization of SF and PCL Blended Electrospinning Films

The mechanical properties and water solubility of electrospinning SF films limit their use as biomaterials. In order to develop a tissue engineering biomaterial with both satisfying biological properties and sufficient biomechanical properties,blended films composed of silk fibroin（ SF） and poly（ ε-caprolactone）（ PCL） were fabricated by electrospinning in this study. Scanning electron microscope（ SEM）, X-ray diffraction（ XRD）,thermal analysis,Fourier transform-infrared（ FT-IR）,Raman spectra,mechanical testing,and water solubility were used to characterize the morphological, structural and mechanical properties of the blended electrospinning films. Results showed that the diameter of the blended fiber was distributed between 600 and1000 nm,and the fiber diameter increased as the PCL content increased. There is no obvious phase separation due to the similarity and intermiscibility,as well as the interactions（ mainly hydrogen bonds）, between the two polymers. Meanwhile, the secondary structures of SF changed from random coils and Silk I to Silk II because of the interactions between SF and PCL. For this reason,the tensile strength and elongation at break of the electrospinning films improved significantly,and the water solubility decreased. In conclusion,the blended electrospinning films fabricated in this study showed satisfying mechanical properties and water insolubilities,and they may be promising biomaterials for applications in tissue engineering for blood vessels,nerve conduits,tendons,ligaments and other tissues.     

The Flow Behavior of Poly（m-Phenyleneisophthalamide） Concentrated Solution

IntroductionPoly(m-phenyleneisophthalamide)(PMIA)fibers arei mportant materials with excellent ther mal and oxidativestability,flame resistance,and dielectric properties.Thedecomposition temperature of PMIA is400430℃andeven under this temperature it releases little har mful gases.Unlike flame-retardant treated materials,PMIAfibers areinherently flame resistance and it will not di minish duringthe life of the fiber.The fiber s low tenacity and highelongation give it textile-like character…     

Fe（CN）_6~（3－）／Fe（CN）_6~（4－）体系扩散系数测定方法的比较

本文用循环伏安法、计时电位法、计时电流法、计时电量法和旋转圆盘电极研究了Ｆｅ（ＣＮ）_６~（３－）／Ｆｅ（ＣＮ）_６~（４－）体系的电化学反应过程，用上述几种电化学方法测定了Ｆｅ（ＣＮ）_６~（３－）／Ｆｅ（ＣＮ）_６~（４－）离子的扩散系数，对测定的方法和结果作了全面的分析比较．     

量子辛型群O（Spq（6））的一种实现

通过Uq（sp（6））的最高权模的自然表示理论,给出了量子辛型群O（Spq（6））的所有定义关系式。     

Silk Fibroin Film Blended with Poly（ ethylene glycol-glycerin）

To improve the toughness of silk fibroin（ SF） films,poly（ ethylene glycol-glycerin）（ PEGG） was synthesized with ethylene glycol and epichlorohydrin. The SF / PEGG blend films were prepared by casting aqueous solution and their structures were characterized. The PEGG was in liquid state at room temperature so it will not be a single phrase at blend film. It crosslinked with SF and made it insolubility in water. The results of X-ray diffraction（ XRD） indicated that the crystallinity of the SF in the blend films decreased with the content of PEGG increasing. The tensile strength and elongation at break of blend films were measured using an instron tensile tester. The results showed that the tensile strength and elongation at break of blend films were high enough for application.After the blend films were stored at room temperature for 100 d,the crystallinity, the tensile strength and elongation at wet state increased. The blend films are superior to SF films in providing excellent flexibility and mechanical properties in both dry and wet states. Based on the fact that SF has good biocompatibility,the SF /PEGG blend film will offer new options in many different biomedical applications.     

Synthesis,Structure and Antitumor Activities of [Ni（dien）2][Ni（CN）4] Complex

Ni(II)-dien complex was prepared and characterized by X-ray diffraction. The crystal belongs to triclinic system, space group P-1, with crystallographic parametersa=0.888 13(18) nm,b=0.890 10(18) nm,c=1. 591 8(3) nm, α=77.71(3)°, β=89.12(3)°, γ=61.24(3)°,Z=2. The two dien molecules coordinate to the central Ni atom, the six nitrogen atoms form a distorted octahedron. Preliminary pharmacological tests showed this complex had antitumor activity against HepG₂ and HL-60 cell linesin vitro. Foundation item, Supported by the National Natural Science Foundation of China (29972034) Biography: Li Tao (1976-), male, Ph. D candidate, research direction: ophthalmology and chemicalbiology.     

Synthesis and Characterization of Poly（methylsilane） as Ceramic Precursor

Polysilanes are novel polymers with Si-Si catenation chain. They can be used as precursors for SiC ceramic, have important applications in anti-oxidation of C/C composites. Poly（methylsilane） （PMS）, which is an ideal precursor to stoichiometric SiC, is synthesized by the sodium polycondensation reaction of monomer CH3SiHCl2. During the reaction, there is an initiation period. In this period there is no obvious exothermic reaction after dropping of monomer, then suddenly eruptive reaction arise and temperature goes up quickly, After the eruption, the polymerization can proceed smoothly. This phenomenon is harmful to scale-up.     

小儿扁桃体淋巴细胞Poly（A）—RNA的制备及其cDNA的合成

采用盐酸胍法从经PHA诱导的小儿扁桃体淋巴细胞中提取总RNA,经Oligo(dT)-纤维素柱层析制备了Poly(A)-RNA。经蔗糖线性密度梯度超速离心步骤,富集了含IL-2mRNA的Poly(A)-RNA。经麦胚无细胞体系翻译实验表明,富集后的Poly(A)-RNA具有良好的模板翻译活性,其~3H-亮氨酸参入活性是对照的5.1倍。又以此富集了的Poly(A)-RNA为模板,按照Watson和Jackson的最新方法合成了小儿扁桃体淋巴细胞的双链cDNA。经碱性凝胶电泳检查,用此方法合成的cDNA长度最长的超过了IL-2的cDNA长度。     

Tb~（3＋），Ce~（3＋）离子在Al_6Si_2O_（13）中的光致发光

采用溶胶－凝胶法合成了以Ａｌ６Ｓｉ２Ｏ１３为基质，掺杂Ｔｂ３＋，Ｃｅ３＋的发光材料．经ＸＲＤ结构分析表明，晶体结构属于正交晶系，其晶胞参数为ａ＝０．７５９５ｎｍ，ｂ＝０．７７５６ｎｍ，ｃ＝０．２８８２ｎｍ．测定了发光材料的激发和发射光谱，研究了从溶胶向凝胶及凝胶向发光体的转变过程．通过实验确定了材料的最佳组成．     

Electrochemical Determination of Trace Amounts of Lead （Ⅱ） and Cadmium （Ⅱ） at a Calix[6]arene Modified Carbon Paste Electrode

0　IntroductionLeadandcadmiumaretwoofthemostabundantheavymetalsintheenvironmentandtheirtoxiceffectshavebeenrecognizedforalongtime.Experi mentalandepidemiologicalstudieshaveprovidedsub stantialevidencethatthemainorgansforleadandcad miumaccumulationinhumansarekidney,liver,lung ,andpancreas .Lowlevelsoflong termexposuretoleadandcadmiumcanbemanifestedbyavarietyofsyndromesandeffectsincludingcancer,renaldysfunction ,hepaticinjury,lungdamageandhypertension[1 ] .Thus ,thede terminationoftracelevelsofl…     

甲基丙烯酸甲酯的活性自由基微乳液聚合

采用双硫酯存在下的活性自由基聚合方法进行了甲基丙烯酸甲酯的活性自由基微乳液聚合研究。比较了三种乳化剂对聚合体系稳定性和分子量控制的影响。在单体含量约8％时，以阳离子型乳化剂十六烷基三甲基溴铵（CTAB）为乳化剂可以得到稳定的微乳液，且具有明显的活性聚合特征，即产物分子量随转化率的增加而增大，实测分子量和理论分子量相近，分子量多分散性系数小于1．3．产物的子量控制在4万以下时达到较高的精度。聚合过程存在明显的聚合恒速期。而用阴离子型乳化剂十二烷基硫酸钠（SDS）和非离子型乳化剂OP－10则需加入长链醇类助乳化剂。助乳化剂虽可提高微乳液的稳定性和单体含量，但不利于微乳液分子量的控制。反应温度对产物分子量及分子量分布的控制和体系的稳定没有明显影响。胶乳直径小于30nm，略大于未加链转移剂的正常微乳液聚合胶乳。产物的立体规整度较高，间规PMMA占59％。     

可逆加成-断裂链转移(RAFT)自由基聚合法制备PMMA/SiO2有机/无机杂化材料

以二硫代苯甲酸异丁腈酯(CPDB)为链转移剂,过氧化引发基团纳米SiO2为引发剂,在80℃的甲苯溶液中进行了甲基丙烯酸甲酯(MMA)的可逆加成-断裂链转移(RAFT)自由基聚合.结果表明,该聚合具有活性自由基聚合的特征,聚合物接枝层的分子量基本可控,单体转化率与分子量具有一定的线性关系,ln([M]0/[M])与反应时间成线性正比关系.通过TEM、AFM对杂化粒子进行了表观形貌分析.     

N-咔唑二硫代甲酸异丙苯酯的合成及应用

以咔唑和α-甲基苯乙烯为原料,合成了以咔唑为Z基团的可逆加成-断裂链转移试剂——N-咔唑二硫代甲酸异丙苯酯(CCBD),该化合物合成简便,可以经重结晶提纯.以CCBD为可逆加成-断裂链转移试剂对苯乙烯、甲基丙烯酸甲酯和丙烯酸乙酯单体进行了RAFT聚合,该聚合具有活性聚合特征,聚合物相对分子质量随转化率升高而增大,并得到相对分子质量分布窄的聚合产物,研究表明CCBD具有很好的RAFT聚合控制能力.     

高分子化学实验的绿色化开设——以可逆加成-断裂链转移(RAFT)聚合反应为例

目的探索高分子化学实验的绿色化开设途径。方法融合绿色化学理念,设计商用蓝光LED诱导的可逆加成-断裂链转移(RAFT)聚合的综合性高分子化学实验教学项目。结果在可见光照射下,仅有三硫代碳酸酯存在时,活性可控聚合制备出聚2-乙烯基吡啶。结论实验方法具有绿色、环境友好、反应条件温和、实验现象明显、实验操作简单易行等优点。     

可逆加成-断裂链转移聚合制备温度敏感色谱材料

利用可逆加成-断裂链转移聚合(RAFT)成功制备了温度敏感色谱材料,FT-IR,XPS,元素分析和TG等方法对改性后的硅胶表征,结果显示成功在硅胶表面接枝了具有温敏性的N-异丙基丙烯酰胺(PNIPAAm).首先将二硫代苯甲酸苄酯(BDTB)作为RAFT的链转移剂固定到硅胶表面,然后在硅胶表面通过RAFT接枝NIPAAm.接枝率随链转移剂与引发剂(CTA/I)的减小而增大.以4种类固醇为分析物,分别在10,30和50℃的温度下,研究不同接枝率的固定相对它们保留时间的影响,HPLC分析结果显示,固定相的温度敏感性能和色谱分离性能随接枝率的增大而提高.结果表明RAFT聚合成功制备了温度敏感色谱材料.     

PS/Ag纳米复合粒子的制备与表征

目的 制备PS/Ag纳米复合粒子.方法 以二硫代苯甲酸异丙苯酯(CDB)为链转移剂,用可逆加成断裂链转移聚合(RAFT)的方法将硫代羰基引入到聚苯乙烯(PS)高分子链中,采用透射电子显微镜(TEM)对其进行了表征.利用PS高分子链中的硫代羰基有保护和稳定Ag纳米粒子的作用,制备了PS/Ag纳米复合粒子.结果 Ag纳米粒子具有良好的单晶结构,且均匀分散于PS胶体粒子中.结论 PS/Ag纳米复合粒子的结构与AgNO_3溶液的加入量有关.     

RAFT法在纳米SiO_2表面接枝PBA及其对POM的改性研究

采用可逆加成-断裂链转移(RAFT)聚合法在纳米二氧化硅(SiO2)表面接枝聚丙烯酸丁酯(PBA),并采用透射电镜(TEM)、广角X射线衍射(WAXD)、差示扫描量热仪(DSC)及热重分析仪(TGA)等手段研究纳米SiO2及SiO2-PBA复合粒子的添加对聚甲醛(POM)结晶性能及热稳定性的影响.结果表明:用RAFT聚合方法有少量的PBA接枝于纳米SiO2表面;纳米SiO2及SiO2-PBA复合粒子的添加不改变聚甲醛的晶型;粒子的添加使用POM结晶温度、熔点和结晶度升高;且粒子的添加均使POM热稳定性提高.     

硫代羰基化合物中Z和R基团结构对苯乙烯RAFT聚合的影响

为了考察RAFT试剂中取代基对其聚合控制性能的影响,合成了具有不同Z基团和R基团结构的二硫代酯化合物,同时合成了具有不同Z基团结构的二硫代氨基甲酸酯化合物,并将这些化合物作为链转移剂,以AIBN为引发剂进行了苯乙烯70℃下的RAFT聚合,考察了Z基团和R基团对这些化合物在苯乙烯自由基聚合中的控制性能。通过测定链转移常数考察了Z基团和R基团对此类化合物在用于RAFT聚合时控制性能差异的现象。结果显示RAFT试剂中Z基团和R基团的结构对其控制性能和链转移常数有很大的影响。当在Z基团中引入共轭结构后可以明显改善其用于苯乙烯聚合的控制性能,链转移常数也有相同的趋势。RAFT试剂中在控制苯乙烯自由基聚合时异丁酸酯基是最有效的R基团,异丁腈酯基次之,而异丙苯基最差。使用二硫代氨基甲酸酯类化合物作为链转移剂进行苯乙烯的自由基聚合过程的结果显示当氮原子处于共轭结构中,可以有效地控制苯乙烯聚合。而当氮原子不处于共轭结构中不能有效的控制苯乙烯自由基聚合。     

RAFT分散聚合诱导自组装制备PDMAs-PSx嵌段共聚物纳米颗粒

可逆加成-断裂-链转移(reversible addition-fragmentation-chain transfer, RAFT)聚合诱导自组装(polymerization-induced self-assembly, PISA)是制备具有特定形貌嵌段共聚物纳米颗粒的高效手段. 以苯乙烯(styrene, St)为分散聚合的单体, PDMA可逆加成-断裂-链转移(reversible addition-fragmentation-chain transfer,RAFT)聚合诱导自组装(polymerization-induced self-assembly,PISA)是制备具有特定形貌嵌段共聚物纳米颗粒的高效手段.以苯乙烯(styrene,St)为分散聚合的单体,PDMA_(23)和PDMA_(38)为大分子链转移剂(chain transfer agent,CTA),乙醇为溶剂,在70℃下探究了纳米颗粒的形貌随不同聚合度(degree of ploymerizations,DPs)的转变情况.由实验结果可知:以PDMA_(23)为链转移剂,可调控苯乙烯的聚合度,得到球、虫、囊泡、复合囊泡等形貌;以PDMA_(38)为链转移剂,可在较宽的聚合度范围内得到均匀的球形纳米颗粒.     

稳定自由基存在下甲基丙烯酸甲酯的聚合研究

研究了以2，2，6，6－四甲基－1－哌啶氧化物（TEMPO）作为稳定基，过氧化苯甲酰（BPO）为引发剂，三氟乙酸酐（TFA）为加速剂，极性单体甲基丙烯酸甲酯的聚合。在TFA的促进下，聚合速率明显加快，17h可达62％的转化率，在单体化率低下30％时，分子量随转率线开增长，分子量分布较窄，转化率较高时，分散性变大，分子量变化不大，随着聚合体系温度升高，分散性变窄，140℃为其较理想的聚合温度，通过对模型聚合物的核磁共振（^1HNMR)）分析，发现氧氮自由基部分脱落，解释了极性单体洒能在稳定基存在下进行活性聚合的原因，对氧氮自由基易从主链脱落的可能解释是酯基的强电子效应削弱了C－O键，从而使氧氮自由基与主链的连接减弱，导致分子量不可控制。