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1.
研究了N,N'-双(3,5-二叔丁基水杨醛)-1,2-环己二胺钴(Ⅱ)[Co(salen*)]存在下氯丁二烯(CP)的自由基聚合, 考察了不同溶剂、 引发剂用量及配体对聚合反应的影响. 结果表明, 随着引发剂用量的增加, 聚合反应的诱导期缩短, 以[ABVN]0/[ Co(salen*)]0=3/1配比投料, 聚合反应表现出较好的可控聚合特征. 在苯、 甲苯、 四氢呋喃(THF)和乙酸乙酯(EA) 4种溶剂中按照[CP]0/[Co(salen*)]0/[ABVN]0=400/1/3的配比投料, 在苯中的可控聚合程度最好: 在低转化率(40%以下)实测聚合物分子量(Mn,GPC)与理论值(Mn,th)吻合, 且分子量随转化率增加呈线性增长. 研究了THF、 三乙胺(NEt3)、 吡啶(Py)及水等不同配体对聚合反应的影响, 发现在添加THF时, 低转化率(40%以下)下Mn,GPCMn,th相符, 分子量分布(PDI)相对较窄.  相似文献   

2.
首次采用2种碳二亚胺(二环己基碳二亚胺(DCC)和N,N′-二异丙基碳二亚胺(DIC))作为催化剂、碘(I2)与偶氮二异庚腈(ABVN)原位生成烷基碘化物为引发剂,实现了甲基丙烯酸甲酯(MMA)的可逆-失活自由基聚合.首先,对比了2种催化剂对该体系催化活性的大小,发现DCC作为催化剂时对聚合的可控程度优于DIC.然后详细考察了DCC用量、引发剂用量和不同溶剂对聚合反应的影响.结果表明,在反向碘转移聚合(RITP)的基础之上添加DCC或DIC,均可以有效降低聚合物的分子量多分散指数(PDI=Mw/Mn).[MMA]0:[I2]0:[ABVN]0:[DCC]0=200:1:1.7:4时具有最佳的可控效果,凝胶渗透色谱(GPC)测定的分子量与理论分子量吻合,且数均分子量随转化率增加呈线性增长,分子量多分散指数较小(PDI1.26).在甲苯、苯、四氢呋喃(THF)、苯甲醚4种溶剂中均有很好的可控聚合特征.最后,通过1H-NMR对所得聚合物结构进行表征,证明为碘原子封端,端基保有度达到97.5%,并成功进行了聚甲基丙烯甲酯的扩链反应;通过自由基捕捉实验、紫外等对碳二亚胺调控MMA聚合的机理进行了讨论.  相似文献   

3.
报道了4个含苯甲酰胺取代的水杨醛亚胺配体: N-(2-苯甲酰胺苯基)-水杨醛亚胺(L1)、 N-(2-苯甲酰胺苯基)-3-甲基水杨醛亚胺(L2)、 N-(2-苯甲酰胺苯基)-3-叔丁基水杨醛亚胺(L3)和N-(2-苯甲酰胺苯基)-3,5-二溴水杨醛亚胺(L4)的合成, 采用 1H NMR和HRMS对其结构进行了表征. 在助催化剂甲基铝氧烷(MAO)作用下, 以L3与TiCl4·2THF为模型催化体系, 在最佳陈化条件(陈化温度为25 ℃, 陈化时间为30 min, 配体与TiCl4·2THF的摩尔比3∶1)下, 考察了L1~L4/TiCl4·2THF催化体系Al/Ti摩尔比、 反应时间、 反应温度和聚合压力, 以及配体结构等对乙烯聚合的影响. 结果表明, 随着在水杨醛骨架上氧原子邻位取代基位阻的增大, 催化体系的活性及所得聚乙烯的分子量均有增加, 其中以L3的催化活性最高, 达到224 kg PE/(mol Ti?h). 采用高温 1H NMR, 13C NMR, GPC-IR和DSC等对由不同配体L1~L4/TiCl4·2THF得到的聚乙烯样品的微观结构与热性能进行了分析与表征, 结果显示样品为线性高密度聚乙烯, Mn=5.9×10 4~11.9×10 4, 分子量分布(PDI)为21.9~72.1.  相似文献   

4.
研究了N,N'-双(3,5-二叔丁基水杨醛)-1,2-环己二胺钴(Ⅱ)[Co~Ⅱ(salen~*)]存在下氯丁二烯(CP)的自由基聚合,考察了不同溶剂、引发剂用量及配体对聚合反应的影响.结果表明,随着引发剂用量的增加,聚合反应的诱导期缩短,以[ABVN]0/[Co~Ⅱ(salen~*)]0=3/1配比投料,聚合反应表现出较好的可控聚合特征.在苯、甲苯、四氢呋喃(THF)和乙酸乙酯(EA)4种溶剂中按照[CP]_0/[Co~Ⅱ(salen~*)]0/[ABVN]0=400/1/3的配比投料,在苯中的可控聚合程度最好:在低转化率(40%以下)实测聚合物分子量(Mn,GPC)与理论值(Mn,th)吻合,且分子量随转化率增加呈线性增长.研究了THF、三乙胺(NEt3)、吡啶(Py)及水等不同配体对聚合反应的影响,发现在添加THF时,低转化率(40%以下)下Mn,GPC与Mn,th相符,分子量分布(PDI)相对较窄.  相似文献   

5.
以四丁基溴化铵(BNBr)或四丁基碘化铵(BNI)作为有机催化剂,碘(I_2)与偶氮二异丁腈(AIBN)原位生成烷基碘化物为引发剂在本体聚合中实现了甲基丙烯酸甲酯(MMA)的可逆催化络合聚合(RCMP).首先,比较了2种催化剂对该体系催化活性的大小,相同实验条件下,BNI作为催化剂时对聚合的控制效果优于BNBr,即在该体系中BNI的催化活性大于BNBr;其次,较为详细地研究了催化剂BNI的用量对MMA可控聚合的影响,结果表明,BNI的浓度在9.43~117.81 mmol/L范围内均有较好的控制效果,当[MMA]∶[I_2]∶[AIBN]∶[BNI]=100∶0.5∶0.75∶0.25,即催化剂的浓度为23.56 mmol/L时反应速率较快,理论分子量与实测分子量(通过GPC进行表征)几乎完全吻合,分子量多分散指数(PDI=M_w/M_n)较小(PDI1.27);最后,通过1H-NMR对所得聚合物的结构进行表征,证明为碘原子封端,M_(n,NMR)与M_(n,GPC)相吻合,端基保有度达到98.8%.  相似文献   

6.
β-环糊精(β-CD)为起始原料, 通过磺酰化及乙二胺基取代等过程, 制备具有端氨基的中间体β-环糊精(6-en-β-CD); 再以6-en-β-CD为引发剂, 通过赖氨酸N-羧基环内酸酐(Lys-NCA)和谷氨酸N-羧基环内酸酐(Glu-NCA)的混合开环聚合(ROP)和脱苄氧羰基(Cbz)保护等反应, 制备了以β-CD为核、 混聚多肽为支臂的星状聚合物[6-聚(谷氨酸-赖氨酸)-β-CD]. 以基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、 核磁共振波谱(NMR)和傅里叶变换红外光谱(FTIR)等对星状聚合物及中间体结构进行表征; 同时采用圆二色光谱(CD)和噻唑蓝(MTT)法对该聚合物的二级结构和体外毒性进行了考察. 结果表明, 所得星状聚合物的重均分子量(Mw)为4626, 多分散系数(PDI)为1.10, 平均聚合度(DP)为27.1; 在水溶液中星状聚合物的二级结构是无规则线团; 在5 mg/mL浓度下, 细胞存活率可达到94%以上, 没有呈现明显体外细胞毒性, 具有潜在的药用前景.  相似文献   

7.
黏合剂和涂料行业中, 聚合物共混物表征是分析的难题, 分离技术的研究一直备受关注. 本文设计并搭建了超高效液相色谱-空间排阻色谱在线联用系统(UHPLC-SEC), 采用羟基聚丁二烯(HTPB)考察了二维色谱系统的溶剂兼容性及正交性, 以苯乙烯-丁二烯嵌段共聚物(SBS)、 苯乙烯-异戊二烯嵌段共聚物(SIS)和聚甲基丙烯酸酯(PMMA)共混物研究了二维色谱系统的适用性. 结果表明, HTPB分子量及分布的UHPLC-SEC测定结果与SEC测定结果一致, 峰尖分子量(Mp)为3407 Da, 重均分子量(Mw)为6573 Da, 分散系数(PDI)为2.36, 相对标准偏差(RSD)均小于5.7%, 系统的溶剂兼容性和正交性良好. UHPLC-SEC法测得聚合物共混物中PMMA, SBS和SIS的Mp, Mw和PDI与单个聚合物的SEC测定结果的相对误差均小于7.1%. PMMA, SBS和SIS共混物在200 °C加热3 h后, PMMA 稳定不变, SBS和SIS组分明显降解. UHPLC-SEC在线联用方法对聚合物共混物的表征结果准确、 重复性好, 为聚合物配方产品的失效分析提供了一种重要且有效的手段.  相似文献   

8.
采用聚乙烯吡咯烷酮(PVP)和聚偏氟乙烯(PVDF)为凝胶剂, 以碘化锂和碘单质为碘源, 碳酸乙烯酯(EC)和碳酸丙烯酯(PC)为溶剂, 制备了染料敏化太阳能电池(DSSCs)用凝胶聚合物电解质(GPE). 使用拉曼光谱、 循环伏安曲线和交流阻抗谱等对GPE进行表征. 结果表明, 聚合物的配比与浓度及碘与碘化锂比例对该电解质性能有很大影响, 当聚合物质量分数为10%、 PVP与PVDF质量比为80∶20、 I2浓度为0.042 mol/L且LiI与I2摩尔比为30∶1时, 制备的GPE在室温下电导率达最大值(3.27 mS/cm). 使用该GPE组装的DSSCs在100 mW/cm2的模拟太阳光照射下, 开路电压为0.64 V, 短路电流为13.6 mA/cm2, 填充因子为0.595, 能量转化效率为5.18%, 并在30 d内表现出了良好的稳定工作性能.  相似文献   

9.
利用原子转移自由基聚合(ATRP)方法, 分别在三氟甲苯、含氟离子液体以及三氟甲苯/含氟离子液体混合溶剂体系中合成了聚苯乙烯-co-聚(2,3,4,5,6-五氟苯乙烯)(PS-co-PPFS)共聚物, 通过1H NMR、19F NMR、元素分析以及凝胶渗透色谱法(GPC)对所得聚合物的分子链结构和组成进行了分析和表征. 随后, 利用静态呼吸图法分别在CS2, CHCl3 和CH2Cl2 中制备了有序多孔薄膜, 用扫描电子显微镜(SEM)观察其表面形貌, 并与利用分子量大小相当的聚苯乙烯均聚物(PS)制备的多孔薄膜进行了对比. 研究结果表明: 在三氟甲苯和含氟离子液体溶剂体系中, 均可利用ATRP 聚合方法获得窄分子量分布的PS-co-PPFS 共聚物(Mn=5200~7900 g·mol-1, i>Mw/Mn=1.12~1.22). 对聚合物薄膜的扫描电子显微镜(SEM)观察和分析显示: 分别以CS2, CHCl3 和CH2Cl2 作为溶剂, 利用静态呼吸图法均可制备出PS-co-PPFS 共聚物多孔薄膜. 然而, 与在CHCl3 和CH2Cl2 中制备的PS 均聚物多孔薄膜的表面形貌不同的是, PS-co-PPFS 共聚物多孔薄膜呈现出无序排列、平均孔径大小不同的两种孔结构; 在CHCl3 中制备所得薄膜的孔结构有序性相对较好, 两种孔的平均孔径分别为0.75 和0.37 μm.  相似文献   

10.
报道了多核Nd-Al双金属配合物活性体对共轭双烯烃的溶液聚合.结果表明,适宜的振荡时间有利于提高活性体的催比活性;通过外加AlEt3,验证了聚合体系的纯度和活性体的稳定性,溶剂类型对活性体催比活性和聚合物分子量影响较大,活性次序为甲苯≥环己烷>正己烷;对产物[η]的影响则相反:甲苯《环己烷<正己烷.不同单体的定向聚合性能有差别,聚丁二烯的顺1,4含量较低,且易受反应条件的影响.  相似文献   

11.
Ethylene polymerization using in situ combinations between a chloroneodymocene precursor and a dialkylmagnesium reagent has been investigated to prepare tailor-made oligomers. Combinations of [Cp*2NdCl2Li(OEt2)2] (1) with 40 equiv. of n-butylethylmagnesium (BEM) or di(n-hexyl)magnesium (DHM) gave oligoethylenes with Mn up to 2500 and narrow molecular weight distributions (Mw/Mn<1.10) in moderate activity (A1 h=79 kg/(mol of Nd h atm) at 80 °C, 1 atm). Under these conditions, ethylene polymerization proceeded in a controlled fashion, with a linear growth of Mn vs monomer conversion, ascribed to an effective chain transfer between the Nd and Mg centers. Combinations of [rac-{Me2Si(η5-2-SiMe3-4-t-Bu-C5H2)2}Nd(μ-Cl)2Li(THF)2] (2) with either BEM or DHM (20–40 equiv.) showed decreased activity, suggesting possibly a different rate-determining-step for ethylene polymerization than for that of higher -olefins. The oligoethylenes obtained from combinations based on 2 have narrow molecular weight distributions (Mw/Mn<1.2) but higher contents of vinyl terminations. Monitoring of the reactions showed also a non-linear growth of Mn vs monomer conversion, especially marked when DHM was used as co-reagent. The 2/DHM combination behaves as a “self-correcting” catalyst system that deviates from the calculated Mn values for a controlled-living polymerization in the early stage of the reaction and re-approach them progressively in the second stage.  相似文献   

12.
以酚锂作为副反应抑制剂, 以正丁基锂或1,1-二苯基乙烯盖帽的正丁基锂为引发剂, 通过顺次添加单体的方法, 合成了结构明确的聚异戊二烯-b-聚甲基丙烯酸甲酯(PI-b-PMMA)和聚甲基丙烯酸正丁酯-b-聚甲基丙烯酸甲酯(PBMA-b-PMMA)2种嵌段聚合物. 嵌段聚合反应中甲基丙烯酸甲酯(MMA)的转化率均高于90%, 通过核磁图谱计算的链节摩尔比与理论设计值吻合. PI-b-PMMA和PBMA-b-PMMA的分子量分别达到4×104和1.6×104. 在环己烷中, 通过顺次添加单体的方法, 合成了结构明确的聚苯乙烯-b-聚异戊二烯-b-聚甲基丙烯酸甲酯(PS-b-PI-b-PMMA)三嵌段共聚物, 各单体的转化率均达到100%, 并且产物中的链节摩尔比和理论设计值一致, 最终产物的分子量达到7.4×104, 分子量分布仅为1.28, 为极性三嵌段热塑性弹性体以及有机玻璃透明增韧剂的工业化奠定了基础.  相似文献   

13.
The silane-induced ring-opening polymerization of a cyclic siloxane, 1,1,3,3-tetramethyl-2-oxa-1,3-disilacyclopentane (2), is catalyzed by a ruthenium cluster, (μ3235-acenapthylene)Ru3(CO)7 (1), to give poly(tetramethylsilethylenesiloxane) with Mn=6300–780,000 and Mw/Mn=1.5–3.0. The molecular weight of the polymer can be controlled by changing the concentration of the monomer solution. Addition of acetone results in formation of the polymer with Mn=4400, spectroscopic analysis of which reveals existence of a siloxy and an isopropoxy moieties at the end group.  相似文献   

14.
Light scattering measurements in toluene solutions are performed for a series of monodisperse polystyrenes with a molecular weight Mw range from 4×103 to 8×106. The scattered polarized intensities Iv and the natural depolarization ratios ρn are registered with different apparatus at λ=633 or 488 nm and the Mw values are deduced through different formulae. The complete Carr and Zimm formula (CLa), from Iv and ρn, and the usual simplified formula (CLb), from Iv, are considered for the classical method. An already demonstrated formula is considered for the new method (New). Values of Mw and related parameters do not depend on the experimental systems used but deviations appear when using different formulae. The deviations are generally low (about 10%) but often systematic: Mw(CLa)<Mw(CLb)<Mw(New). The most important difference concerns the effect of destructive interferences for Mw>5×105: the new formula leads to a lower increase from θ=90° to θ→0 for Mw values (θ is the observation angle). For instance, in the 8×106 sample, Mw(θ→0)/Mw(θ=90°)=3.6 instead of 6.1, which implies a revision of the usual determination of the radius of gyration, Rg.  相似文献   

15.
Yb[C(SiMe3)3]2 initiates the living polymerization of methyl methacrylate (MMA) at −78°C to give the polymer with Mn of 51.0×104 (Mw/Mn=1.1) and high isotacticity (97%) in a quantitative yield. Mixing of the acetone solution of resulting polymer (Mn=16.3×104) with the acetone solution of syndiotactic poly(MMA) (Mn=15.7×104) prepared by the (C5Me5)2SmMe(THF) initiator produces desired stereocomplex in high yield bearing very high Tm whose tensile modulus is higher than the respective isotactic and syndiotactic poly(MMA)s. Yb[C(SiMe3)3]2 also generated isotactic (98%) poly[2-(dimethylamino)ethyl methacrylate] (DMEMA), and (C5Me5)2SmMe(THF) affords the syndiotactic (97%) polymer in high yields. The combination of isotactic poly(MMA)-block-poly(DMEMA) (97/3) and syndiotactic poly(MMA)-block-poly(DMEMA) (97/3) provides the amphiphathic stereocomplex. In sharp contrast to the catalysis of Yb[C(SiMe3)3]2 in toluene, the addition of THF or HMPA resulted in the formation of syndio-rich poly(MMA).  相似文献   

16.
To improve interfacial phenomena of poly(dimethylsiloxane) (PDMS) as biomaterials, well-defined triblock copolymers were prepared as coating materials by reversible addition-fragmentation chain transfer (RAFT) controlled polymerization. Hydroxy-terminated poly(vinylmethylsiloxane-co-dimethylsiloxane) (HO–PVlDmMS–OH) was synthesized by ring-opening polymerization. The copolymerization ratio of vinylmethylsiloxane to dimethylsiloxane was 1/9. The molecular weight of HO–PVlDmMS–OH ranged from (1.43 to 4.44) × 104, and their molecular weight distribution (Mw/Mn) as determined by size-exclusion chromatography equipped with multiangle laser light scattering (SEC-MALS) was 1.16. 4-Cyanopentanoic acid dithiobenzoate was reacted with HO–PVlDmMS–OH to obtain macromolecular chain transfer agents (macro-CTA). 2-Methacryloyloxyethyl phosphorylcholine (MPC) was polymerized with macro-CTAs. The gel-permeation chromatography (GPC) chart of synthesized polymers was a single peak and Mw/Mn was relatively narrow (1.3–1.6). Then the poly(MPC) (PMPC)–PVlDmMS–PMPC triblock copolymers were synthesized. The molecular weight of PMPC in a triblock copolymer was easily controllable by changing the polymerization time or the composition of the macro-CTA to a monomer in the feed. The synthesized block copolymers were slightly soluble in water and extremely soluble in ethanol and 2-propanol.

Surface modification was performed via hydrosilylation. The block copolymer was coated on the PDMS film whose surface was pretreated with poly(hydromethylsiloxane). The surface wettability and lubrication of the PDMS film were effectively improved by immobilization with the block copolymers. In addition, the number of adherent platelets from human platelet-rich plasma (PRP) was dramatically reduced by surface modification. Particularly, the triblock copolymer having a high composition ratio of MPC units to silicone units was effective in improving the surface properties of PDMS.

By selective decomposition of the Si–H bond at the surface of the PDMS substrate by irradiation with UV light, the coating region of the triblock copolymer was easily controlled, resulting in the fabrication of micropatterns. On the surface, albumin adsorption was well manipulated.  相似文献   


17.
Characteristics of methyl methacrylate (MMA) polymerization using oscillating zirconocene catalysts, (2-Ph-Ind)2ZrX2 (X = Cl, 1; X = Me, 2), mixtures of rac- and meso-zirconocene diastereomers, (SBI)ZrMe2 [3, SBI = Me2Si(Ind)2] and (EBI)ZrMe2 [4, EBI = C2H4(Ind)2], as well as diastereospecific metallocene pairs, rac-4/Cp2ZrMe2 (5) and rac-4/CGCTiMe2 [6, CGC = Me2Si(Me4C5)(t-BuN)], are reported. MMA polymerization using the chloride catalyst precursor 1 activated with a large excess of the modified methyl aluminoxane is sluggish, uncontrolled, and produces atactic PMMA. On the other hand, the polymerization by a 2/1 ratio of 2/B(C6F5)3 or 2/Ph3CB(C6F5)4 is controlled and produces syndiotactic PMMA. Mixtures of diastereomeric ansa-zirconocenes 3 or 4 containing various rac/meso ratios, when activated with B(C6F5)3, yield bimodal PMMA; this behavior is attributed to the meso-diastereomer that, in its pure form, affords bimodal, syndio-rich atactic PMMA. For MMA polymerization using diastereospecific metallocene pairs, rac-4/5 and rac-4/6, the isospecific catalyst site dominates the polymerization events under the conditions employed in this study, and the aspecific and syndiospecific sites are largely nonproductive, thereby forming only highly isotactic PMMA.  相似文献   

18.
Thermogravimetric analysis of hydroxyl terminated polybutadiene (HTPB) and its fractions of different molecular weights separated by preparative GPC shows two major stages of weight loss of different nature in a nitrogen atmosphere. The first stage is primarily depolymerisation, cyclisation and crosslinking of molecules and the second stage is mainly the decomposition of the residue from the first stage. The kinetic parameters, viz. activation energy E and pre-exponential factor A using four different non-isothermal integral equations show a systematic increase with increase in molecular weight for the first stage, whereas for the second stage, the effect of molecular weight on E and A values is not prominent. The increase in E and A values for the first stage is attributed to the formation of greater number of cyclised and crosslinked products from molecules of higher dimensions. Quantitative correlations between the kinetic constants and the molecular weight parameters were derived for the first stage as a quadratic curve following the equation: E or ln A = K1K2/M (where K1 and K2 are empirical constants whose values are different for the different molecular weight averages, viz. Mn, Mw and Mz and for the different equations).  相似文献   

19.
In situ reaction of Li[closo-1-Ph-1,2-C2B10H10] with 7-azabicyclo [4.1.0] heptane results in the formation of the disubstituted carborane, closo-1-Ph-2-(2′-aminocyclohexyl)-1,2-C2B10H10 (1), in 63% yield. Decapitation of (1) with potassium hydroxide in refluxing ethanol produces the cage-opened nido-carborane, K[nido-7-Ph-8-(2′-aminocyclohexyl)-7,8-C2B9H10] (2), in 80% yield. Deprotonation of the above monoanion with two equivalents of n-butyllithium followed by reaction with anhydrous MCl4 · 2THF (M = Zr, Ti) provides d0-half-sandwich metallocarboranes, closo-1-M(Cl)-2-Ph-3-(2′-σ-(H)N-cyclohexyl)-2,3-η5-C2B9H9 (3 M = Zr; 4 M = Ti) in 53% and 42% yields, respectively. The reaction of Li[closo-1,2-C2B10H11] with 7-azabicyclo [4.1.0] heptane in THF affords closo-1-(2′-aminocyclohexyl)-1,2-C2B10H10 (5) in 59% yield. Immobilization of the carboranyl amino ligand (1) to an organic support, Merrifield’s peptide resin (1%), has been achieved by the reaction of the sodium salt of (5) with polystyryl chloride in THF to produce closo-1-(2′-aminocyclohexyl)-2-polystyryl-1,2-C2B10H10 (6) in 87% yield. Further reaction of the dianion derived from (6) with anhydrous ZrCl4 · 2THF led to the formation of the organic polystyryl supported d0-half-sandwich metallocarborane, closo-1-Zr(Cl)-2-(2′-σ-(H)N-cyclohexyl)-3-polystyryl-2,3-η5-C2B9H9 (7), in 38% yield. These new compounds have been characterized by elemental analyses, NMR, and IR spectra. Polymerizations of both ethylene and vinyl chloride with (3) and (7) have been performed in toluene using MMAO-7 (13% ISOPAR-E) as the co-catalyst. Molecular weights up to 32.8 × 103 (Mw/Mn = 1.8) and 9.5 × 103 (Mw/Mn = 2.1) were obtained for PE and PVC, respectively.  相似文献   

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