短链支化聚乙烯的合成与表征

合成了两类结构明确的乙烯共聚物, 通过FTIR, GPC, ¹H NMR和¹³C NMR表征了产物的分子结构, 分别研究了分子量和短链支化含量对两类共聚物结晶性能的影响. 采用阴离子聚合制备分子量(M_w)20000~110000、分子量分布为1.1的1,2-结构摩尔分数为7%左右的聚丁二烯. 加氢反应后得到乙烯/1-丁烯模型共聚物的熔点和结晶度随着分子量的增加而下降. 采用茂金属催化剂Et[Ind]₂ZrCl₂催化乙烯与1-己烯共聚合, 制备分子量为100000左右, 共聚单体摩尔分数为0~5.5%的乙烯/1-己烯共聚物, DSC结果表明其熔点和结晶度随着共聚物中1-己烯含量的升高而降低.     

ABA型聚L-丙氨酸-聚乙二醇嵌段共聚物的合成及其表征

利用L-α-丙氨酸和三聚光气反应制备了N-羧基-α-丙氨酸-环内酸酐(NCA).以聚乙二醇(PEG)为原料.制备了端氨基聚乙二醇(PEG-NH₂),并以此作为引发剂,引发NCA开环聚合.合成了不同组成和分子量的聚L-丙氨酸-聚乙二醇(PLAA-PEG-PLAA)嵌段共聚物.利用IR、¹H NMR、DSC、WAXD、CD等方法对共聚物结构进行了表征.结果表明,PEG-NH₂引发NCA开环聚合得到的是嵌段共聚物,通过¹H NMR谱得到共聚物组成及数均分子量;引入PEG的结果使聚L-丙氨酸的亲水性有所改善;CD测诚结果表明共聚物在水溶液中主链主要以α-螺旋构象存在.     

水分散体系中苯乙烯和甲基丙烯酸甲酯梯度共聚物的合成与表征

以2-溴代异丁酸乙酯(EBiB)为引发剂,CuBr/CuBr₂/1,10-邻二氮菲(phen)为复合催化剂,十二烷基磺酸钠(SLS)为乳化剂,考察了水分散体系中苯乙烯(St)和甲基丙烯酸甲酯(MMA)的原子转移自由基共聚合的可控性和相对反应活性.在此基础上,通过反应进料法在水分散体系中进行了St和MMA的梯度共聚合,反应表现出“活性”聚合的特征,即所得共聚物的数均分子量随着单体转化率的增加而增大,分子量分布较窄(M_w/M_n<1.50).用¹HNMR跟踪分析了聚合反应过程中共聚物微观组成的变化规律,结果表明,共聚物链中MMA链节的累积含量和瞬时含量都随着共聚物相对链长的增加而增加,即随着聚合物相对链长的增加共聚物的微观组成从St链节占主导地位逐渐变化为以MMA链节占主导地位,表明确实形成了St和MMA的梯度或渐变共聚物.     

丙烯酰胺多面体低聚倍半硅氧烷在超临界CO2中的RAFT聚合

以超临界CO₂为聚合介质, 硫代苯甲酰基特丁基硫酯(TTBT)为链转移剂, 通过可逆加成-断裂链转移(RAFT)聚合制备了聚丙烯酰胺多面体低聚倍半硅氧烷(PAMPOSS)均聚物及其与甲基丙烯酸甲酯(PMMA)的嵌段共聚物(PAMPOSS-b-PMMA). 对产物结构组成和分子量及其分布进行表征. 结果表明, 在TTBT的控制下, POSS的均聚物和嵌段共聚物具有高分子量及窄分子量分布. 含POSS单体在超临界CO₂中为均相聚合, POSS聚合物的结晶性在一定程度上影响其在超临界CO₂中溶解性.     

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第一部分 PP-EPR-PP嵌段共聚物的合成和表征 通过聚丙烯、乙丙共聚物和嵌段共聚物分子量随聚合时间的增大而在间歇加氢下不增大,肯定了本工作所用TiCl₃-Et₂AlCl催化剂有足够长的寿命,有合成嵌段共聚物的可能。由红外光谱确定了向单体和自动离析的链转移反应的存在,分级实验表明在嵌段共聚物中确实含有无规的低分子量的链转移产物,因此生成嵌段杂质是不可避免的。     

TiCl4/XROH/MgCl2/Et3Al催化剂合成宽分子量分布乙烯/1-己烯共聚物

采用MgCl₂负载TiCl₄及1,3-二氯-2-丙醇给电子体(XROH),与三乙基铝助催化剂组成的催化剂体系,合成了1-己烯共聚率高且宽分子量分布的乙烯/1-己烯共聚物。 讨论了催化体系的组成、配比和聚合条件对乙烯/1-己烯共聚合行为,共聚物结构、分子量及分子量分布的影响。 结果表明,n(Ti)∶n(Mg)=10∶1,n(XROH)∶n(MgCl₂)=2.6∶1,n(Al)∶n(Ti)=100∶1,乙烯压力0.45 MPa,聚合温度80 ℃,聚合时间2 h,共聚单体(1-hexene)浓度0.25 mol/L时,催化效率达23.2 kg/g cat。 采用¹³C NMR、X-ray、SEM、WAXD、DSC、GPC等测试技术对催化剂、共聚物的结构进行了表征。 结果表明,在Zieglar-Natta(Z-N)催化体系中,给电子体多卤代醇与TiCl4结合,载体MgCl2的晶体结构发生了变化。 结晶度降低,有利于催化剂负载量的提高(ω(Ti)=4.8%)和催化效率增大。 催化体系产生了多种活性中心,使聚烯烃分子量分布变宽(15~20)。 多卤代醇还可增强1-己烯与乙烯的共聚能力,在共聚物中1-己烯的摩尔分数达5.1%。     

双(环戊二烯基)二氯化锆催化合成乙烯-笼型倍半硅氧烷杂化共聚物及其结构表征

通过双(环戊二烯基)二氯化锆(Cp₂ZrCl₂)催化剂和改良的甲基铝氧烷(MMAO)助催化剂, 合成了无机-有机杂化共聚物. 研究了2种具有不同单乙烯基反应基团的笼型倍半硅氧烷(POSS)与乙烯的聚合. 对共聚产物的结构、 热力学性质、 分子量及其分布等进行了研究. 共聚单体(POSS)的插入率在0.01%~0.30%之间, 随着共聚单体在共聚物中摩尔分数的增大, 聚合物的熔点和熔解热降低. 共聚物的热重分析结果显示, 乙烯-POSS共聚物拥有更高的热分解温度以及较高的热分解残留量. 随着POSS的加入, 聚合物的分子量明显提高, 聚合物的分子量分布变宽.     

完全交替结构乙烯-丙烯共聚物的制备与表征

对顺-1,4含量为100%的高顺式聚异戊二烯(HCPI)进行加氢反应,得到了序列结构高度规整的乙烯-丙烯交替共聚物(alt-EP).所用的HCPI有适当的分子量(Mn=41×104)和极窄的分子量分布(Mw/Mn=1.02).HCPI的加氢反应以环烷酸镍和三异丁基铝为催化剂,在60℃和4.0MPa氢压的条件下反应3h,加氢产物的加氢度为100%.GPC测试结果显示所得乙烯-丙烯交替共聚物保持了窄分布的特点,表明HCPI加氢后未发生交联和降解反应;NMR,FTIR和广角X射线衍射测试结果表明此乙烯-丙烯交替共聚物具有高度规整的序列结构,为完全交替结构的乙烯-丙烯共聚物.并通过TGA和DSC对乙烯-丙烯交替共聚物的热性能进行了表征.     

丙烯酸羟乙酯与马来酸酐的共聚及表征

以过硫酸铵引发丙烯酸羟乙酯和马来酸酐水溶液聚合,合成了不同摩尔比的共聚物。采用毛细管膨胀计测定了共聚合反应的转化率,通过酸碱滴定测定了共聚物的组成,并采用YBR法得到丙烯酸羟乙酯和马来酸酐的竞聚率分别为r₁=2.3188和r₂=0.0272,表明要得到组成均匀的共聚物,需要将丙烯酸羟乙酯缓慢滴加到马来酸酐中。此外,通过电位滴定法测定了丙烯酸羟乙酯与马来酸酐的投料摩尔比为7∶3时,聚合物的pK_a1和pK_a2值分别为4.33和7.59。     

丙烯酰胺-丙烯酸钠共聚物的键结构和光散射研究

用溶液聚合方法制备了一组单体含量相同、分子量不同的丙烯酰胺-丙烯酸钠(AM-AA)共聚物样品,用¹³CNMR和常规光散射方法进行了表征。该组样品的化学组成是均一的(AA摩尔含量16.9±1.1%),AA单体在大分子链中的序列分布为孤立、无规的,聚电解质在盐水体系中的光散射理论适用于共聚物在0.12mol/LNaCl水溶液体系。用恒化学位下的折光指数增量代替恒盐组成的折光指数增量,可从一次常规光散射实验分别求得共聚物样品的真实、第二维利系数A₂和均方旋转半径〈R²〉_z,其关系为:A₂=0.0619M_w^-0.21,〈R²〉_z^1/2=0.0210M_w^0.54.     

Phase Separation in Aqueous Solutions of Binary Copolymers of Acrylamide with Sodium 2-Acrylamido-2-Methylpropanesulfonate and Sodium Acrylate

Phase separation in aqueous solutions of binary copolymers of acrylamide with sodium 2-acryl-amido-2-methylpropanesulfonate and sodium acrylate is studied over the temperature range from 20 to 100°C, as influenced by addition of calcium, magnesium, and sodium chlorides, inorganic salt concentration, and molecular characteristics of the copolymers.     

自交联型含氟丙烯酸酯共聚物的合成与表征

含氟丙烯酸酯;自交联;无皂乳液;接触角滞后     

Dielectric properties of some photo crosslinking acrylate ester copolymers

Photo crosslinking due to the photo polymerization of unsaturated acrylic side-groups attached to copolymers of glycidyl methacrylate and methyl methacrylate (GMA-MMA) by reaction with acrylic acid in the presence of benzoin methyl ether as photolabile initiator has been investigated. The composition of these copolymers based on (GMA-MMA, 30:70) were determined by [¹H] NMR spectroscopy. The reactivity ratios for the GMA-MMA system were determined using the Kelen-Tüdös method.

The dielectric properties of copolymers based on GMA-MMA acrylate ester (30:70) and homopolymers of MMA in combination with different polyfunctional acrylate ester monomers before and after exposure to UV irradiation have been studied in a solid state matrix, over a frequency range of 100 Hz to 50 kHz and at temperatures in the range 20–70°C.     

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE COPOLYMERS

The permeability coefficients of a series of copolymers of vinylidene chloride (VDC)with methyl acrylate (MA), butyl acrylate (BA) or vinyl chloride (VC) (as comonomer)to oxygen and carbon dioxide have been measured at 1.0 MPa and 30℃, while those towater vapor have been measured at 30℃ and 100% relative humidity All the copolymersare semicrystalline. VDC/MA copolymers have lower melting temperature compared withVDC/BA copolymers, while that melting temperature of VDC/VC copolymer is higherthan that of VDC/acrylate copolymers with the same VDC content. The barrier propertyof the copolymers is predominantly controlled by crystallite, free volume fraction, andcohesive energy The permeability coefficients of VDC/MA copolymers to oxygen, carbondioxide, and water vapor were successfully correlated with the ratio of free volume tocohesive energy.     

Microstructure determination of N-vinyl-2-pyrrolidone/butyl acrylate copolymers by NMR spectroscopy

The copolymer composition of N-vinyl-2-pyrrolidone/butyl acrylate (V/B) copolymers was determined from the quantitative ¹³C{¹H} NMR spectra. The monomer reactivity ratios for N-vinyl-2-pyrrolidone (V) and butyl acrylate (B) were found to be r_V=0.11±0.07, r_B=0.54±0.19, using the Kelen–Tudos and non-linear least-square error-in-variable (EVM) methods. The ¹³C{¹H} and ¹H NMR spectra of these copolymers are overlapping and complex. The complete spectral assignment of the carbon and proton NMR spectra were done by employing distortionless enhancement by polarization transfer (DEPT) and two-dimensional (2D) ¹³C–¹H heteronuclear single quantum correlation spectroscopy experiments. The 2D total correlation spectroscopy (TOCSY) (¹H–¹H homonuclear TOCSY) NMR spectrum was used to ascertain the various geminal and vicinal couplings in the copolymer.     

明胶与丙烯酸乙酯接枝共聚的SDS-聚丙烯酰胺凝胶电泳研究

明胶与丙烯酸乙酯接枝共聚的ＳＤＳ－聚丙烯酰胺凝胶电泳研究刘孝恒,阎天堂（中国科学技术大学近代化学系,合肥,２３００２６）关键词接枝,明胶,组分,平均分子量,电泳在天然高分子接枝改性的研究中,有关明胶的报道已有不少［１～６］,其中多数采用常规定量分析法...     

BARRIER PROPERTY AND STRUCTURE OF ACRYLONITRILE/ACRYLIC COPOLYMERS

A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate(EA) as comonomer (5--23 wt%) was prepared by free-radical copolymerization. The per-meability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor also measured at 100% relative humidityand at 30℃. All the AN/acrylic copolymers are semicrystalline. As the acrylate contentincrease, the permeability coefficients of the copolymers to oxygen and carbon dioxide areincreased progressively but those to water vapor are decreased progressively The gas per-meability coefficients of the polymers were correlated with free-volume fractions or the ratioof free volume to cohesive energy.     

An Improved Synthetic Method for Preparing Polyoxyethylene Macromers and a Study of Their Copolymerization with Alkyl Acrylates

Polyoxyethylene macromers were synthesized by polymerization of ethylene oxide in dimethylsulfoxide by using potassium napthalide in tetrahydrofuran as initiator, followed by termination with methacroyl chloride. Potassium naphthalide is more active as an initiator than sodium naphthalide. The initiator in this case was confirmed to be of the monoanionic type. The molecular weight of the macromers can be varied from 2 × 10³ to 1.2 × 10⁴with M_w/M_n = 1.07-1.12. The macromers were characterized by UV, IR, and ¹H NMR, and copolymerized with butyl acrylate, methyl acrylate, or methyl methacrylate. The grafting efficiency can reach about 90%. The graft copolymers were purified by extractions and characterized by GPC, IR, and a Bruss membrane osmometer. The average grafting number of the copolymers varied from 10 to 15.     

包覆Fe2O3超微粒的苯乙烯/丙烯酸/丙烯酸丁酯核-壳型复合共聚物的性能研究

对采用种子乳液聚合法合成的包覆Fe₂O₃超微粒的苯乙烯/丙烯酸/丙烯酸丁酯(St/AA/BA)核-壳型复合共聚物材料进行玻璃化温度测试,结果表明,加入Fe₂O₃超微粒,使复合共聚物的玻璃化温度显著降低.对复合共聚物的流变行为研究表明,复合共聚物的非牛顿指数均小于1,且随着Fe₂O₃含量增加,非牛顿性增强,表观粘度下降,粘流活化能降低.     

Effect of pendent group structures on the chemical selectivity and performance of sulfonated copolymers as novel pseudophases in electrokinetic chromatography

Amphiphilic copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) with dihydrocholesteryl acrylate (pDHCHAt) or tert-octyl acrylamide (ptOAm) as comonomers were synthesized, characterized and used as new polymeric pseudostationary phases in electrokinetic chromatography. High-efficiency separations with theoretical plates around 500,000 to 870,000/m were achieved. Linear solvation energy relationships analysis of 20 solutes was performed to investigate the retention mechanism. Polycyclic aromatic hydrocarbons (PAHs) were separated under 30% v/v acetonitrile. The separation of nine aromatic model solutes by pDHCHAt showed significantly different selectivity from that of sodium dodecyl sulfate. Although only minor difference in selectivity was found for small aromatic compounds on pDHCHAt and poly(AMPS-lauryl acrylate), significantly different retention mechanism was found for PAHs and n-dodecanophenone comparing both copolymers. Significant chemical selectivity difference was found for selected small aromatic compounds on ptOAm and poly(AMPS-stearyl acrylamide).