本体聚合制备环氧丙烷-四氢呋喃共聚醚研究——Ⅰ.凝胶色谱法测定分子量和官能度

测定原理端羟基环氧丙烷-四氢呋喃共聚醚(POTHF共聚醚)是一种新型的“遥爪”型(Telechlic)预聚体,由它制备的聚氨酯具有较好的低温力学性能。由于预聚体的分子量及其分布,特别是官能度对成品材料的力学性质影响较大,故准确测定这些链结构参数是十分重要的. 测定数均官能度(了。)的常用方法川是通过测定样品的数均分子量(厕,)和怒基当量饮/equ)来计算的: 万。[g/equ〕(1) 当应用式(1)来测定PO一THF共聚醚的f,时,实验值总是要比理论值低得多(见表1).造成偏差的原因是由于样品中含有难以衰1常舰法润定po一THF共旅雌的,能度样品助催化剂数均官能度理论值实验值PTP(I)PTP(11)PTP(111) 甲醇l,2一丙二醇1,2,3一丙三醇     

具有可控温敏相变行为的四氢呋喃-缩水甘油超支化共聚醚的合成

采用四氢呋喃(THF)和缩水甘油(glycidol)进行阳离子开环共聚,一步合成了主链中含有柔性聚四氢呋喃线型链段的温敏性超支化共聚醚.采用定量13C-NMR确定了共聚醚的超支化结构,同时计算了其支化度.利用体积排除色谱-多角度激光光散射(SEC-MALLS)对聚合物分子量及分布进行了表征.紫外-可见光光谱(UV)测试发现共聚醚水溶液透过率在最低临界溶解温度(LCST)附近呈现剧烈变化,但是其相变速率缓慢,相变平衡时间可达30 min;且聚合物溶液的相变速率和紫外光透过率变化具有温度依赖性.采用透射电镜(TEM)对相变过程观察后发现,这种缓慢相变过程是由于超支化共聚醚组装形成的胶束随温度升高发生不同程度聚集所致.     

二芳环并-14-冠-4-二醇的合成及其异构体的分离

作者研究了1,1-(邻亚苯基氧)-双-(2,3-环氧丙基)醚与邻苯二酚, 4-叔丁基邻苯二酚和邻萘二酚在叔丁醇回流温度下, 以氢氧化锂作为碱和模板试剂的亲核取代反应,合成了三种二芳环并-14-冠-4-二醇, 用柱层析法分离了它们的三对异构体, 并经IR,^1H NMR, MS的元素分析鉴定。该法为合成对称的或不对称的二芳环并-14-冠-4-二醇或某些羟基冠醚提供了简单方便的途径。     

毛细管电色谱法测定果蔬中粉唑醇对映体的含量

采用原位聚合反应,制备一种磺丁基醚-β-环糊精修饰甲基丙烯酸聚合物毛细管手性电色谱开管柱(SECDP)。采用该电色谱柱,并在流动相中添加少量磺丁基醚β-环糊精,利用固定相和流动相中的磺丁基醚β-环糊精的协同作用,成功地拆分了手性农药粉唑醇对映体。考察了添加剂浓度、pH值、施加电压、温度及有机调节剂的含量对手性分离的影响,初步优化了开管电色谱柱拆分粉唑醇对映体的条件。优化的流动相组成为10 mmol·L~(-1)硼酸钠(pH=9.2),含3.0 mmol·L~(-1)磺丁基醚β-环糊精和体积分数为15%甲醇,施加电压15 kV,温度20℃,压力进样(3 psi×3 s),检测波长204 nm。在上述条件下,粉唑醇对映体分离度可达1.85,分析时间仅为8~12 min。黄瓜、梨、苹果和西红柿果蔬样品用乙腈提取,磁性石墨化碳净化,在上述优化条件下测定果蔬中粉唑醇对映体的残留量。粉唑醇对映体在1.3~250μg·m L~(-1)范围呈良好的线性关系,线性回归方程为:第一个对映体y_1=92.56+176.81x_1,r_1=0.9993;第二个对映体y_2=46.46+177.97x-2,r_2=0.9998。固定相和流动相中带负电荷的磺丁基醚-β-环糊精不仅能提供较强正向电渗流(EOF),同时有较高的手性分离选择性。所发展的开管毛细管电色谱方法是一种操作简单,分离测定快速,溶剂耗量小,测试成本低,环境污染小的方法。     

共聚单体对MBA凝胶纤维RAFT聚合制备聚合物微米管的影响

在不同丙烯酸酯类共聚单体存在下,通过可逆加成断裂链转移(RAFT)聚合,将N,N'-亚甲基双丙烯酰胺(MBA)凝胶纤维转化为聚合物微米管.主要研究了RAFT试剂及共聚单体官能度对产物收率及形貌的影响,采用扫描电子显微镜、透射电子显微镜、红外吸收光谱、元素分析和热失重分析等手段分析所得产物.结果表明,适量RAFT试剂的加入有助于形成形貌规整的聚合物微米管;共聚单体的加入可显著提高聚合物微米管的收率,并且随着共聚单体官能度的增加,对收率的促进效果越明显.对比不同链长的二官能度共聚单体对聚合物微米管形貌的影响,发现随着链长的增加,聚合物微米管的管壁增厚.通过在单官能度共聚单体反应体系中加入少量四官能度单体,显著提高了聚合物微米管的收率.     

分子排阻色谱法测定灰树花菌丝体β-葡聚糖的相对分子质量及其分布

采用分子排阻色谱法,利用3台不同的液相色谱仪及相应GPC软件测定并计算β-葡聚糖受试物的相对分子质量及其分布。选择的色谱条件为SB-804HQ凝胶色谱柱(7.8 mm×300mm),流动相为0.2g·L~(-1)叠氮化钠溶液,流量0.5mL·min~(-1),柱温35℃,进样量25μL,2410示差折光检测器(RI),以系列标准葡聚糖Shodex STANDARD P-82为相对分子质量标准品。灰树花GF-932发酵菌丝体β-葡聚糖的重均相对分子质量(M_r)在134 195～251053amu范围内,相对分子质量分布宽度(M_r/M_n)在1.64～2.61之间。受试物灰树花菌丝体β-葡聚糖是具有一定分子质量分布范围的高纯度的聚合物。     

四氢呋喃开环聚合的研究——Ⅳ.发烟硫酸-高氯酸引发四氢呋喃及环氧丙烷的共聚合

用21％或28％发烟硫酸-高氯酸引发四氢呋喃及环氧丙烷(THF:PO=100:5-15(克))进行共聚合反应,收率为50—60％,四氢呋喃的损耗不超过10—15％,产物分子量在1000—2000之间可调。与通常用三氟化硼或五氯化磷及二元醇制备的四氢呋喃-环氧丙烷共聚醚不同;当环氧丙烷用量低时,收率并不降低;产物的端羟基官能度为2;以伯醇端基为主(约65—70％)。     

聚苯乙烯的机械性能与耐热性改性研究进展

系统地评述了不同方法改性聚苯乙烯(PS)的机械性能与耐热性,包括(未官能化、官能化)无机填料直接填充或在聚合过程中原位填充改性;(未改性、改性)聚合物直接共混或在聚合过程中原位共混改性;离子交联、互穿聚合物交联网络、共价交联改性;从单体出发采用无规、接枝或嵌段共聚改性;以及同时使用两种方法的耦合改性(如共混-填充、共聚-共混、共聚-填充、离子交联-共混、离子交联-填充)等。在此基础上,对各种改性方法的优缺点进行了比较与讨论。     

通过醚的α-位C(sp3)–H键官能化合成醚类衍生物的研究进展

醚及其类衍生物是有机化合物中的重要组成部分,许多生物活性分子、药物和天然产物中也存在醚类结构。近年来通过醚类分子（包括环醚和非环醚）的α-位C(sp³)–H官能化来合成了多种不同类型的醚类衍生物已取得了令人瞩目的研究成果。本综述从醚α-位C(sp³)–H官能化所需的反应条件出发,对2017年到2020年来的研究成果进行了综述。      

高效液相色谱流动相手性添加剂法拆分氯苯甘醚对映体

以羟丙基-β-环糊精(HP--βCD)作为流动相手性添加剂,建立了拆分氯苯甘醚对映体的高效液相色谱方法。测定中用ODS柱(4.6 mm×200 mm,5μm)作为分离柱,用甲醇、乙腈、水体积比为25比25比50的混合液(其中含HP--βCD 28.3 g.L-1)作为流动相,流量为0.5 mL.min-1,紫外检测波长为228 nm。按此方法氯苯甘醚对映体的分离度可达1.54。5次连续测定所得结果显示对映体的保留时间值的相对标准偏差分别为0.36%和0.11%;其峰面积值的相对标准偏差分别为0.83%和0.84%。     

逆流法对凝胶色谱峰加宽效应的研究

在以无孔玻璃珠为填料的色谱柱上研究了流动相中的分离能力和峰加宽效应。得到一定的分离能力。根据Kelley和Billmeyer描述流动相中峰加宽效应的理论,塔板高度和溶液的分子量有关而和分子量分布无关。但实验表明,对于具有相同分子量,但分子量分布不同的样品峰宽不同。苯的逆流峰加宽因子h稍大于直流峰加宽因子h′。产生这个差别的原因可以用在逆转过程中流速场受到干扰来解释。 在以多孔硅胶为填料的柱中对一系列不同分子量、分子量分布和化学结构的样品考察了逆流峰加宽因子,h,和淋出体积,Ve,之间的关系。实验表明h和Ve之间的关系具有普适性,这个结果和Tung的一致。在多孔填料柱上对苯同样得到h>h′。这个结果意味着用逆流法得到的h来校正GPC体系造成的峰加宽稍嫌不够。 只有对于分子量分布很窄的样品,其逆流淋出曲线的形状才非常接近高斯分布。     

用多分散高聚物标样作凝胶色谱的分子量分离和扩展效应同时校准

根据凝胶色谱柱在理想工作条件下单分散高分子组分的校准关系与多分散试样的实效关系之间的理论联系,建议了一种简单的觅数方法,同时作凝胶色谱柱的分子量分离和扩展因子的校准。用本法从窄分布的聚苯乙烯和宽分布的1,2-聚丁二烯级分的实验谱图得到的所用凝胶色谱柱的扩展因子与淋出体积间的关系相互重合,与试样种类无关。     

Ein verfahren zur eichung der gelchromatographie (GPC) mit präparaten beliebiger,bekannter molekulargewichtsverteilung

If, in GPC calibration, the mean elution volume (or centre of gravity volume) of the elution curves obtained with monomolecular samples is used, the mean elution volume of a polymolecular mixture is a weight-average. According to the calibration curve, a molecular weight average can be attributed to the mean elution volume. For the special case of a logarithmic-linear calibration curve, this is the geometric (weight) mean of the molecular weight. Thus one can perform broad-standard calibration of GPC without interference by column dispersion. The potential application for non-linear calibration curves is discussed. It is considered how calibration functions for the higher moments of the monomolecular elution curves could be determined and how universal calibration should be performed if the standards are polydisperse relative to hydrodynamic volume. Absolute determination of polydispersity becomes possible with an additional z-detector.     

Determination of molecular weight distribution of cellulose by conversion into tricarbanilate and fractionation

Two samples of cellulose (molecular weight 2.97 × 10⁵ and 1.25 × 10⁵) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone-water elution mixture with the column temperature gradually increasing from ?30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light-scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (average M _w/M _n = 1.37); the [η] values and the Mark-Houwink constants (K = 5.3 × 10^-3, a = 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for analytical purposes).     

Monte Carlo simulation of size exclusion chromatography for branched polymers formed through free‐radical polymerization with chain transfer to polymer

The elution curves of size exclusion chromatography (SEC) for branched polymers formed through free‐radical polymerization that involves chain transfer to polymer were theoretically investigated by using a Monte Carlo method. We considered two types of measured molecular weight distribution (MWD), (1) the calibrated MWD relative to standard linear polymers, and (2) the MWD obtained by using a light scattering photometer (LS) in which the weight‐average molecular weight of polymers within the elution volume is determined directly. It was found that the calibrated MWD clearly underestimates the high molecular weight tail, and the measured distributions are narrower than the true MWD. On the other hand, the present simulation results showed that the LS method gives reasonable estimates of the true MWDs. The mean square radius of gyration of the polymer molecules having the same molecular weight was also investigated. The radii of gyration showed clear deviation from the Zimm‐Stockmayer equation^[1] because of the non‐random nature of branched structure and the difference in the primary chain length distribution.     

Monte Carlo simulation of size exclusion chromatography for randomly branched and crosslinked polymers

The elution curves of size exclusion chromatography for nonlinear polymers formed through random branching and crosslinking of long polymer chains were simulated with a Monte Carlo method. We considered two types of measured molecular weight distributions (MWDs): (1) the MWD calibrated relative to standard linear polymers and (2) the MWD obtained with a light scattering (LS) photometer in which the weight‐average molecular weight of polymers within the elution volume is determined directly. The calibrated MWDs clearly underestimate the molecular weights for both randomly branched and crosslinked polymers, and this technique can be used to assess the degree of deviation from the true MWD. When the primary chains conform to the most probable distribution, the calibrated MWD can be estimated reasonably well with the Zimm–Stockmayer equation for the g factor with the help of the relationship between the average number of branch points per molecule and the degree of polymerization. However, the LS method gives good estimates of the true MWD for both randomly branched and crosslinked polymers, although the agreement is better for the branched ones. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2009–2018, 2000     

蚕蛹水解液的分子量测定

凝胶过滤法是测定蛋白质分子量的常用方法之一,但标准蛋白质不易得到,且保存较困难。本工作用已知分子量的聚乙二醇作标样,采用凝胶过滤色谱外插法定量测定蚕蛹酶解液的分子量。实验色谱柱填料用Sephadex—50,聚乙二醇分子量为20000～1000,洗脱液用紫外光谱检测。根据洗脱体积与蛋白质分子量成直线关系的原理,作分子量与洗脱体积的关系曲线,并用已知分子量的细胞色素C验证。实验表明,该法所得结果与聚丙烯酰胺凝胶电泳和GPC法的测定结果一致。     

Molecular weight determination of vinylidene chloride copolymers by gel-permeation chromatography and viscometry

This is the first report on the characterization of several pairs of random copolymers of vinylidene chloride by gel-permeation chromatography in conjunction with viscometry. Such copolymers have not previously Received much attention, so we first determined the individual viscosity–molecular weight relationship. The K–a values were compared with known values for the parent homopolymers. We then derived calibration curves (different for each composition) and the calculation of the average molecular weight. These results are compared to those obtained by direct methods, without fractionation, and to kinetic observations. This method avoids misinterpretation of viscosity data and elution volume. Chromatograms may indicate heterogeneity of the compounds as related to polymerization conditions.     

特征线法在求解非线性液相吸附色谱模型中的应用

本文应用特征线法求解非线性液相吸附色谱分离过程模型，论述了特征线法的原理和步骤，讨论了时间步长和空间步长对模型数值解的影响，并用色谱分离甘露醇和山梨醇以及分离蔗糖和还原糖的实验进行验证，用特征线法计算的理论流出曲线与实验流出线吻合较好。本文还分折了模型中各个参数的灵敏度，结果表明：吸附等温方程Q＝Ci*／（ai＋biCi*）中参数ai比参数bi以及总传质系数ki有更高的灵敏度。     

Method of calibrating gel permeation chromatography with whole polymers

Column systems for gel permeation chromatography are usually calibrated by eluting a series of sharp polymer fractions of known molecular weights and by correlating their elution volumes with molecular size or weight. A different method for calibration is proposed in which only one polymer sample, with a broad, well-characterized molecular weight distribution, is used. The cumulative distribution and the integrated, normalized GPC chromatogram are successively superimposed, and molecular weights and corresponding elution volumes are correlated. It is found that calibration curves obtained in this manner show a definite curvature. A possible explanation and correction for this behavior is given, based on the concentration dependence of elution volumes.