Indirect detection in reversed-phase liquid chromatography: Ion-pair retention models for anionic analytes and mobile phase components on polystyrene polymers using an alkaline mobile phase

Summary Retention models for anionic analytes and mobile phase compounds in reversed-phase ion-pair chromatographic systems have been studied. The solid phase was a polystyrene-divinylbenzene copolymer. The analytes were mono- and divalent anions monitored by indirect detection technique. The mobile phase was highly alkaline and contained a detectable anion, sulfanilic acid.Expressions for the ion-pair retention of solutes and mobile phase components have been developed assuming Langmuir distribution of ion-pairs to a solid phase with one kind of binding site. The validity of the expressions and the origin of system peaks have been confirmed by determination of distribution constants using linear regression.     

Synthesis of block copolymer containing dextran and polyamide sequences

A novel AB-type block copolymer composed of dextran and polyamide sequences was prepared through the following two approaches. One is a coupling reaction of a terminal functional group introduced in the dextran chain with that in the polyamide chain, such as the reaction of an amine group with an acyllactam group or that of a lactone group with an amine group at the corresponding chain ends. The other is an anionic polymerization of a bicyclic lactam activated with a trimethylsilylated dextran derivative having an acyllactam end group. The latter procedure was found to be more effective for the preparation of the block copolymer having a high molecular weight polyamide sequence.     

Viscoplastic flow and shear thickening in concentrated diblock copolymer solutions

Concentrated (typically 6%) solutions of a polystyrene-polyisoprene diblock copolymer in low viscosity paraffinic solvents form a micelle system by precipitating the polystyrene blocks, whereas the polyisoprene blocks are in solution. Besides viscoplastic behavior without thixotropy, this system exhibits a pronounced shear thickening in steady-state shear flow. The micelles are stable up to shear rates of more than 10⁵ s^–1. The properties of the solutions, especially the shear-thickening behavior, depend on the thermal history of the samples as well as on the solvent properties and are sensitive to flow field disturbances occurring in rotational viscometer devices with a profiled surface structure as commonly used to avoid wall slip in dispersed materials. The shear thickening is found to be related to the formation of a long-range ordered structure which also gives rise to the yield point. This long-range order enables aggregate flow with less energy dissipation at low shear rates. Shear-induced break-up of the aggregates appears as a shear-thickening transition which is observed in different types of flow fields.     

生物可降解磷酸酯-碳酸酯共聚物的合成及性能研究

通过光气，二氯磷酸酯和双酚Ａ反应，合成六种磷酸酯 碳酸酯共聚物，用ＩＲ、１Ｈ ＮＭＲ及元素分析表征了共聚物，测量了Ｍｎ和热学性质．初步研究了在ｐＨ７４磷酸盐缓冲溶液中，核糖核酸酶或碱性磷酸酶存在下的体外降解性能及其对抗肿瘤药物５ Ｆｕ的释放性能．     

嵌段共聚物微胶束行为的研究Ⅰ．体积排斥色谱法研究聚（苯乙烯－异成二烯）二嵌段共聚物在选择性溶剂中微胶束的形成过程

采用体积排斥色谱研究聚（苯乙烯－异成二烯）二嵌段共聚物在选择性溶剂－二氧六环／甲醇混合体系中以ＰＩ为核ＰＳ为壳的微胶柬形成过程，以及在正庚烷／乙酸异戊酯混合体系中以ＰＳ为核ＰＩ为壳的微胶束形成过程。讨论了温度、混合溶剂的配比和共聚物分子量对微胶束形成的影响。根据体积排斥色谱图估算了形成微胶束时的表观缔合能和微胶束的表观缔合数．     

淀粉共聚物的合成与应用

本文介绍了淀粉共聚物的合成方法,包括自由基引发、阴离子引发和其它引发方法等;以及共聚物的应用范围:增稠剂、絮凝剂、粘合剂、吸水剂和上浆剂等.     

Synthesis and characterization of electroactive copolymer with phenyl-capped aniline tetramer in the main chain by oxidative coupling polymerization

A novel electroactive alternating copolymer, with fixed conjugated length of oligoaniline (phenyl-capped aniline tetramer) in the main chain, was successfully synthesized via oxidative coupling polymerization. The structure of the copolymer was systematically studied by Fourier-transform infrared (FTIR) spectra, NMR, elemental analysis (EA), UV-vis spectra and X-ray powder diffraction (XRD). And its electrochemical behavior was studied by cyclic voltammetry (CV) measurement. It was found that the obtained copolymer bearing phenyl-capped aniline tetramer segments had a reversible electrochemical property in the cyclic voltammetry, and the copolymer was oxidized to its emeraldine oxidation state and then to the pernigraniline oxidation state, which was same as that of polyaniline. Moreover, the thermal properties of the copolymer were evaluated by thermogravimetric analysis (TGA). The electrical conductivity of the obtained copolymer was about 1.43 × 10⁻⁷ S cm⁻¹ at room temperature.     

环氧乙烷与苯乙烯两亲性聚合物的合成

Graft eopolymer eontaining poly(ethylene oxide)side chains on a polystyrene backbone were acrylamided. The amide groups in the copolymers were ionized by using potassium naphthalene, and grafting was achieved by utilizing the amide anions as initiator sites for the polymerization of ethylene oxide at 70℃. The graft copolymers was characterized with respect to molecule weight and composition using NMR, IR, GPC, and DSC. GPC result from the graft copolymer sample suggested a narrow size distribution.     

Non-equilibrium self-assembled structures in thick PS-b-PMMA copolymer films

Phenomena associated with the order-disorder transition (ODT) of block copolymers have been studied by optical light microscopy, SAXS, SEM, TEM and DSC. Observations have been made on almost symmetric polystyrene-block-poly(methyl methacrylate) samples of three molecular weights and their mixture. We observed non-equilibrium supermolecular structures several microns in diameter in the bulk of thick PS-b-PMMA films (ca. 100 μm thickness) prepared by vacuum drying of films cast from a non-selective solvent (after a short-term annealing above the T_g). Apparent LDOT (lower disorder-to-order transition) behaviour is observed for samples with non-equilibrium morphology surviving from solution as deduced from SAXS 1/I_m vs 1/T and the full width at half-maximum vs 1/T plots.The measurements point to complex behaviour near the ODT, but homogenization of samples upon long-term annealing well above the T_g temperature call into existence common stacks of lamellae observable in SEM images of microphase-separated samples. This verifies the opinion that the observed apparent LDOT behaviour of samples II, III and II + III is associated with the frozen non-equilibrium morphology surviving from solution. This is confirmed by SAXS measurement on a homogenized sample displaying the expected UDOT behaviour. It has been demonstrated that self-assembled structures prepared by vacuum drying of films cast from a non-selective solvent are non-equilibrium structures and their successive ordering is difficult due to a relative narrow temperature interval between T_g and degradation temperature. The conditions under which BCP films are prepared thus have a pronounced effect on the microstructure and microphase ordering process.     

Adsorption of polystyrene-poly(4-vinylpyridine) diblock copolymer on the assembled latex film

The Layer-by-Layer (LbL) technique was effectively used to embed anionic polystyrene (PS) latex particles into the assembled film deposited on a glass substrate. The high surface coverage of particles on poly(ethyleneimine) (PEI)-coated glass, determined from scanning electron microscopy (SEM) (80%), was attained within 1 h when using the latex containing sodium chloride (5 × 10⁻⁵ mol/l) at pH 6. After immersing the particles coated substrate in the polystyrene-poly(4-vinylpyridine) diblock copolymer (PS-PVPy) dissolved in tetrahydrofuran, the contact angle value indicated that the PS-PVPy could be adsorbed on the film to provide PS block at the outermost layer. The selective solvent, block length of PVPy, latex concentration, immersion time and ionic strength of aqueous solution of poly(allylamine hydrochloride) (PAH) previously adsorbed on the substrate showed influence on the adsorption of the block copolymer and, hence, the contact angle of the film.