悬浮聚合法制备单分散聚硅氧烷微球

采用悬浮聚合法以正硅酸乙酯(TEOS)和甲基三甲氧基硅烷(MTMS)为主要原材料,制备球形度良好的单分散聚硅氧烷微球。并同时研究了反应体系中反应条件对微球粒径大小及其分布的影响。通过扫描电镜(SEM)、动态光散射(DLS)和红外光谱(FT-IR)等分析手段分别对微球的形貌、分布和结构等进行了表征。确定最优的反应条件为:同时满足温度为40℃且氨水浓度为0.01%时,微球呈球形度良好的单分散状态。     

改进的微悬浮聚合法制备聚合物微球

微悬浮聚合法是制备聚合物微球的方法之一,它是先将单体相分散为一定粒度的微液滴,再在低速搅拌(75～100r/min)下进行聚合反应~[1,2],对聚合设备无特殊要求,且避免了悬浮聚合法制备微球时连续数小时的高速搅拌~[3],只要有合适的均化器即可大批量制备1～50μm的聚合物微球,且可适当控制粒度.但由于一般单体在分散介质中均有一定的溶解性,且液滴粒径越小单体溶解度越大,致使聚合过程中单体可通过介质扩散而产生单体在不同粒     

改进的种子聚合——单分散交联聚苯乙烯微球的合成

 本文结合了种子聚合法和二步溶胀法的特点,提出用改进的种子聚合法以合成粒径大于3微米、粒度呈单分散的交联聚苯乙烯微球。文中采用的粒径为1—2微米的聚苯乙烯胶乳种子是由无皂乳液聚合法制备的。文章研究了溶胀温度、溶胀剂比例、溶胀时间、交联剂、小分子化合物及表面活性剂等因素对生成微球的粒径和分散性的影响。     

反相悬浮聚合分散剂的合成及性能

聚丙烯酸（钠）的吸水速度快,吸水量大,通常在有机介质环己烷、戊烷、（甲基）环戊烷中进行反相乳液聚合法生产,但一般只能获得颗粒细小的粉末状树脂,在介质中沉降速度慢,工程上易起粉尘危害．吸水树脂颗粒细小也影响树脂性能［１］,采用反相悬浮聚合法合成聚丙烯酸...     

变温反相悬浮聚合制备温度敏感性聚合物微凝胶

报道了一种利用变温的途径制备具有温度敏感性聚合物凝胶微粒的悬浮聚合方法.以正庚烷为连续相,过硫酸铵和四甲基乙二胺为引发剂,采用将具有反向温敏性的可降解大分子单体水溶液在低温下分散好以后再升高到聚合温度的变温反相悬浮聚合的方法制备了反向温敏性的可降解微凝胶.该方法避免了由于分散相在聚合温度下发生物理凝胶化所导致的分散困难等问题.考察了微凝胶的温敏性、粒径分布和降解行为等,并研究了油水比对微凝胶形貌的影响.     

改进的种子聚合——单分散交联聚苯乙烯微球的合成

本文结合了种子聚合法和二步溶胀法的特点,提出用改进的种子聚合法以合成粒径大于3微米、粒度呈单分散的交联聚苯乙烯微球。文中采用的粒径为1—2微米的聚苯乙烯胶乳种子是由无皂乳液聚合法制备的。文章研究了溶胀温度、溶胀剂比例、溶胀时间、交联剂、小分子化合物及表面活性剂等因素对生成微球的粒径和分散性的影响。     

种子溶胀悬浮聚合法制备分子印迹聚合物微球

 以酪氨酸为印迹分子 ,甲基丙烯酸为功能单体 ,三羟甲基丙烷三甲基丙烯酸酯 (TRIM )为交联剂 ,采用种子溶胀悬浮聚合法在水溶液中制备了一系列分子印迹聚合物微球 (MIPMs)。利用扫描电镜 (SEM)对此微球的粒径大小、粒径分布、表面孔与孔径分布等进行了分析研究 ,探讨了影响其形貌的主要因素 ,并将所得微球用作固定相研究了其分子选择吸附性能。研究表明 ,种子溶胀悬浮聚合法能够制得单分散性较好的、表面带有微孔的分子印迹聚合物微球 ,且该微球呈现出较好的特异吸附性能。     

用多孔玻璃膜管悬浮聚合法制备单分散性聚苯乙烯微球

Monodisperse polystyrene microspheres are prepared by shell porous glass(SPG)-suspension polymerization. The influences of SPG on size and size dispersity of the microspheres are investigated. The properties of the microspheres are studied by GPC, TEM and SEM. The results indicate that the polystyrene microspheres possess definite monodispersibity and their particle size is in the range of 5～12μm.     

单分散功能化聚硅氧烷微球的制备及其应用

采用悬浮聚合法以正硅酸乙酯(TEOS)和γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)为主要原材料,制备表面功能化的单分散聚硅氧烷微球。采用扫描电镜(SEM)、动态光散射(DLS)和红外光谱(FT-IR)等分析手段分别对功能性微球的微观形貌、粒径分布和微观结构进行表征。将这种表面功能性的单分散聚硅氧烷微球按照0.4%的添加量加入光学级聚碳酸酯(PC)树脂中,可制备出透光率75.6%、雾度94.6%性能优良的光散射材料。     

聚丙烯酰胺对粘土悬浮体的絮凝与稳定作用

研究了分子量为220万的10种水解度的PAM对高岭土的絮凝动力学曲线和对钠蒙脱土泥浆的稳定作用，发现各项性能都存在一个水解度最佳区，对高岭土的絮凝能力下在34％－41％处，钠蒙脱土悬浮体的宾汉姆屈服值τ0最大值在30％－40％处，凝胶强度τs在15％－20％处，本文从大分子形态和分散相电性质，对结果进行了讨论，指出了30％左右的水解PAM可以在钠蒙脱土和高岭土的悬浮液中，选择絮凝高岭土。     

间氯苯胺的乳液聚合及聚合物链结构表征

聚苯胺以其良好的电化学稳定性和掺杂可逆性 ,成为一类优良的电活性聚合物 [1,2 ] ,但其溶解性差 ,限制了它的加工及应用 .用取代基对聚苯胺的结构进行修饰 ,可有效地提高其加工性能 [3,4 ] ,但有关含吸电子取代基的苯胺衍生物聚合的报道尚少 .Ranger等 [5]指出 ,含强吸电子取代基团的聚苯胺不易用化学氧化聚合方法制备 ,并提出被氧化单体中的 N7和 C4位置必须具有相近的电子自旋密度 ,才能进行“头 -尾”偶联 ,而含强吸电子取代基团的苯胺单体中这两个位置的反应能力是不等价的 ,但可采用与母体共聚的方法可制备含强吸电子取代基 (如— C…     

水溶液微悬浮聚合法制备酸性药物吲哚美辛分子印迹微球及其色谱表征

以带有羧基的酸性药物吲哚美辛为模板分子、碱性的4-乙烯基吡啶为功能单体,采用水溶液微悬浮聚合法制备了用于色谱分离的微米级分子印迹微球.详细讨论了流动相中缓冲溶液的pH值对吲哚美辛在MIMs柱上的容量因子(k′)、分离因子(α)和印迹因子(β)的影响.通过MIMs柱对吲哚美辛和4-氨基吡啶(4-AP)的保留行为的比较,证明以4-乙烯基吡啶为功能单体制得的MIMs对吲哚美辛的识别作用,主要靠吡啶环上氮原子与吲哚美辛羧基之间的离子键相互作用,以及吡啶环与模板分子之间的π-π相互作用.     

分散聚合技术及其研究进展

介绍了分散聚合体系中各组分及反应条件对反应过程和最终产物性能的影响,简要归纳了分散聚合成核机理、稳定机理及其反应动力学,并着重阐述了近年来分散聚合发展的新技术以及制备的功能微球在各领域的应用等方面的研究进展.分散聚合与其它非均相聚合方法相比,是制备粒径范围在1-10μm且单分散性较好的聚合物微球的有效方法.最近,许多新思路不断引入分散聚合体系,如采用水和超临界CO2作为分散介质,尝试微波和辐射引发聚合以及按照活性聚合机理进行反应等.     

Pulsed Laser Polymerization at Low Conversions: Broadening and Chain Transfer Effects

Pulsed laser polymerization (PLP) is widely employed to measure propagation rate coefficients k_p in free radical polymerization. Various properties of PLP have been established in previous works, mainly using numerical methods. The objective of this paper is to obtain analytical results. We obtain the most general analytical solution for the dead chain molecular weight distribution (MWD) under low conversion conditions which has been hitherto obtained. Simultaneous disproportionation and combination termination processes are treated. The hallmarks of PLP are the dead MWD discontinuities located at integer multiples of n₀ = k_pt₀C_M, where t₀ is the laser period and C_M is the monomer concentration. We show that chain transfer reduces their amplitude by factors , consistent with numerical results obtained by other workers. Here c_tr is the chain transfer coefficient and Ln₀ (L = integer) are the discontinuity locations. Additionally, transfer generates a small amplitude continuous contribution to the MWD. These results generalize earlier analytical results which were obtained for the case of disproportionation only. We also considered two classes of broadening: (i) Poisson broadening of growing living chains and (ii) intrinsic broadening by the MWD measuring equipment (typically gel permeation chromatography, GPC). Broadening smoothes the MWD discontinuities. Under typical PLP experimental conditions, the associated inflection points are very close to the discontinuities of the unbroadened MWD. Previous numerical works have indicated that the optimal procedure is to use the inflection point to infer k_p. We prove that this is a correct procedure provided the GPC resolution σ is better than nequation/tex2gif-stack-1.gif. Otherwise this underestimates Ln₀ by an amount of order σ²/n₀.

Schematic of a chain transfer reaction with monomer as the transfer agent.     

聚合度3～6甲壳寡糖的制备与TOF-MS分析

本文用自制酸性蛋白酶粗酶液降解壳聚糖,研究了降解过程中温度、pH值、反应时间、酶用量及壳聚糖脱乙酰度(DD)对酶降解能力的影响。以85.5%脱乙酰度(DD)、分子量(Mw)为56.0×104的壳聚糖为底物,45℃、pH4.6降解数小时,降解产物由红外光谱、分子量测定(GPC)和基体辅助激光解吸电离飞行时间质谱(MALDI TOF MS)表征。主要降解产物的脱乙酰度有所降低;酶解8h,其水解产物用NaOH调至pH9无沉淀,9h分子量降为0.93×103,经MALDI TOF MS分析产物为聚合度3～6的甲壳寡糖,3～6糖中各糖含量分别为13.3%、27.3%、49.0%、10.1%。     

用活性阴离子聚合设计合成高分子链构造的新进展

综述了采用活性阴离子聚合方法制备新型高分子链构造的新进展,包括“π”形聚合物,“H”形聚合物,“哑铃”形聚合物,ABC杂臂星形聚合物,超支化聚合物,环状聚合物,“蝌蚪”形聚合物,“蜈蚣”形聚合物和“刺钢丝”形聚合物等。     

Emulsion Polymerization of Styrene and Vinyl Acetate with Cationic Surfactant

Summary: In this study, the emulsion homopolymerization system containing vinyl acetate and styrene, potassium persulfate, and a new cationic surfactant was studied in the classical glass emulsion polymerization reactor. The effects of new polymeric emulsifier on the physicochemical properties of obtained vinyl acetate and styrene latex properties were investigated depending on surfactant percentage in homopolymerizations.     

Ab Initio Calculation of the Propagation Kinetics in Free Radical Polymerization: Chain Length and Penultimate Effects

Summary: In this work, Quantum Chemistry is applied to investigate the propagation kinetics in free radical polymerization. Energies, structures and transition state geometries are determined using density functional theory, which combines good accuracy with reasonable computational demand. In particular, B3LYP functional is used to evaluate the exchange and correlation energy with the 6-311+G(d,p) basis sets. The capabilities of the approach with respect to the prediction of the kinetic constants of elementary processes relevant to polymeric systems (propagation reactions) is first tested using literature experimental data as reference values. 1 Namely, two different monomers of industrial relevance have been selected, acrylonitrile and styrene. For such systems, the effect of chain-length on the propagation rate coefficient is examined. Finally, for the selected monomer pair, the relative reactivity (so-called reactivity ratios) is also analyzed, in particular considering the penultimate effect.     

Application of Chitosan and Its Derivatives in Analytical Chemistry: A Mini-Review

Recent progress in the application of chitosan and its derivatives in analytical chemistry, especially their application in the field of separation science including as capillary coating materials, chromatographic column fillings, and adsorption materials, during the past 8 years is reviewed.     

分散聚合水基聚苯胺乳胶微球制备与表征

水溶性空间稳定剂聚乙烯吡咯烷酮（PVP）存在时，采用分散聚合制备水溶性单分散的聚苯胺(PAn)乳胶粒子，采用透射电子显微镜（TEM）观察粒子形态及尺寸；利用紫外-可见吸收光谱对胶体分散体系进行表征.实验结果表明，当PAn含量较少（w< 16.78％）时， PAn-PVP复合乳胶粒子呈米粒状；当PAn含量较大（w >23.22％）时， PAn-PVP复合乳胶粒子呈球形.