含磷苯丙乳液的合成

采用预乳化工艺,半连续种子聚合法,通过丙烯酸丁酯(BA)、苯乙烯(St)、丙烯腈(AN)、丙烯酸(AA)以及磷酸酯功能性单体Y自由基聚合反应,合成了一种功能性苯丙乳液.考察了乳化剂种类、乳化剂用量、乳化剂复配比、引发剂用量、软硬单体比、功能单体AA的用量以及含磷单体Y的用量对乳液及涂膜性能的影响.结果表明,采用阴离子型...     

Preparation of iodine containing quaternary amine methacrylate copolymers and their contact killing antimicrobial properties

A novel quaternary amine methacrylate monomer (QAMA) was synthesized by amination of dimethacrylate with piperazine followed by its quaternization using an alkyl iodide. Copolymerization of QAMA with 2‐hydroxyethyl methacrylate was carried out by free radical bulk polymerization technique at room temperature using ammonium persulfate and N,N,N′,N′‐tetramethyl ethylenediamine as a redox initiator. The monomer as well as copolymers was characterized by FTIR and ¹H NMR spectral studies. Thermal and physical characteristics of copolymers of varying compositions of QAMA were evaluated by thermogravimetric analysis, differential calorimetry, contact angle and scanning electron microscopy. The antibacterial activity of the synthesized quaternary amine dimethacrylate copolymers against Escherichia coli and Staphylococcus aureus was studied by zone of inhibition and colony count method. QAMA copolymers showed broad‐spectrum contact killing antibacterial properties without releasing any active agent as checked by iodide‐selective ion meter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1038–1044, 2006     

分散因素对氯乙烯微悬浮聚合的影响及对策

本文对氯乙烯微悬浮聚合中影响氯乙烯分散的诸因素:乳化剂及其助剂,氯乙烯以及分散系统自聚等进行了分析,并针对目前生产中出现的问题提出相应对策。     

氧化还原引发乳液聚合单体水溶性与动力学之间的关系

本文研究了以过硫酸钾／焦亚硫酸钠为氧化还原引发体系，在苯乙烯、醋酸乙烯酯为具体单体的乳液聚合中，单体水溶性与动力学之间的关系。通过实验考察了聚合温度、搅拌速率、电解质浓度对聚合反应转化率～时间关系的影响，并讨论了单体水溶性、自由基水相反应和聚合速率等之间的内在联系。同时得出该氧化还原引发下苯乙烯和醋酸乙烯酯体系的表观活化能分别为４７．０６ｋｊ／ｍｏｌ和约７０ｋＪ／ｍｏｌ。     

VAc／MMA半连续乳液共聚合的研究：Ⅰ种子乳液共聚合

以过硫酸铵为引发剂，十二烷基硫酸钠为乳化剂，于７０℃下进行了ＶＡｃ＝ＭＭＡ种子乳液共聚合。试验考察了组分和操作条件对体系稳定性，聚合速度及组成分布等的影响，同时，从理论上给出了加料速率与体系稳定性因子间的关系。     

聚醋酸乙烯酯共聚胶液的改性研究

聚醋酸乙烯酯作为常用的胶粘剂之一,有明显的优点,但随着环保和绿色生活的要求,其有毒和耐水性等缺陷影响了其更好发展.本研究利用醋酸乙烯酯与其它烯类单体的共聚,制备出了无毒、快干、胶接强度高、耐水性好的高性能聚醋酸乙烯酯共聚改性胶液,并对其相关影响因素及工艺条件的确定进行了讨论.     

In vitro Streptococcus mutans biofilm formation on surfaces of chlorhexidine-containing dentin bonding systems

This in vitro study evaluated the influence of chlorhexidine diacetate (CDA) when blended within dentin bonding systems (DBSs) on Streptococcus mutans (S. mutans) biofilm formation.One commercially available 0.2% wt CDA-containing DBS (Peak Universal Bond) and five experimental 0.2% wt CDA-containing DBS formulations (experimental Adper Scotchbond 1XT plus experimental resins, R₂, R₃, R₄, R₅) were assessed vs their no-CDA containing counterparts. Twenty-eight DBSs disks were prepared for each group (6.4 mm×1.0 mm) and cured for 80 s at 800 mW/cm² in a nitrogen atmosphere. A modified Drip-Flow Reactor was used to grow S. mutans biofilms on specimen surfaces for 24 h and adherent, viable biomass was evaluated using a tetrazolium salt assay (MTT). Two specimens from each of the tested materials were processed with LIVE/DEAD stain and observed using laser confocal microscopy (CLSM) while two disks from each group were examined by using scanning electron microscopy (SEM).MTT assay, CLSM and SEM observations showed that CDA addition decreased, increased or did not change S. mutans biofilm formation. The lowest biofilm formation was obtained with Peak Universal Bond and R₅ (with and without CDA).It may be concluded that the chemical composition of DBSs determines their ability to promote or hamper biofilm formation. Therefore, CDA addition may be helpful in modulating biofilm formation provided that DBS formulation is tuned and optimized.     

Incorporation of Very Insoluble Monomers in Waterborne Coatings

The benefits of polymerizing very insoluble monomers in aqueous media, avoiding the use of energy‐intensive procedures, by implementing two novel synthesis techniques based on the emulsifier combination in emulsion polymerization and on miniemulsification by phase inversion temperature are investigated. The performance of standalone polymers consisting of monomers, namely lauryl methacrylate, isobornyl acrylate, and 1H,1H,2H,2H‐perfluorodecyl acrylate, and of formulated binders with these monomers incorporated either through blending or in situ polymerization, is evaluated with special emphasis on their water‐barrier properties (e.g., uptake, whitening, immersion, and vapor resistance) and on their chemical resistance. The performance of the standalone polymers is found to be similar to that of polymers prepared by high‐shear miniemulsion polymerization, while the performance of the formulated binders is generally superior to a commercial coating formulation based on a binder recommended for water resistance.     

DOPO‐Based Phosphorus‐Containing Methacrylic (Co)Polymers: Glass Transition Temperature Investigation

A two‐step synthetic procedure is designed for preparing new flame‐retardant methacrylic monomers containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a substituent side group. DOPO and methacrylate moieties are linked by linear aliphatic hydrocarbon spacers (3 to 11 carbon atoms). Copolymerization with methyl methacrylate is carried out leading to copolymers containing between 2 and 10 wt% phosphorus. All homo‐ and copolymers exhibit a unique glass transition temperature (T_g ). A new group contribution for DOPO‐based substituent is extracted that leads to reasonable estimations of T_g s of other published polymers. The Fox equation provides a good estimation of T_g s for most copolymers and for physical blends of poly(methyl methacrylate) (PMMA) and DOPO. When using monomers having three and four carbon atoms in the hydrocarbon spacer, the T_g of copolymers remains close to that of PMMA over a wide range of composition.     

High activity and wide temperature window of Fe‐Cu‐SSZ‐13 in the selective catalytic reduction of NO with ammonia

Fe‐Cu‐SSZ‐13 catalysts were prepared by aqueous solution ion‐exchange method based on the one‐pot synthesized Cu‐SSZ‐13. The catalysts were applied to the selective catalytic reduction (SCR) of NO with NH₃ and characterized by the means of XRD, UV‐Vis, EPR, XPS, NH₃‐TPD, and so on. The selected Fe‐Cu‐SSZ‐13‐1 catalyst exhibited the high NO conversion (>90%) in the wide temperature range (225–625°C), which also showed good N₂ selectivity and excellent hydrothermal stability. The results of XPS showed that the Cu and Fe species were in the internal and outer parts of the SSZ‐13 crystals, respectively. The results of UV‐Vis and EPR indicated that the monomeric Cu²⁺ ions coordinated to three oxygen atoms on the six‐ring sites and Fe monomers are the real active species in the NH₃‐SCR reaction. Furthermore, the influence of intracrystalline mass‐transfer limitations on the Fe‐Cu‐SSZ‐13 catalysts is related to the location of active species in the SSZ‐13 crystals. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3825–3837, 2015