丙烯酰胺在离子液体中的聚合反应研究

以四氟硼酸1-丁基-3-甲基咪唑([bmim]BF4)离子液体为反应溶剂,以过氧化苯甲酰-N,N-二甲基苯胺氧化还原体系为引发剂引发聚合了丙烯酰胺。采用粘度法测定了聚丙烯酰胺的相对粘均分子量,考察了聚合反应时间、反应温度、引发剂浓度对聚合物分子量和聚合反应单体转化率的影响。结果表明,丙烯酰胺可以在[bmim]BF4离子液体中进行氧化还原聚合,聚合物分子量随反应温度的升高而下降,聚合反应速率随着温度的升高而升高,得到的聚丙烯酰胺分子量可高达7.32×107以上,且水溶性良好。     

丙烯酰胺聚合物自由基聚合引发体系研究进展

丙烯酰胺类聚合物是应用较为广泛的水溶性高分子化合物,自由基聚合是大规模生产聚丙烯酰胺的有效方法。文章对自由基聚合偶氮类引发剂、氧化还原引发体系、复合引发体系的特点和研究应用进行了讨论,认为采用水溶性偶氮引发剂、含胺的氧化还原引发体系、含胺基功能性单体类引发剂等新型引发剂能制备高分子量的聚合物,合理设计新型复合引发体系可利于聚丙烯酰胺相对分子质量的进一步提高。     

疏水性聚丙烯酰胺的合成实验研究

疏水性聚丙烯酰胺是一种重要的疏水缔合水溶性聚合物,它可以通过多种方法合成。本文结合均相共聚法和表面活性大单体法2种方法,以丙烯酸和Span80为原料首先合成了一种具有表面活性的疏水缔合型单体Span80-AA,然后将Span80一AA与丙烯酰胺聚合反应合成疏水性聚丙烯酰胺,并研究了时间、引发剂浓度、溶剂配比、大单体含量和温度对疏水聚合物粘度和分子量的影响,从而得到比较合适的实验条件。     

超低分子量聚丙烯酰胺的水溶液聚合

本文从丙烯酰胺单体出发,以过硫酸铵为引发剂,甲酸钠为链转移剂,采用水溶液聚合法合成了分子量在(2.6～10)×104范围内的聚丙烯酰胺,探讨了反应温度、单体浓度、分子量调节剂、引发剂等因素对聚合物分子量的影响.     

高分子量聚丙烯酰胺的制备

丙烯酰胺溶液通过聚合反应制备了分子量大于2100万高分子量聚丙烯酰胺。聚合反应最佳条件为：单体须经离子交换树脂进行纯化，EDTA浓度为0．1mg／L，单体浓度为25％～30％，引发剂浓度为15mg／L，引发温度在15-20℃，聚合体系适宜的pH值范围7．5～8.5之间。探讨了聚合工艺条件对聚合物分子量的影响。     

采用ATRP反应合成嵌段共聚物P(n-BMA-b-NIPAM)的研究

采用原子转移自由基聚合(ATRP)反应合成了甲基丙烯酸正丁酯/N-异丙基丙烯酰胺嵌段共聚物(P(n-BMAb-NIPAM))。考察了引发剂、催化剂、反应温度等对聚合反应结果的影响,最终确定较为合适的反应条件,制备出分子量确定、分子量分布较窄的大分子引发剂,并成功引发第二单体继续通过ATRP反应,获得P(nBMA-b-NIPAM)。研究结果表明:所确定的ATRP反应体系能实现n-BMA的可控聚合,获得末端带溴原子的聚甲基丙烯酸正丁酯(P(n-BMA-Br))作为大分子引发剂继续通过ATRP反应引发N-异丙基丙烯酰胺(NIPAM),最后获得分子量确定、分子量分布较窄的嵌段共聚物P(n-BMA-b-NIPAM)。实验证明,利用高价态铜络合体系可以实现单体的可控聚合,而且可以保持聚合物末端较高的卤官能度。     

丙烯酰胺-丙烯酸钠共聚物的合成

含丙烯基的丙烯酰胺和丙烯酸钠,在引发剂存在下,都容易各自引发聚合成聚丙烯酰胺和聚丙烯酸钠.由于聚丙烯酰胺在水溶液中不电离,故称为非离子型聚丙烯酰胺.它在水中的溶解度随分子量增大而降低.通常很难制备分子量大于500万的水溶性聚丙烯酰胺;也很难制备分子量超过300万的聚丙烯酸钠.     

不同引发体系作用下合成疏水缔合聚丙烯酰胺衍生物的研究

摘 要 疏水缔合聚丙烯酰胺衍生物是一种大分子主链或侧链上含有少量疏水基团的新型水溶性功能高分子材料，在水溶液中具有良好的耐盐、耐温、增粘作用和贮存稳定性。利用分散聚合法，研究了采用不同体系的自由基引发剂及引发剂摩尔组成对聚合反应时间和聚合物分子量的影响，最终选择一种较好的引发体系。     

高分子量聚乙烯吡咯烷酮合成——水溶液聚合的研究(摘要)

<正> N-乙烯基吡咯烷酮(NVP)的水相溶液聚合体系中,用水溶性的过氧化氢作为聚合引发剂不易获得高分子量聚乙烯吡咯烷酮(PVP)。而用偶氮二异丁腈作引发剂时可得到分子量高的聚合物,但是,聚合反应不易控制,反应的重现性差。二者均在NVP水相溶液聚合制取高分子量PVP时都存在一定的缺点。 笔者提出一种水溶性的偶氮类化合物C-1作为NVP的水相溶液聚合的引发剂,在通常的聚合条件下可以方便地制得高分子量的聚乙     

阳离子聚丙烯酰胺的研制

阳离子聚丙烯酰胺是一种用途广泛的有机高分子聚合物,其分子量和阳离子度是决定其性能的重要指标。在氧化-还原引发体系中,以丙烯酰胺(AM)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体共聚合成了阳离子型聚丙烯酰胺聚合物(CPAM),考察了反应温度、酸碱度、引发剂、单体及阳离子单体浓度等因素对CPAM分子量和阳离子度的影响。结果表明,较高分子量和阳离子度CPAM的最佳聚合条件为:聚合单体浓度为35%,阳离子单体的含量约15%,引发剂0.4%,反应体系温度35℃,pH值为6左右。     

A new polymerization method and kinetics for acrylamide: Aqueous two‐phase polymerization

The concept of aqueous two‐phase polymerization and a new polymerization method for the preparation of water‐soluble polymers are presented. The phase diagram of poly(acrylamide) (PAAm)‐poly (ethylene glycol) (PEG)‐water two‐phase system was measured by the gel permeation chromatography (GPC). The aqueous two‐phase of PAAm‐PEG‐water system can be easily formed. The critical concentration of phase separation was affected by the molecular weight of PEG. The aqueous two‐phase polymerization of acrylamide (AAm) has been successfully carried out in the presence of PEG by using ammonium persulfate (APS) as the initiator. The polymerization behaviors with varying concentration of AAm, initiator and PEG, the polymerization temperature, the molecular weight of PEG, and emulsifier types were investigated. The activation energy of aqueous two‐phase polymerization of AAm was 132.3 kJ/mol. The relationship of initial polymerization rate (R_p0) with APS and AAm concentrations was R_p0 ∝ [APS]^0.72 [AAm]^1.28. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

催化乳液合成可溶性超支化聚合物的IFIRP法研究

描述了可进行催化乳液聚合合成可溶性超支化聚合物的一种新的聚合物合成过程——引发剂残片嵌入自由基聚合（IFIRP,Initiator-Fragment Incorporation Radical Polymerization）。分别以高浓度的偶氮二异丁酸甲酯（MAIB）和α-甲基苯乙烯（α-MS）为引发剂及阻聚剂,在十二烷基磺酸钠（SDS）和水及苯形成的乳液中,通过IFIRP过程,在70～80℃条件下将单体二异丁烯酸乙二酯（EGDMA）聚合反应3 h即可得到可溶性的超支化聚二异丁烯酸乙二酯纳米粒子聚合物。研究发现,当EGDMA、MAIB和α-MS浓度分别为1.0、2.0和2.0 mol/L时,到80℃为止未见到凝聚现象发生,生成可溶性聚合物的产率为44%左右,相对分子质量分布在1.2～1.5之间。分析结果表明共聚物的成分为（质量分数）：α-MS为57%,MAIB为24%,含双键的EGDMA为5%,不含双键的EGDMA为14%。     

Synthesis, characterization, and controllable drug release of dendritic star-block copolymer by ring-opening polymerization and atom transfer radical polymerization

A series of well-defined dendritic star-block copolymers were successfully synthesized by combination of living ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) with the hydroxyl-terminated dendrimer polyester. Dendritic star-shaped poly(l-lactide)s (PLLAs) were prepared by bulk polymerization of l-lactide (l-LA) with dendrimer polyester initiator and tin 2-ethylhexanoate catalyst. The number-average molecular weight of these polymers linearly increased with the molar ratio of l-LA to dendrimer initiator. Dendritic star-shaped PLLA was converted into a PLLABr macroinitiator with 2-bromopropionyl bromide. Dendritic star-block copolymers could be obtained via ATRP of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). The molecular weight distributions of these copolymers were narrow. The molecular weights of dendritic star-shaped polymers and star-block copolymers could be controlled by the molar ratios of monomer to initiator and monomer conversion. The thermal properties of these dendritic star-shaped polymers and star-block copolymers were investigated. The behavior of model drug chlorambucil release from the copolymer indicated that the rate of drug release could be effectively controlled by altering the pH values of the environment.     

Cationic Polymerization of β-Pinene Using B(C6F5)3 as a Lewis Acid for the Synthesis of Tackifiers in Pressure Sensitive Adhesives

β-pinene is a well-known bio-based monomer that can be polymerized via cationic polymerization to give low molecular weight resins that find use commercially as tackifiers. However, the controlled synthesis of these polymers by cationic polymerization is challenging due to the reactivity of commonly used Lewis acid catalysts and the propagating carbocationic species with water. Here, the cationic polymerization of β-pinene under mild conditions using the water stable Lewis acid tris(pentafluorophenyl)borane is demonstrated. It is shown that when combined with a suitable alcohol initiator the molecular weight of the polymer can be tuned while the kinetics are largely controlled by the concentration of tris(pentafluorophenyl)borane. The final poly(β-pinene) is shown to perform well as a tackifier in the formation of pressure sensitive adhesives based on polystyrene-b-polyisoprene-b-polystyrene triblock copolymers.     

Free‐radical bulk polymerization of styrene with a new trifunctional cyclic peroxide initiator

The bulk free‐radical polymerization of styrene in the presence of a new cyclic trifunctional initiator, 3,6,9‐triethyl‐3,6,9‐trimethyl‐1,4,7‐triperoxonane, was studied. Full‐conversion‐range experiments were carried out to assess the effects of the temperature and initiator concentration on the polymerization kinetics, molecular weight, and polydispersity. Gel permeation chromatography was used to measure the molecular weight and the molecular weight distribution of polystyrene. When this multifunctional initiator was used for styrene polymerization at higher temperatures, it was possible to produce polymers with higher molecular weights and narrower molecular weight polydispersity at a higher rate. This showed that the molecular weight and polydispersity were influenced by the initiator concentration and the polymerization temperature in an unusual manner. Moreover, polystyrene, obtained with trifunctional peroxide, had O? O bonds in the molecular chains and was investigated with differential scanning calorimetry and gel permeation chromatography. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1035–1042, 2004     

Mass transfer and radical flux effects in dispersed‐phase polymerization of isooctyl acrylate

The kinetics of dispersed phase polymerization of a highly water‐insoluble monomer (isooctyl acrylate) were explored in emulsion, miniemulsion, and microsuspension polymerization. The effects of monomer water solubility and choice of initiator (oil‐ vs. water‐soluble) strongly impact the final product (particle size and molecular weight distribution). For emulsion polymerization, as the surfactant concentration was increased, there was a transition from homogenous to micellar nucleation near the CMC, then a drop in nucleation rate at high surfactant concentration due to insufficient radical flux to support more nucleation. For miniemulsion polymerization, a slow rate of growth of (droplet) nucleation with surfactant concentration was found, followed (at the CMC) by an increase in the rate of nucleation with added surfactant as the mode of nucleation switched to micellar. The conversion‐time kinetics of microsuspensions could be modeled with a bulk polymerization model. IOA is sufficiently insoluble in the aqueous phase that emulsion polymerization may or may not be reaction limited. The presence of a stabilizer such a PAA, the use of an oil‐soluble initiator such as BPO, and the insolubility of IOA in the aqueous phase all push the polymerization locus toward droplet (microsuspension) nucleation and bulk kinetics.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5649–5666, 2006     

Synthesis in inverse emulsion and associating behavior of hydrophobically modified polyacrylamides

An inverse free‐radical emulsion polymerization technique was used to prepare copolymers of acrylamide and two different hydrophobic comonomers: N,N‐dihexylacrylamide (diC6) or N,N‐diphenylacrylamide (diPh). The products of the reaction were high molecular weight hydrophobically modified water‐soluble polymers (HMWSPs) encapsulated within water droplets dispersed in an organic medium. A comparison of the copolymer compositions prepared under different experimental conditions showed that the level of incorporation of diPh in the final copolymer depended strongly on its localization in the emulsion (aqueous or oil phase) and on the nature of the redox initiator pair (water‐soluble or oil‐soluble). The rheological properties of the HMWSPs in aqueous solution were investigated as a function of the comonomer content and the nature of the initiator, using steady‐flow experiments. The thickening properties were found to be directly correlated to the conditions of synthesis and were optimal when the initiator and the hydrophobic comonomer were located in two distinct phases. An examination of the viscosity as a function of shear rate showed that these solutions exhibit typical characteristics of hydrophobically associative polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 916–924, 2004     

Toward an understanding of the role of water‐soluble oligomers in the emulsion polymerization of styrene–butadiene–acrylic acid. Function of carboxylic acid

In a further effort to understand the role of water‐soluble oligomers formed during the emulsion terpolymerization of styrene/butadiene/acrylic acid (St/Bu/AA), the reaction temperature, initiator concentration, and ionic strength were varied and the kinetics and resulting oligomers were characterized as a function of reaction time. The rate of polymerization (R_p) was observed to increase with increasing temperature and initiator concentration; the reasons for this vary. The increase in R_p with increasing initiator concentration is mainly attributed to the increase in the number of oligomeric radicals formed and, subsequently, the resulting number of particles (N_p). Increasing the temperature increases the water solubility of both monomers and polymers, which results in changes in the composition and molecular weight of the oligomeric radicals being formed. The primary reaction locus in the St/Bu/AA system was noted to shift to the aqueous phase after most of the styrene and butadiene had reacted, based on the unreacted AA profile. The role of water‐soluble oligomers (both oligomeric radicals and dead oligomers) during the emulsion polymerization of St/Bu with acrylic acid can be described by three periods: (1) particle generation and (2) before and (3) after the critical surface saturation concentration (CSSC) is reached during the particle growth period. The incorporation of AA monomer into the oligomer chains after the CSSC may cause destabilization of the latexes through a bridging flocculation mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1988–1999, 2003     

Synthesis and characterization of a calcium‐ and sodium‐containing acrylamide‐based polymer and its effect on soil strength

Soil degradation is a significant problem throughout the world. One strategy that can be used to improve soil physical properties is the use of soil conditioners, particularly anionic polyacrylamides. Synthetic water‐soluble anionic acrylamide‐based polymers have wide applications in agriculture, such as mulch and agrochemicals, and can also be used as soil modifiers for erosion control, nondesertification, and soil stabilization. In this study, anionic polyacrylamides containing cationic metal ions were prepared by free‐radical polymerization. Anionic polymer with negative charges was produced by the reaction of mono‐ and divalent inorganic salts with acrylamide monomer via solution polymerization. Hydrolysis of the polymer was carried out by using calcium chloride and sodium carbonate in their soluble forms, and the negative charges on the polymer were regulated by variation of the molar ratios of inorganic salts with respect to the acrylamide monomer concentration. The molecular weight and charge density of the anionic charged polymers were improved and manipulated by using these methods. The molecular structure of the polymers was characterized and confirmed by common techniques. The effect of the polymers on soil strength was evaluated, and the results showed that the addition of anionic polymer having a high molecular weight improved the behavior of soil components. J. VINYL ADDIT. TECHNOL., 19:140–146, 2013. © 2013 Society of Plastics Engineers