Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The T_g of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388     

Efficient synthesis of branched poly(acrylic acid) derivatives via postpolymerization modification

The utility of pentafluorophenyl esters for the selective introduction of functional units and branch points in well-defined poly(acrylic acid) (PAA) derivatives is demonstrated using a combination of controlled radical polymerization and postpolymerization modification. Reversible addition-fragmentation chain transfer enables the synthesis of well-defined copolymers—poly(pentafluorophenyl acrylate-co-tert-butyl acrylate)—with the active ester repeat units serving as attachment points for reaction with primary amines, specifically tris(2-(t-butoxycarbonyl)ethyl)methyl amine (Behera's amine). Deprotection using trifluoroacetic acid removes both the backbone and side chain t-butyl esters to give a series of branched PAA derivatives containing novel tricarboxylic acid side chains that are well suited to complexation and multidentate interactions. Surprisingly, the active ester homopolymer is shown to have the highest reactivity with Behera's amine when compared to copolymers with lower incorporation of pentafluorophenyl esters, suggesting an intriguing interplay of neighboring group effects and steric interactions. The ability to tune the efficiency of postpolymerization modification gives a library of PAA derivatives.     

AM/AA/APEG/NANB共聚物的合成与性能研究

通过丙烯酰胺(AM),丙烯酸(AA),烯丙醇聚氧乙烯醚(APEG)和N,N-二烯丙基苄胺(NANB)制备共聚物P(AM/AA/APEG/NANB)。确定了最佳反应条件:m(AM)∶m(AA)=6.5∶3,APEG为5 wt%,NANB加量0.2 wt%,pH为7,反应温度40℃,引发剂0.4 wt%。通过IR和1H NMR确定了聚合物的分子结构,并对其进行性能测试。结果表明:2000 mg·L-1的AM/AA/APEG/NANB溶液具有较好的流变性能(120℃,粘度保留率:38.56%;1000 s-1,粘度保留率:17.93%)和抗盐性能(20 000 mg·L-1Na Cl,2000 mg·L-1Mg Cl2或Ca Cl2,粘度保留率分别为22.14%、18.34%和15.33%),且提高采收率可达16.12%。     

弱凝胶钻井液成胶剂AM/AMPS/OA_8的合成与表征

针对水平井、大斜度井钻井过程中井眼润滑性、岩屑携带以及钻井速度的影响等问题,通过合理的分子设计,以丙烯酰胺(AM)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和实验室自制疏水单体丙烯酸正辛醇OA_8为原料,利用胶束聚合法,制备了一种弱凝胶成胶剂AMAMPSOA_8,其结构经1H NMR和IR表征。以AMAMPSOA_8在低剪切速率下的表观粘度为指标设计正交试验,确定最优反应条件为:AM与AMPS摩尔配比为4.8∶1,引发剂用量为单体总质量的0.04%,疏水单体浓度为0.75%,于70℃反应9 h。该条件下,0.5%AMAMPS0A_8聚合物溶液在低剪切速率3 r·min~(-1)下表观粘度可达23 680 mPa·s。利用热分析仪、高温滚子炉、高温高压流变仪对产物性能进行了研究。研究表明:AMAMPSOA_8的抗温性能可达160℃;聚合物溶液体系有明显的触变性,在40 min后溶液切力增加幅度变缓。     

Multi-bond network hydrogels with robust mechanical and self-healable properties

Multi-bond network(MBN) which contains a single network with hierarchical cross-links is a suggested way to fabricate robust hydrogels. In order to reveal the roles of different cross-links with hierarchical bond energy in the MBN, here we fabricate poly(acrylic acid) physical hydrogels with dual bond network composed of ionic cross-links between carboxylFe3+ interactions and hydrogen bonds, and compare these dually cross-linked hydrogels with singly and ternarily cross-linked hydrogels. Simple models are employed to predict the tensile property, and the results confirm that the multi-bond network with hierarchical distribution in the bond energy of cross-links endows hydrogel with effective energy-dissipating mechanism. Moreover, the dually cross-linked MBN gels exhibit excellent mechanical properties(tensile strength up to 500 k Pa, elongation at break ~ 2400%) and complete self-healing after being kept at 50 °C for 48 h. The factors on promoting self-healing are deeply explored and the dynamic multi-bonds are regarded to trigger the self-healing along with the mutual diffusion of long polymer chains and ferric ions.     

A Safety Strategy for Producing Poly(Acrylic Acid) of Low Molar Mass

The synthesis of poly(acrylic acid) (PAA) of low molar mass under safe conditions is difficult due to the high polymerization rate of acrylic acid (AA) and the fast heat generation. The aqueous‐solution “semibatch” polymerization of non‐ionized AA in almost starved conditions involves high initiator loads when low molar masses are required. This article proposes the simultaneous feeding of AA and nonconventional chain transfer agents (CTA) as a strategy aimed at controlling both the molar masses and the generated heat rate. Three CTAs are investigated: 2‐mercaptoethanol, thioglycolic acid, and isopropyl alcohol. Even when PAA of relatively low molar mass can be produced by adequately selecting the flow rates and concentrations of both AA and CTA, it is found that the nature of CTA can have a significant effect on the polymerizations kinetics. The mechanisms responsible for these effects are discussed with the help of a representative mathematical model.

     

Heavy Metals in Acrylic Color Paints Intended for the School Children Use: A Potential Threat to the Children of Early Age

Heavy metals are the harmful elements, regarded as carcinogens. Nevertheless, owing to their physical and chemical properties, they are still used in the production of several commercial products. Utilization of such products increases the chance for the exposure of heavy metals, some of them are categorized as probable human carcinogens (Group 1) by the International Agency for Research on Cancer. Exposure of heavy metals to school children at early age can result severe life time health issues and high chance of emerging cancer. Thus, we have performed study relating to the presence of heavy metals in acrylic color paints commonly used by the school children. Acrylic paints of different colors were assayed for seven potential heavy metals manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) using microwave digestion and iCAPQ inductively coupled plasma mass spectrometry (ICP-MS) system. The optimized method including paints digestion reagents nitric acid (HNO₃, 65%, 5 mL) and hydrofluoric acid (HF, 40%, 2 mL) have offered excellent method performance with recovery values ranged between 99.33% and 105.67%. The elements were identified in all of the analyzed samples with concentrations ranged from 0.05 to 372.59 µg/g. Cd constitutes the lower percentage (0.05%), whereas Zn constitutes high ratio contribution which was tremendously high (68.33%). Besides, the paints contamination was also color specific, with considerably total heavy metal concentrations found in brunt umber (526.57 µg/g) while scarlet color (12.62 µg/g) contained lower amounts. The outcomes of our investigation highlight the necessity for guidelines addressing the heavy metals in acrylic color paints intended for the school children usage.     

基于聚乙二醇接枝丙烯酸树酯光固化电解质的制备及性能研究

聚氧化乙烯(PEO)(聚乙二醇(PEG))和丙烯酸树脂在聚合物基电解质中具有很好的应用,本文通过紫外光引发单/双官能度的聚乙二醇接枝丙烯酸树脂单体聚合构建了离子电导率高、易于封装,可避免电解质泄漏的准固态聚合物电解质.通过调控聚乙二醇二甲基丙烯酸酯(PEGDA)和甲氧基聚乙二醇单甲基丙烯酸酯(PEGMA)2种单体的比例以及锂盐溶液的含量,成功制备出具有高离电导率的准固态聚合物电解质.采用傅里叶变换红外光谱仪(FTIR),电化学工作站对PEGMA/PEGDA基聚合物电解质进行表征,研究各组分比例对电解质的电化学性能影响.当PEGMA/PEGDA单体比例为75/25,锂盐溶液的占比为75%时,形成的薄膜状态电解质表现出1.96×10^?3 S·cm^?1的高离子电导率,较原始配比提高了14倍.将制备的电解质应用于电致变色器件,在580个变色循环后,器件依然可以实现稳定快速的颜色切换,2种颜色变换时间均在3 s以内,本文中研究的聚醚接枝丙烯酸树酯基电解质材料在电致变色器件中有较好的应用前景.     

Study on Dyeing Properties of Functional Acrylic Fiber

Anti‐mite acrylic fiber is a new type of functional fiber which incorporates a small amount of anti‐mite agent. Basic dye can be used in the dyeing of the functional acrylic fiber. Compared with the dyeing properties of conventional fibers, the dyeing properties of the functional acrylic fiber have new characteristics such as different dyeing temperature, time, amount of leveling agent and pH level due to the rough surface and larger size of micro‐channels in the functional fiber structure that helps basic dye molecules to diffuse into the fiber.     

Tetralactam-modified gold electrodes for amperometric detection of acrylic acid

The presence of toxic acrylamide in a wide range of food products such as potato crisps, French fries or bread has been confirmed by Swedish scientists from Stockholm University. The neurotoxicity and possible carcinogenicity of this compound and its metabolites compel us to control them by quantitative and qualitative assays. Exposing acrylamide to pH extremes results in its hydrolysis to acrylic acid or its salt. In this work, we present the use of gold electrodes coated with self-assembled monolayers (SAMs) containing tetralactam molecules and its precursor as active elements for voltammetric detection of acrylic acid in water solution. The host molecules have been immobilised on the electrode surface by covalent Au–S bond or by embedment method into the thiol layer via hydrophobic and van der Waals interactions. Interactions with analytes were confirmed by Osteryoung square-wave voltammetry.