单体对分子印迹聚合物分子识别能力的影响：量子化学计算与实验研究

采用密度泛函方法计算功能单体与印迹分子的结合能,以与目标分子结合能最大的单体分子来合成分子印迹聚合物.为此,以茶碱为印迹分子,氯仿为溶剂,首先计算了茶碱与甲基丙烯酸、丙烯酰胺和三氟甲基丙烯酸的结合能,其强度顺序为：三氟甲基丙烯酸 > 甲基丙烯酸 > 丙烯酰胺.然后以茶碱为印迹分子、氯仿为溶剂、二甲基丙烯酸乙二醇酯为交联剂,分别采用上述3种单体合成分子印迹聚合物并测定了其分子识别能力,实验结果和量子化学计算结果具有一致性.最后,采用1H NMR考察了茶碱和上述3种单体之间的氢键作用,揭示出二者相互作用的内在机制.研究结果表明量子计算方法可以应用于合成分子印迹聚合物时单体的选择.     

Effects of monomer structure on the morphology of polymer network and the electro‐optical property of reverse‐mode polymer‐stabilized cholesteric texture

The morphologies of the polymer networks in the polymer network/LC composite of reverse‐mode polymer‐stabilized cholesteric texture (PSCT) films was observed. The polymer network/LC composite was prepared from photopolymerization of the acrylate monomers, which had rod‐like rigid cores in monomer/LC mixture. The effects of the structure of the acrylate monomers on the morphology of polymer network were studied. The acrylate monomer without flexible pacers between the acrylate functional groups and the rigid core formed rice‐grain‐like polymer network with poor orientation. The acrylate monomer with flexible pacers formed fiber‐like polymer network with better orientation. Meanwhile, the effects of morphology of polymer network on the electro‐optical property of reverse‐mode PSCT films were also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

离子印迹聚合物功能单体的研究进展

阐述了不饱和羧酸类（甲基丙烯酸、丙烯酸和乙烯基苯甲酸）、芳香杂环类（吡啶类、咪唑类和喹啉类）、水杨醛类希夫碱以及Salen配体等功能单体的性能、优点、用途等方面的研究进展,以及基于上述单体制备的离子印迹聚合物吸附特性和应用性能等,展望了离子印迹聚合物功能单体未来的发展方向：一是功能单体种类需要进一步丰富;二是其所具有的性能和功能等还有待于完善。其中,季铵盐化5-氯甲基水杨醛类希夫碱功能单体具有强亲水性能和多官能团特性,对其进行性能研究将会是探索此类功能单体在应用方面的热点内容之一。     

Spontaneous Crystallization in Athermal Polymer Packings

We review recent results from extensive simulations of the crystallization of athermal polymer packings. It is shown that above a certain packing density, and for sufficiently long simulations, all random assemblies of freely-jointed chains of tangent hard spheres of uniform size show a spontaneous transition into a crystalline phase. These polymer crystals adopt predominantly random hexagonal close packed morphologies. An analysis of the local environment around monomers based on the shape and size of the Voronoi polyhedra clearly shows that Voronoi cells become more spherical and more symmetric as the system transits to the ordered state. The change in the local environment leads to an increase in the monomer translational contribution to the entropy of the system, which acts as the driving force for the phase transition. A comparison of the crystallization of hard-sphere polymers and monomers highlights similarities and differences resulting from the constraints imposed by chain connectivity.     

直纺型改性聚对苯二甲酰对苯二胺的研制

研究了加入一系列第３单体改性聚对苯二甲酰对苯二胺后，在不同的缩聚工艺下助剂加入量、单体配比、聚合溶液浓度以及反应时间进行了考察，确定了制备高分子量改性聚对苯二甲酰对苯二受胺树脂的最佳工艺条件。聚合物溶液经直接纺丝得到初步拉伸丝。     

Molecular design and application of divinyl monomers to synthesis of UV-curable latex

A new method for simplifying the preparation of unsaturated latex was investigated. Four divinyl monomers were designed, and based on quantum chemical calculations, (z)-4-(2-(acryloyloxy)ethoxy)-4-oxobut-2-enoic acid (cis-AEOEA) was selected as the only nonelectron-donating divinyl monomer whose active double bond is prone to polymerize, while the inactive one is left in polymer form. The inactive double bond can also be activated by the formation of charge transfer complex polymerization systems with electron-donating comonomers and activity that is in direct proportion to the electron-donating ability of comonomers. This result was proved using an orthogonal experimental design L9₃⁴, and the UV-curing performance of unsaturated latex membranes was studied.     

功能性单体在偏光片压敏胶粘剂合成中的应用研究

采用高、低分子量丙烯酸酯共聚物共混改性的方法来制备偏光片用压敏胶粘剂,通过调节功能性单体丙烯酸AA、丙烯酸羟乙酯HEA等的用量来探讨其对偏光片用压敏胶粘剂性能的影响。     

改性水性硝化纤维素乳液研究

采用醇酸树脂转相乳化法和丙烯酸酯类单体互穿聚合物网络聚合法制备改性硝化纤维素乳液。研究了醇酸树脂、丙烯酸酯类单体乳化剂用量等因素对乳液性能的影响。结果表明，丙烯酸酯类单体改性互穿聚合物网络聚合法制得的乳液效果好.     

乳液型无纺布用粘合剂的研究

研究了聚合单体、乳化剂、交联剂、引发剂、聚合工艺对产品性能及生产稳定性的影响。实验表明:以醋酸乙烯酯(VAC)和丙烯酸丁酯(BA)为单体,N-羟甲基丙烯酰胺(HAM)和衣康酸(ITA)为交联剂,以壬基酚聚氧乙烯醚磺基琥珀酸盐(OS)和壬基酚聚氧乙烯醚(OP)为乳化剂,以过硫酸铵(APS)为引发剂,投料质量比为VAC∶BA∶HAM∶ITA∶OS∶OP∶APS=85∶15∶3∶2∶2.5∶1.5∶0.8,采用预乳化滴加工艺,反应温度为75℃时制得的乳液,用泡沫涂布法生产无纺布,效果良好且成本低廉。     

Facile synthesis and characterization of hyperbranched poly(aryl ether ketone)s obtained via an A2 + BB′2 approach

A fast and highly efficient approach for the synthesis of hyperbranched poly(aryl ether ketone)s (HPAEKs) via the polycondensation of A₂ and BB′₂ monomers is described. Commercially available hydroquinone (HQ, A₂ monomer) and easily synthesized 2,4′,6‐trifluorobenzophenone (TF, BB′₂ monomer) were thermally polycondensed to prepared fluoro‐ or phenolic‐terminated HPAEKs with K₂CO₃ and Na₂CO₃ as catalysts. During the reaction, the fluorine at the 4′‐position of TF reacts rapidly with the phenolic group of HQ, forming predominantly dimers and some other species. The dimer can be considered as a new AB′₂ monomer. Further reactions among molecules AB′₂ and AB′₂ with some other species result in the formation of HPAEKs. Fourier transform infrared and ¹H NMR spectra revealed the structures of the resultant polymers. The degree of branching (DB) of the fluoro‐terminated hyperbranched polymers was determined to be in the range 50–57% from ¹H NMR spectra, whereas the DB of the phenolic‐terminated hyperbranched polymers was determined to be 100%. These hyperbranched polymers exhibit excellent solubility in general organic solvents and possess moderate molecular weights with broad distributions determined using gel permeation chromatography. Moreover, the structure and performance of the HPAEKs can be conveniently regulated by adjusting the type and feed ratio of the two monomers. Copyright © 2010 Society of Chemical Industry     

含氟高分子表面活性剂的合成及其乳化性能的研究

以甲基丙烯酸十二氟庚酯(RfAA)、甲基丙烯酸(MAA)或2-丙烯酰胺-2-甲基丙磺酸(AMPS)、甲基丙烯酸聚乙二醇酯(PEGMA)为共聚单体,以亲氟-亲水-空间位阻的方式,合成了两种含氟高分子表面活性剂P(RfAA-PEGMA-MAA)和P(RfAA-PEGMA-AMPS)。考察了它们对RfAA的乳化性能,探讨了单体种类、单体含量、引发剂用量以及链转移剂用量对单体转化率和聚合物乳化性能的影响。结果表明,n(RfAA)∶n(MAA或AMPS)∶n(PEGMA)=5∶3∶2,引发剂用量为单体总质量的4%,链转移剂用量分别为单体总质量的3%、2%时,所合成的两种含氟高分子表面活性剂对RfAA均表现出了良好的乳化性能,它们的最低表面张力分别为56.3、49.1 mN/m,CMC均约为0.002 g/mL。     

Process design for the removal of residual monomer from latex products using supercritical carbon dioxide

One of the most important environmental incentives for the polymer industry is to reduce the residual monomer in polymer products. Although several techniques are available for the removal of residual monomer, most methods are rather energy intensive and time consuming. Since supercritical carbon dioxide (scCO₂) is known to have a plasticizing effect on many polymers and is a good solvent for most commonly used monomers, a scCO₂-based process forms an interesting alternative. This paper focuses on the development of a post-emulsion polymerization process, which decreases the amount of methylmethacrylate (MMA) in polyMMA lattices using scCO₂. Typically, the method comprises a counterflow process, in which part of the residual monomer is converted by the increased diffusion inside the polymer particles due to the swelling by scCO₂. In addition, the amount of residual monomer is further reduced by the extraction capacity of scCO₂. Experimental studies have shown that the scCO₂ extraction of MMA is the predominant effect as compared to the enhanced polymerization due to plasticization. From a mass transfer model, the largest resistance in the extraction process appears to be situated in the water phase near the scCO₂ interface due to a relatively small surface area as compared to the overall polymer-water interfacial area. A viability study, including equipment sizing and economic evaluation, has shown that the removal of residual monomer from latex products using scCO₂ in principle yields a process which is both technically and economically feasible, capable to meet the future requirements.     

Enhancing oil repellency of electron beam-grafted polyethylene terephthalate fabric with 2-(perfluorohexyl) ethyl acrylate monomer via pre-irradiation

Electron beam (EB)-induced graft polymerization is advantageous for the surface modification of fabrics. We investigated the effect of monomer concentration and the addition of alkyl groups on the oil repellency of polyethylene terephthalate (PET) fabrics treated with monomers containing fluoroalkyl groups through EB-induced graft polymerization via pre-irradiation. We use 2-(perfluorohexyl) ethyl acrylate (FEA) and stearyl acrylate (SA(C18)) with long alkyl chains as vinyl monomers to induce reaction with radicals generated from EB irradiation. The weight gain and surface morphology of the PET fabrics change with the FEA monomer concentration. The uniformity of the EB-grafted PET fabric surface is determined at low monomer solution concentrations. Results of X-ray photoelectron spectroscopy analysis show that adding 0.1 mol/L of FEA monomer to the EB-grafted PET fabric yields the highest dodecane contact angle of 93.4° and a surface fluorine concentration of 39.8%. The addition of SA(C18) monomer to the FEA monomer decreases the dodecane contact angle by 77.5° and yields a surface fluorine concentration of 19.1%. EB graft polymerization via pre-irradiation results in a uniformly treated surface, and stable oil repellency is achieved when using solely the FEA monomer at a lower monomer concentration than that used in a similar irradiation method reportedly previously.     

塑/塑复合用水性复膜胶的研制

在丙烯酸酯单体中加入一种特殊功能单体(HT),通过种子乳液聚合法制备了一种塑/塑复合用水性丙烯酸酯复膜胶(FM-45)。研究了丙烯酸酯复合功能单体配比对FM-45的剥离强度、乳化体系以及应用性能等影响。结果表明:当复合功能单体中m(丙烯酸)∶m(丙烯酸羟丙酯)∶m(HT)=2∶3∶1、w(复合乳化剂)=0.6%(相对于单体总量而言)时,FM-45的综合性能最佳。     

A new method to determine monomer concentration in the polymer particles of emulsion polymerization systems by dynamic light scattering

Emulsifier‐free emulsion polymerization of styrene was performed in the presence of small amount of methacrylic and itaconic acids as carboxylic acid monomers and potassium persulfate as an initiator at 70°C to prepare monodisperse polymer particles. Diameter of monomer swollen polymer particles (d_pswol) was measured by dynamic light scattering for samples taken from the reaction mixture during the Intervals II and III of the emulsion polymerization. Graphically treatment of d_pswol versus conversion data allowed us for the first time to directly determine the critical monomer conversion (x_c), from which constant monomer concentration in the polymer particles (C_MP) during the Interval II was then calculated. x_c and C_MP were obtained to be 0.379 and 5.68, respectively. C_MP value is in good agreement with that obtained by centrifugation method and those reported in the literature for the similar system. Attempts were also made to evaluate the average number of growing chain per particle ( ) during the Interval II of emulsion polymerization of styrene. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Emulsion Semi-Batch Terpolymerization Process Using Hybrid Emulsifiers for Synthesizing New Emulsion Pressure Sensitive Adhesives (EPSAs)

In order to obtain a suitable formulation of designing direct synthesis of acrylic latexes to be used as emulsion pressure sensitive adhesives (EPSA), having high shear resistance together with high peel strength and tack, free radical emulsion polymerization of hard monomers, such as styrene (St), vinyl acetate monomer (VAM), methyl methacrylate (MMA) and butyl methacrylate (BMA), and soft monomers, butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA) along with multifunctional monomers, namely acrylic acid (AA), were carried out. The effect of the type of hard and soft acrylic monomers, the type and level of emulsifiers, and the initiator concentration on the emulsion polymer stability and final properties of the EPSA were investigated. The results obtained showed an optimized composition. This composition led to a significant increase in shear strength and peel strength to 909 kPa and 0.45 N/mm, respectively, while the synthesized PSA was still too tacky, 5.5 cm, according to adhesion performance testing. For making this successful balance of the conflicting adhesion properties of PSA, a series of anionic and nonionic emulsifiers were investigated. It was interestingly found out that the hybrid emulsifiers (anionic coupling with nonionic) with the optimized compositions could enhance the stability of the emulsion system and improve the properties of PSA compared with the mono-emulsifier. We also tried to adjust the initiator concentration with the level of the optimized hybrid emulsifier, polyoxyethylene alkyl phenyl ether (K30), dioctyl sulfosuccinate (DOSS), and sodium vinyl sulfonate (SVS) with the ratio 2:1:1, resulting in a highly preferred proportion of the 0.5 part of the initiator versus 1.25 parts of the hybrid emulsifier in terms of the total weight of the monomers.     

Graft polymerization of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto starch

Mixtures of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid (AASO₃H) were graft polymerized onto starch by cobalt-60 irradiation, and the water absorbency and water solubility of the resulting products were determined. The conversion of monomers to polymer was nearly quantitative when pregelatinized wheat starch and a water solution of the two monomers were simultaneously irradiated (simultaneous irradiation conditions). Products with high water absorbency were obtained with equal weights of starch and total monomers when acrylamide:AASO₃H ratios ranged from 9:1 to 1:3. Water solubility of these polymers was over 50%. Neither of the two monomers gave absorbent polymers when graft polymerized individually onto starch. Although highly absorbent products were also obtained at a total monomer:starch ratio of 2:5, ratios of 1:5 and lower gave products with poor absorbency. Neutralization of AASO₃H with sodium hydroxide before graft polymerization drastically reduced both the water solubility and absorbency of the final products. A reaction with granular starch was also carried out under simultaneous irradiation with a total monomer:starch ratio of 2:5 and with equal weights of the two monomers. Conversion of monomers to polymer was once again nearly quantitative. To obtain good water absorbency from this granular product, it was necessary to first neutralize the AASO₃H portion with alkali, then disperse the polymer in hot water, and finally dry the resulting water dispersion. Graft copolymers with good water absorbency were also obtained by adding preirradiated starch to a water solution of acrylamide and AASO₃H, although only partial conversions of monomers to polymer were realized. Selected products from the various graft polymerizations were fractionated by extraction with either water or a 1% solution of sodium chloride. The synthetic polymer content of the resulting fractions and the percentage of AASO₃H in the synthetic portion of each polymer were determined. The M _n of some of the synthetic polymers was also determined after removal of carbohydrate by enzymatic hydrolysis.     

丙烯酸酯PSA环形初粘力影响因素研究

以反应型乳化剂(DNS-86)/阴离子型乳化剂(2A1)为复合乳化剂、甲基丙烯酸(MAA)与甲基丙烯酸羟乙酯(HEMA)为极性单体和正十二硫醇为链转移剂时,采用单体预乳化法和半连续乳液聚合法制备丙烯酸酯PSA(压敏胶)乳液。考察了PSA胶带的基材、干胶厚度、烘干条件、复合乳化剂、极性单体和链转移剂等对环形初粘力的影响。结果表明:当基材为白色BOPP(双向拉伸聚丙烯)薄膜、干胶厚度为50μm、烘干时间为3 min、烘干温度为110~115℃、w(正十二硫醇)=0.09%、同时引入MAA和HEMA极性单体、w(复合乳化剂)=1.5%和m(2A1)∶m(DNS-86)=2∶1时,相应丙烯酸酯PSA乳液的环形初粘力相对最大(14.73 N/25 mm)。     

Ionic autocrosslinking of water-based polymer latices: A new concept of acid–base interaction occurring upon film formation

Latices of the terpolymer styrene/butyl acrylate/acido-basic monomer, the monomer having either a basic chemical group or an acidic chemical group, were separately prepared by free-radical emulsion polymerization using the nonionic surfactant poly(oxy-1,2-ethanediyl) as steric stabilizer. The basic polymer latices were prepared using 1, 3 or 5% of 2-(dimethylamino)ethyl methacrylate, whereas the acidic polymer latices were prepared using 1, 3 or 5% of acrylic acid (mol% relative to conventional monomers, styrene and butyl acrylate). Blends of the basic and the acidic polymer latices were prepared by simply mixing equal molar quantities of basic and acidic latices. The resulting blends were stable as the steric stabilization prevented unlike particles from colliding. Upon film formation, coalescence of the particles took place, with formation of ionic clusters due to proton exchange from the acidic monomer units to the basic monomer units of neighbouring unlike particles. This constitutes a reversible ionic crosslinking at the periphery of neighbouring particles, which affects the various film properties to different extents.     

Particle nucleation in emulsion copolymerization containing multifunctional monomers

Characteristic features of particle nucleation and growth in the emulsion copolymerization of styrene and multifunctional monomers such as ethylene glycol dimethacrylate and divinylbenzene were investigated. It was found that in these emulsion copolymerization systems the rate of polymerization per particle decreased drastically with an increase in the content of the multifunctional monomer in the initial monomer feed, and the number of polymer particles produced, on the other hand, increased corresponding to the decrease in the rate of polymerization per particle. The increase in the number of polymer particles produced was explained on the basis of Smith-Ewart theory, which predicts that the number of polymer particles produced would increase inversely proportional to the 0.4 power of the volumetric growth rate per particle, that is the rate of polymerization per particle during the interval of particle formation (Interval I). It was pointed out that the decrease in the rate of polymerization per particle in Interval I would be due mainly to a decrease in the monomer concentration in the polymer particles which was caused by crosslinking networks of the resultant polymer.