偏氯乙烯-丙烯腈悬浮共聚物的组成研究

研究了偏氯乙烯 丙烯腈 (VDC AN)悬浮共聚体系中AN的水溶性对单体相组成和树脂组成的影响 .结果表明 :由于AN部分地溶于水 ,使有机相AN的含量降低 ,导致共聚树脂的组成明显地不同于本体聚合模型的计算预测值 .为了准确地计算预测VDC AN共聚树脂的组成 ,本文假设溶于水的AN向有机相迁移的速度比聚合反应速度快得多 ,AN在两相的溶解分配近似为平衡态 .计算中先用描述AN在VDC/水系统中溶解分配的Marker式校正有机相AN的含量 ,然后根据校正后的AN含量用Mayo Lewis式计算预测VDC AN悬浮共聚物的组成 ,计算中有关的竞聚率值取自于文献中本体聚合的值 .计算结果与实验值一致     

AN/St悬浮共聚体系中AN在水/油两相间分配及其对共聚物组成的影响

研究了丙烯腈/苯乙烯(AN/St)悬浮共聚体系中AN在水/油两相间的分配及其对AN/St共聚物组成的影响.结果表明,AN分配于水/油两相间,使油相AN的含量低于相同单体配料比的本体聚合,导致生成的AN/St共聚物组成偏离本体共聚.为了准确预测进而控制AN/St悬浮共聚物的组成,提出了在考虑AN相分配的基础上计算AN/St悬浮共聚物组成的模型.计算结果与实验值一致,计算中用到的油相实际竞聚率与本体聚合相同,但该悬浮聚合的表观竞聚率随水/油比的变化而发生较大改变.     

氯乙烯/N-苯基马来酰亚胺共聚物组成控制和优化

研究了氯乙烯 /N 苯基马来酰亚胺 (VC/PMI)共聚物组成随转化率的变化 ,体系中共聚物的累积组成偏差小于 0 0 5或 0 1的单体配比范围很小 ,采用加入第三单体丙烯腈 (AN)的方法进行改善 ,并以PMI在共聚物中的累积组成偏差作为控制参数 ,得到了PMI在共聚物中的累积组成偏差小于 0 0 5和 0 1的VC/PMIlAN较优的配比范围 .结合悬浮聚合工艺的特点 ,确定了VC/PMI/AN悬浮共聚的最佳单体配比范围为f1=0 72～ 0 84 ,f2 =0 0 2～ 0 0 4 ,f3 =0 1 2～ 0 2 4 .     

Determination of gelation dose of a vinylidene chloride/acrylonitrile copolymer irradiated with gamma-rays by a spectrophotometric technique

The gelation dose of a vinylidene chloride (VDC)/acrylonitrile (AN) random copolymer irradiated with γ-rays in vacuum is first determined by conventional techniques, such as viscometry and solubility. The onset of gelation was determined to be 5.8 Mrad for this copolymer of composition 20% AN/80% VDC. The same gelation dose is also determined by a spectrophotometric method which is based on the recording of u.v.-vis spectra of solutions of this copolymer in THF. The advantages of this new technique for determination of gelation dose over the conventional methods are discussed.     

甲基丙烯酸甲酯水溶性对其悬浮均聚动力学的影响

通过比较在大水油比下的甲基丙烯酸甲酯 (MMA)悬浮均聚的实验数据以及本体聚合实验结果 ,发现单体的水溶性对其聚合动力学有影响 ,不能用本体聚合动力学代替其悬浮聚合动力学 .为了能更好了解单体的水溶性对其悬浮聚合动力学的影响以及影响动力学的原因 ,在MMA本体聚合动力学模型基础上 ,进一步提出 3个假设 :扣除溶于水相部分的单体量、增长和终止速率参数降低、少部分的油溶性引发剂被带到水相中 ,得到改进的悬浮聚合动力学模型 .运用该模型能很好预测水油比、聚合温度、引发剂浓度等对MMA悬浮聚合动力学的影响 ,且与实验数据能较好吻合     

偏氯乙烯-氯乙烯悬浮共聚物的结晶与熔融性能

研究了聚合温度、共聚物组成、低分子助剂用量等对偏氯乙烯 (VDC) 氯乙烯 (VC)悬浮共聚树脂的结晶度、熔融峰温度的影响 ,并用Florry的聚合物熔点降低理论预测共聚树脂熔点随共聚组成、低分子助剂用量的变化规律 ,为VDC VC悬浮共聚树脂的合成工艺条件和加工性能的改善提供理论基础 .     

丙烯腈与衣康酸在DMSO/H_2O中的聚合及聚合物性能表征

采用丙烯腈 (AN)与衣康酸 (IA)为共聚单体 ,以偶氮二异丁腈为引发剂在混合介质二甲基亚砜 水(DMSO H2 O)中自由基沉淀共聚合 ,合成了高分子量的聚丙烯腈 .通过正交设计方法研究了聚合反应条件 ,如反应温度、单体浓度、混合介质DMSO H2 O配比等对聚合反应的转化率的影响 ,还重点探讨了混合介质DMSO H2 O配比对转化率和粘均分子量的影响 .采用DSC ,TG ,IR等手段研究了PAN均聚物及 (PAN co IA)的结构与性能 .研究结果表明 ,增加反应温度 ,降低单体浓度 ,降低喂料AN IA配比中IA的含量 ,均有利于提高聚合反应的转化率 .AN与IA共聚反应的转化率随着反应介质中DMSO含量的增加而降低 ,同时聚合物的粘均分子量也降低 .对于喂料AN IA配比中IA含量相同的P(AN co IA)共聚物 ,高分子量P(AN co IA)共聚物比常规低分子量的放热峰起始温度低 ,放热峰宽     

Synthesis and heavy-metal-ion sorption of pure sulfophenylenediamine copolymer nanoparticles with intrinsic conductivity and stability

Novel copolymer nanoparticles were easily synthesized with a polymerization yield of 59.3 % by an oxidative precipitation polymerization of aniline (AN) and m-sulfophenylenediamine (SP) in HCl without any external stabilizer. The polymerization yield, size, morphology, electroconductivity, solubility, solvatochromism, lead and mercury ion adsorbability of the HCl-doped copolymer salt particles were studied by changing the AN/SP ratio. The AN/SP (80:20) copolymer particles are found to have the minimal number-average diameter(84.4 nm), minimal size polydispersity index (1.149), high stability, good long-term stability, powerful redispersibility in water, high purity, and clean surface because of a complete elimination of the contamination from external stabilizer. The copolymer salts possess a remarkably enhanced solubility, interesting solvatochromism, and widely adjustable electroconductivity moving across nine orders of magnitudes from 10(-9) to 10(0) S cm(-1). The AN/SP (70:30) copolymer particles have the highest Hg2+ adsorbance and adsorptivity of 497.7 mg g(-1) and 98.8 %, respectively, which are much higher values than those of other materials. The sorption mechanism of lead and mercury ions on the particles is proposed. The copolymer bases with 5-10 mol % SP unit show excellent film formability, flexibility, and smooth appearance. The copolymer should be very useful in the fabrication of cost-effective conductive nanocomposite with low percolation threshold and in removal of toxic metallic ions from waste water.     

THE EFFECT OF MONOMERS FEEDING METHODS ON EMULSION COPOLYMERIZATION OF VINYLIDENE CHLORIDE AND ACRYLATES

The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.     

Facile synthesis and optimization of conductive copolymer nanoparticles and nanocomposite films from aniline with sulfodiphenylamine

A new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine-4-sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV-visible spectroscopy, X-ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above-mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought-after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90x10(-4) to 1.15x10(-2) S cm(-1) with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98% of the transparency, 94% of the strength, and 5x10(7) times the conductivity of a pure cellulose diacetate film.     

Facile synthesis and characterization of the copolymers and their pure nanoparticles from aniline with 4‐sulfonic diphenylamine

Copolymer nanoparticles from aniline (AN) and 4‐sulfonic diphenylamine (SDP) were simply synthesized for the first time by an oxidative precipitation polymerization with inorganic oxidants in an acidic aqueous medium without any external emulsifier or stabilizer. The polymerization yield, intrinsic viscosity, solubility, solvatochromism, electrical conductivity, and thermal stability of the copolymers were systematically studied through changes in the AN/SDP ratio, polymerization temperature, oxidant species, monomer/oxidant ratio, and acidic medium. The molecular structure of the copolymers was characterized with elemental analysis, IR, and ultraviolet–visible spectra. The polymers exhibited very good solubility in polar solvents, water, and NH₄OH, and this was mainly attributable to the presence of sulfonic acid side groups. The electrical conductivity of the copolymers increased greatly, from 6.00 × 10^?4 to 2.55 × 10^?1 S/cm, with increasing AN content. The size of the copolymer particles, determined by laser particle analysis and atomic force microscopy (AFM), strongly depended on the polymer state and oxidant/monomer ratio. Pure dedoped particles of the AN/SDP (50/50) copolymer at an oxidant/monomer ratio of 1/2 exhibited minimum length/diameter ratios of 62/44 and 45/30 nm by AFM and transmission electron microscopy, respectively. The copolymers showed typical four‐step weight‐loss behavior in nitrogen and air and higher thermostability in nitrogen. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3380–3394, 2004     

Aqueous dispersion polymerization: a new paradigm for in situ block copolymer self-assembly in concentrated solution

Reversible addition-fragmentation chain transfer polymerization has been utilized to polymerize 2-hydroxypropyl methacrylate (HPMA) using a water-soluble macromolecular chain transfer agent based on poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC). A detailed phase diagram has been elucidated for this aqueous dispersion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies (i.e., pure phases). Unlike the ad hoc approaches described in the literature, this strategy enables the facile, efficient, and reproducible preparation of diblock copolymer spheres, worms, or vesicles directly in concentrated aqueous solution. Chain extension of the highly hydrated zwitterionic PMPC block with HPMA in water at 70 °C produces a hydrophobic poly(2-hydroxypropyl methacrylate) (PHPMA) block, which drives in situ self-assembly to form well-defined diblock copolymer spheres, worms, or vesicles. The final particle morphology obtained at full monomer conversion is dictated by (i) the target degree of polymerization of the PHPMA block and (ii) the total solids concentration at which the HPMA polymerization is conducted. Moreover, if the targeted diblock copolymer composition corresponds to vesicle phase space at full monomer conversion, the in situ particle morphology evolves from spheres to worms to vesicles during the in situ polymerization of HPMA. In the case of PMPC(25)-PHPMA(400) particles, this systematic approach allows the direct, reproducible, and highly efficient preparation of either block copolymer vesicles at up to 25% solids or well-defined worms at 16-25% solids in aqueous solution.     

Aqueous block copolymer-surfactant mixtures and their ability in solubilizing chlorinated organic compounds. A thermodynamic and SANS study

Within the topic of surfactant enhanced solubilization of additives sparingly soluble in water, volumetric, solubility, conductivity, and small-angle neutron scattering (SANS) experiments on mixtures composed of alpha,omega-dichloroalkane, surfactant, copolymer, and water were carried out at 298 K. The triblock copolymers (ethylene oxide)132(propylene oxide)50(ethylene oxide)132 (F108) and (ethylene oxide)76(propylene oxide)29(ethylene oxide)76 (F68) were chosen to investigate the role of the molecular weight keeping constant the hydrophilic/hydrophobic ratio. The selected surfactants are sodium decanoate (NaDec) and decyltrimethylammonium bromide (DeTAB) with comparable hydrophobicity and different charged heads. The alpha,omega-dichloroalkanes were chosen as contaminant prototypes. For the water + surfactant + copolymer mixtures, both the volume and the SANS results straightforwardly evidenced that (1) monomers of NaDec and copolymer unimers generate small mixed aggregates, (2) monomers of DeTAB combined with copolymer unimers do not form aggregates, and (3) unimeric copolymer is solubilized into NaDec and DeTAB micelles. The alpha,omeaga-dichloroalkanes presence induces the F108 aggregation even at very low copolymer composition. The addition of surfactant disintegrates the F108 aggregates and, consequently, the additive is expelled into the aqueous phase. Once F108 is in the unimeric state, it forms copolymer-micelle aggregates which incorporate the oil. In the case of F68 both the volumetric and the SANS data reveal that the additive does not alter the copolymer unimeric state. Moreover, they show that for the aqueous DeTAB-F68 system the additive trapping in both the copolymer-micelle aggregate and the pure micelles takes place being enhanced in the former aggregate in agreement with solubility experiments. For the NaDec-F68 mixtures, an additional solubilization process in the premicellar copolymer-surfactant microstructures occurs. SANS and conductivity data show that the additive incorporation into the mixed and the pure micelles does not essentially influence the structural properties of the aggregates.     

An experimental study on the kinetics and mechanisms of styrene polymerization in oil‐in‐water microemulsion initiated by oil‐soluble initiators

In order to clarify the kinetic role of oil‐soluble initiators in microemulsion polymerization, the oil‐in‐water (O/W) microemulsion polymerizations of styrene are carried out using four kinds of azo‐type oil‐soluble initiators with widely different water‐solubility. The results are compared with those observed when a water‐soluble initiator, potassium persulfate (KPS) is used. For all the oil‐soluble initiators used, the molecular weight of polymers and the average size of polymer particles do not change with the monomer conversion and the initial initiator concentration. The monomer conversion is expressed as a function of r_i^0.5t, where r_i is the rate of radical generation in the whole reaction system and t is the reaction time. These characteristics are quite the same as those observed when KPS is used as an initiator. When the polymerizations are carried out with the rate of radical generation in the whole reaction system fixed at the same value, the rates of polymerization are almost the same for all the oil‐soluble initiators employed, irrespective of their water‐solubility, but are significantly lower (ca. 1/3) than that with KPS. Then, the following conclusions are given: (1) The radicals generated not only in the aqueous phase, but also in the micelle and polymer particle phase are almost equally effective for the polymerization. However, (2) only a small portion (ca. 1/9) of the radicals generated in both phases participate in the polymerization. (3) Bimolecular termination of a growing radical in the polymer particle with an entering radical and with a pair of radicals generated in the polymer particles is negligible, and hence, the molecular weight of polymers is determined only by chain transfer to monomer.     

Synthesis and properties of processable conducting copolymers from N‐ethylaniline with aniline

Copolymers were synthesized through the chemically oxidative polymerization of N‐ethylaniline (EA) and aniline (AN) in five acid aqueous media. The polymerization yield, intrinsic viscosity, molecular weight, solubility, solvatochromism, electrical conductivity, and mechanical properties of the copolymer films were systematically studied through changes in the comonomer ratio, polymerization temperature, oxidant, oxidant/monomer ratio, and acid medium. Open‐circuit‐potential and temperature measurements of the polymerization solutions showed that the polymerization rate depended on the EA content, and the polymerization was an exothermic reaction. The resultant copolymers were characterized in detail with IR, ultraviolet–visible, and ¹H NMR spectroscopy, gel permeation chromatography, wide‐angle X‐ray diffractometry, and scanning electron microscopy. The reactivity ratios of the monomer pair were calculated from the ¹H NMR spectra of the copolymers formed at a low conversion. The polymers exhibited good solubility and interesting solvatochromism in most of the solvents and variable conductivity with the EA/AN ratio and doping state. The conductivity of the HCl‐doped copolymers increased monotonically from 5.61 × 10^?7 to 2.55 × 10^?1 S/cm with decreasing EA content from 100 to 0 mol % and showed a percolation transition between EA concentrations of 20 and 30 mol %. The EA/AN copolymers also had excellent film formability and flexibility together with high mechanical and oxygen‐enriching properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6109–6124, 2004     

偏氯乙烯-丙烯腈-苯乙烯共聚物颗粒发泡行为研究

用显微镜实时监测实验方法研究了偏氯乙烯 (VDC) 丙烯腈 (AN) 苯乙烯 (St)共聚物颗粒的发泡行为 ,考察的影响因素包括共聚物组成、发泡剂浓度、颗粒粒径、发泡温度等 .实验发现 ,共聚物中AN或St单元含量提高 ,发泡速率降低 .提高发泡温度或增加发泡剂浓度 ,均加快发泡速率 .由于在聚合物颗粒发泡时存在发泡剂损失 ,小粒径的VDC AN St共聚物颗粒发泡速率快 .当颗粒发泡生长较快时 ,发现有生长过头现象 ,这可能是由惯性生长造成的     

粒径可控的聚乙烯醇交联微球VA/DVB的制备

以醋酸乙烯酯(VAc)为主单体,二乙烯基苯(DVB)为交联剂,聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了交联微球VAe/DVB.重点考察了分散剂用量、搅拌速率、油水两相比例、NaCl用量等因素对交联微球的形成及其粒度的影响.使用甲醇对微球VAc/DVB进行醇解反应,制得了聚乙烯醇交联微球VA/DVB.结果表明:交联微球VA/DVB的物理形态决定于前驱体微球VAc/DVB的形貌与粒径.在悬浮聚合体系中,分散剂用量、搅拌速率与油水两相比是影响交联微球制备的主要因素,当分散剂用量太少(<0.3%)、搅拌速率太慢(<200 r/min)与油水两相体积比太大(>l:4)时,共聚合体系中均不能发生成球过程.控制悬浮聚合的反应条件,可以制备出球形度好、粒径可调控的交联微球VA/DVB.影响醇解反应的主要因素是反应温度,适宜的温度是40℃,反应15 h醇解度可达92%.     

Core-shell emulsion copolymerization of styrene and acrylonitrile on polystyrene seed particles

Seeded emulsion copolymerization of an azeotropic composition of styrene (St) and an acrylinitrile (AN) comonomer mixture in polystyrene (PS) seed at different polymerization temperature of 55–75°C were investigated. The kinetic data showed a transition temperature at 65°C, above which the activation energy of polymerization is low, 6.1 Kcal/mol, compared with 9.8 Kcal/mol below it. The particle-size results and thin layer chromatographic (TLC) data showed two types of particle of different composition and morphology in the final latex system: a smaller size of (St–AN) copolymer and a larger size of core-PS and (St–AN) copolymer shell, with a zone of PS grafted (St–AN) copolymer in between. Various polymerization parameters, that is emulsifier concentration, type of seed particle and its size, and monomer/polymer ratio, were studied and their effects on particle size and particle morphology were examined. The percent of grafted core-PS was 10% below a polymerization temperature of 65°C and 40% above that temperature. By adjusting the size and number of the seed particles, monomer-polymer ratio, and emulsifier concentration conditions were established in which a final copolymer latex with “perfect” core-shell morphology was achieved.     

Effect of reaction medium on copolymerization of acrylonitrile and methyl acrylate

The copolymerization of acrylonitrile (AN) with methyl acrylate (MEA) has been investigated in three types of polymerization, i.e., emulsion polymerization in water with a water-soluble initiator, suspension polymerization in water with an oil-soluble and water-insoluble initiator, and solution polymerization in dimethyl sulfoxide (DMSO). Monomer reactivity ratios at 50°C. for AN and MEA are found to be r₁ = 0.78 ± 0.02, r₂ = 1.04 ± 0.02 in emulsion polymerization; r₁ = 1.02 ± 0.02, r₂ = 0.70 ± 0.02 in DMSO solution polymerization; r₁ = 0.75 ± 0.05, r₂ = 1.54 ± 0.05 in suspension polymerization. The large differences found in the reactivity ratios may be attributed to the different ratio of concentration of two monomers in the loci of polymerization. Chemically, AN is somewhat more reactive than MEA as shown by the reactivity ratios in DMSO. In the case of the suspension polymerization, the MEA/AN ratio in the polymer particles in which polymerization occurs may be higher than that in the total phase. Experimental results of the emulsion polymerization show that the emulsion polymerization of AN occurs both in the particles and in water. In addition, rates of the copolymerization of AN with MEA have also been investigated.     

Polymerization and characterization of novel poly(acrylonitrile‐co‐styrene/pyrrole) nanoparticles: A comparison between microwave and conventional method

In this study, poly(acrylonitrile‐co‐styrene/pyrrole) or poly(AN‐co‐ST/Py) copolymer was successfully synthesized using microwave preparation technique, and its comparison with the conventional heating method is investigated. Different polymerization factors affecting on the preparation conditions and conversion yield such as monomer concentration, comonomers ratio, initiator concentration, cosolvent ratio, cosolvent type, polymerization temperature, and polymerization time have a considerable effect on the conversion yield %, functional groups, and molecular weight. The copolymerization process was approved by Fourier transform infrared, thermogravimetric analysis, ¹H NMR spectroscopy, and gel permeation chromatography. The formation of poly(AN‐co‐ST/Py) nanoparticles was confirmed by SEM, and their possible formation mechanisms were also proposed. The SEM images of poly(AN‐co‐ST/Py) prepared by the microwave method showed that the synthesized copolymer had spikes or rods with spherical structure of the produced copolymers than the poly(AN‐co‐ST/Py) nanoparticles prepared by the conventional heating method. Microwave method showed advantages for the produced copolymers compared to that prepared by conventional method, where it can offer a copolymer in short time, high yield, and more thermally stable copolymers, rather than conventional method.