New polyisobutylene starsXI. Synthesis and characterization of allyl-telechelic octa-arm polyisobutylene stars

The synthesis and characterization of a novel star comprising eight allyl-terminated polyisobutylene (PIB) arms radiating from a calix[8]arene core is described. The synthesis was accomplished by a core-first method, by inducing the living polymerization of isobutylene (IB) by a suitably functionalized calix[8]arene initiator (1) in conjunction with BCl₃-TiCl₄ coinitiators, and terminating the growth of the living PIB^⊕ arms by allyltrimethylsilane. The relative concentrations of BCl₃ and TiCl₄ are critical for the synthesis of well-defined 8-arm stars. Characterization of the products (which included triple detector GPC studies and ¹H NMR spectroscopy) indicated quantitative allylation. A mechanism which summarizes the experimental observations is proposed. Received: 17 July 1997/Revised version: 11 September 1997/Accepted: 19 September 1997     

Synthesis and characterization of a novel octa-arm polyisobutylene star

Summary The synthesis and characterization of a novel telechelic star consisting of a well defined C-pentyl-calix[4]1,3-dicumyl alcoholarene (3) core out of which radiate eight well-defined polyisobutylene arms, each fitted with an allyl terminus is described. The synthesis was accomplished by a core-first method, by inducing the living polymerization of isobutylene by 3 in conjunction with BCl₃-TiCl₄ coinitiators. The product was characterized by GPC coupled with laser light scattering (LLS) and referactive index (RI) detectors, and by ¹H NMR spectroscopy. Quantitative functionality analysis indicated the presence of exactly eight PIB arms per molecule. Received: 3 April 2001 / Revised version: 22 June 2001 / Accepted: 22 June 2001     

The synthesis of chlorine-terminated telechelic polyisobutylene

In synthesizing chlorine-terminated telechelic polyisobutylene (PIB) with a p-DCCCp-dichlorocumene/BCl₃/CH₂Cl₂ system, it is found that cycloalkylation occurs parallel with propagation. The factors leading to cycloalkylation were investigated in detail, to clarify its origin, to define its effects upon the molecular parameters of the polymer produced and to find ways to suppress it. It is found that cycloalkylation drastically influences MW, MWD and functionality of the polymer produced. High temperature, high medium polarity, low monomer concentration and the order of addition of BCl₃ and p-DCC are the main factors favoring cycloalkylation.     

Scale-up of nanoparticle synthesis in diffusion flame reactors

The scaling-up of diffusion flame aerosol reactors is investigated for synthesis of nanoparticles. Three co-flow burners of different dimensions are studied at various precursor, oxidant and fuel flow rates. An operation line relating product particle size with reactant outlet conditions, flow rate and burner size is developed showing how the three reactors can produce silica and titania nanoparticles of the same size and morphology. This operation line shows the limit of fast reactant mixing where the diffusion flame aerosol reactors perform as premixed ones. An operation diagram is obtained for different silica production rates and a scale-up procedure is developed.     

Novel amphiphilic membranes of poly(N,N-dimethyl acrylamide) crosslinked with octa-methacrylate-telechelic polyisobutylene stars

Summary A series of novel amphiphilic networks were synthesized by free-radical mediated copolymerization/crosslinking of N,N-dimethyl acrylamide (DMAAm) with various molecular weight octa-methacrylate telechelic polyisobutylene stars (PIB(MA)₈) as crosslinking agents. The overall composition of the PDMAAm-l-PIB(MA)₈ networks were controlled by controlling the concentration of the starting materials. Crosslinking was essentially complete as indicated by negligible sol fractions in both methanol and n-hexane. Swelling ratios and swelling rates of various PDMAAm-l-PIB(MA)₈ in water and n-heptane were determined and contrasted with those of networks prepared with di- and tri-methacrylate-telechelic PIB croslinkers (PIB(MA)₂ and PIB(MA)₃). The mechanical properties of water-swollen tubules made of PDMAAm-l-PIB(MA)₈ were studied and compared with tubules made with PIB(MA)₂ and PIB(MA)₃. Received: 30 January 2002 / Revised version: 6 May 2002 / Accepted: 7 May 2002     

聚异丁烯丁二酸酐中聚异丁烯的液相色谱分析

利用高效液相色谱,采用外标法测定聚异丁烯丁二酸酐中间产品中聚异丁烯的含量,采用示差检测器进行检测。色谱柱为自制改性氧化铝柱（4.6mm×250mm,15.0μm）,正己烷为流动相,流速为1mL/min。标准曲线相关性良好,聚异丁烯平均线性范围为3.8-111g/L,其线性相关系数为0.9998,相对标准偏差为2.08%,回收率为98.5%-101.5%。该方法简便、经济、结果准确。     

乳化炸药用聚异丁烯丁二酰亚胺热合法探究

介绍了乳化炸药用聚异丁烯丁二酰亚胺热合原理及工艺流程。对氯化法和热合法生产的聚异丁烯丁二酰亚胺在粉状乳化炸药中的使用效果作了比较。     

Scale-up of the synthesis of ureidopyrimidinone functionalized telechelic poly(ethylenebutylene)

The scale-up of the synthesis of high purity hydrogen-bonded supramolecular polymers is described. The synthesis involves functionalization of telechelic hydroxy-terminated poly(ethylenebutylene) with 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonding groups via dibutyltindilaurate catalyzed urethane formation. A procedure with optimized reaction conditions was developed and applied on a 10 dm³ mini plant scale. The hydrogen-bonded supramolecular polymer was isolated in a yield of 86% (803 g) and the 2-ureido-4[1H]-pyrimidinone functionalization of the end product was accurately determined with ¹⁹F NMR to be 99.8% of the available hydroxy end groups in the telechelic hydroxy terminated poly(ethylenebutylene). Tensile tests showed that the product of the optimized large scale synthesis has better mechanical properties than the product of the unoptimized synthesis reported earlier.     

Halogen-free polyisobutylene by in situ methylation of living polyisobutylene using dimethylzinc

Summary Halogen-free polyisobutylene (PIB) was synthesized by in situ methylation of living PIB using dimethylzinc. Quantitative methylation of living PIB was achieved within 60 min using a ratio of [(CH₃)₂Zn]/[TiCl₄]₀= 1 without any side reactions. Under similar conditions, living PIB capped with 1,1-diphenylethylene (PIB-DPE⁺) yielded close to 1:1 mixture of methoxy- and methyl-functionality. By using the ratio of [(CH₃)₂Zn]/[TiCl₄]₀≥ 3, however, quantitative methylation of PIB-DPE⁺ could be achieved in 120 min without any side reactions as confirmed by spectroscopic and chromatographic analyses. Received: 1 February 2000/Revised version: 23 April 2000/Accepted: 23 April 2000     

功能性聚异丁烯

在异丁烯正离子聚合中加入乙烯基于基三甲基氯化胺，该化合物不仅没有破坏聚合体系，而且1H—NMR谱图证实还有部分共聚合进入聚异丁烯，使传统的聚异丁烯带上了亲水性基团，赋予聚异丁烯一定的亲水性。     

Multi-arm star-branched polyisobutylene ionomers

A series of multi-arm star-branched polyisobutylenes was synthesized via living carbocationic polymerization. Arms with molecular weights ranging from 10,000 to 30,000 g/mol were prepared using the cumyl chloride/TiCl₄/pyridine initiation system in 60/40 (v/v) hexane/methyl chloride at − 80 °C and linked by sequential addition of divinylbenzene. The weight average number of arms per star polymer, N _w, scaled inversely with arm molecular weight and ranged from 32 to 5. Star-telechelic ionomers were produced by sulfonation of the aromatic initiator residue at the end of each arm, followed by neutralization. Sulfonation was quantitative as indicated by acid-base titration. Potassium ionomers were elastic solids which were marginally soluble in THF; the precursors were tacky and freely soluble in THF. Ionic modification did not alter the glass transition temperature (− 66 °C), but the thermal decomposition temperature in N₂ was increased from 375 to 400 °C. Received: 25 July 1997/Accepted: 27 August 1997     

Synthesis and characterization of novel well-defined stars consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane core

The synthesis and characterization of novel stars, octa(polyisobutylenedimethylsiloxy)octasilesquioxane (T₈ ^DPIB), consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane (T₈ ^D) core are described. The synthesis involves: 1) The synthesis of allyl-terminated polyisobutylene (PIB^█01█) prearms, 2) The synthesis of octa(hydrodimethylsiloxy)octasilsesquioxane (T₈ ^DH) precore and 3) Star formation by hydrosilation of PIB^█01█ with T₈ ^DH. Conditions for the precision synthesis and characterization of well-defined octa-arm stars are described. Received: 13 September 1996/Accepted: 14 October 1996     

Scale-up of fluidized-bed hydrodynamics

The scale-up of fluidized beds is not an exact science. However, using proven techniques based on experience and mathematical and/or design models can minimize risk and uncertainty when scaling up fluidized beds. Scaling, which maintains that certain dimensionless groups be matched in different sized units for hydrodynamic similarity to be achieved, is different than scale-up, and generally can not be applied to pilot plants used for scale-up. Scaling is typically more useful to be applied to cold model studies that can be used to improve the operation of an existing plant. Deep fluidized beds of Group A materials can cause significant gas bypassing leading to poor gas-solids contacting. Because commercial beds are generally deeper than beds used in pilot plants, care must be taken to ensure that beds that do not exhibit gas bypassing in smaller units, do not have gas bypassing in commercial systems.     

中试规模合成邻硝基苯乙醇

该文研究了重要中间体邻硝基苯乙醇的合成工艺。结果表明,对于邻硝基甲苯的羟甲基化反应,效果最好的催化剂为氢氧化钠水溶液,且质量分数为20%的氢氧化钠水溶液的催化效果最佳,强碱型阴离子交换树脂因溶于二甲亚砜不适用于该反应。在质量分数20%的氢氧化钠水溶液催化下,羟甲基化反应最佳反应温度为50℃,甲醛与邻硝基甲苯的最佳摩尔比为0.4~0.5。在该条件下,按已转化的邻硝基甲苯计,邻硝基苯乙醇质量收率为110%,摩尔收率为90.7%。产品邻硝基苯乙醇的结构经红外、核磁等表征确证。该实验结果已经经过一次性投邻硝基甲苯120 kg的生产型中试验证,邻硝基苯乙醇质量收率为105.2%,摩尔收率为86.7%。     

Scale-up of Microfiltration Processes

A flow rate and resistance-based approach for upscaling of microfiltration processes from lab scale to process scale is presented, in correlation with biopharmaceutical processes. Basic element is the modeling of filtration curves using a resistance-in-series model based on the Darcy equation. The influences of the filtration setup and the fouling layer are described as additional resistances that change in course of filtration. The necessary parameters, such as setup resistances and filtration areas, are determined by water flow rate measurements. The model is validated by filtration of a particulate test solution. The presented approach can be used for constant flow and constant pressure driven filtration processes.     

液体搅拌的放大

介绍了几种常用的液体搅拌放大的判据,并对流量型搅拌、气液分散、液液分散、固液悬浮以及结晶过程的搅拌,分别提出了适用的放大判据。对于几何学条件,有的可以是几何相似的,有的则不能采用几何相似。还讨论了以单位容积功率作为放大判据时,可能出现的问题和改进措施。     

Dynamic rheological properties of polyisobutylene

The viscoelastic properties of polyisobutylene melts were investigated as functions of temperature, molecular weight, and molecular weight distribution. The effect of molecular weight distribution was studied through the use of blends of narrow distribution polymers. The Ninomiya and Ferry theory was used successfully to predict the viscosity of the blends. It was observed that the temperature coefficient for flow was independent of molecular weight distribution and of molecular weight. It was shown, at least in the case of polyisobutylene melts, that the temperature dependence of elasticity is less for polymers with greater polydispersity.     

Facile synthesis of diphenylethylene end-functional polyisobutylene and its applications for the synthesis of block copolymers containing poly(methacrylate)s

The convenient synthesis of methoxy-free 1,1-diphenylethylene end-functionalized polyisobutylene (PIB-DPE) has been accomplished by capping living PIB with 1,4-bis(1-phenylethenyl)benzene, followed by hydride transfer reaction with tributylsilane. The proposed method eliminates the need for methylation of the capped living PIB in which large excess of dimethylzinc must be used, resulting in a large amount of inorganic salt contamination. The obtained PIB-DPE was quantitatively lithiated with 1.5-fold excess n-butyllithium in tetrahydrofuran (THF) at room temperature. The methine proton at the chain end remained intact during the lithiation procedure. The resulting macroanion efficiently initiated the polymerization of alkyl methacrylates. Poly(methyl methacrylate) (PMMA)-b-PIB-b-PMMA, poly(2-hydroxyethyl methacrylate) (PHEMA)-b-PIB-b-PHEMA and poly(tert-butyl methacrylate) (P^tBMA)-b-PIB-b-P^tBMA have been prepared with high blocking efficiency by the proposed methodology. Complete hydrolysis of P^tBMA-b-PIB-b-P^tBMA into poly(methacrylic acid) (PMAA)-b-PIB-b-PMAA was realized in THF/1,4-dioxane, as confirmed by FTIR, ¹H NMR, and DSC analyses.