Spacer effect of novel bifunctional organophosphorus monomers in metal-imprinted polymers prepared by surface template polymerization

The interfacial activity and the molecular structure of functional monomers are critical factors that determine the success of synthesizing metal-imprinted polymers by surface template polymerization. From this point of view, first we prepared three distinct novel bifunctional organophosphorus monomers that are interspaced, in each case, by an alkyl spacer having a specific length. Each monomer carries two phosphonic acid groups and two aromatic groups in its molecular structures. Further, by using the synthesized bifunctional monomers, we prepared highly selective Zn(II)-imprinted polymers by the surface template polymerization initiated from a water-in-oil emulsion. To evaluate the template effect, we conducted diagnostic adsorption studies on Zn(II)-imprinted and unimprinted polymers with zinc ions. A high interfacial activity was found to be required for the functional monomers to create the predominant template effect. It became clear that Zn(II)-imprinted polymers having bifuctional monomers with 12-length alkyl chains (1,12-dodecanediol-O, O′-diphenyl phosphonic acid: DDDPA) yielded the best results. Moreover, analysis results of adsorption behavior supported a high-performance of the Zn(II)-imprinted polymers with DDDPA. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2727–2734, 1998     

Ring-opening polymerization of cyclic carbonates by alcohol–acid catalyst

Ring-opening reactions of 1,3-dioxepan-2-one ( 1 ) and 1,3-dioxan- 2 -one (2) with several alcohols were examined. The reactions proceeded without trifluoroacetic acid (TFA) in low conversions, while they proceeded smoothly with TFA to afford the ring-opened adducts and oligomers. Ring-opening polymerizations of 1 and 2 were also carried out by alcohol–acid catalysts to afford the corresponding polycarbonates (M _n = 2500−6800). The molecular weights increased with increase of the conversions of 1 and 2. The observed polymerization rates of 1 and 2 were determined as 24.4 × 10⁻⁶ and 0.8 × 10⁻⁶ s⁻¹, respectively. Mechanistic aspects were studied by NMR spectroscopy. The methylene protons α and β to the carbonate moieties shifted to lower fields in 0.06–0.11 ppm in the ¹H-NMR spectra by the addition of TFA. Downfield shifts of the carbonyl carbon signals of 1 and 2 were observed in 3.94–4.15 ppm in the ¹³C-NMR spectra. These results strongly suggest that the cyclic carbonates are activated by TFA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2463–2471, 1998     

Synthesis of new hybrid monomers and oligomers containing cationic and radical polymerizable vinyl groups and their photoinitiated polymerization

New hybrid vinyl monomers with both cationic- and radical-polymerizable vinyl groups were synthesized by the reaction of bis[1(chloromethyl)-2-(vinyloxy)ethyl]terephthalate ( 3 ) with unsaturated carboxylic acids using 1,8-diazabicyclo[5.4.0]-undecene-7 (DBU) as a base. The reaction of 3 with methacrylic acid 4a was carried out using DBU in DMSO at 70°C for 24 h to give an 86% yield of the hybrid vinyl monomer ( 5a ). Polycondensation of 3 with unsaturated dicarboxylic acids was also performed using DBU to give hybrid vinyl oligomers with radical polymerizable C (DOUBLE BOND) C groups (V_R) in the main chain and cationic polymerizable vinyl ether moieties (V_C) on the side chain. The photopolymerization of these hybrid vinyl compounds proceeded smoothly in bulk using either a cationic photoinitiator such as a sulfonium salt or a radical photoinitiator such as acyl phosphine oxide under UV irradiation. © 1996 John Wiley & Sons, Inc.     

Synthesis and polymerization of 7,7-bis(alkoxycarbonyl)-1,4-benzoquinone methides

7,7-Bis(methoxycarbonyl)-, 7,7-bis(ethoxycarbonyl)-, and 7,7-bis(isopropoxycarbonyl)-1,4-benzoquinone methides ( 4a, 4b , and 4c ) were successfully prepared as pure, isolable yellow-orange needles. The values of the first reduction potential for 4a, 4b , and 4c were measured in dichloromethane containing tetrabutylammonium perchlorate by cyclic voltammetry to be −0.54, −0.55, and −0.55 V, respectively, indicating that the alkyl groups do not significantly affect their electron-accepting properties. An anionic initiator butyllithium induced the homopolymerizations of 4a–c at 0°C, but a cationic initiator boron trifluoride etherate did not of 4a–c at 0°C. Compounds 4a and 4b homopolymerized with a radical initiator 2,2′-azobis(isobutyronitrile) (AIBN), but 4c did not, probably due to a larger steric hindrance effect of the isopropyl group compared with methyl and ethyl groups. Homopolymerizable compound 4a copolymerized with styrene in benzene in the presence of AIBN in a random fashion to give the monomer reactivity ratios r₁ ( 4a ) = 2.40 ± 0.40 and r₂ (styrene) = 0.01 ± 0.02 at 60°C and the Q and e values of 4a were 21.2 and +1.13, respectively, indicating that 4a is a highly conjugative and electron-accepting monomer, while the nonhomopolymerizable compound 4c copolymerized with styrene in a perfectly alternating fashion in benzene in the presence of AIBN at 60°C. No copolymerizations of 4a or 4c with 7,7,8,8-tetracyanoquinodimethane took place in dichloromethane in the presence of AIBN at 60°C. © 1996 John Wiley & Sons, Inc.     

Effect of branching on the thermal properties of novel branched poly(4‐ethyleneoxy benzoate)

Poly(4‐ethyleneoxy benzoate) (PEOB) was synthesized by the self‐condensation of ethyl 4‐(2‐hydroxyethoxy) benzoate (E4HEB) under transesterification conditions. Branched PEOB was prepared by the condensation of E4HEB with an AB₂ monomer, ethyl 3,5‐bis(2‐hydroxyethoxy) benzoate (EBHEB), under similar conditions. Varying amounts of branching (0–50%) were introduced into the linear polymer by changes in the composition of the comonomers in the feed. The solution viscosity of the polymers indicated that they had reasonable molecular weights; the extent of branching in these copolymers was established from their ¹H NMR spectra. Differential scanning calorimetry studies indicated that, as expected, the introduction of branching drastically affected the percent crystallinity of the copolymers (as seen from their ΔH_m, the enthalpy of melting), and when the extent of the incorporation of the AB₂ monomer exceeded 10 mol %, the copolymers were completely amorphous. The melting temperatures of the copolymers decreased with an increase in the branching content, whereas the peak crystallization temperature in quenched (amorphous) samples followed the exactly opposite trend. The glass‐transition temperatures (T_g) of the branched copolymers first decreased at low extents of branching, passed through a minimum, and then increased to attain the T_g of the pure hyperbranched polymer of EBHEB. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 261–268, 2000     

Solvent effects on the free‐radical copolymerization of styrene with butyl acrylate. I. Monomer reactivity ratios

The free‐radical copolymerization of styrene with butyl acrylate was carried out in benzene and benzonitrile at 50°C. Differences between the apparent reactivity ratios determined in this work and those previously reported in bulk indicated noticeable solvent effects. This is explained by a qualitative bootstrap effect. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 60–67, 2000     

Synthesis and characterization of new soluble aromatic polyamides based on 4‐(1‐adamantyl)‐1, 3‐bis(4‐aminophenoxy)benzene

A set of new aromatic polyamides were synthesized by the direct phosphorylation condensation of 4‐(1‐adamantyl)‐1,3‐bis‐(4‐aminophenoxy)benzene with various diacids. The polymers were produced with high yields and moderate to high inherent viscosities (0.43–1.03 dL/g), and the weight‐average molecular weights and number‐average molecular weights, determined by gel permeation chromatography, were in the range of 37,000–93,000 and 12,000–59,000, respectively. The polyamides were essentially amorphous and soluble in a variety of solvents such as N,N‐dimethylacetamide (DMAc), cyclohexanone, and tetrahydrofuran. They showed glass‐transition temperatures in the range of 240–300 °C (differential scanning calorimetry) and 10% weight‐loss temperatures over 450 °C, as revealed by thermogravimetric analysis in nitrogen. All the polymers gave strong films via casting from DMAc solutions, and these films exhibited good mechanical properties, with tensile strengths in the range of 77–92 MPa and tensile moduli between 1.5 and 2.5 GPa. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1014–1023, 2000     

APS引发制备高分子量PDMDAAC

以已知杂质种类和含量的一步法工业二甲基二烯丙基氯化铵(DMDAAC)单体水溶液为原料,用过硫酸铵(APS)为引发剂,采取低温一次性加入引发剂,分阶段升温方式进行聚合反应,通过合成工艺的优化方法,得到了最高特性黏数值为3.17 dL/g的聚二甲基二烯丙基氯化铵(PDMDAAC),单体转化率为94.8%,采用NMR、IR光谱测试技术对产物进行了结构表征。分别考察了DMDAAC质量分数为57.5%~70.0%、APS与DMDAAC质量比为0.15∶100~0.40∶100、Na4EDTA与DMDAAC质量比为0~0.014 2∶100、聚合反应引发温度T1在40~50℃、聚合反应熟化温度T3在50~90℃范围内的以上5个因素对产物特性黏数和单体转化率的影响规律。结果表明,DMDAAC质量分数为65.0%、APS与DMDAAC质量比为0.35∶100、Na4EDTA与DMDAAC质量比为0.007 1∶100、T1为46℃、T2为50℃,T3为70℃,各反应3 h为最佳工艺条件。     

Process Engineering for Production of Chiral Hydroxycarboxylic Acids from Bacterial Polyhydroxyalkanoates

An efficient process for the production of (R)‐hydroxycarboxylic acids (RHAs) from polyhydroxyalkanoates (PHAs) was developed. It involved the synthesis of PHA in bacteria, followed by bringing the culture broth directly to a pH optimal for in vivo PHA degradation, thus avoiding cell collection by centrifugation and pellet resuspension. The optimal pH was maintained to allow maximal release of RHAs. Using this process, cells having a dry weight (w) of 1.8 g · L⁻¹ and 45% (w/w) PHA exhibited a linear PHA degradation rate of about 0.059 g · L⁻¹ · h⁻¹ in the first 9 h. Concomitantly, RHAs were released with a rate of 0.057 g · L⁻¹ · h⁻¹. Further incubation of up to 15 h resulted in almost 90% (w/w) degradation of PHA. Based on this approach in combination with chemostat and a plug flow reactor a continuous process for the production of RHAs could be achieved.

     

Analytical Results of a Two-Species Predator-Prey Model

We propose a sequential monomer reaction model for a two-species predator-prey system, in which the aggregates of either species can spontaneously produce or lose one monomer and meanwhile, a type-B aggregate can prey upon one monomer of a type-A aggregate when they meet. Using the mean-field rate equation approach, we analytically investigate the kinetic behavior of the system. The results show that the evolution of the system depends crucially on the details of the rate kernels. The aggregate size distribution of either species approaches the conventional or modified scaling form in most cases. Moreover, the total size of either species grows exponentially with time in some cases and asymptotically retains a constant quantity in other cases, while it decays with time and vanishes finally in the rest cases.