Synthesis and radical polymerization of a vinyl monomer having a sulfonylacylurea moiety and hydrolysis of the obtained polymer

The radical polymerization of N-acryloyl-N′-(p-tolylsulfonyl)urea ( 2 ), prepared easily by the reaction of p-toluenesulfonyl isocyanate with acrylamide, was carried out in DMF, DMSO, or NMP at 60°C by use of AIBN as an initiator to give a polymer 3 in a good yield. Copolymerization parameters of 2 were evaluated by the copolymerization with MMA. Polymer 3 was readily hydrolyzed in an aqueous NaOH solution (1M) at room temperature to give poly(acrylic acid). The reason for the higher activity for hydrolysis of 3 compared to an ordinary amide is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1515–1519, 1998     

Synthesis,characterization, and hydrolysis of PVAc-PS-PVAc via charge transfer polymerization

An ABA triblock copolymer of polyvinyl acetate-b-polystyrene-b-polyvinyl acetate (PVAc-PS-PVAc) was successfully synthesized with a binary system composed of polystyrene with N,N-dimethylaniline end groups (PS_da) and benzophenone to initiate the polymerization of vinyl acetate under UV irradiation. The PS_da was obtained by capping the living polystyrene macrodianion with p-(dimethylamino) benzaldehyde in excess. The PVA-PS-PVA could then be obtained by hydrolysis of PVAc-PS-PVAc in the sodium ethoxide benzene solution. The intermediates and desirable copolymers were characterized by GPC, IR, and ¹H-NMR in detail. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2595–2600, 1999     

Thermal decomposition and hydrolysis of polyacrylamide-co-tert-butyl acrylate

Hydrolysis and thermal decomposition of polyacrylamide tert-butyl acrylate (PAtBA) copolymer were investigated. Carbon-13 nuclear magnetic resonance (¹³C NMR) spectroscopy was used to monitor the structural changes of the PAtBA. Hydrolysis of the amide groups occurred only after the complete conversion of tBA. Activation energy for the amide groups of the PAtBA was found to be 86.4 kJ/mol. Gas chromatography was used to identify gas products of the thermal decomposition of PAtBA. Gas analysis showed conclusively the formation of isobutene and carbon dioxide from the tBA groups of the copolymer. Tertiary butanol was found to be the hydrolysis product in the aqueous phase at temperatures from 60 to 130 °C. Kinetics governing the contribution of tBA and amide groups to the total degree of hydrolysis of the PAtBA is presented. An nth order equation was used to check for the hydrolysis reaction order of both the amide and the tBA groups. Analysis of ¹³C NMR spectra revealed that tBA groups were randomly distributed on the PAtBA copolymer chain.     

The influence of methacryloxypropyltrimethoxysilane on the sol-gel process of TEOS

The influence of MPS on the hydrolysis and condensation process of TEOS is studied by means of hydrolysis time (t _H) and gelation time (t _G) curves. The addition of MPS to a mixture of TEOS, ethanol and water results in a substantial increase in t _G. The increase is most pronounced when adding takes place in the acid step of the sol-gel process of TEOS.In acid environment hydrolysis of MPS will be dominant compared to hydrolysis of TEOS. This results in an effective decrease of the amount of water available for the hydrolysis of TEOS. However, this decrease in water concentration cannot explain the complete effect of the addition of MPS. The hydrolysed MPS will also be incorporated in the gel network and will strongly influence the cross-linking ability. The lesser functionality of MPS compared to TEOS and the steric hindrance of the acrylate group results in a large increase in t _G.     

The basic processes of polymerization and its real kinetic analysis

The method of computer experiments can be successfully applied to radical polymerization with the inclusion of initiation, propagation and termination. The convenient PC-program TAkin for non-linear estimation of the parameters of calorimetric and thermoanalytical experiments was applied for determination of the activation parameters of chain propagation and termination. The overall evaluation of three or more data sets was preferred. The determination of the kinetic parameters proceeds satisfactorily of the measured curves are strongly different, e.g. with a changed start temperature of modified application of batch and semi-batch technique, including acceptable experimental errors. Eight recommendations for laboratory experts are given.The autors thank Prof. H. A. Schneider (UniversitÄt Freiburg, FMF, Meierstr. 21, D79104 Freiburg) for helpful discussions concerning the rational application of modern kinetic methods.     

Characterization and optimization of poly(glycidyl methacrylate-co-styrene) synthesized by atom transfer radical polymerization

Styrene (S) and glycidyl methacrylate (GMA) copolymers were synthesized by atom transfer radical polymerization (ATRP) under different conditions. The effect of initiators, ligands, solvents, and temperature to the linear first-order kinetics and polydispersity index (PDI) was investigated for bulk polymerization. First-order kinetics was observed between linearly increasing molecular weight versus conversion and low polydispersities (PDI) were achieved for ethyl 2-bromo isobutyrate (EBiB) as an initiator and N,N′,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr as a catalyst. The copolymers with different compositions were synthesized using different in-feed ratios of monomers. Copolymers composition was calculated from ¹H NMR spectra which were further confirmed by quantitative ¹³C{¹H} NMR spectra. The monomer reactivity ratios were obtained with the help of Mayo-Lewis equation using genetic algorithm method. The values of reactivity ratios for glycidyl methacrylate and styrene monomers are r_G = 0.73 and r_S = 0.42, respectively.     

17O NMR investigation of phosphite hydrolysis mechanisms

The use of solution 17O NMR spectroscopy in verifying the mechanism of trialkyl phosphite hydrolysis is presented. Trimethyl phosphite was reacted with 17O-labeled H2O at different temperatures and two reactant concentrations, with the reaction being monitored by 17O NMR. Kinetic details elucidated from the NMR spectra are also discussed.     

Mechanism for hydrolysis of double six-membered ring tetraborate anion

[B₄O₅(OH)₄²⁻] is a representative borate anion with a double six-membered ring structure, but there is limited knowledge about the hydrolysis mechanisms of [B₄O₅(OH)₄²⁻]. Density functional theory-based calculations show that the tetraborate ion undergoes three-step hydrolysis to form [B(OH)₄⁻] and an ring intermediate, [B₃O₂(OH)₆⁻]. Other new structures, such as linear trimer, branched tetraborate, analogous linear tetraborate, are observed, but they are not stable in neutral systems and change to ring structures. [B₃O₂(OH)₆⁻] hydrolyzes to [B(OH)₄⁻] and [B(OH)₃] in the last two steps. The structure of borate anion and the coordination environment of the bridge oxygen atom control the hydrolysis process. [B₄O₅(OH)₄²⁻] always participates in the hydrolysis reaction, even with a decrease in concentration. [B₃O₃(OH)₄⁻], [B(OH)₄⁻], and [B(OH)₃] have different roles in “water-poor” and “water-rich” zones. Concentration and pH of solution are the key factors that affect the distribution of borate ions.     

Surface modification of multiwalled carbon nanotubes with biocompatible polymers via ring opening and living anionic surface initiated polymerization. Kinetics and crystallization behavior

Multiwalled carbon nanotubes (MWNTs) were functionalized with 2‐hydroxyethyl benzocyclobutene (BCB‐EO) through a Diels–Alder cycloaddition reaction. The functionalized MWNTs were utilized for the surface initiated ring opening (ROP) catalyzed and anionic polymerization of ε‐caprolactone (ε‐CL) and ethylene oxide (EO), respectively. The kinetics of the ROP of ε‐CL was monitored through thermogravimetric analysis (TGA) which revealed that the polymerization proceeds very fast as compared to that of EO and that both polymerizations could be controlled with time. ¹H NMR, Raman and FTIR spectroscopy, TGA, DSC, and transmission electron microscopy (TEM) were employed for the characterization of these polymer/CNT hybrids. DSC results showed that a remarkable nucleation effect is produced by MWNTs that reduced the supercooling needed for crystallization of both PεCL and PEO. Furthermore, the isothermal crystallization kinetics of the grafted PεCL and PEO was substantially accelerated compared to the neat polymers. The strong impact on the nucleation and crystallization kinetics is attributed to the covalent MWNT‐polymer bonding. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4379–4390, 2009     

Flowerlike hybrid horseradish peroxidase nanobiocatalyst for the polymerization of guaiacol

In this study, the catalytic activity and stability of flowerlike hybrid horseradish peroxidase (HRP) nanobiocatalyst (HRP-Cu ²⁺ ) obtained from Cu ²⁺ ions and HRP enzyme in the polymerization reaction of guaiacol were analyzed. We demonstrated that HRP-Cu ²⁺ and hydrogen peroxide (H ₂ O ₂ ) initiator showed significantly increased catalytic activity and stability on the polymerization of guaiacol compared to that of free HRP enzyme. Poly(guaiacol) was observed with quite high yields (88%) and molecular weights (38,000 g/mol) under pH 7.4 phosphate-buffered saline (PBS) conditions at 60 °C with 5 weight% of HRP-Cu ²⁺ loading. HRP-Cu ²⁺ also shows very high thermal stability and works even at 70 °C reaction temperature; free HRP enzyme denatures at that temperature. Furthermore, HRP-Cu ²⁺ provided considerable repeated use and showed some degree of catalytic activity, even after the fourth recycle, in the polymerization of guaiacol.     

Characterization of silicone phases by alkaline hydrolysis and CGC analysis

A simple way to elucidate the functional group substitution on silicone chains is presented. The polymer is decomposed into its monomers by alkaline hydrolysis. These monomers are converted into trimethylsilyl derivatives, which are then analyzed and identified by capillary gas chromatography/mass spectrometry.     

Characterization of poly(acrylamide-co-acrylates) obtained by inverse microemulsion polymerization

Two series of poly(acrylamide-co-acrylates) with compositions rangingfrom 10 to 55 mol % acrylate units were prepared by radical polymerization in inverse microemulsions. The compositional analyses of the samples were performed using elemental analysis, potentiometry and¹³C NMR. The comparison between the three methods indicates that¹³C NMR is the most reliable one, avoiding errors which often arise from associated water in hydrophilic polymers. The copolymer viscosity exhibits a maximum behavior around 40 mol % acrylate content, a lower value than that already observed for co-polymers prepared in homogeneous solution. The production of copolymers presenting high intrinsic viscosities ( 3700 cm³g^–) is achieved using an inverse microemulsion as the polymerization medium operating at lower temperature.     

Kinetics of the iodine transfer polymerization of vinylidene fluoride

The kinetics of the iodine transfer polymerization (ITP) of vinylidene fluoride (VDF) was achieved in the presence of three different chain‐transfer agents (CTAs): 1‐iodoperfluorohexane (C₆F₁₃I), 1‐iodo‐2H,2H‐perfluorooctane (C₆F₁₃CH₂CF₂I), and 1,1,2,2‐tetrafluoro‐3‐iodopropane (HCF₂CF₂CH₂I). ITPs of VDF carried out in the presence of C₆F₁₃I and C₆F₁₃CH₂CF₂I showed the following: (1) a linear increase in DP_n versus α_VDF, which evidenced the controlled character of ITP, although the polydispersity indices were slightly high (ca 1.5), and (2) theoretical DP_n values close to the targeted ones. In contrast, neither of these statements was observed for the ITP of VDF in the presence of HCF₂CF₂CH₂I achieved under the same conditions, even if the synthesized oligomers could be reactivated. Although the C_Tr values of C₆F₁₃I and C₆F₁₃CH₂CF₂I were close (i.e., 7.7 at 75 °C), that of HCF₂CF₂CH₂I was lower (0.3 at 75 °C). The percentages of ? CF₂I and ? CH₂I functionalities were also assessed, and in the course of the reaction, a reduction of ? CF₂I end groups was noted. Then, the mechanism of the ITP of VDF was proposed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5763–5777, 2006     

Studies of the compositions of Pd(II) hydrolysis products

The characterization of the clusters formed on alkaline hydrolysis of [PdCl₄]^2– was performed using¹⁷O,²³Na,³⁵Cl,¹³³Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)₂] _n ·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993.     

Multi-objective dynamic optimization of semi-batch polymerization processes

An improved evolutionary algorithm is proposed to perform multi-objective dynamic optimization of a semi-batch styrene polymerization process. The target is to determine the optimal feeding trajectories and the reactor operating temperature, which maximize the monomer conversion rate and minimize the initiator residue concentration in the final product. The optimization problem has been formulated as a multi-objective mixed-integer nonlinear problem (MOMINLP). The proposed approach allows the effective computation of the optimal operating strategies for the production of polymers with the average molecular weight and the polydispersity index required.     

NMR Study of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam. II. Investigation of the propagation center

The nature of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam initiated by octanoylium hexachlcroantimonate, SbCl₅, and Ph₃CAsF₆ in perdeuterated tetrachloroethane or its mixture with o-dichlorobenzene was studied using ¹H, ¹³C, ¹⁹F, ³¹P, ⁷⁵As, and ¹²¹Sb nuclear magnetic resonance (NMR) of model oligomers and the products of their end-capping with triphenylphosphine. In all cases, the nature of the propagation center has been found to be of an acylium ion pair with an SbCl₆^? or AsF₆^? counterion coordinated with the nearest benzoylamide group and cosolvated by the solvent. © 1994 John Wiley & Sons, Inc.     

Cellulose and hemicellulose hydrolysis models for application to current and novel pretreatment processes

Acids catalyze the hydrolysis of cellulose and hemicellulose to produce sugars that organisms can ferment to ethanol and other products. However, advanced low- and no-acid technologies are critical if we are to reduce bioethanol costs to be competitive as a pure fuel. We believe carbohy drate oligomers play a key role in explaining the performance of such hydrolysis processes and that kinetic models would help us understand their role. Various investigations have developed reaction rate expressions based on an Arrhenius temperature dependence that is first order in substrate concentration and close to first order in acid concentration. In this article, we evaluate these existing hydrolysis models with the goal of providing a foundation for a unified model that can predict performance of both current and novel pretreatment process configurations.     

微乳液中苯乙烯聚合反应的研究

测定了十二烷基磺酸钠(As)/正丁醇/20%苯乙烯/水体系相平衡。用油溶性偶氮二异丁腈(AIBN)和水溶性过二硫酸钾(K~2S~2O~8)为引发剂,研究了油包水(W/O)、双连续(BC)和水包油(O/W)型微乳液介质中苯乙烯的聚合反应。得到了苯乙烯转化率和聚苯乙烯分子量与体系水含量之间的关系,讨论了微乳液结构对聚合作用的影响。并通过电镜观察了聚苯乙烯的形貌,求得了聚苯乙烯的粒径,同时用^1HNMR研究了苯乙烯在微乳液液滴中的增溶位置,分析了聚合作用的实验结果。