甲基丙烯酸三苯基甲酯与甲基丙烯酸甲酯光学活性共聚物的结构特征

采用１３Ｃ－ＮＭＲ，ＩＲ及ＷＡＸＳ表征了甲基丙烯酸三苯基甲酯（ＴｒＭＡ）与甲基丙烯酸甲酯（ＭＭＡ）光学活性共聚物结构．阐明了具有单向螺旋链的光学活性共聚物组成的非均一性及其光学活性随组成变化呈ｓ型曲线的特征．     

Endgroups in Copolymers of Acenaphthylene with Methyl Methacrylate Prepared with Azoisobutyronitrile as Initiator

Copolymers of acenaphthylene (ACN) with methyl methacrylate (MMA) have been prepared with azobis(isobutyronitrile-β, β-¹³C₂) as initiator, The endgroups derived from the initiator have been examined by ¹³C-NMR spectroscopy; those attached to ACN units have been distinguished from those attached to MMA units and quantitative comparisons of their numbers have been made. It has been deduced that at 60°C ACN is four times as reactive as MMA toward the (CH₃)₂ C(CN) radical. The marked preference for initiation involving ACN means that, for all copolymers, the ratio of ACN to MMA is appreciably greater for the sites adjacent to the (CH₃)₂ C(CN)– endgroups than for the whole copolymer.     

Dimethylketene: Plasma-generated gas-phase precursor of photoluminescence chromophores in plasma polymerized films of methyl methacrylate and tetramethyl-1,3-cyclobutanedione

Gas-phase chemistry of tetramethyl-1,3-cyclobutanedione (TMCB) and formaldehyde plasmas have been studied within situ Fourier Transform Infrared (FTIR) Spectroscopy. Our previous work indicated that methyl methacrylate (MMA) dissociates to intermediate species of dimethylketene (DMK) and formaldehyde in MMA plasmas. This investigation of DMK dimer (TMCB) and formaldehyde plasmas is a continuation of our effort to understand the plasma polymerization chemistry of MMA. FTIR spectra confirmed the presence of DMK in TMCB plasmas and a polymeric thin film was deposited. Formaldehyde plasmas did not deposit any film for our experimental condition. Furthermore, plasma polymerized TMCB (PPTMCB) films exhibit UV photoluminescence similar to that of PPMMA films. Therefore, DMK is proposed to be the gas-phase precursor of photoluminescence chromophores in both PPMMA and PPTMCB films. Paper based on the results presented during the workshop of the Engineering Research Center for Plasma-Aided Manufacturing held in Madison, Wisconsin, in Spring 1996.     

In situ FTIR investigation of MMA plasmas,plasma-polymerized films,and reaction mechanisms

Methyl methacrylate (MMA) plasmas and plasma-polymerized methyl methacrylate (PPMMA) films were studied in situ with FTIR and FTIR/ATR (attenuated total reflection) in an r.f. capacitively coupled glow discharge. A statistically designed experiment was conducted by varying the r.f. power, process pressure, and MMA flow rate. MMA plasma fragments were identified from the gas-phase FTIR measurements. They include the intermediate species such as dimethylketene, formaldehyde, allene, and propene; small hydrocarbons such as acetylene, methane, and ethylene; and oxygenates such as carbon dioxide, carbon monoxide, and methanol. Statistical analysis techniques (correlation analysis, analysis of variance and regression analysis) were used on both gas and film data. Gas-phase reaction mechanisms are proposed, and the relationship between the gas and film data is investigated to understand the film deposition chemistry. The deposition rate is positively correlated to the relative concentrations of MMA fragments which are identified as the major film precursors in the deposition process. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 587–602, 1998     

Analysis of PPMMA films from oxygen plasma using X-ray photoelectron spectroscopy

Plasma polymerized methyl methacrylate (PPMMA) films have been synthesised on silicon substrates in RF glow discharge using oxygen plasma. The electron beam delineation sensitivity of the PPMMA films has been studied systematically by varying oxygen and monomer flow rates. X-ray photoelectron spectroscopy (XPS) analysis clearly illustrates how C/O ratio in the films determines the properties of PPMMA films as electron beam resist. © 1994 John Wiley & Sons, Inc.     

Synthesis of water-soluble Mo(0) tetracarbonyl complexes containing nitrogen donor ligands and polymerization of methyl methacrylate

Water-soluble Mo(0) tetracarbonyl complexes containing a α-diimine ligand have been prepared. All the complexes were characterized by elemental, LC-MS (APCI), FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopy. The pH dependent phase transfer of these complexes was investigated. This pH dependent phase transfer was accomplished over 10 times with no evidence of complex decomposition. Their catalytic activities on methyl methacrylate polymerization were determined.     

Head-to-head vinyl polymers. XI. Preparation and characterization of poly(methyl acrylate) and poly(methyl methacrylate) consisting of head-to-head and head-to-tail units through cyclopolymerization of acrylic and methacrylic anhydrides

Acrylic anhydride (AAn) and methacrylic anhydride (MAAn) were polymerized with radical initiator in polar solvents at high temperatures. The polymers obtained were found to consist of five-and six-membered ring structures by comparing IR spectra of the polymers with those of model compounds, succinic anhydride, and glutaric anhydride. Hydrolysis and methylation of the polymers gave new polymers composed of head-to-head (HH) and head-to-tail (HT) methyl acrylate (MA) or methyl methacrylate (MMA) units. The content of HH unit of these HH/HT polymers was determined by ¹H-NMR and ¹³C-NMR spectra. The softening, glass transition, and thermal degradation temperatures of the poly(MA) with HH and HT units were found to somewhat increase with increasing of the content of the HH units. On the other hand, the glass transition and thermal degradation temperatures of the poly(MMA) with HH and HT units increased similarly, but the softening temperature decreased as the content of the HH units increased.     

Characterization of organometallic polymers by 13C- and 119Sn-NMR: Configurational/compositional triads in poly(tri-n-butyltin methacrylate/methyl methacrylate)

The 1:1 and 2:1 formulations of the free radical initiated copolymers of methyl methacrylate (MMA) and tri-n-butyltin methacrylate (TBTM), and the homopolymer, poly(TBTM), are characterized by ¹³C- and ¹¹⁹C-NMR structural analyses were performed on the tributyltin-free hydrolyzate, a copolymer of MMA and methacrcylic acid (MAA). Configurational sequencing at the triad level is performed using the α-methyl region of the ¹³C-NMR spectrum. The probability of isotactic (meso) dyad placement at 80°C in the homopolymer (0.19) is determined to be significantly less than the probabilities observed for the copolymers (0.23–0.24). Random compositional sequencing is established for the copolymers through a comparison of the carbonyl regions of the ¹³C-NMR spectra of the hydrolyzates with the carbonyl regions in published spectra of structurally characterized copolymers of MMA and MAA. The ¹¹⁹Sn chemical shift and the tin-carbon J coupling for the polymers are dependent on the solvent employed. This dependence is attributed to electron donor or acceptor interactions between the solvent and the strong Sn? O dipole. The tin-containing copolymers exhibit multiple ¹¹⁹Sn resonances, which appear related to compositional sequencing.     

The flame-retardant material - 1. Studies on thermal characteristics and flame retardance behavior of phosphorus-containing copolymer of methyl methacrylate with 2-methacryloxyethyl phenyl phosphate

2-Methacryloxyethyl phenyl phosphate/methyl methacrylate (MEPP/MMA) copolymers were synthesized by the bulk polymerization of MMA in the presence of various amounts of MEPP. MEPP was prepared by the esterification of phenyl dichlorophosphate with 2-hydroxyethyl methacrylate, followed by hydrolysis. Structural and compositional details of MEPP were obtained by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, ³¹P nuclear magnetic resonance, and mass spectrometer, as well as by elemental analysis. The monomer reactivity ratios of MEPP/MMA system were calculated by the methods of Fineman-Ross, Kelen-Tüdös, and Joshi-Joshi. The thermal degradation temperature of the MEPP/MMA copolymers was considerably enhanced by only a slight decrease in T_g, as determined by differential scanning calorimetry and thermogravimetric analysis experiments. The fire-retardant properties of MEPP/MMA copolymers were also studied by LOI and UL-94 tests, indicating that an MEPP/MMA copolymer with only 2.17 wt% phosphorus can effectively inhibit burning.     

Determination of Compositional,Configurational Sequences in High Conversion Methyl Methacrylate-Methacrylic Acid Emulsion Copolymers Using a Rapid and Selective Counting Procedure

High conversion methyl methacrylate (MMA)-methacrylic acid (MA) copolymers prepared by two different emulsion polymerization processes were characterized in terms of composition and sequence distribution by ¹H- and ¹³C-NMR, taking into account the conversion effect. A rapid and selective counting procedure for calculating the compositional configurational pentads (512 values) in these copolymers is described. From this counting procedure and using the Klesper's assignment of the 18 peaks observed in the ¹³C-NMR carbonyl resonance spectrum of the copolymers, a relatively good agreement was found between the calculated and experimental fractions of each peak intensity. Moreover, this study allows differences in compositional homogeneity to be characterized as a function of the nature of the emulsion polymerization process.     

Macromers by carbocationic polymerization. IV. Synthesis and characterization of polyisobutenyl methacrylate macromer and its homopolymerization and copolymerization with methyl methacrylate

This article describes the synthesis and characterization of a new macromer, polyisobutenyl methacrylate (PIB-MA), its free-radical homopolymerization and copolymerization with methyl methacrylate (MMA) to afford the graft copolymer poly(methyl methacrylate-g-isobutylene) (PMMA-g-PIB), the characterization of these polymers, and some physical-mechanical (stress-strain) measurements of the graft copolymer. The key intermediate toward the synthesis of the target macromer was the preparation of polyisobutenyl chloride PIB-Cl^t by the minifer technique. As shown by ¹ H-NMR spectroscopy, and independently by IR spectroscopy coupled with M?_n determination, the PIB-MA macromer carries one terminal methacrylate function per polyisobutylene chain. The free-radical homopolymerization of PIB-MA to very high-molecular-weight product was achieved in bulk at 60°C. The free-radical copolymerization of PIB-MA with MMA also occurs readily and is a convenient route to PMMA-g-PIB. The reactivity of PIB-MA is almost identical to that of MMA; however, in highly viscous systems its rate of diffusion to the reaction site is reduced.     

GLC-MS analysis of the fatty acids of the seed oil,triglycerides, and cyanolipid of Paulliania elegans (Sapindaceae) – a rich source of cis-13-eicosenoic acid (paullinic acid)

The fatty acids of the total lipids, triglycerides, and the cyanolipid of Paullinia elegans (Sapindaceae) have been analyzed as their methyl esters and 4,4-dimethyloxazoline derivatives by gas chromatography-mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and ¹³C-nuclear magnetic resonance (NMR) spectroscopy. cis-13-Eicosenoic Acid (Paullinic acid) (44.4%) and cis-11-octadecenoic acid (cis-vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid of P. elegans was identified as 2,4-dihydroxy-3-methylenebutyronitrile derivative by IR, ¹H-NMR, ¹³C-NMR spectroscopy and was quantified by ¹H-NMR spectroscopy (71.4%).     

Synthesis and Characterization of Novel Methacrylic Copolymers: Determination of Monomer Reactivity Ratios

A new methacrylic monomer, 4‐nitro‐3‐methylphenyl methacrylate (NMPM) was prepared by reacting 4‐nitro‐3‐methyl phenol dissolved in methyl ethyl ketone (MEK) in the presence of triethylamine as a catalyst. Copolymerization of NMPM with methyl methacrylate (MMA) has been carried out in methyl ethyl ketone (MEK) by free radical solution polymerization at 70±1°C utilizing benzoyl peroxide (BPO) as initiator. Poly (NMPM‐co‐MMA) copolymers were characterized by FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopy. The molecular weights (M_w and M_n) and polydispersity indices (M_w/M_n) of the polymers were determined using a gel permeation chromatograph. The glass transition temperatures (T_g) of the copolymers were determined by a differential scanning calorimeter, showing that T_g increases with MMA content in the copolymer. Thermogravimetric analysis of the polymers, performed under nitrogen, shows that the stability of the copolymer increases with an increase in NMPM content. The solubility of the polymers was tested in various polar and non‐polar solvents. Copolymer compositions were determined by ¹H‐NMR spectroscopy by comparing the integral peak heights of well separated aromatic and aliphatic proton peaks. The monomer reactivity ratios were determined by the Fineman‐Ross (r₁ =7.090:r₂=0.854), Kelen‐Tudos (r₁=7.693: r₂=0.852) and extended Kelen‐Tudos methods (r₁=7.550: r₂= 0.856).     

表面引发的原子转移自由基聚合法在聚偏二氟乙烯表面制备可控的聚甲基丙烯酸甲酯刷

采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。     

A Transformable and Bulky Methacrylate Monomer That Enables the Synthesis of an MMA-nBA Alternating Copolymer: Sequence-Dependent Self-Healing Properties

In this study, we designed a methacrylate molecule with an alkyl-substituted trichloro salicylic acid pendant as a transformable bulky monomer to enable the synthesis of an alternating copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA). The adamantyl-substituted methacrylate monomer ( 1-Ad ) showed very low homopolymerization propensity in radical polymerizations, but afforded the alternating copolymer with nBA via copolymerization. The 1-Ad units in the resultant copolymer were quantitatively and selectively transformed into MMA via transesterification with methanol to yield the alternating copolymer of MMA and nBA. Its alternating sequence was clearly demonstrated by a structural analysis via ¹³C NMR spectroscopy as well as the low reactivity ratios for the 1-Ad and nBA pair. Finally, we verified the superior self-healing ability of the alternating copolymer compared to that of the corresponding 1 : 1 statistical copolymer.     

四配位硅单体及其共聚物的制备和结构表征

研究了直接从无定形二氧化硅出发, 与乙二醇、氢氧化钾反应, 生成高反应活性的五配位硅钾化合物, 并以此为原料与含活泼氯的3-氯丙烯反应制备出含双键官能团的四配位硅单体. 讨论了合成单体的条件如温度、反应时间、反应物浓度、溶液pH值及溶剂等因素的影响. 然后以该四配位硅单体与甲基丙烯酸甲酯(MMA)在偶氮二异丁腈(AIBN)作引发剂下进行自由基聚合得到支链含硅共聚物. 并借助于红外光谱(IR)、核磁共振(¹³C和¹H, ²⁹Si)、能谱元素分析对合成的单体进行了结构表征; 用红外光谱(IR)、热失重谱(TG)、差示扫描量热谱(DSC)、凝胶渗透色谱法(GPC)等现代测试手段对支链含硅共聚物进行了结构表征及热性能分析. IR表明四配位硅单体在1646 cm^－1处是C＝C的伸缩振动吸收峰, 在共聚物中此峰消失; TG表明共聚物在249.6 ℃才开始失重, 552 ℃有机部分失重完毕; GPC分析表明共聚物的数均分子量为8.7万.     

Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane

The preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl-containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri-, tetra-, penta-, hexa-, hepta-, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, ²⁹Si-, ¹H-, and ¹³C-NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.     

Structure of a novel nitrido technetium complex with the peptide chelate ligand KYCAR

A novel nitrido technetium complex was synthesized by the reaction of the KYCAR (lysyl-tyrosyl-cystyl-alanyl-arginine) ligand with [(n-C₄H₉)₄N][⁹⁹TcNCl₄]. The structure of the complex was analyzed by ¹H- and ¹³C-NMR and IR spectroscopy as well as by elemental analysis. The nitrido technetium complex with KYCAR has a square pyramidal structure in which two KYCARs coordinate to the Tc atom through both an N and a deprotonated S atom of cysteine. The complex possesses a trans configuration.     

A Study on End Group Characterization of Poly(phenacyl methacrylate) Polymer Produced by Free Radical Polymerization

Free‐radical homopolymerization and copolymerization of phenacyl methacrylate (PAMA) with methyl methacrylate (MMA) was done using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator in 1,4‐dioxane at 60°C. ¹H‐NMR and FT‐IR spectroscopy confirmed the existence of OCH₂ and CH signals and unsaturated structure and CN stretch at the chain end of low molecular weight poly(phenacyl methacrylate)[poly(PAMA)], respectively. The six‐membered ring with both ester and ether at the end group was detected by ¹H‐NMR. In the poly(PAMA), the end groups formed due to chain transfer reactions were found in large concentrations. The mechanism of the formation of end groups has been presented. The behavior of free radical polymerization of PAMA was compared with that of phenoxycarbonylmethyl methacrylate (PCMMA). The molecular weight distribution of the homo and copolymers was determined using gel permeation chromatography. Thermal properties of the polymers were determined using differential thermal analysis (DTA) and thermogravimetric analysis (TGA).     

A Study on End Group Characterization of Poly(phenacyl methacrylate) Polymer Produced by Free Radical Polymerization

Free‐radical homopolymerization and copolymerization of phenacyl methacrylate (PAMA) with methyl methacrylate (MMA) was done using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator in 1,4‐dioxane at 60°C. ¹H‐NMR and FT‐IR spectroscopy confirmed the existence of OCH₂ and CH signals and unsaturated structure and CN stretch at the chain end of low molecular weight poly(phenacyl methacrylate) [poly(PAMA)], respectively. The six‐membered ring with both ester and ether at the end group was detected by ¹H‐NMR. In the poly(PAMA), the end groups formed due to chain transfer reactions were found in large concentrations. The mechanism of the formation of end groups has been presented. The behavior of free radical polymerization of PAMA was compared with that of phenoxycarbonylmethyl methacrylate (PCMMA). The molecular weight distribution of the homo and copolymers was determined using gel permeation chromatography. Thermal properties of the polymers were determined using differential thermal analysis (DTA) and thermogravimetric analysis (TGA).