Low molecular weight polyacrylic acid with pendant aminomethylene phosphonic acid groups

Low molecular weight poly(acrylic acid‐co‐vinyl aminomethylene phosphonic acid)s were prepared by consecutively applying the Hofmann degradation and the Mannich reaction to polyacrylamide and poly(acrylamide‐co‐acrylic acid)s. ¹H‐NMR, ³¹P‐NMR, and microanalysis were used for structural analyses. These polymers were tested as anti‐scalent and they showed better anti‐scalent effect than commercial poly(acrylic acid)s. The scale inhibition properties of copolymers increased with increasing amount of aminomethylene phosphonic acid groups. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 870–874, 2000     

绿色高分子材料--聚乳酸

本文概述了聚乳酸的基本性质和市场状况,着重论述了聚乳酸的工艺原理与应用,指出了聚乳酸是一种新型的绿色环保高分子材料。     

Vapor phase nitration of benzene over solid acid catalysts IV. Nitration with nitric acid (3); supported sulfuric acid catalyst with co-feeding of a trace amount of sulfuric acid

In the vapor phase nitration of benzene with diluted nitric acid, we have succeeded in keeping a high nitration activity of the supported sulfuric acid catalyst for more than 2 months by co-feeding a trace amount of sulfuric acid (H₂SO₄/HNO₃ = 1/5000 (wt. ratio)). The results after 60 days on-stream over 10 wt.%–H₂SO₄/SiO₂ catalyst are as follows: yield of nitrobenzene (NB), 93% based on HNO₃; selectivity of NB, 97% based on HNO₃; productivity of NB (STY), 0.76 kg/kg cat h. These performances were demonstrated in bench scale experiments using molded silica or quartz supports. Finally, nitration reactions of toluene and chlorobenzene were conducted and compared with each other over several solid acid catalysts developed by us.     

Effect of boric acid on the stabilization of poly(acrylonitrile-co-itaconic acid)

The effect of boric acid on the stabilization of poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) was studied in detail by differential scanning calorimetry (DSC) incorporating with thermogravimetry (TG) in air and nitrogen. In nitrogen atmosphere the ionic cyclization of the doped P(AN-co-IA) copolymer was badly retarded by boric acid, however, the free radical cyclization was little influenced. In air atmosphere boric acid was found to weaken the first exothermic peak corresponding to dehydrogenation and cyclization reactions, and enhance the second exothermic peak corresponding to the oxidative reactions resulting in a great expansion of the heat evolved. The activation energy of stabilization was calculated with Kissinger method, the results indicated that boric acid seemed to be effective to reduce the activation energy. TG studies showed that boric acid could reduce the weight loss during stabilization, which could be attributed to the crosslinking of polymer chains caused by the reaction between boric acid and the hydroxyl groups.     

Fatty acid composition of selected roes from some marine species

Fifteen roes from different marine fish species available in Spain were analyzed in order to determine their fatty acid (FA) composition, especially the eicosapentaenoic acid (20:5n‐3, EPA) and docosahexaenoic acid (22:6n‐3, DHA) contents. Roes from Atlantic bonito (Sarda sarda), European squid (Loligo vulgaris), cuttlefish (Sepia spp.), lumpfish (Cyclopterus lumpus), European hake (Merluccius merluccius), Atlantic salmon (Salmo salar) and gonads of male Atlantic mackerel (Scomber scombrus) reached EPA + DHA amounts higher than 30% of the total FA, and among them, roes from lumpfish, European hake and salmon provide different FA type ratios that could make them adequate as dietary sources of EPA and DHA.     

Polycondensation of lactic acid catalyzed by organic acid anhydrides

Poly(lactic acid) was prepared by the utilization of the acid anhydrides cis‐butenedoic anhydride, phthalic anhydride and pyromellitic dianhydride as catalysts. The effect of the amount of catalyst, temperature and reaction time on the polymerization was investigated in detail. The results show that the acid anhydride catalysts are very efficient in bulk polycondensation, giving poly(D ,L ‐lactic acid) with average molecular weights (M_w) of (1.7–2.3) × 10⁴ in high yield. Copyright © 2007 Society of Chemical Industry     

降低湿法磷酸中硫酸含量的工艺技术

采用在湿法磷酸中加入磷矿浆来降低磷酸的硫酸含量。介绍采用磷矿浆脱除硫酸根的反应原理,工艺路线的选择,矿浆添加量的计算及实施效果。通过计算,脱硫后反应、过滤装置生产能力提高,30万t/a磷酸装置每年节省硫酸8 700 t,减少消耗支出300多万元。     

N-甲基-D-天冬氨酸的合成

以D-天冬氨酸为主要原料,经酯化反应合成D-天冬氨酸二甲酯盐酸盐,收率95.6%;D-天冬氨酸二甲酯盐酸盐在DMF溶剂中与碘甲烷反应生成N-甲基-D-天冬氨二甲酯,进一步在碱性条件下水解生成N-甲基-D-天冬氨酸,收率83.5%。产物用红外光谱、核磁共振等进行了确证。     

Poly(acrylic acid)-grafted magnetic nanoparticle for conjugation with folic acid

Poly(acrylic acid) (poly(AA))-grafted magnetite nanoparticles (MNPs) prepared via surface-initiated atom transfer radical polymerization (ATRP) of t-butyl acrylate, followed by acid-catalyzed deprotection of t-butyl groups, is herein presented. In addition to serve as both steric and electrostatic stabilizers, poly(AA) grafted on MNP surface also served as a platform for conjugating folic acid, a cancer cell targeting agent. Fourier transform infrared spectroscopy (FTIR) was used to monitor the reaction progress in each step of the syntheses. The particle size was 8 nm in diameter without significant aggregation during the preparation process. Photocorrelation spectroscopy (PCS) indicated that, as increasing pH of the dispersions, their hydrodynamic diameter was decreased and negatively charge surface was obtained. According to thermogravimetric analysis (TGA), up to 14 wt% of folic acid (about 400 molecules of folic acid per particle) was bound to the surface-modified MNPs. This novel nanocomplex is hypothetically viable to efficiently graft other affinity molecules on their surfaces and thus might be suitable for use as an efficient drug delivery vehicle particularly for cancer treatment.     

Glass polyalkenoate dental cements based on physical blends of poly(acrylic acid) and poly(vinyl phosphonic acid)

Physical blends of spray-dried poly(acrylic acid), PAA, with poly(vinyl phosphonic acid), PVPA, have been prepared and used in experimental dental cements by mixing them with basic sub-45 μm acid-degradable fluoroaluminosilicate glass powders and adding water. The effect of varying the ratio of PAA to PVPA, of altering the molar mass of PAA, and of using glasses of differing basicity have been investigated. The compressive strengths of the best of the cements formed from these blends were comparable to those formed from the individual polyacids, i.e. about 160 MPa.     

改性聚天冬氨酸/聚丙烯酸复合吸水性树脂的制备与敏感性研究

以丙烯酸(AA)为单体,过硫酸钾(KPS)为引发剂,改性聚天冬氨酸(MKPAsp)作为交联剂,通过水溶液聚合法制得新型改性聚天冬氨酸/聚丙烯酸(MKPAsp/PAA)复合吸水性树脂。通过红外光谱、热失重分析(TGA)和扫描电镜(SEM)对复合吸水性树脂进行了表征。SEM表明AA的加入,改善了孔道结构,使孔密度增加,孔径更加均匀规则。研究了具有不同组成复合吸水性树脂在不同温度、pH和盐溶液中的溶胀性能,结果表明MKPAsp/PAA复合吸水性树脂低临界溶解温度(LCST)比聚天冬氨酸(KPAsp)提高了10℃,表现出良好的温度敏感性;在pH为6和10的溶液中出现2个吸液峰值;复合吸水性树脂的耐盐性较KPAsp得到了提高,且在不同价态的氯盐中吸液倍率顺序为Na~+Fe~(3+)Ca~(2+)。制得的MKPAsp/PAA复合吸水性树脂在去离子水和90mmol/L的Na Cl溶液中的最佳吸液倍率达到886.7和165.1 g/g,分别比KPAsp树脂提高了3.8倍和2.3倍。     

区带毛细管电泳法测定香草醛、阿魏酸和香草酸

建立了一种区带毛细管电泳法测定中草药中香草醛、阿魏酸和香草酸的方法。在优化的条件下,3种物质在10 min内得到良好分离。香草醛、阿魏酸和香草酸峰面积和质量浓度分别在2~200、2~200和1~200μg.mL-1范围内成良好线性。香草醛、阿魏酸和香草酸的检出限分别为0.49、0.56和0.38μg.mL-1。该方法被用于分析实际样品并做加标回收实验,得到令人满意的结果。     

Salt-, pH- and temperature-responsive semi-interpenetrating polymer network hydrogel based on poly(aspartic acid) and poly(acrylic acid)

In this study, a novel salt-, pH- and temperature-responsive semi-interpenetrating network (semi-IPN) hydrogel, composed of poly(aspartic acid) (PAsp) and poly(acrylic acid) (PAAc), was prepared. PAsp/PAAc semi-IPN hydrogel being ionic in nature, the swelling behavior was significantly influenced by various swelling medium. The structure of the triply responsive hydrogel was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the salt-, temperature- and pH-sensitivities were investigated through measuring equilibrium swelling ratios in various environmental solutions. The results indicate that there is a structure of polyelectrolyte complex in the hydrogel, and that the responsive behaviors of this hydrogel to alternating changes in inorganic salt (different physiological bio-fluids), pH and temperature are improved because of the incorporation of PAsp. In addition, during the repeatable swelling and shrinkage period, the semi-IPN hydrogel shows suitable mechanical strength. The salt-, pH- and temperature-responsive hydrogel will have wider applications in biomedical areas.     

Polymerization of maleic acid and itaconic acid studied by FT‐Raman spectroscopy

In this research, we used a new redox free radical initiation system consisting of potassium persulfate (K₂S₂O₈) and sodium hypophosphite (NaH₂PO₂). In the presence of NaH₂PO₂, the thermal decomposition of K₂S₂O₈ is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K₂S₂O₈/NaH₂PO₂ initiation system in an aqueous solution, and monitored the polymerization process with FT‐Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disappearance of the characteristic bands of MA as the thermal decomposition of K₂S₂O₈ progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001     

聚乳酸合成技术研究进展

聚乳酸因可生物降解、性能优异、应用广泛而深受青睐。本文介绍了2种主要化学合成聚乳酸的方法：丙交酯开环聚合法和乳酸直接缩聚法。分析了这2种方法的优势和缺陷：丙交酯开环聚合法设备简单,可得到大分子量的聚乳酸,缺点是成本较高,整个工艺复杂,路线长;乳酸直接缩聚法原料乳酸来源充足,价格便宜,单体转化率较高,工艺简单,不需要经过中间体的纯化,因而成本较低,缺陷是较难得到高分子量的聚合物。文中指出积极开展聚乳酸的合成工艺研发、进一步降低生产成本是当前聚乳酸研究的重要课题,重点在于简单易行的高分子量聚乳酸合成工艺的突破。     

Crystalline oligomeric stereocomplex as an intermediate compound in racemic poly(DL-lactic acid) degradation

Hydrolytic degradation of intrinsically amorphous poly(DL -lactic acid) was re-examined in pH 7.4 isoosmolar phosphate buffer at 37°C. Size-exclusion chromatogarphy, X-ray scattering and differential scanning calorimetry were used to monitor molecular weight and morphology changes up to the ultimate degradation stage. It was found that heterogeneous degradation of poly(DL -lactic acid) yielded a crystalline residual material of low molecular weight. Comparison with a stereocomplex made of equimolar poly(L -lactic acid) and poly(D -lactic acid) showed that the poly(DL -lactic acid) degradation residue was actually an oligomeric stereocomplex. The formation of stereoregular oligomeric enantiomers agreed well with the predominantly isotactic structure of poly(DL -lactic acid) obtained by ring-opening polymerization of DL -lactide and argued in favour of the stereodependence of main chain ester bond cleavage.     

Interactions between poly(acrylamide)–poly(itaconic acid) and cerium(IV)–nitrilotriacetic acid redox pair in the synthesis of acrylamide and itaconic acid homo‐ and copolymers

Homopolymers of itaconic acid (PIA) and its copolymers with acrylamide (P(IA‐AAm) were synthesized using ceric ammonium nitrate (NH₄)₂Ce(NO₃)₆ in combination with nitrilotriacetic acid (NTA) as redox initiator, and potassium persulphate at pH 1. The chain structures of the resulting products have been studied by FTIR spectroscopy. It is concluded from a comparison of spectroscopic results with gravimetric and viscometric data that the depressions in the yields and viscosity numbers in the case of Ce(IV)–NTA redox pair result from interactions between the constituents of the redox initiator and IA. Spectra of the insoluble and pale yellow precipitates, which are formed during the first 4 h of the reaction, after addition of Ce(IV) solution to the NTA and NTA–IA homogeneous solutions, also indicate the presence of various oxidation products. Furthermore, it is observed that H‐bonded homopolymer complex obtained from PAAm–PIA blends, prepared from aqueous solutions containing equal unit moles of each polymer, contain both ordered and defective structures. © 2001 Society of Chemical Industry     

多聚磷酸/乙酸表面功能化改性PBO纤维

采用多聚磷酸/乙酸(PPA/AcA)改性处理聚对苯撑苯并二噁唑(PBO)纤维,采用接触角、X射线光电子能谱(XPS)、热失重分析(TGA)和扫描电镜(SEM)等手段对PBO纤维进行分析表征。结果表明,PPA/AcA成功包覆在PBO纤维表面,使其亲水性提高,纤维表层发生溶胀,粗糙度增加。     

聚甲基丙烯酸-苯乙烯-甲基丙烯酸的合成

以萘钠为引发剂双向引发活性阴离子聚合制备嵌段共聚物聚甲基丙烯酸叔丁酯-苯乙烯-甲基丙烯酸叔丁酯(PTBMA—PS—PTBMA)，并在碱性条件下水解合成了ABA型两亲嵌段共聚物聚甲基丙烯酸-苯乙烯-甲基丙烯酸(PMAA—PS—PMAA)。对产物进行了傅立叶红外光谱分析，热分析及凝胶色谱分析。当苯乙烯与α-甲基丙烯酸叔丁酯投料质量比为54：46时，所得共聚物相应嵌段质量比为79：2l左右。     

The synthesis of poly (lactic acid)-fulvic acid graft polymer and its effect on the crystallization and performance of poly (lactic acid)

ABSTRACT

The poly (lactic acid)-fulvic acid graft polymer (PLA-FA) was synthesized with lactic acid and fulvic acid (FA). The optimum parameters were determined by orthogonal experiment. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy exhibited that FA was successfully grafted onto PLA. Then, PLA/PLA-FA composites were prepared with PLA-FA as fillers by melt blending. The structure characterization and performance tests demonstrated that PLA-FA effectively enhanced the comprehensive performance of PLA composites. The rheological analysis demonstrated that PLA-FA had plasticization effect. The non-isothermal crystallization kinetics demonstrated that PLA-FA promoted the crystallization rate of PLA composites, improving toughness of PLA composites.