酚酸结构对酚酸-g-聚甘露糖醛酸抗氧化性能的影响

海藻酸钠水解产物聚甘露糖醛酸（PM）的羧基与乙二胺（EDA）的一个氨基反应制得了中间体PM-EDA,PM-EDA分别与8种酚酸（PA）接枝共聚，制得了8种接枝共聚物酚酸-g-聚甘露糖醛酸（PA-g-PM）。对PM-EDA的制备条件进行了优化，探究了PA结构对PA-g-PM抗氧化活性的影响。结果表明，在n(PM)∶n(EDA)=1∶1.5,n(PM)∶n（碳二亚胺）∶n(N-羟基琥珀酰亚胺)=1∶2∶1,pH 8.0条件下反应24 h，获得最高取代度（17.27%）的PM-EDA。8种PA-g-PM的接枝率在（4.171±0.16）～(8.880±0.32)mg没食子酸/g之间。UV-Vis、FTIR、XRD表征证实酚酸已成功接枝到PM上。相比于PM,8种PA-g-PM对1,1-二苯基-2-三硝基苯肼（DPPH）自由基的清除率和对铁的还原力均显著提升。PA-g-PM的抗氧化性能与其中的酚羟基个数呈正相关关系，含有对位酚羟基的PA-g-PM的抗氧化性能优于含有邻位酚羟基的PA-g-PM的抗氧化性能，PA-g-PM中的酚羟基被甲氧基取代后抗氧化性能减弱。     

聚丙烯酸酯接枝聚氨酯树脂制备与性能研究

以聚酯多元醇和异佛尔酮二异氰酸酯(IPDI)合成了异氰酸酯基封端的聚氨酯预聚体,并与自制含羟基的聚丙烯酸酯进行接枝,再加胺类扩链剂和分子质量调节剂,合成了固含量为30%的酯醇溶PUA树脂。讨论了异氰酸酯指数R值[即n(-NCO):n(-OH)]、聚氨酯(PU)与聚丙烯酸树脂(PA)的反应温度、PA羟基含量和PU/PA质量比对树脂及油墨性能的影响,结果表明:当R=2.0、PU与PA反应温度为60℃、PA羟基质量分数为1.13%和PU/PA质量比为2/1时,PUA树脂的综合性能较好。     

新型多巴基生物可降解梳状聚合物的合成及性能研究

以3,4-二羟基苯丙氨酸(DOPA)作为生物基单体,通过对酚羟基保护、缩聚、脱保护,得到聚多巴PDOPA;以PDOPA为大分子引发剂,用酚羟基引发丙交酯(乳酸二聚体)开环聚合,制备具有梳状结构的接枝聚合物——聚多巴-g-聚乳酸(PDOPA-g-PLA)。用凝胶渗透色谱仪、光学接触角仪、差示扫描量热仪、热失重分析仪和万能试验拉力机等考察了所得共聚物的分子量、热性能、表面浸润性、力学性能及降解性等性能。结果表明,PDOPA-g-PLA具有较好的溶解性、热稳定性和力学性能,并且具有一定的降解性。     

海藻酸钠离子交换过程的圆二色谱

引言 海藻酸钠胶是从海藻细胞壁和细胞间质中提取的天然生物大分子,由古洛糖醛酸(记为G单元)与其立体异构体甘露糖醛酸(记为M单元)两种结构单元通过α(1-4)糖苷键链接而成的线性嵌段共聚物.     

大孔树脂分离丹参酚酸转化液中丹酚酸A工艺研究

考察了7种大孔树脂对丹酚酸转化液中丹酚酸A的吸附与解析性能。结果表明AB-8树脂性能最好,最佳条件为:柱径高比1:7,pH=2～3,吸附浓度3.5mg/mL,吸附速度1.5mL/min,最大上样量38.67mg/g(干树脂),洗脱流速2mL/min,用10BV30%甲醇水洗脱杂质,15BV50%甲醇水洗脱丹酚酸A,丹酚酸A纯度可达79%以上。     

不同种蜂蜜抗氧化活性的研究

用四种不同的蜂蜜(黄连蜂蜜、中峰蜂蜜、野桂花蜂蜜、野菊花蜂蜜)作为研究对象,通过测定这四种蜂蜜的总酚含量的,探讨这四种不同的蜂蜜在超氧阴离子自由基中的消除功能以及在羟基自由基的消除功能,同时还测定四种不同蜂蜜的总还原能力。结果表明,这四种蜂蜜有明显不同的抗氧化能力,与蜂蜜的量呈正相关关系;四种蜂蜜中的酚酸含量与还原能力、氧化能力呈正比例关系,酚酸含量比较高的蜂蜜抗氧化能力较高。     

紫薯中花色苷及色素抗氧化性能的密度泛函理论研究

采用密度泛函理论中的B3LYP/6-31G(D)方法,对紫薯中两种花色苷和两种花色素(芍药-3-葡萄糖苷,矢车菊-3-葡萄糖苷,芍药色素,矢车菊色素)以及各自的脱氢自由基进行结构优化,基于分子的几何结构、酚羟基解离能BDE、HOMO和LUMO的能级及能级差△E(LUMO-HOMO)分析了紫薯中四种化合物的抗氧化活性强弱。结果表明,C4'位酚羟基为最大反应活性位点,C5、C7位酚羟基都有一定的活性,C3位糖苷上的酚羟基不具有抗氧化活性。矢车菊色素抗氧化活性大于芍药色素,矢车菊色素-3-葡萄糖苷抗氧化活性大于芍药色素-3-葡萄糖苷,且花色素抗氧化性能要优于相应的花色苷的抗氧化性能。     

酚酸酶法改性壳聚糖及其产物抗菌性能的研究

通过酚类物质与壳聚糖酶法接枝以提高壳聚糖的抗菌性质。利用酪氨酸酶催化氧化酚类接枝至壳聚糖得到壳聚糖-酚类衍生物,通过红外光谱分析确定衍生物结构,采用抑菌圈法对其抗菌性能进行测定。IR表明壳聚糖-酚类衍生物在3400 cm~(-1)、1384 cm~(-1)、1654 cm~(-1)处的吸收均有一定程度的减弱,在1637 cm~(-1)出现C=N的伸缩振动峰。表明酚酸已接枝至壳聚糖分子上;壳聚糖-酚类衍生物的抑菌性能较壳聚糖有明显的提高。     

PP/PA6复合材料结构与力学性能的研究

通过熔融共混法制备了聚丙烯/聚酰胺6(PP/PA6)复合材料。研究了PA6和不同增容剂(马来酸酐接枝PP和马来酸酐接枝聚烯烃弹性体)对PP性能的影响。通过力学性能测试、DSC和SEM对PP/PA6复合材料的结构和性能进行了系统研究。结果表明:加入8%PA6和5%增容剂时,复合材料的综合力学性能最佳;PA6对PP有异相成核作用;在增容剂的作用下,PA6均匀地分散于PP基体中,从而起到良好的改性作用。摘要:     

聚天冬氨酸接枝共聚物的缓蚀性能研究

将不同比例官能团如羟基和磺酸基分别引入到聚天冬氨酸的分子中,合成聚天冬氨酸接枝共聚物,并对其缓蚀性能进行了评定.结果表明,含磺酸基聚天冬氨酸接枝共聚物的缓蚀性能一般,其中接枝比例为0.2的缓蚀效果最好,为71.85%,与聚天冬氨酸的72.53%相差不多;而含羟基聚天冬氨酸接枝共聚物具有较好的缓蚀性能,其中接枝比例为1.0,缓蚀率高达89.93%,比聚天冬氨酸的72.53%提高很多.     

Antioxidative properties of phenolic acids and interaction with endogenous minor components during frying

The ability of selected phenolic acids to improve the frying performance of canola oil was evaluated in a frying test. The frying performance of the oil was assessed by analysis of total polar components (TPC), level of 4‐hydroxynonenal (HNE), and the rate of formation of volatile carbonyl compounds (VCC). All the tested phenolic acids; ferulic acid (FA), caffeic acid (CA), dihydrocaffeic acid (HCA), gallic acid (GA), and vanillic acid (VA) significantly increased the frying performance of canola oil triacylglycerols (CTG). At the end of the frying test, the amount of TPC in CTG was 22.9 ± 1.0% compared to a maximum of 18.8 ± 0.8% in CTG fortified with the phenolic acids. Similarly, the level of HNE was reduced by up to 45% when it was supplemented with phenolic acids. The results showed that ethyl ferulate (EF) was a better antioxidant than FA under frying conditions; HCA offered a slightly better protection than CA; and the cinnamic acid derivative, FA was better than VA, its benzoic acid analogue. A significant synergy was observed between phenolic acids and the sterol fraction isolated from canola oil. The observed synergy was attributed to the possible formation of steryl phenolates during the frying test. Practical applications: The poor thermal stability of polyunsaturated oils limits their application for prolonged frying. PUFA offer important health benefits and can improve nutritional value of fried foods. Contrary to the commonly applied synthetic antioxidants, the phenolic acids tested in this study often are part of endogenous oil components present in oilseeds and also in some oils, and are known for their positive health benefits. Thus, the simple phenolic acids, especially the cinnamic acid derivatives may be applied as potent antioxidants to protect oils during thermal processes used for food production.     

多乙烯多胺桥联受阻酚类抗氧剂的合成及其清除DPPH·性能

以二乙烯三胺和三乙烯四胺为桥联基，β-(3,5-二叔丁基-4-羟基苯基)丙酰氯为抗氧化功能基团，通过酰胺化缩合反应合成了两类具有不同对位桥联基团的受阻酚类抗氧剂。采用傅里叶红外光谱和核磁共振氢谱证实了合成的多乙烯多胺桥联受阻酚类抗氧剂的化学结构。DPPH法研究了多乙烯多胺桥联受阻酚类抗氧剂清除自由基的性能，并探索了酚羟基个数和对位桥联基结构对受阻酚类抗氧剂清除自由基性能的影响。结果表明，多乙烯多胺桥联受阻酚类抗氧剂具有良好的清除DPPH·能力，且随着抗氧剂分子中酚羟基个数的增加，清除DPPH·的活性增加，分子中含有4个酚羟基的三乙烯四胺受阻酚类抗氧剂的抗氧化效率（AE）达到2.65×10^-2 L/(mol·s)。对位桥联基结构对受阻酚类抗氧剂清除DPPH·能力有较大影响，季戊四醇为桥联基的受阻酚类抗氧剂1010清除DPPH·能力最强，其抗氧化效率（AE）为3.08×10^-2L/(mol·s)；乙二胺为核的1.0代树枝状受阻酚类抗氧剂清除DPPH·能力最弱，其抗氧化效率（AE）为2.60×10^-2 L/(mol·s)。     

Peroxyl and hydroxyl radical scavenging activity of some natural phenolic antioxidants

The autoxidation of linoleic acid dispersed in an aqueous media and the antioxidant effect of hydroxytyrosol, oleuropein, caffeic acid and tyrosol were studied. Linoleic acid autoxidation rate was estimated by the increase of conjugated diene level and by the decrease of linoleic acid content in the samples. The phenolic compounds exhibited an antioxidant activity which increased in the order: tyrosol < caffeic acid < oleuropein < hydroxytyrosol. The analysis of the hydroperoxide isomers pointed out that hydroxytyrosol, oleuropein and caffeic acid at a concentration of 10⁻⁴M inhibited the formation oftrans- trans isomers in the increasing order: caffeic acid < oleuropein < hydroxytyrosol. This inhibition could be related to the ability of phenolic compounds to scavenge peroxyl radical. Tyrosol did not inhibit the formation oftranstrans isomers. Phenolic compounds were degraded as a consequence of their antioxidant activity and their degradation rate was positively correlated to their antioxidant efficacy. These phenolic compounds, at a concentration of 6 × 10⁻³M, also scavenged hydroxyl radical, with an efficiency which increased in the order: tyrosol < hydroxytyrosol < oleuropein < caffeic acid. Polar substituents at the para position, such as in caffeic acid and oleuropein, were correlated with higher hydroxyl radical quenching ability.     

Antioxidation and mechanism of phosphites including the free phenolic hydroxyl group in polypropylene

Inhibiting the degradation of polypropylene (PP) in melt processing and usage is an important issue in the plastic industry. It is becoming more and more urgent to increase the antioxidation of phosphites alone while maintaining the water resistance. In this study, one phosphite antioxidant, named bis‐2,2′‐methyl‐4,6‐di‐tert‐butylphenyl phosphite (BM46TBPP), which contains a water‐resistant inner ring and a free phenolic hydroxyl group together, was synthesized. Then, antioxidation in PP was characterized with multiple extrusions and oxidation induction times (OITs). Finally, the hydrogen‐donating ability of this antioxidant was tested with 2,2‐diphenyl‐1‐picrylhydrazyl radical colorimetry to explain the antioxidation mechanism. The results show that the phosphite BM46TBPP displays better antioxidation than tris(2,4‐di‐tert‐butylphenyl) phosphite (Irgafos 168) in melt processing and OIT testing. Furthermore, the priority of this antioxidant was more obvious when it was used in the presence of oxygen, so the antioxidant even made the PP stabilized by it alone show a longer OIT value than the PP stabilized by the complex system including Irgafos 168 and 2,4‐di‐tert‐butylphenol because there was a free phenolic hydroxyl group in the BM46TBPP antioxidant molecule and the hydroxyl group made the antioxidant show intermolecular synergistic antioxidation through hydrogen donation to radicals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44696.     

Antioxidant effect and antimicrobial activity of phenolic sulfides

Some phenolic compounds containing both phenolic hydroxyl groups and sulfide groups in the molecules were prepared by Michael addition and radical addition reactions of ethanethiol and ethanedithiol witho-, m- andp-vinylphenol. The antioxidant effect of these products on the autoxidation of lard was examined by an oven test at 60°C. The antimicrobial activities of these products were evaluated by an agar dilution method. Three kinds of gram-positive and three kinds of gram-negative bacterial strains, as well as six kinds of fungal strains were used for the test. It was found that the Michael addition products showed considerably better antioxidant effects than BHT, whereas the radical addition products did not show any antioxidant effect. The antioxidant effects of these compounds were influenced by the positions of the sulfide groups in their molecules. The phenolic sulfides tested in this report showed good antimicrobial activities against bacteria and fungi.     

Synthesis of chloromethylstyrene‐tetraethyleneglycol dimethacrylate copolymer beads having various phenolic derivatives immobilized via amide bond and their antioxidation activity

Resins having phenolic derivatives were prepared by treating a resin (RAS‐4G), having benzylamino groups, with benzoic acids containing phenolic hydroxyl groups. The RAS‐4G was prepared by treating macroreticular chloromethylstyrene‐tetraethyleneglycol dimethacrylate (4G) copolymer beads with potassium phthalimide in N,N‐dimethylformamide, followed by reflux in an ethanol/hydrazine monohydrate mixture. 4‐Hydroxy benzoic acid, (2,4‐, 3,4‐, and 3,5‐)dihydroxy benzoic acids, 3,4,5‐trihydroxy benzoic acid, etc., were used as benzoic acids with phenolic hydroxyl groups. The antioxidation ability of the resins having phenolic derivatives was investigated against the generation of 1,4‐dioxane hydroperoxide. The resins showed high inhibition ability against the generation of hydroperoxide. In particular, the resin (RAS‐4G‐3,4‐DHBA) having two phenolic hydroxyl groups had the highest inhibition ability. The resins were found to act as radical scavengers during the generation of 1,4‐dioxane hydroperoxide by UV irradiation in the presence of oxygen. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2097–2104, 2005     

受阻酚类抗氧剂结构与其抗氧化性能的影响关系

选取了3种酚羟基个数不同的受阻酚类抗氧剂为研究对象,通过性能测试、氧化诱导温度测试以及羰基指数测试等对添加抗氧剂后合成的聚乙烯进行对比分析,考察抗氧剂结构对聚乙烯性能的影响。结果表明,虽然受阻酚类抗氧剂中酚羟基的个数增多可以提高抗氧剂的抗氧化效果,但耐老化性能变弱,因此优选适宜的酚羟基个数对于提升受阻酚类抗氧剂的抗氧化性能十分必要。     

Surface grafting of polyacrylamide from polyethylene‐based copolymer film

Atom transfer radical polymerization (ATRP) was used to grow polyacrylamide from the surface of ethylene–acrylic acid copolymer (EAA) film. The surface functionalization constituted initiator immobilization and surface graft polymerization. All reaction steps were conducted at 24 ± 3°C; polymerization was done in aqueous solution. For initiator immobilization, the carboxylic acid groups on EAA film were converted to acid chloride groups; further reaction with ethanolamines gave hydroxyl groups onto which 2‐bromoisobutyryl bromide initiator was attached. ATR‐FTIR data indicated that 1.64 ± 0.09 times higher initiator density was achieved by using diethanolamine, relative to ethanolamine. Acrylamide monomer was polymerized from the initiator by ATRP to yield nondistorted, transparent films with polymerization times of up to 1 h. For films prepared using diethanolamine, 1 h polymerization time reduced the static water contact angle by more than 50°, significantly increasing the hydrophilicity of the film surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1589–1595, 2004     

硼改性酚醛树脂的合成与性能

利用半成品酚醛树脂粉与硼酸直接混合,然后固化得到硼含量不同的硼酚醛树脂,并用傅里叶红外光谱、热重分析和冲击试验等方法对其性能进行了分析。红外分析结果表明,硼酸与酚醛树脂中的酚羟基、苄羟基发生了反应,生成了新的交联键。热分析结果发现,在酚醛树脂中加入硼酸能提高树脂的耐热性,当硼酸加入量为10%时达到最高值。硼酚醛树脂的冲击强度先随硼酸加入量的增大而增加,在5%时达到最大值,然后下降。     

HRP催化淀粉与酚类接枝聚合物的合成研究

以辣根过氧化物酶(HRP)/H2O2为催化体系,催化降解淀粉和3,5-二羟基苯甲酸(3,5-DBA)进行自由基接枝共聚反应,合成了淀粉和酚类接枝共聚物。探讨了温度和pH对酶活力的影响以及接枝条件对接枝共聚反应的影响。通过FTIR、1HNMR和GPC对接枝改性淀粉的化学结构进行了表征。产物用作皮革鞣剂时,显示了良好的应用性能。