端基转化对聚乙二醇单甲醚非等温结晶动力学的影响

通过聚乙二醇单甲醚(MPEG)与马来酸酐反应制备具有双端基活性的聚乙二醇单甲醚单马来酸酯(MPEGMA)。利用POM研究了MPEG和MPEGMA的结晶形态,结果表明MPEG和MPEGMA都存在十字消光现象,但两者结晶形态存在差别。用DSC技术研究了非等温结晶动力学,用Jeziorny法和Mo法描述了MPEG和MPEGMA非等温结晶动力学,研究表明随降温速率的增大,两种材料的结晶速率均增大;MPEG的端羟基与马来酸酐发生酯化反应完成端基转化后,MPEG原有的分子运动受到抑制,导致端基转化产物MPEGMA的结晶速率降低,MPEGMA与MPEG结晶成核方式和生长机理产生差异。     

马来酸酐/丙烯酸丁酯双单体接枝聚丙烯

采用熔融法进行马来酸酐(MAH)和丙烯酸丁酯(BA)双单体接枝聚丙烯(PP)的研究。结果表明,在一定工艺条件下,仅添加一单体马来酸酐时,接枝率G在其加入量为4%(质量分数)时达到最大(0.65 mmol/g PP);马来酸酐添加量保持不变,接枝率随第二单体丙烯酸丁酯添加量增加而出现一极值(1.34 mmol/g PP),比一单体接枝聚丙烯的接枝率高出一倍,并高于文献值(0.36 mmol/g PP)。经红外光谱、热失重分析和差示扫描量热分析表明,马来酸酐、丙烯酸丁酯均与聚丙烯发生接枝反应,并且以短支链的形式连接在PP的主链上。     

聚乙二醇对四氢呋喃共聚醚/多官能度异氰酸酯粘合剂体系固化反应动力学和力学性能的影响

为了提高四氢呋喃共聚醚(PET)/多官能度异氰酸酯(N-100)粘合剂体系的力学性能,在体系中分别添加不同量的聚乙二醇(PEG200),制备PET/PEG/N-100聚氨酯弹性体胶片。分别利用非等温差示扫描量热法(DSC)和单轴拉伸实验,研究了其固化反应的动力学和力学性能。结果表明,PEG200的端羟基与异氰酸酯基团的反应活性要高于PET;PEG200的加入能提高粘合剂体系的反应活性;当异氰酸酯基团与羟基基团的物质的量比(R值)为1.2时,PET/N-100聚氨酯弹性体的力学性能较佳;当PEG与PET的羟基物质的量比为1∶1时,聚氨酯弹性体的力学性能较为理想,其玻璃化转变温度变化不大,并出现冷结晶峰。     

马来酸酐接枝氯化聚丙烯的表面性质及粘接作用

研究了马来酸酐在氯化聚丙烯分子链上的接枝对其表面性质的影响,探讨了马来酸酐接枝氯化聚丙烯与聚丙烯及金属的粘接作用及耐水性。结果表明:随着MAH接枝率的增加,水与CPP-g-MAH的接触角逐步减小,CPP-g-MAH的表面能及极性部分增大;CPP-g-MAH对不锈钢、聚丙烯有良好的粘接作用,其粘接性能要明显优于CPP及市售的TS-2聚丙烯胶粘剂,随着接枝率的增加,粘接强度增大;CPP-g-MAH对聚丙烯的粘接作用具有良好的耐水性,经96 h 100℃沸水的浸泡,粘接强度没有发生明显下降。     

DCP引发高全同聚丁烯-1熔融接枝马来酸酐

研究了在双螺杆挤出机中,苯乙烯(St)存在下马来酸酐(MAH)熔融接枝高全同聚丁烯-1(iPB-1)的过程。分别考察了温度、MAH和St用量对接枝率和熔体流动速率(MFR)的影响。结果表明,双螺杆挤出机反应区的适宜温度为170℃,在此温度下,MAH含量到5%时,接枝率达到最大;MAH含量一定时,MAH∶St=1∶1时两种单体可以较好地相互作用,并在引发剂的作用下优先生成苯乙烯与马来酸酐的共聚物(SMA),然后再与iPB-1大分子链自由基或链端自由基发生反应,生成接枝物,此时接枝率达到最大。     

反应挤出法制备马来酸酐接枝聚乳酸

采用反应挤出方法制备了聚乳酸(PLA)与马来酸酐(MAH)的接枝共聚物,研究了工艺条件和配方对产物接枝率和熔体流动速率的影响。结果表明,聚乳酸的接枝反应主要依赖于大分子侧链自由基进行,过高的螺杆转速或过高的挤出反应温度会引发聚乳酸的降解反应,不利于产物接枝率的提高;在适宜的反应条件下(马来酸酐含量2%,DCP含量0.35%,温度180℃,螺杆转速100 r/min),可以方便制得马来酸酐接枝聚乳酸产物(接枝率≥0.45%);SEM观察显示,马来酸酐接枝聚乳酸有效改善了PLA/淀粉共混材料的相容性。     

水悬浮体系中三单体接枝聚丙烯的改性

在水悬浮体系中,经自由基引发聚丙烯(PP)与马来酸酐(MAH)、苯乙烯(ST)及丙烯酸丁酯(BA)接枝聚合制备接枝产物(PP-g-PMSB),同时体系中产生了非接枝的聚合物(PMSB′)。结果表明,随单体含量增加,接枝率和PMSB′含量升高,且在接枝率高于5.25%时出现微量凝胶。三单体以长支链形式接枝到PP主链上,随接枝率的增加,PP-g-PMSB热稳定性和极性提高,熔体流动速率减小。接枝率5.50%时,PP-g-PMSB水接触角为79.52°;PMSB′含量3.25%时,水接触角降低至69.62°。     

聚丙烯接枝交联物的结晶行为

以马来酸酐(MAH)和三烯丙基异氰脲酸酯(TAIC)固相法接枝等规聚丙烯(iPP)制备了高接枝率、高极性的PP接枝交联物，并研究了接枝物的流变特性、结晶与熔融行为和结晶形态。在接枝链上引入TAIC后稳定了分子结构，熔体流动速率减小。接枝物的结晶峰温、熔融峰温、结晶度及结晶速度均低于纯PP。但是较高接枝率的交联物的成核作用很强．其等温结晶行为不同于PP和MPP，成核和生长方式为瞬时成核的二维晶粒生长。     

马来酸酐固相接枝微晶纤维素

研究了马来酸酐(MAH)固相接枝微晶纤维素(MCC)的反应工艺,并通过红外光谱、X射线衍射对微晶纤维素及其接枝产物进行了对比表征。红外结果表明,接枝产物在1719.13cm-1处出现了酯基的伸缩振动吸收峰,可定性地说明马来酸酐与微晶纤维素发生了接枝反应。X射线衍射结果表明,接枝反应并没有改变微晶纤维素的结晶结构,仅使其结晶度下降。文中探讨了接枝反应温度、时间和MAH用量等因素对接枝取代度的影响。当马来酸酐与微晶纤维素质量比为8%,反应温度90℃,反应时间3h,可得到取代度达0.1的马来酸酐接枝微晶纤维素。     

马来酸酐接枝聚丙烯对云母填充聚丙烯的增容作用

以马来酸酐接枝聚丙烯（MPP）为云母填充聚丙烯（PP/mica)的界面相容剂，研究了MPP的添加量对PP/mica的力学,同观形态以及PP/mica熔体的流变行为和非等温结晶行为的影响。结果表明，加入MPP使PP/mica的国学得以全面的提高，PP/mica样品断面的电镜照片表明，MPP的加入使云母与聚丙烯的界面粘结得到改善；PP/mica熔体的表观粘度明显高其聚丙烯基体，随着MPP含量的增加，PP/mica的表观粘度下降，幂律指数也发生变化，云母对聚丙烯具有明显的成核,但随MPP含量的增加，云母的成核效率逐渐减弱。     

超临界CO2中两亲共聚物的合成及其对PVDF膜亲水化改性

以超临界CO2流体为反应介质,通过固相接枝反应合成了具有PEG侧链的聚(苯乙烯-马来酸酐)(SMA)功能化梳状两亲共聚物(SMA-g-MPEG),用1 H NMR和FT-IR表征了SMA-g-MPEG的结构和组成。并以SMA-g-MPEG为亲水改性材料通过非溶剂诱导相分离法制备PVDF共混复合膜。表面元素分析结果表明SMA-g-MPEG共聚物中的PEG侧链在膜表面形成富集;纯水接触角测定和BSA吸附试验表明膜的亲水性和抗蛋白质污染性能得到明显的提高。     

一种可阻止非特异性蛋白质吸附的新型聚乳酸材料——聚乙二醇接枝聚乳酸

通过直接酰胺化反应,用氨基封端聚乙二醇(H2N-PEG-NH2)对马来酸酐改性聚乳酸(MPLA)进行了本体改性。用红外、核磁和差示扫描技术对改性材料进行了表征,用FITC荧光标记牛血清白蛋白(FITC-BSA)对材料的非特异性吸附进行了检测。结果表明,聚乙二醇被成功地接枝到MPLA上,与聚乳酸(PLA)和MPLA相比,得到的产物(PPLA)明显降低了对牛血清白蛋白的非特异性吸附,仅为PLA的37.3%。     

Surface modification of natural rubber latex films via grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion

Natural rubber (NR) latex films with surface grafted poly(ethylene glycol) (PEG) chains were prepared by UV-induced graft copolymerization of methoxy poly(ethylene glycol) monomethacrylate (PEGMA) onto the plasma-pretreated NR latex films. PEGMA macromononers of different molecular weights were used. The UV-induced graft copolymerization of PEGMA onto the plasma-pretreated NR latex films was also explored with PEGMA of different macromonomer concentrations and with different UV graft copolymerization time. The surface microstructures and compositions of the PEG-modified NR latex films were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. In general, higher macromonomer concentration and longer UV graft copolymerization time led to a higher graft yield. Water contact angle measurements revealed that the hydrophilicity of the NR latex film surface was greatly enhanced by the grafting of the PEG chains. The NR surface with a high density of grafted PEG was very effective in reducing protein adsorption and platelet adhesion. A lower graft concentration of the high-molecular-weight PEG was more effective than a high graft concentration of the low-molecular-weight PEG in reducing protein adsorption and platelet adhesion. © 2001 Kluwer Academic Publishers     

P(NIPAAm-PEGMA)接枝聚丙烯多孔膜表面的抗污染及自清洁性能

以等离子体引发方法制备了聚(N-异丙基丙烯酰胺-聚乙二醇甲基丙烯酸酯)(P(NIPAAm-PEGMA))接枝的聚丙烯(PP)多孔膜。考察了改性膜水通量及表面润湿的温敏性质,并研究了其表面抗牛血清白蛋白(BSA)污染及自清洁性能。结果表明,聚乙二醇(PEG)侧链引入后,P(NIPAAm-PEGMA)保留了体积相转变性质,并在低临界溶解温度(LCST)上下均能展现良好的表面亲水性。得益于表面亲水性的改善,改性膜在过滤BSA溶液时的通量衰减率降低至18.8%。经简单的变温水清洗,BSA污染膜的水通量恢复率可达98.2%,且表面甚少污染物残留。P(NIPAAm-PEGMA)接枝链的亲水性及体积相转变是实现改性膜表面自清洁的原因。     

一种含亚胺基的螯合型吸附剂的制备及对钯离子的吸附

为制备一种能螯合钯离子的新型含亚胺基团的吸附剂,首先对聚丙烯无纺布(PP)进行预辐照接枝丙烯腈(AN),然后进一步和二乙烯三胺(EDTA)反应。结果表明,胺化反应时间越长,腈基基团转化为亚胺基团的转化率越高。当温度高于120℃,有一部分聚丙烯溶解于胺化试剂中。考察了吸附时间和钯离子初始浓度对吸附量的影响。结果表明,制备的螯合型吸附剂对钯离子的吸附性能良好。对接枝后和胺化后的样品用红外光谱仪和差示扫描量热仪进行了表征。     

新型聚醚接枝聚羧酸型高效混凝土减水剂的合成与性能

通过高分子反应法的新型合成路线,用SO3磺化的方法．对苯乙烯马来酸酐共聚物进行磺化,引入磺酸基团,通过磺酸基团的自催化作用,在马来酸酐基团上进行酯化接枝,合成出带有聚氧乙烯醚侧链的聚羧酸型高效减水荆。减水荆在低掺量下即有很好的减水效果,在掺量为0．6%水泥质量时．混凝土减水率可达36％以上,3d、28d抗压强度分别为207%、171％,90min内混凝土坍落度基本无损失。     

Polysulfone based amphiphilic graft copolymers by click chemistry as bioinert membranes

A series of well-defined amphiphilic graft copolymers with hydrophobic polysulfone (PSU) as backbones and hydrophilic poly(ethylene glycol) (PEG) as side chains were synthesized and characterized. For this purpose, PSUs were converted to azido-functionalized polymers by successive chloromethylation and azidation processes to give clickable PSUs. Then, the ω-hydroxyl function of the commercially available PEG-OH was converted into propargyl functionality by simple esterification process. Ultimately, the alkyne functionalized PEO was successfully grafted onto the PSUs by click chemistry. The final polymers and intermediates at various stages were characterized by ¹H NMR, FT-IR, and GPC techniques. The bioinert character of PEG grafted PSU was confirmed by static protein adsorption and prokaryotic and eukaryotic cell adhesion studies, and compared to that of unmodified PSU.     

Characterization of poly(L-lysine)-graft-poly(ethylene glycol) assembled monolayers on niobium pentoxide substrates using time-of-flight secondary ion mass spectrometry and multivariate analysis

Control of protein adsorption onto solid surfaces is a critical area of biomaterials and biosensors research. Application of high performance surface analysis techniques to these problems can improve the rational design and understanding of coatings that control protein adsorption. We have used static time-of-flight secondary ion mass spectrometry (TOF-SIMS) to investigate several poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) adlayers adsorbed electrostatically onto negatively charged niobium pentoxide (Nb(2)O(5)) substrates. By varying the PEG graft ratio (i.e., the number of lysine monomers per grafted PEG chain) and the molecular weights of the PLL and PEG polymers, the amount of protein adsorption can be tailored between 1 and 300 ng/cm(2). Detailed multivariate analysis using principal component analysis (PCA) of the positive and negative ion TOF-SIMS spectra showed changes in the outermost surface of the polymer films that were related to the density and molecular weight of the PEG chains on the surface. However, no significant differences were noted due to PLL molecular weight, despite observed differences in the serum adsorption characteristics for adlayers of PLL-g-PEG polymers with different PLL molecular weights. From the PCA results, multivariate peak intensity ratios were developed that correlated with the thickness of the adlayer and the enrichment of the PEG chains and the methoxy terminus of the PEG chains at the outermost surface of the adlayer. Furthermore, partial least squares regression was used to correlate the TOF-SIMS spectra with the amount of protein adsorption, resulting in a predictive model for determining the amount of protein adsorption on the basis of the TOF-SIMS spectra. The accuracy of the prediction of the amount of serum adsorption depended on the molecular weight of the PLL and PEG polymers and the PEG graft ratio. The combination of multivariate analysis and static TOF-SIMS provides detailed information on the surface chemistry and insight into the mechanism for protein resistance of the coatings.