EC/CA共混物的相容性和热稳定性

EC/CA共混物的相容性和热稳定性;乙基纤维素;醋酸纤维素;溶液共混;相容性     

Effect of Interfacial Adsorption on the Stability of Thin Polymer Films in a Solvent-induced Process

The stability of ultrathin polymer films plays a crucial role in their technological applications. Here, we systematically investigated the influence of interfacial adsorption in physical aging and the stability of thin polymer films in the solvent-induced process. We further identify the stability mechanism from the theory of thin film stability. Our results show that the aging temperature and film thickness can strongly influence the stability of thin PS films in acetone vapor. Physical aging can greatly improve the stability of thin polymer films when the aging temperature T_(aging1)T_g. A thinner PS film more quickly reaches a stable state via physical aging. At short aging time, the formation of the adsorbed layer can reduce the polar interaction; however, it slightly influences the stability of thin polymer films in the solvent-induced process. At later aging stage,the conformational rearrangement of the polymer chains induced by the interfacial effect at the aging temperature T_(aging1) plays an important role in stabilizing the thin polymer films. However, at T_(aging2)T_g, the process of physical aging slightly influences the stability of the thin polymer films.The formation of the adsorbed layer at T_(aging2) can reduce the short-range polar interaction of the thin film system and cannot suppress the instability of thin polymer films in the solvent-induced process. These results provide further insight into the stable mechanism of thin polymer films in the solvent-induced process.     

Solubility and diffusivity of water and of salts in an aromatic polyamide film

The solubility and the diffusivity for water and NaCl in a fully aromatic polyamide (PA) film have been determined. From these the “intrinsic permeability characteristics” of this polymer have been calculated and its suitability for desalination by reverse osmosis is compared with that of the commonly used cellulose acetate (CA). It has been found that, although the solubility of NaCl in the PA film is higher than that in a CA film, PA membranes will reject salt better than CA membranes having identical structure and morphology. This is because the diffusivity of NaCl through the PA film is substantially lower, and the permeability of water through it (as well as the solubility and the diffusivity of water in it) are higher than the comparable values for CA films.     

苯并噁嗪/环氧树脂/4,4′-二氨基二苯砜三元共混体系玻璃化转变温度的研究

采用动态热机械分析(DMA)研究了苯并噁嗪/环氧树脂/4,4′-二氨基二苯砜(DDS)三元共混体系玻璃化转变温度(Tg)与固化剂DDS含量的关系.随着DDS含量的增加,三元体系的交联密度呈现先增加后降低的变化趋势,介于聚苯并噁嗪和苯并噁嗪/环氧树脂体系之间;但是三元体系的Tg却逐渐降低,当DDS的含量超过20 mol%时,低于聚苯并噁嗪的Tg.差示扫描量热法(DSC)的结果表明,DDS对苯并噁嗪和环氧树脂都有很强的固化效果.通过测定体系的凝胶化时间,借助Arrhenius方程,判断三元体系的初始反应过程,推测了固化体系可能的网络化学结构.对各体系DMA曲线中损耗模量,储能模量和力学损耗因子的变化情况分析,结果表明体系最终Tg受氢键相互作用、交联密度和网络规整性以及链段的刚性等因素综合影响,其中氢键的类型和相互作用的强弱对Tg的影响最大.     

Antibacterial cellulose acetate films incorporated with N‐halamine‐modified nano‐crystalline cellulose particles

Cellulose acetate (CA) membranes have been widely used as food packaging materials as well as reverse osmosis systems. This study presents the manufacturing of composite CA film with antibacterial properties which is essential for CA film applications in the industry. N‐Halamine precursor of polymethacrylamide‐modified nano‐crystalline cellulose particles (NCC‐PMAMs) were prepared and incorporated into CA film. The composite films with intercalated structure were formed via a solvent‐casting technique. After chlorination, the composite film CA/NCC‐PMAM‐Cl‐1.0 with 1.82 × 10¹⁶ atoms/cm² covalently bonded chlorine showed excellent antibacterial properties by inactivating 6.04 logs of Staphylococcus aureus and 6.27 logs of Escherichia coli within 10 and 5 min, respectively. According to X‐ray diffraction spectra, NCC‐PMAMs behaved as a facilitator for film crystallization. The mechanical strength of the composite film also increased compared with that of pure CA film. However, the composite film became brittle and the maximum decomposition temperature decreased slightly. Preliminary data of in vitro cytocompatibility evaluation indicate that the film is not toxic and has potential use in food packaging. Copyright © 2016 John Wiley & Sons, Ltd.     

苯与DOP在LDPE与PEMA基体中无限稀释扩散系数的测定及研究

用逆流气相色谱法测定了苯、邻苯二甲酸二辛酯(DOP)在293～373K间在低密度聚乙烯(LDPE)、聚甲基丙烯酸乙酯(PEMA)基体中的无限稀释扩散系数,拟合了扩散系数与温度倒数的对数线性关系,并求得扩散活化能,发现它在玻璃化温度附近出现转折,且两者之间存在0．6倍关系。通过检验Vrentas-Duda自由体积扩散模型,发现在小分子无相变情况下该模型比较准确。     

5-位取代吡唑啉化合物的发光行为及其在电致发光领域中的应用

合成了一系列5位不同取代的2－吡唑啉化合物，研究了取代基对吡唑啉化合物 物理性质的影响。结果表明，在吡唑啉化合物的5位引入稠环取代基提高了吡唑啉 化合物的熔点；同时，5位取代基的电位性质还影响着化合物的发光行为。DSC差热 分析结果给出1，3－二苯基－5－（9－菲基）－2－吡唑啉（TAP7）的玻璃化温度 (T_g)为96 ℃；并研究了其在电致发光器件上的应用性能。结果表明TAP7是一种具 有高热稳定性的空穴传输及蓝光发光材料。     

乙酰丙酮钛螯合物掺杂丙烯酸酯共聚物水溶胶

乙酰丙酮钛螯合物掺杂丙烯酸酯共聚物水溶胶;乙酰丙酮钛螯合物; 丙烯酸酯共聚物水溶胶;掺杂     

聚苯醚羧酸盐的链结构

本文用热学,力学和光散射方法研究了聚苯醚羧酸盐的链结构。羧化聚苯醚(CPPO)在二氧六环溶液中用0.5N NaOH(或 CsOH)的醇水溶液中和成钠型或铯型的 CPPO 离聚体,用 DSC测定一系列羧盐含量的 CPPO 离聚体的玻璃化转变温度得到形成离子微区的临界阳离子浓度约为5mol%,动态力学谱中在高于玻璃化转变温度域出现的α松弛峰亦证明了微相结构的存在。SAXS 结果表明其离子微区的尺寸约为3nm,其尺寸大小和离聚体中阳离子浓度无关。     

A2和B3型单体缩聚合成超支化偶氮聚氨酯研究

通过双官能度异氰酸酯基单体MDI(A2)与三官能度羟基偶氮单体(B3)的缩聚反应,得到了超支化偶氮聚氨酯,利用核磁共振、热分析、紫外-可见光谱、红外光谱、GPC等方法对其结构和性能等进行了详细表征.该聚合物在干涉的p偏振Ar+激光照射下,可得到周期性规则的正弦波形表面起伏光栅.     

溶剂诱导聚合物结晶的研究进展

溶剂诱导结晶(SINC)又称为液体诱导结晶,它是结晶性高聚物在溶剂(或包括其蒸汽)作用下,在低于通常Tg下诱导结晶,而在高于通常Tg时能加速结晶的现象。本文主要对溶剂诱导结晶的机理、动力学和形态学进行了讨论。     

以化学键为加和单元研究二元共聚物的玻璃化温度

以玻璃化转变的热力学理论为基础,根据相邻C原子的不同取代情况对主链化学键进行分类,假定化学键的刚性能具有加和性,从而对Gibbs-DiMarzio方程进行了修订,提出了新的Tg-序列结构-共聚物组成关系方程.新方程中包含不同三元组序列的摩尔分率和相关均聚物、周期共聚物的Tg,方程中的所有参数可以通过实验测定或计算得到,没有纯粹的拟合参数,在共聚物的结构与Tg之间建立了直接而唯一的关系,因而此方程可以方便地解释各种共聚物Tg-组成关系曲线.如果二元共聚体系的周期共聚物或交替共聚物尚未合成,还可以通过该方程由无规共聚物的Tg-组成曲线对其Tg进行预测.将该方程应用到MMA-St、E-VAc无规共聚物,得到很好的结果.     

光响应性超疏水偶氮苯自组装多层膜的制备及性质研究

近年来,偶氮苯类化合物的光学顺反异构现象已引起人们的广泛关注[1~7].在紫外光照射下,偶氮苯由反式结构转变为顺式结构,引起分子的偶极矩发生变化,导致分子的吸收光谱、尺寸及表面能等均发生变化[7].偶氮苯表面能的改变可引起其表面浸润性发生变化.据文献[1~4]报道,偶氮苯膜在紫外光照射前后接触角最大改变了11°.浸润性是固体表面的一个重要特性,主要受固体表面的化学组成和微观几何结构(粗糙度)影响[8~11].通常,与水的接触角大于150°的表面称为超疏水表面;而与水的接触角小于5°的表面称为超亲水表面.本文以2-(4-偶氮苯基苯氧基)丙烯酸…     

Reversible wettability of a chemical vapor deposition prepared ZnO film between superhydrophobicity and superhydrophilicity

A superhydrophobic ZnO thin film was fabricated by the Au-catalyzed chemical vapor deposition method. The surface of the film exhibits hierarchical structure with nanostructures on sub-microstructures. The water contact angle (CA) was 164.3 degrees, turning into a superhydrophilic one (CA < 5 degrees) after UV illumination, which can be recovered through being placed in the dark or being heated. The film was attached tightly to the substrate, showing good stability and durability. The surface structures were characterized by scanning electron microscopy and atomic force microscopy.     

二乙酸甘油酯封端的齐聚L-丙交酯增塑改性聚L-丙交酯薄膜

以二乙酸甘油酯(GD)引发L-丙交酯(LLA)开环聚合合成了二乙酸甘油酯封端的齐聚L-丙交酯(OGLA),并以此为增塑剂,以溶液共混法制备了OGLA与高分子量聚L-丙交酯(PLLA)的共混膜.采用DSC研究了共混膜的T_g和结晶性变化,考察了共混膜的力学性能和渗出性.结果表明:随着OGLA含量的增加,共混物T_g下降,结晶度降低,柔性提高;与聚乳酸相比,随着OGLA含量的增加,拉伸强度、弹性模量有一定程度降低,但断裂伸长率有较大程度的提高,力学性能得到较好的平衡;OGLA增塑体系与GD增塑体系相比较,优势在于避免了小分子增塑剂的渗出.     

DETECTION OF T_g BY MODULATED DIFFERENTIAL SCANNING CALORIMETRY

The glassy transition of the polyethylene terephthalate (PET) sampleswhich have been subjected to solvent induced crystallization (SINC) was investigated bymodulated differential scanning calorimetry (MDSC) and density measurement. The dif-ferential of heat capacity signal, d C_p/dT from MDSC, was used to monitor the SINCprocess. It reveals that the T_g temperature shifts to higher value with the advancement ofSINC. When the toluene-immersing time was longer (168h), the detection of T_g becomemore difficult, because some smaller peaks emerged at the lower temperatures and theseare explained as the movement of small segments in the amorphous region. These observedresults are due to the morphology and structure introduced by the SINC process.     

含硝基偶氮苯侧基的丙烯酸酯类液晶聚合物的合成、结构与性质研究——Ⅱ.分子结构对T_g的影响

利用DSC研究了分子结构对含硝基偶氮苯侧基的丙烯酸酯液晶聚合物玻璃化温度的影响。结果表明,随柔性间隔基长度增加,T_g降低;当引入丙烯酸甲酯(MA)作为非晶共聚组分时,T_g降低;T_g真随MA摩尔百分含量增加而降低;当引入丙烯酸作为非晶共聚组分时,T_g升高。     

Efficient alternative of antimicrobial nanocomposites based on cellulose acetate/Cu-NPs

The current research presents an efficient, cheap, and safe antimicrobial material for widespread use based on copper nanoparticles (Cu-NPs) loaded on cellulose acetate (CA) matrix. A reduction process of CuSO₄·5H₂O has been performed to prepare Cu-NPs. The nanosized copper particles included oxidized Cu (15–20 nm). Two different loads of Cu-NPs were used in this study, 2% and 6% mol.%. The presence of Cu-NPs incorporated with CA films slightly affected the tensile index of the films, where low and high-loaded Cu-NPs enhanced the tensile index by small values ranged from 0.640 to 0.650 and 0.667, respectively. A study on the antibacterial activity of these nanocomposites was carried out for Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. It has been found that CA containing Cu-NPs (2%) exhibited the highest antimicrobial activity against all test microbes including S. aeureus (21 mm), P. aeruginosa (18 mm), C. albicans (19 mm), and Aspergillus niger (15 mm). Results also revealed that CA film with 6% exhibited lower activity than film with 2% Cu-NPs. The morphological properties of CA/Cu-NPs films were characterized by scanning electron microscopy and transmission electron microscope in addition to X-ray diffraction. Low-loaded Cu-NPs showed homogenous distribution through CA matrix while, the high-loaded Cu-NPs were agglomerated through CA matrix. Thermal properties illustrated the enhancement of thermal stability of the film with increasing the loaded Cu-NPs.     

INVESTIGATION OF THE TRANSITIONS OF OLIGO-POLYSULFONES BY DSC

The transitions of bisphenol A and phenolphthalein o|igopolysulfones were investigated by DSC. It is found that both the oligomers have three transitions within the temperature range (230-550K) studied. Considering the strong dependence of the appearance of the two transitions, lower and higher than T_g, on the specimens' thermal history, i. e., temperature and time of heat-treatment, and their particular molecular strueture, it is proposed that these two transitions are morphological in origin arid are due to the disordering of relatively short range order of very small regions, and to the disordering of relatively well-ordered intraor/and intermoleeular segments, respectively. Equations for linear relationship between T_g and 1/_n for both the oligomers are given in the paper.     

侧基含羟基的主链偶氮苯液晶共聚酯的合成及其光响应行为

以4,4’-双(6-羟基己氧基)联苯(BHHBP)、4,4’-双(6-羟基己氧基)偶氮苯(BHHAB)为液晶基元,利用苹果酸二乙酯(DM)和苯基丁二酸(PSA)采用无规共聚,合成了侧基含羟基的偶氮苯液晶共聚酯(Az-LCP).先在液晶态下拉伸取向,然后用六亚甲基二异氰酸酯(HDI)交联制备单畴取向偶氮苯液晶交联网络.通过核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)测试,对合成的Az-LCP进行结构表征,通过示差扫描量热分析(DSC)、X射线衍射(XRD)、偏光光学显微镜(POM)等对其液晶相变行为进行表征,研究了偶氮苯含量、交联密度、薄膜厚度对其光致弯曲行为的影响.结果表明,偶氮苯含量10%,交联12 h的Az-LCP1具有最佳的光致弯曲回复行为.