急冷温度及凝胶剂添加量对植物甾醇/谷维素油凝胶物理特性的影响

为促进植物甾醇/谷维素油凝胶在零反式、低饱和的营养型塑性脂肪中的应用,以大豆油为基料油,植物甾醇/谷维素为凝胶剂,在不同急冷温度(5、20℃)及凝胶剂添加量下制备油凝胶,测定不同急冷温度及凝胶剂添加量下植物甾醇/谷维素油凝胶的晶型、晶体形态、物理稳定性、质构和热力学特性的变化。结果表明：随着凝胶剂添加量的升高,油凝胶中晶体排列逐渐致密,硬度增大,熔点升高;尽管急冷温度对油凝胶的晶型(β晶型)没有明显影响,但相对于5℃急冷,20℃急冷得到的油凝胶晶体组装更为致密,物理稳定性增强;在与传统甘三酯固脂对比SFC与硬度和熔点的关系中发现,在油凝胶体系中熔点随SFC的增加呈现非线性关系增长,但低固体脂肪含量(4.85%)即可赋予植物甾醇/谷维素油凝胶较高的硬度。综上,急冷温度及凝胶剂添加量对植物甾醇/谷维素油凝胶的物理特性具有显著的影响。     

一种新型高储能密度定形相变材料

采用山梨醇和对甲基苯甲醛合成了1,3∶2,4-二(4-甲基苯甲醛)山梨醇(MDBS),并将其作为石蜡类定形复合相变材料(PCM)的凝胶因子,然后以利用凝胶因子形成的三维网络结构作为石蜡的支撑材料,制备了一系列高储能密度的定形复合相变材料。对其进行凝胶解缔温度测试和泄漏量测试发现,添加一定量MDBS制备定形复合相变材料,可使定形复合相变材料中主储能材料——石蜡的含量大幅提高到90%以上,同时也为复合定形相变材料的开发提供了一条新的研究思路。     

A Novel Route to Multiphase Polymer Systems Containing Nano‐Droplets: Radical Polymerization of Vinylic Monomers in Gelled Water‐in‐Oil Miniemulsions

Summary: A new strategy for the synthesis of composite polymers with larger volume fraction of aqueous inclusions less than 1 µm in diameter is presented. A water‐in‐oil miniemulsion of aqueous droplets in a continuous, cross‐linkable monomer phase is prepared. The addition of an organo‐gelator allows the immobilization of the droplets in a solid gel, thus avoiding the usual demixing upon polymerization of the continuous phase. This pregelled system is then converted into a composite polymer by photoinitiated free radical polymerization. Such coatings may be used for an improved climate control of buildings or as a deposit for the controlled release of actives from polar nano‐droplets.

SEM image of a cross‐linked composite polymer showing controlled droplet inclusions with a maximal diameter of 500 nm.     

相选择性超分子凝油剂的研究现状

针对近年来出现的较严重的海上溢油污染事故,分析了海上石油污染的原因及其治理措施,介绍了凝油剂的应用现状。对处理水中溢油较有前景的凝油剂,尤其是相选择性超分子凝油剂的研究现状进行了综述;主要介绍了糖类衍生型、氨基酸衍生型、胆甾衍生型和有机酸及其盐衍生型相选择性超分子凝油剂,指出了它们在制备新型低价、高效、环保、可重复利用凝油剂方面的巨大潜力。开发使用简单、室温下能快速胶凝溢油、形成凝油块强度高的相选择性超分子凝油剂,或将凝油剂和吸油剂相结合是将来的发展方向。     

含密胺基团的偶氮苯类凝胶因子的合成及其凝胶性能

以对硝基苯酚和三聚氯氰为原料,合成了含密胺基团的偶氮苯类凝胶因子AZO-1和AZO-2。考察了AZO-1和AZO-2的临界凝胶温度(Tc)和临界凝胶浓度(CGC),并利用SEM和紫外吸收光谱对凝胶的微观结构以及光响应行为进行了测定。结果表明,AZO-2较AZO-1具有更高的临界凝胶温度和更低的临界凝胶浓度,表现出较好的凝胶性能。AZO-1和AZO-2的凝胶纤维聚集结构不同,AZO-1纤维取向性较好,排列紧密;AZO-2纤维相互缠绕成三维网络结构,以簇状堆积为主。AZO-1和AZO-2经UV光照后仍可以稳定凝胶,但纤维形态结构发生了一定程度的变化。凝胶因子在不同状态下的红外光谱表明,分子间作用力在凝胶形成过程中起重要作用。     

The formation of supramolecular liquid-crystal gels for enhancing the electro-optical properties of twisted nematic liquid crystals

We report that the supramolecular liquid-crystal (LC) physical gel can be formed through the fibrous self-assembly of the polyfluorene-based π-conjugated polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), in twisted nematic LC system for the first time. With the utility of alignment layers, the F8BT molecules can be aligned and formed the LC physical gels with the formation of self-assembled supramolecular structures in the twisted nematic LCs. In contrast to conventional LC physical gels, the presence of anisotropic π-conjugated structure makes the twisted nematic LC system exhibit excellent electro-optical properties of driving voltage reduction and contrast ratio enhancement owing to the conjugated polymer having a high π-electron delocalization degree which can efficiently drive LC molecules in much lower operating voltages. The self-assembled supramolecular network has revealed the potential for applying in various LC display devices with the ability of improving their electro-optical performance.     

Enzymatic synthesis of mannitol dioctanoate and its utilisation in the preparation of structured edible oil

The medium‐chain dialkanoate of low‐calorie sugar and fatty acids which can be easily released is normally regarded as a potential candidate of gelator in structured edible oil preparation. This study focused on the synthesis, purification of mannitol dioctanoate and its utilisation in the preparation of structured edible oil. The mixture of acetone and n‐hexane with a ratio of 7:3 (v/v) was used as the media of the reaction, and the ratio of octanoic acid to mannitol was 3:1 with Novozyme 435 as catalyst. Then, the mixture was fractionated via water/n‐hexane extraction, and the purity reached 90%. HPLC‐MS, ¹H and ¹³C NMR analysis showed it was 1, 6‐di‐O‐octanomannitol, which is our target product. In structured vegetable oil preparation, 0.8–1.8% (w/w) addition of product can form gelation. The rheological measurements of the organogels showed G′, G″ increased during the first 2 weeks and then tended to be stable.     

基于POSS核凝胶因子的光、热双控液晶物理凝胶

本文创新性地将POSS核树枝状凝胶因子(POSS-G1-BOC)加入基体液晶分子5CB中,并且将偶氮苯化合物(Azo)作为光响应剂掺杂至该体系中制备得到液晶物理凝胶。通过管反演法、DSC、旋转流变仪等方法研究液晶物理凝胶的凝胶行为。采用SEM、紫外分光光度计、雾度仪等手段研究液晶物理凝胶的表观形貌、紫外吸收、透光率等。研究结果表明:在凝胶因子含量仅为0.5wt%即可形成凝胶强度良好的液晶物理凝胶,且此时体系溶胶-凝胶温度可达到111℃,远高于基体液晶的相转变温度35℃,具有良好的热稳定性。由于体系中偶氮苯光响应剂的存在,使得其对365nm紫外光及455nm蓝光也具有可逆的响应行为。本文成功地制备了具有光、热双控性质的液晶物理凝胶,为其在防伪商标、食品包装材料、光热传感器、生物医用材料等领域的应用提供了可能。     

A heat transfer model and supporting experiments to guide the uniform gelation of molecular oleogels during scale-up

The quest for novel vegetable oil structuring strategies has been progressing since the discovery of the deleterious impacts of trans fats. Although oleogelation using bioderived molecular gelators has been proven to be successful as an alternative to traditional hydrogenation methods, efforts are needed to meet the industrial requirements. A major constraint during the fabrication of oleogels is to achieve consistency in physical properties during scale-up. Experiments showed that gelation fails to occur when larger volumes were prepared based on the minimum gelation concentration (MGC) of gelators, determined using the smallest oil volume (1 ml), a general laboratory practice. This observation was consistent with all the molecular gelators used in this study; sorbitol dioctanoate, mannitol dioctanoate, and 12-hydroxystearic acid. To understand this behavior, a mathematical model was developed since gelator network propagation is governed by the cooling rate. The model indicates that maintenance of a minimal thermal gradient via uniform heat dissipation and gelation time is necessary to achieve homogeneous gel propagation across the vial. With these predictions, we hypothesized and confirmed that oleogels with constant surface area-to-volume ratio could result in identical gelation times and consistent physical properties (MGC, melting temperature, melting enthalpy, yield stress, solid phase content, and oil binding capacity) during scale-up.