Influence of length and structure of aryl boronic acid crosslinkers on organogels with partially hydrolyzed poly(vinyl acetate)
Influence of length and structure of aryl boronic acid crosslinkers on organogels with partially hydrolyzed poly(vinyl acetate)
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DOI：
10.1007/s00396-018-4326-7
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发表时间：
2018-06-01
影响因子：
2.4
通讯作者：
Weiss, Richard G.
中科院分区：
文献类型：
--
作者：
Duncan, Teresa T.;Weiss, Richard G.
由40%水解的聚醋酸乙烯酯（40PVAc）和三种芳基硼酸组成的有机凝胶，并在几种液体中进行了表征，以了解交联剂的长度和结构对凝胶性能的影响。来自H-1核磁共振、稳态和时间分辨荧光以及流变学的数据被用来关联交联程度和凝胶的整体物理性质。苯-1,4-二硼酸（1,4- bdba）和4,4'-联苯二硼酸（bPDBA）与40PVAc形成的凝胶比苯-1,3-二硼酸形成的凝胶稳定时间更长。令人惊讶的是，在溶液中添加两种模型二醇（1,3-丙二醇和1,2-乙二醇）甚至40PVAc时，1,4- bdba或bPDBA的稳态和时间分辨荧光性质几乎没有受到影响。此外，与1,4- bdba相比，40PVAc似乎更有效地形成交联，从而产生更硬的凝胶。我们将这些趋势归因于bPBPA更长的长度、灵活性和线性。总体而言，本文报告的结果表明，交联剂的微小结构变化可以显著改变双组分有机凝胶网络的许多体积性质。它们还为制造具有特定所需性能的凝胶提供了清晰的“蓝图”，适用于需要几乎无水系统的一系列应用。
Organogels composed of 40% hydrolyzed poly(vinyl acetate) (40PVAc) and three arylboronic acids have been formed and characterized in several liquids to gain insights into the role of crosslinker length and structure on the properties of the gels. Data from H-1 NMR, steady-state and time-resolved fluorescence, and rheology have been employed to correlate the degrees of crosslinking and the bulk physical properties of the gels. Benzene-1,4-diboronic acid (1,4-BDBA) and 4,4'-biphenyldiboronic acid (bPDBA) formed gels with 40PVAc that were stable for longer periods than those with benzene-1,3-diboronic acid. Surprisingly, the steady-state and time-resolved fluorescence properties of 1,4-BDBA or bPDBA were affected very little in solution upon addition of two model diols (1,3-propanediol and 1,2-ethanediol) or even 40PVAc. Furthermore, 40PVAc appeared to form crosslinks more efficiently, resulting in stiffer gels, with bPDBA than with 1,4-BDBA. We attribute these trends to the greater length, flexibility, and linearity of bPBPA. Overall, the results reported here demonstrate that minor structural changes in the crosslinker can alter significantly many of the bulk properties of two-component organogel networks. They also provide a clear 'blueprint' for making gels with specific desired properties for a range of applications that require virtually water-free systems.