Facile synthesis of branched poly(vinyl alcohol)s
Facile synthesis of branched poly(vinyl alcohol)s
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DOI：
10.1021/ma061221d
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发表时间：
2006-08-08
期刊：
影响因子：
5.5
通讯作者：
Sherrington, D. C.
中科院分区：
文献类型：
--
作者：
Baudry, R.;Sherrington, D. C.
聚乙烯醇(PVOH)是一种普遍存在的合成聚合物，广泛应用于生物和医疗产品以及个人、家庭和工业产品。目前可用的材料范围都具有线性主干结构，具有有趣的溶解性、流变性和界面性质。如果能够合成具有支化主干结构的互补聚合物，特别是如果方法与目前的方法只有很小的变化，那么后者可能会大大拓宽。我们现在已经通过传统的由乙酸乙烯酯(VAc)和三烯丙基三氮杂三酮(TTT)在2-异丙氧基乙醇(IPE)溶剂中和合适的硫醇自由基链转移剂存在下的自由基共聚合合成了支化的PVOHs，然后将支化的聚乙酸乙烯酯S(PVAc)S(PVAc)与甲醇醇解。平衡TTT和硫醇的摩尔比，可以实现对支化材料的高转化率，同时抑制产品的交联和凝胶化。来自TTT共聚单体的支化点在醇解步骤中被证明是保守的，使用多检测器尺寸排除色层(SEC)仪器对PVAc前体和衍生的PVOHs进行了广泛的表征，证实了这两类聚合物的高度支化性质。通过对一些样品的重新乙酰化，最终确认了PVOH样品的支化结构，实际上是为了再生它们的PVAc前体。SEC对后者的分析确实表明，它们在结构上与最初的前体PVAcs非常相似。这种合成支化PVOHs的新方法对目前使用的线性PVOHs的工业工艺进行了相对较小的调整，因此具有良好的放大和开发前景。
Poly(vinyl alcohol) (PVOH) is a ubiquitous synthetic polymer that finds widespread application in biological and medical products through to personal, domestic, and industrial products. The currently available range of materials all have linear backbone architectures with interesting solubility, rheological, and interfacial properties. The latter might be significantly broadened if complementary polymers with branched backbone architectures could be synthesized, especially if the methodology involved only minor changes from that currently practiced. We have now synthesized branched PVOHs via conventional free radical copolymerization of vinyl acetate (VAc) and triallyl-triazine-trione (TTT), in 2-isopropoxy ethanol (IPE) solvent in the presence of appropriate thiol free radical chain transfer agents, followed by alcoholysis of the so-formed branched poly( vinyl acetates)s (PVAc) s with methanol. Balancing the mole ratio of TTT to thiol allows high conversion to branched materials to be achieved while inhibiting cross-linking and gelation of the products. The branch points derived from the TTT comonomer have been shown to be conserved during the alcoholysis step, and extensive characterization of the PVAc precursors and the derived PVOHs using multiple detector size exclusion chromatographic ( SEC) instrumentation has confirmed the highly branched nature of both groups of polymers. Final confirmation of the branched architecture of the PVOH samples has been made by reacetylation of some samples, in effect to regenerate their PVAc precursors. SEC analysis of the latter has indeed shown these to be architecturally very similar to the original precursor PVAcs. This novel methodology for synthesizing branched PVOHs involves relatively minor adjustments to the currently used industrial process for linear PVOHs and so offers good prospects for scale-up and exploitation.