THE POLYMERIZATION OF MONOSILICIC ACID
THE POLYMERIZATION OF MONOSILICIC ACID
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DOI：
10.1021/ja01637a017
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发表时间：
1954-01-01
影响因子：
15
通讯作者：
ALEXANDER, GB
中科院分区：
文献类型：
--
作者：
ALEXANDER, GB
本文研究了一元辛酸在0.1摩尔溶液中于1.90 ℃下在pH值约为1 ~ G范围内的聚合反应。它的结论是，必须有不同的机制，为聚合反应在1.90以上和以下约pH 3.2，因为在这两个范围内的聚合速率曲线的斜率是完全不同的。在低pH下，聚合度随时间的平方根线性增加。同样在此范围内，聚合物似乎相对均匀，分子量分布均匀，而在pH 3以上，获得更不均匀的分布。在pH值为6时，一元酸几乎瞬间聚合。聚合反应不仅受pH影响，而且速率随温度升高、浓度升高以及某些催化剂（特别是低pH下的氟离子）而增加。而分子量分布的指示是通过测量聚碳酸酯解聚的速率获得的。在钼酸存在下聚合形成硅钼酸。
The polymerization of monosilicic acid in 0.1 molar solution at 1.90 has been studied over the pH range of about 1 to G. It is concluded that there must be different mechanisms for polymerization of silicic acid at 1.90 above and below about pH 3.2, since the slope of the polymerization rate curves is quite different in these two ranges. At low pH, the degree of polymerization increases linearly with the square root of time. Also inthis range, the polymer appears to be relatively homogeneous with regardto molecular weight distribution while, above pH 3, a more heterogeneous distribution is obtained.. At pH 6, monosilicic acid polymerizes almost instantaneously. Not only is polymerization influenced by pH, but the rate increases with increasing temperature, increasing concentration, and also by certain catalysts, particularly fluoride ions at low pH. The number average molecular weight of the polysilicic acid was determined by the freezing point method, while an indication of the molecular weight distribution was obtained by measuring the rate at which the polysilicic acid depoly-merizes in the presence ofmolybdic acidto form silicomolybdic acid.