It looks like that the "acrylamate units" in your context actually refers to "acrylamide units".

If I am not wrong, your text is from this article "Adsorption of Polyacrylamide on Smectite, Illite, and Kaolinite" at
http://soil.scijournals.org/cgi/content/abstract/70/1/297

This article is talking about "polyacrylamide". Its subunits should be acrylamide, not "acrylamate". Please see the following references about polyacrylamide (聚丙烯酰胺) and acrylamide (丙烯酰胺).

http://en.wikipedia.org/wiki/Polyacrylamide

"Polyacrylamide is an acrylate polymer (-CHCHCONH2-) formed from acrylamide subunits that is readily cross-linked."

http://en.wikipedia.org/wiki/Acrylamide

"The chemical compound acrylamide (acrylic amide) has the chemical formula C3H5NO. Its IUPAC name is 2-propenamide."


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Note added at 15 hrs (2006-11-06 18:47:54 GMT)
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The U.S. patent 4,743,388 John Xu cited is exactly the same as what Joysong cited at http://www.proz.com/kudoz/1612332

If you look at the PDF file that Joysong cited:
http://www.freepatentsonline.com/4743388.pdf
you will see that there is no double C=C bond in the formula of "substituted acrylamic acid (V)". Therefore, it can't be called as "丙烯酰胺酸" (which doesn't even exist).


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Note added at 1 day16 hrs (2006-11-07 20:06:39 GMT)
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To make my point simpler, the word "acrylamate" in this context is a typo. It may also refer to "acrylate".

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Note added at 1 day16 hrs (2006-11-07 20:10:59 GMT)
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It was found that the words "acrylamate" or "polyacrylamate" that appeared in some other on-line articles were also typos. In some cases, it actually refers to "acrylamide" or "polyacrylamide", respectively.

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Note added at 3 days16 hrs (2006-11-09 19:28:21 GMT)
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有人坚持认为"acrylamate"应译为“丙烯酰胺酸酯”。我在此简单说明一下，为什么“丙烯酰胺酸”和“丙烯酰胺酸酯”根本不存在。顾名思义，“丙”就意味着此化合物含有三个碳原子，“烯”就意味着含有碳碳双键，“酰胺酸”就意味着它同时含有“酰胺基”和“羧基”。实际上，在这一含三个碳的化合物中，烯、酰胺、酸三者不可能得兼。只有在含四个或四个以上碳原子的化合物中，烯、酰胺、酸三者才可以得兼，例如，顺丁烯酰胺酸，俗称马来酰胺酸(maleinamic acid)，其化学式是HOC(=O)CH=CH－C(=O)NH2。

我们先看一看“丙酰胺酸”。“丙酰胺酸”是存在的，但它的分子中不含碳碳双键。丙酰胺酸的英文名称是malonamic acid或2-carbamoylacetic acid，化学式是HOC(=O)CH2－C(=O)NH2。 下一链接显示了它的结构式：
http://ctd.mdibl.org/voc.go;jsessionid=0C865B159B6F67AC10224...

众所周知，一个碳原子只有4个价电子，它最多只能形成4根共价键。上述丙酰胺酸中任一端的那个碳原子已经不可能再与中间的那个碳原子形成双键。换言之，无论HOC(=O)=CH－C(=O)NH2还是HOC(=O)CH=C(=O)NH2都是不可能存在的。学过有机化学的人，只要画一画结构式，就会明白“丙烯酰胺酸”是不可能存在的。“丙烯酰胺酸酯”当然就更不可能存在。

之所以化些时间再作以上说明，只是为了纠正一个错误概念。KudoZ points对我而言，并不重要。