w********h
发帖数: 12367 | 1 来自主题: Macromolecules版 - 推荐几篇文章 (1) 我说的是怎样才能证明是gel，不是说已知是gel怎么定gelation point；
(2) 对于我所说的gel，从G">G'到G"=G'最后到G'>G"是可以判定为gel的；
(3) 在我提供的第二篇文献中，谈到long chain branching与gelation的相似之处，
至于在第三篇文献中提到Winter用tan(delta)=G"/G'=constant来作为gelation point，
是指已知gelation或者类似的long chain
branching发生。但是不是损耗角一和frequency无关，就是gel呢？看看所有polymer的Ro
use region吧。另外有很多weakly associated的
gel有整个的flow regime, rubbery regime, glassy regime, 显然在大多数的情况
下G"/G'和频率是有依赖关系的，难不成它不是gel?所以我觉得Winter这个标准其实
只是一个general的标准，包括block copolymer disorder---order transition在
内的(如 |
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c*****e
发帖数: 238 | 2 大家有没有兴趣探讨一下physical gelation?
关于thermodynamics of gelation,有实验依据最好,已有的theory也可以.
本人倒是读过一些,包括M. Rubinstein, F. Tanaka, J. Joanny, A. Semenov..
不知道大家觉得哪个比较有道理.
physical gelation到底是不是thermodynamic transition,是什么样的transition.
与glass transition有多少关系,有什么不同? |
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c*****e
发帖数: 238 | 3
就
的
而
？
如
This is a good but unanswered question. If the bonding is permanent and you
are using monomer with multiple functional group, then gelation should always
happen as a result of percolation. If you have bi-functionalized monomers, the
number fraction of multiple functionalized monomers has to exceed some
critical ratio for percolation to occur. If the reaction rate is slow, my
expectation is that gelation will occur as the percolation process is fairly
well represented by the mean field |
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C**********e
发帖数: 3957 | 4 谢谢=D
原来那个莫名其妙的10分是您给的阿
刚才我还奇怪来着，所以准备捐了 =]
既然大叔知道意大利冰淇凌德工艺细腻，那肯定知道具体怎么细腻阿~
说说看做法，大家可以依葫芦画瓢的来个galeto或者gelator
ps:那个说意大利冰淇凌好吃的同学别生气，我想信下功夫的东西一定好吃；就是我说
话比较直... |
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d****i
发帖数: 360 | 5 One more paper please! Thanks a lot! E-mail: x**********[email protected]
Cho J, Heuzey MC, Begin A, Carreau PJ. Physical gelation of chitosan in the
presence of beta-glycerophosphate: the effect of temperature.
Biomacromolecules
2005;6:3267–75. |
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d********O
发帖数: 1196 | 7 Title: Preparation of macroporous methacrylate-based monoliths for
chromatographic applications by the Reactive Gelation Process
2010, Volume 1217, Pages 4675-4681
doi:10.1016/j.chroma.2010.04.077
Please send to D********[email protected] , if this is more convenient for you.
Thanks again! |
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b*****9
发帖数: 56 | 8 【 以下文字转载自 Macromolecules 讨论区 】
发信人: bobhu09 (bob), 信区: Macromolecules
标 题: paper help,thanks
发信站: BBS 未名空间站 (Thu Feb 3 14:50:58 2011, 美东)
Dietrich Stauffer, Antonio Coniglio and Mireille Adam, Gelation and
critical phenomena, Advances in Polymer Science 1982,44:103-158 |
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W*****s
发帖数: 684 | 10 Injectable and biodegradable hydrogels: gelation, biodegradation and
biomedical applications Yulin Li,João Rodriguesa and Helena Tomás
Chem. Soc. Rev., 2012,41, 2193-2221
DOI: 10.1039/C1CS15203C
Thanks! |
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w******e
发帖数: 953 | 11 Cellulose
June 2012, Volume 19, Issue 3, pp 687-694
Date: 29 Feb 2012
Gelation of cellulose nanocrystal suspensions in glycerol
Annie Dorris, Derek G. Gray |
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z**h
发帖数: 224 | 12 if G''/G' is independent of frequency, that is the gelation point.
you
hehe... |
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w********h
发帖数: 12367 | 13 个人感觉这个条件既不充分，也不必要。
倒象是block copolymer disorder to order transition在terminal regime的转折
点。
我们看一个东东是不是gel，首先要看这种weak association是不是足够强壮到出现
G'>G"的plateau regime. 如果作者根本就没有有强有力的证据说明这个gelation，
比如(1) 粘度是不是随温度etc有个sharp的增加？(2) 在某些 frequency region
G'>G". 如果这两个证据都没给，反而告诉我这个gel是fluid-like，我不能接受。
G">G'
】
is
differiente |
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c*****e
发帖数: 238 | 14 There is little doubt, if any at all, about the definition of chemical gel,
like rubber.
As for physical gel, no one understands what on earth it is.
Experimentalists tend to use the characteristic dynamic response as an
identification of gelation. This is not quite different from naked eye observation
of the gel phase in the solution.
Generally gel is believed to be an elastic liquid, with solid like behavior at
short time scales, but liquid like in nature. So far there is little satisfactory
d |
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z**h
发帖数: 224 | 15 at the gelation point, the G' and G" have the same dependence of frequency,
so the ratio is independent of frequency. P344, Polymer physics, Ralph,Colby.
decreases |
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z**h
发帖数: 224 | 16 来自主题: Macromolecules版 - 推荐几篇文章 xixi, i am right, i like it.
"The frequency independence of the loss tangent provides the most reliable and
generally valid rheological method to determine gelation."
tangent=G'/G" |
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w********h
发帖数: 12367 | 17 星型主要是因为arm retraction导致的contour length fluctuation。。。这是
目前流行的说法, who knows对不对。。。。
星型多臂也不接近枝化罢。。。
枝化分好几种：短侧链，长侧链，高度枝化。。。。
星型一般在制备过程容易做到monodisperse，
而枝化控制起来就不是那么容易，反应到一定程度突破percolation就gelation乐。。。 |
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s****e
发帖数: 2934 | 18 就讨论高分子缩聚的最普通的情况。本人认为，高分子在溶液中发生crosslink之后会出
现两种情况，一种是分子量增大到不溶于溶剂的地步从而沉淀，另一种是gelation，形成
整个network。区别是后者官能团的反应速度大于前者。我的想法对吗？各位有什么高见
？ |
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r******0
发帖数: 2753 | 19 Flory had covered gelation of radical polymerization, but it is different to
step polymerization model. |
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b*****9
发帖数: 56 | 20 Dietrich Stauffer, Antonio Coniglio and Mireille Adam, Gelation and
critical phenomena, Advances in Polymer Science 1982,44:103-158 |
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