x**********1
发帖数: 28 | 1
stability
BASF 的pH 在7-9之间 |
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ik
发帖数: 167 | 2 This is the abstract:
The authors describe a highly sensitive colorimetric method for the
determination of ascorbic acid. It is based on the finding that nanosheets
of reduced graphene oxide that were functionalized with poly(sodium styrene
sulfonate) (PSS-rGO) possess peroxidase-like activity that catalyzes the
oxidization of the substrate 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to
form a blue product that can be quantified by photometry or visually. If
ascorbic acid is present, a fraction... 阅读全帖 |
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w********h
发帖数: 12367 | 3 anyway, Mn Mw issue is just for the sake of physics.
block copolymer chain: (Sty)n-----b-----(MMA)m
n Styrene segments and m MMA segments.
monomer |
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c****n
发帖数: 134 | 4 This criterion was listed in Quirk's book "Anionic polymerization",
but personally I don't think it is a good criterion.
Block copolymer may not be formed if you add propylene to living anionic
polystyrene...
block copolymer will be formed only when two monomer are similar in reactivity
in a specific polymerization (such as styrene and butadiene in anionic
polymerization). when the two monomers are quite different in reactivity, the
block copolymer may not be formed or there may be contaminatio |
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c****n
发帖数: 134 | 5 A thermoplastic elastomer...and I need to see the morphology
for butadiene and styrene, it is well-known.
but now I need to taint a poly(vinyl ether).
any idea? perhaps I can acknowledge you in a paper :)
(this is last result for a paper.
To measure the TEM, my boss has to cooperate with another prof.
with a promise of coauthorship...I am sad. I worked so hard, it is too easy
for the cooperator!) |
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b*o
发帖数: 47 | 6 Good discussion and it is becoming more interesting. The two premises you
pointed out are really my assumptions. Here we need to differentiate what we
mean by monomers in polymer physics and the real chemical monomers. If we take
the chemical sense, the monomer is not a kai=0 solvent for the corresponding
polymer, i.e., PS in styrene. In the physics sense, the monomer in the test
polymer should not be able to differentiate, in the aspect of nearest
neighbour interaction enthalpy sense, if its no |
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w***o
发帖数: 3830 | 7 啊？
MAO用的很广泛啊
都不光是metallcene体系吧。。。
styrene我总是觉得是electron density 不够
毕竟共轭着呢 |
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b**s
发帖数: 589 | 8 Look at this,
you will know why only this insite catalyst can polymerize styrene
A bond drag the metal and let it open up
I used to make a double core metallocene
so it can make PE with two different MW at the same time, double peak PE |
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a***n
发帖数: 578 | 9 any book desribe this? catalysts/conditions? thanks in advance... |
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c****n
发帖数: 134 | 12 random copolymer? very little information from Sci-finder
but you can try anionic copolymerization of st with butadiene
then hydrogenate the copolymer... |
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w********h
发帖数: 12367 | 17 my boss told me Langer initiated this idea six years ago and talked to him,
he didn't follow up, now Langer got eveything lah.
The first author did postdoc in Langer's group.
Before that, only several Macromol Chem Phys papers under Suter in ETH.
http://www.sciencemag.org/cgi/content/full/308/5719/236?maxtoshow=&HITS=10&hit
s=10&RESULTFORMAT=&author1=craig+hawker&searchid=1113597928104_10041&stored_se
styrene
and
and |
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d**a
发帖数: 3715 | 22 Probably some difunctional styrenes or curing points such as epoxy group in
it so that a long baking time is needed to crosslink them thermally. |
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s****e
发帖数: 2934 | 23 ☆─────────────────────────────────────☆
fishclistoff (一切靠人品) 于 (Wed Sep 6 12:20:38 2006) 提到:
got a question when reading a paper:
"After polystryene/toluene spin-coat, it was dried for 4 days at 70 C".
Why it needs such a long baking time, any particular reasons?
A beginner for polymer, thanks for helping out.
☆─────────────────────────────────────☆
dena (dean) 于 (Wed Sep 6 20:53:41 2006) 提到:
Probably some difunctional styrenes or curing points such as epoxy group in
it so that a lon |
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a*i
发帖数: 1652 | 24 来自主题: Macromolecules版 - 加热聚合？ styrene |
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m***n
发帖数: 70 | 25 来自主题: Macromolecules版 - 请教ATRP 一般常用的monomer如styrene, methacrylates, acrylates, acrylonitrile都可以的
。但是其他如acrylamides比较困难。
关于高分子量ATRP的文章好像已经有一些了，你可以查一下。
papers |
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w********h
发帖数: 12367 | 26 ***** Information for SoR Members *****
Rheologist - Requisition #0700420
Chevron Phillips Chemical Company LLC, and its affiliates, is one of
the world's top producers of olefins and polyolefins and a leading
supplier of aromatics, alpha olefins, styrenics, specialty chemicals,
piping,
and proprietary plastics. Chevron Phillips Chemical employs over 5,000
professionals at manufacturing sites and research / technology centers
around the world. Chevron Phillips Chemical has the people, assets,
an |
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s****e
发帖数: 2934 | 27 这个东西很毒，千万不要碰到皮肤上，手套至少要带3层，在hood里用，我们用0.5%的
溶液10分钟，sample放在一个玻璃的jar里面（close system），样品放在一个垫子上
，周围瓶底滴上RuO4溶液利用它的vapor就足够stain了，盖上盖子（盖子如果是金属的
，要垫上teflon sheet），10分钟，然后把sample拿走，用styrene monomer kill剩下
的RuO4，保证反应完全。sample拿去vacuum 几个小时，或overnight除水，因为RuO4是
aqueous。
非常非常毒，千万小心！！！尤其你第一次做没有经验，最好是和做过的人一起做。 |
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a*i
发帖数: 1652 | 28 I need to do copolymerization of MMA with Styrene
Is there any initiator commercially available?
ATRP is no-no for biomecial applications...Is RAFT okay?
Thanks! |
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y***e
发帖数: 6082 | 29 RAFT好点吧，你就用AIBN试试呗，不过现在老马在听说诸多牛人尝试ATRP搞生物应用，并
且提出催化剂的问题后，在不断完善和改进，未来ATRP搞出个道道来，都是为他攒了rp
I need to do copolymerization of MMA with Styrene
Is there any initiator commercially available?
ATRP is no-no for biomecial applications...Is RAFT okay?
Thanks! |
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t***u
发帖数: 20182 | 30 MMA和styrene？你搞block，还是random？ |
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c*s
发帖数: 2145 | 31 除了水意外 POLY STYRENE SULFONATE |
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c*s
发帖数: 2145 | 32 Certainly one can make a great deal of this claiming. Maybe next step he can
also make deal of "acrylic-styrenic hybrid system" or sth else, hehe |
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k*******n
发帖数: 2399 | 33 本人本身不是做高分子聚合的，只是在一个particle stablized emulsion体系里面用
了styrene作聚合单体。发现增加里面的particle浓度导致聚合速率降低，该particle
是7% 的SWNT负载在SiO2上。增加particle浓度从表观上是减小了聚合物颗粒的大小(~
um)。我看见不少emulsion polymerization都是增加particle浓度增加了反应速率，因
为emulsion droplet变小的话会导致反应体系compartamentalization降低bimolecular
termination的可能。我现在怀疑是不是该颗粒会quench聚合的radical，本人用AIBN
作为引发剂。该颗粒具有SWNT, COOH, Co, Mo和SiO2在表面上。本人提出另外一个可能
是emulsion drop变小，减少了monomer bimolecular reaction的速率。 那种更具有可
能性。先谢谢了。 |
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k*******n
发帖数: 2399 | 34 为什么用引发剂不同就不是emulsion polymerization了？是不是emulsion
polymerization应该是由反应体系本身决定的吧？不同的是我用了SWNT/SiO2
nanoparticle作为emulsion stablizer。 体系见Http://pubs.acs.org/doi/abs/10.1021/la901380b。我目的是为了用这个emulsion system可以不需要加入表面活性剂直接制备sphere-size的CNT/Polymer composites。在解释的时候，比较迷惑的是为什么particle加入多会导致styrene conversion速率降低。 |
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t***u
发帖数: 20182 | 35 那这个就是pikering emulsion。我猜，假设所有initiator都在core里面，如果增加
particle浓度，droplet变小，但是数量会增多，总体来说core里面styrene对于
initiator的相对浓度降低，所以速度降低，这个反应用的多少度？AIBN的t1/2不一样
吧。 |
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k*******n
发帖数: 2399 | 36 这的确是属于pickering emulsion polymerization，每个反应体系AIBN initior,
styrene,和water的用量都是固定的，不同的只是改变emulsifier particle的浓度。表
观上，正如你所说的，聚合反应的vessel变小。反应温度是65度。我估计是particle可
能会终止链增长。 |
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r******0
发帖数: 2753 | 37 其实你已经说了你不是学高分子化学的，或许我就不该对你这么挑剔。但我觉得还是有
必要提醒你一下，你做的这个严格来说不能叫emulsion polymerization。不管你别的
东西怎么变，styrene + AIBN 这个组合怎么做都不会是emulsion polymerization，只
会是suspension polymerization。不信的话，你去看看emulsion polymerization的定
义是怎样的。 |
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d**a
发帖数: 3715 | 38 Thank you so much for your reply.
Can I purify the styrene using a silica gel column?
Yes. A is a aromatic solid compound and easy to dissolve in toluene.
Then what your suggestion for the reaction time,temperature, and the
selection of initiator?
Thanks.
A |
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a*i
发帖数: 1652 | 39 I would polymerize styrene first. If PS is obtained, I'll go ahead with
copolymerization under the same condition. Otherwise, you shouldn't worry
about copolymerization in the first place.
group
commercially
, |
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d**a
发帖数: 3715 | 40 Thank you all for your help. The reason I used a solvent is that because my
monomer is a solid at R.T. As agi suggested, I will try to polymerize
styrene first in a 5 g scale, using 1/100 molar ratio of AIBN in THF at 65 oC overnight. |
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r******0
发帖数: 2753 | 41 It might be easy to do the polymerization but it could be a little bit
harder to prove that your monomer COPOLYMERIZED with styrene. |
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d**a
发帖数: 3715 | 42 How about a high resolution NMR? I think it is easy to prove the existence
of my monomer but not styrene. |
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r******0
发帖数: 2753 | 43 It could be hard to prove that you get the copolymer instead of a mixture of
two homopolymers. Now u may have proved that your monomer can be
polymerized but u cannot say it can copolymerize with styrene. |
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a*i
发帖数: 1652 | 45 yes. Perhaps I just discovered something big in Polymer Science...
will run GPC... |
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a********c
发帖数: 60 | 46 Most likely you got somethingelse there. I'd be suprised if you can
repeat it.
in a |
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r******0
发帖数: 2753 | 47 I bet redox initiation.
with
and |
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d**a
发帖数: 3715 | 48 en,make sense. Previously this monomer has been successfully copolymerized
with styrene in a molar ratio of 50/50. I will try a living polymerization
to see what will happen. |
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d*****i
发帖数: 77 | 49 带thio的Macro chain transfer agent （如P4VP-CTA)加AIBN和monomer（如styrene）
能用RAFT合成纯P4VP-co-PS 的block copolymer吗？没做过RAFT。不过从机理来看理论
上应该会有一半是PS 的homopolymer啊！
不知我是否理解有误。请大侠指教！
拜谢！ |
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b******0
发帖数: 45 | 50 为什么加这么多AIBN？
和反应温度有关，AIBN和polymer-CTA比是2：1，也未必结果不好。
styrene 温度高的话，不需要引发剂也行。
反应控制不好，可能有些其它中止的PS均聚物。试试沉淀在cyclohexane里，或者用
cyclohexane洗掉PS均聚物 |
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