f**********r
发帖数: 91 | 1 用THF溶解polymer（含有20%左右的disulfide键）做GPC的时候，发现含有disulfide
键的polymer在THF中会降解，过几个小时，分子量会变小一些，但是不知道为什么，按
理说这种polymer对氧气不敏感，氧气应该是往省城disulfide键的方向的。谢谢了。 |
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a*i
发帖数: 1652 | 2 Please see description below (LC experience is the key). No sponsorship for
green card; provides relocation assistance (Houston, TX). Please send me
your CV so I can forward to hiring manager.
Key responsibilities:
• Supervision of analytical scientists and technicians that provide
analytical support to key innovation projects, assist in addressing product
quality issues, and selected analytical services to key customer projects.
• Develop lab procedures and practices that supp... 阅读全帖 |
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s**********8
发帖数: 25265 | 4 柱子能tolerate多少醇? 加醇去non specific interaction, 对polymer.
protein该加盐? |
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C**********e
发帖数: 1608 | 5 FTIR也可以做定量分析。。GPC也可以。。。你要搞个REFERENCE，比如测一批已经知道
浓度的图谱，找特征峰做ANALYTICAL BAND。面积积分。推线性关系。。然后未知的再
倒推。。 |
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n**o
发帖数: 6 | 8 如果你能有任何合成的分子结构可以提供，请跟我联系。关键是价格和质量。价格要低
，质量要好。要货时能及时供货，并且分析数据齐全（一定要有核磁和质朴，最好有LC
/MS或HPLC图，高分子要有GPC图）
化合物多少都没有问题，能提供一个也行。关键要纯度。我们也不要签合同，也不需要
你的任何个人信息。具体的想法是这样的：货在你那儿，你只要给我发个list和结构图
，有人从我公司购买时，我会从payroll直接给你汇款，你再给我寄货。如能长期合作
，互惠互利。 |
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k*********h
发帖数: 1841 | 9 PDI小的话，做个GPC和NMR,可以算单体分子量也可以看特征峰 |
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g*****6
发帖数: 583 | 10 HPLC chemist. 主要做HPLC, 也做GPC, LC-MS.是从有机合成转过来的。想问问HPLC
chemist在公司里的稳定性怎样，job market怎样，是不是比合成的要好很多。
谢了 |
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B*****n
发帖数: 654 | 11 【 以下文字转载自 Texas 讨论区 】
发信人: Boolean (Soso), 信区: Texas
标 题: 能求个 工作推荐不? polymer chemistry 方向的
发信站: BBS 未名空间站 (Wed Oct 8 18:56:16 2014, 美东)
人在TAMU, 找工作中, 有人能帮帮忙么?
10+ years polymer research scientist/engineer with strong experience in
advanced polymer material synthesis and characterization. Expertise in
polymer coating, extrusion, casting films Rheology analysis of polymeric
systems, polymer additives R&D experience, polymer composites preparation
and nano-material synthesis & characterization. A... 阅读全帖 |
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v******r
发帖数: 292 | 12 东部留意高分子相关行业 碰到合适职位时注意把自己定义为 chemical engineer 或
polymer engineer/scientist,分析就换一个面具 哈哈
常见关键字 coating, product development, project management, process
improvement, process control; adhesive, thin film, design of experiment, 6
sigma, GPC, HPLC, MS, FTIR, SEM/TEM, rheology 等等 生化我已经很久没留意了,
好像大多都跟养细胞有关的。
syntheses 的建议就不要去做了,除非大公司 且待遇好
纯属个人建议,且听且珍惜 |
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q****i
发帖数: 6923 | 13 (3) Senior Polymer Scientist (Cleveland, OH)
Duties/Responsibilities:
•My exciting new Client is searching for a dynamic individual with
experience in organic and polymer synthesis, and polymer application
development. This Senior Polymer Scientist will be part of an application
development group of scientists and chemists. Responsibilities will include
conducting laboratory synthesis and polymer characterization, interpreting
and reporting results, maintaining instrumentation, documenting... 阅读全帖 |
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c***x
发帖数: 1990 | 14 你自己看看 这位号称高分子斑竹的LZ一年内都发过什么文章吧。
版内文章搜索列表
查找讨论区'Macromolecules'内， 标题含：'' 作者为：'qingxi'，'365'天以内的文章
序号 标记 作者 日期 标题
1 * qingxi Nov 3 chemistry posdoc opening
2 * qingxi Nov 17 Re: 在线急问
3 * qingxi Nov 17 Re: 20个包子求助
4 * qingxi Nov 23 请教一个很难的和分子量有关的计算
5 * qingxi Nov 23 Re: 请教一个很难的和分子量有关的计算
6 * qingxi Dec 9 Re: 一个关于Metathesis 中Ru Catalyst的问题
7 * qingxi Dec 9 Re: 请推荐本POLYESTE... 阅读全帖 |
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n*p
发帖数: 1253 | 15 ☆─────────────────────────────────────☆
qingxi (作为兔子一定要长得呆) 于 (Fri Jul 16 17:37:01 2010, 美东) 提到:
引言：
我曾经在mitbbs论坛发了有关妈妈的信息，http://www.mitbbs.com/article/ChineseMed/12563569_3.html 说西医正在谋杀我妈妈，受到很多人的指责，现在就让事实来说话。
我的妈妈胃癌晚期手术后化疗吃的东西全部呕掉，连水都喝不了，我们明智的放弃了痛苦的西医，转为中医治疗。在中医的治疗下，我妈妈再没有受任何罪，既不痛苦又恢复超快。一个月就能够逛街，做全家人的饭，两个多月诸症俱消，心情舒畅。最近看到买买提上很多绝望的人在发
兹瞬×饲笾急富ǖ羲谢睿以埠退且谎淖叩搅巳松淖畹凸取Ｋ煌氖牵笔蔽矣兄幸骄憷植康呐笥衙歉业闹С趾妥８＃易约阂布嵝胖幸侥芄话崖杪杈然乩础Ｎ艺夥菪⑿奶炜闪梦矣龅搅撕靡缴以说淖吖戳恕Ｎ腋庑┤朔⒐ㄒ樗强粗幸剑
有人搭理我，因为没有人相信。所以要把这个帖子发出来，让大家看一看我和妈妈共同经历的这个真实的故事。
我经妈妈同意，贴... 阅读全帖 |
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z*******g
发帖数: 9 | 16 Poly(1-vinylimidazole) (PVI)
Stable???I do GPC for it 3 times.It changed from time to time.Donno why.....
Thanks! |
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J******t
发帖数: 32 | 18 Try GPC first. It will give only one peak if it is copolymer.
A blend of two polymers will usually give two peaks due to the different
properties even if they have similar M and PDI.
Then you can try another experiment : Light or X-ray scattering.
I think this will take some time to get an answer, however it will usually
give a definite answer. |
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z***x
发帖数: 9 | 19 I have made a polyethylene. GPC shows two different peaks, each peak has the
PDI of around 1.1. and the first peak shows about two times molecular weight
of the second peak.
Is there any simple way to separate these two polymers.
Thanks a lot |
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w********h
发帖数: 12367 | 20 用GPC分离得多少时间啊？
的
CO
个
溶
the
weight |
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z***x
发帖数: 9 | 21 I need the polymer for NMR analysis.
and we don't have recycle GPC in my lab. //sigh.
and the polyethylene I made is perfect linear and very low molecule weight.
one is around 600(Mn), the other is around 2000 (Mn).
I think the fractionation by suitable solvent will be the easist way to carry
out. then the problem will be what kind of solvent and temperature. I wonder
if anyone can give me some hints.
Thanks
的
CO
个
溶
the
weight |
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k***i
发帖数: 2 | 22 now I have a SMA sample, Mw = 240kg/mol and MA = 2%(wt) (reported). I want to
analysize the maleic anhydride percentage in this random copolymer.
1, I coupled SMA with PEG-amine (5k), but it is difficult to seperate SMA-PEG
from the unreacted PEG-amine by solvent soluability; ( it is possible by GPC,
but i think it is boring, to slow)
2, By 13C-NMR, I got 4%. But I doubt this method.( could 13C-NMR be used to
analysize quantatively？）
are there any other better methods for this characterization? |
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u*****s
发帖数: 23 | 23 maybe you can use 2D H1 NMR. I have seen some book said that the monomer
percetange of random copolymer can be gotten from this method.
to
SMA-PEG
GPC, |
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c*s
发帖数: 2145 | 24 来自主题: Macromolecules版 - 有关ATRP ATRP聚合的产物做GPC时是否需要除铜离子？如何去除？3ks |
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y****u
发帖数: 50 | 25 I am a little puzzled. what is your question again?
If your concern is about the (number) average molecular weight of PMMA in
PSt-PMMA diblock copolymer: First get wt% of PMMA (by NMR or whatever), then
get Mn of diblock from GPC. |
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t***m
发帖数: 114 | 26 就是你说的这个
Mn from GPC or 膜渗透
wt% from NMR
then wt of PMMA segment |
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w********h
发帖数: 12367 | 27 我的低分子量的PBD(Mw=2K)GPC结果显示含有少量高分子量的东西（分子量大约60K)，
如何除去？我只要一点点纯的2K（大约0.5g)就可以了.过柱子这种方法就算了，我
等不及，最好是什么不同溶剂分几次的方法。什么溶剂比较好呢？toluene+环己烷？ |
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y****u
发帖数: 50 | 29 then ask Quirk to do it again
he won't fail you :P
我的低分子量的PBD(Mw=2K)GPC结果显示含有少量高分子量的东西（分子量大约60K)
？ |
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c****n
发帖数: 134 | 31 for well-defined polymers, NMR can be used to evaluate MW
If every polymer chain has a head group or end group,
we can use its integration intensity and that of the monomer units to cal. MW.
However, when MW is high, as the relative concentration of head group or end
group is quite low,
great error may occur.
GPC is good. but for a new polymer, you have need to know the dn/dc first. |
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c****n
发帖数: 134 | 32 just got the GPC results...
100% crossover; PDI < 1.1
it's just the first experiment hehe
I got the secret :) |
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t***m
发帖数: 114 | 33 en,i am using hyperbranched polymers
the GPC results have noticable difference with linear one
I got from DLS that single molecule is more sphere-like
compared with linear one |
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c****n
发帖数: 134 | 34 There is an amphiphilic triblock copolymer.
The center is hydrophobic, and the end blocks hydrophilic.
The hydrophilicity of the end blocks can be controlled
as the content of the -OH group can be controlled during polymn.
when the block copolymer with high -OH content is dissolved in THF,
it looks clear and homogeneous.
but the solution can't pass through a membrane for GPC sample preparation.
I believe it is because of the physical association of the end blocks...
but a group member said it co |
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w******r
发帖数: 43 | 35 1. What kind of filter did you use, nylon type or Teflon type? Or did you try
didfferent type filter?
2.You can try to dissolve your polymer in DCM and do the filtration again.
I do not think it was crosslinked. Even if there are some crosslinks in your
polymer, you should still be able to see some signals in the GPC trace.
blah)
membrane
can |
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d****n
发帖数: 237 | 36 这几天在网上寻找post-doc机会，一个老头从别人手里得到了
我的简历，今天中午问我什么时候可以毕业，晚上就问我能不
能phone conversation，我知道这相当于面试。问题是，这个
老头是搞分离的，而我除了用过GC,HPLC和GPC这几个设备之外
好像就和色谱没什么关系了。
我还没回复他面试的事情，但是就在这几天了。
我该准备些什么？ |
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h***s
发帖数: 111 | 37 I just made SBS triblock by coupling of S-x and y-B-y. How can I prove that it
is a triblock insted of SB diblock? PB has a PDI of 2. It is hard to tell by
GPC.
Thanks! |
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w********h
发帖数: 12367 | 38
我想三\四\五\六个arm都做阿。。。
快告诉我怎么控制单分散。。。。
我的GPC curve很正常阿，单个的对称峰
转化律底是个什么概念？就是反应时间稍微少一些是么？ |
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a***n
发帖数: 578 | 39 what is GPC? it is likely that the interviewer doesn't know as well. hehe |
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s*****o
发帖数: 65 | 40 It is true. The reaction of end group with initiator is very critical to the
polymer property. They have trouble on this now. So they also ask me study
stability.
Frictionate means to seperate it. I am think the end group may be seprated
from monomer by GPC. I am not sure too.
Two batches of monomer maybe means that they used different methods to make
it. I was surprised too. I asked two time. They told me two batch monomer are
really different.
they
because
like an
looks
email them
fractions. |
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s*****o
发帖数: 65 | 41 They didn't mention the difference. I was stupid today. I should ask very
clearly. I am afraid to ask too much to lose face.
This noon after I come back I sent a thank you note and asked the monomer
prepartion methods. I aslo suggested use UV, NMR,or IR. But I also said I keep
research to say if I can use GPC to find out the end group. The manager didn't
reply my email. Maybe no hope.
the
make
are |
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s*****o
发帖数: 65 | 42 Thank you so much for you advice. Can you tell me waht UV or Fluoresence can
detact what?
know
GPC. |
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s*****o
发帖数: 65 | 43 Thanks a lot for your help. You must be very good at polymer chemistry. I
have studied a polymer chemistry course. But I almost never used it. I mainly
work on polymer materails. So it is a hard job for me.
I plan to call or email the manager monday. I will tell him I can't test the
end group by GPC alone. I will combine some other methods.
I will send them email or call them monday ask
can
end
only
by |
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w***o
发帖数: 3830 | 44 GPC?
using light scattering |
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B****W
发帖数: 100 | 46 It's easy to be synthesized, but hard to be characterized. the polymer is not
soluble in common GPC solvent. I need to titrate the endgroups to get the MW,
and usually it's not accurate. So just try to save some time and trouble :) |
|
B****W
发帖数: 100 | 47 Actually I did find a paper using NMR to characterize the MW and
endgroup. I am going to try it.
Nylon dissolves pretty well in fluorinated solvent, and some alcohols. B
ut unfortunately, we only use THF for GPC in my school. Anyway, thanks :) |
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b***e
发帖数: 115 | 48 来自主题: Macromolecules版 - help who has the GPC molecular weight caculation program.
or where can I get a free one.
Thanks. |
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D********g
发帖数: 533 | 49 我个人觉得算出来的都是非常近似的值，而我更愿意去相信GPC的值而不是计算出来的
值~
我觉得你可以这样，一个分子单元的尺度应该是纳米级别的，你可以册出来整个链的长
度，看看这条链的聚合度有多少~
少. |
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c**********d
发帖数: 12 | 50 第一次做GPC。我也不太懂。 有熟悉的同学可否大概的科普一下？我的这个结果是不是
不太合理？
谢谢。 |
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