z**h
发帖数: 224 | 1 diblock copolymer phase separation happens when chiN>10.5 from mean filed
theory.
structure
的block的平均长度决定,在这种近似下每一种segment的block的等效长度大概是N^(1/2) |
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c*****e
发帖数: 238 | 2 Forgot to mention that this criterion is for symmetric diblock copolymers.. |
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z**h
发帖数: 224 | 3 no, it is not only for symmetric. for symmetric diblock copolymer, lamellae
morphology will form after phase separation. with the change of volume
fraction of two blocks, the morphology will change also.
filed
的block的平均长度决定,在这种近似下每一种segment的block的等效长度大概是N^(1/2) |
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z**h
发帖数: 224 | 4 yes. for asymmetric it is bigger than 10.495
diblock
lamellae
copolymers..
的block的平均长度决定,在这种近似下每一种segment的block的等效长度大概是N^(1/2) |
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r****r
发帖数: 14 | 5 That looks right. Wunderlich has a paper about the Tg of two components in
block copolymers. He concluded that the two Tg will get closer to each other
and glass transition region will be broader. |
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c****n
发帖数: 134 | 6 It was covered in the qualification Exams last winter.
I can only remember that
Poly(vinyl carbazole) is photoconductive, and it can be used in photocopying.
This semester, I proposed synthesis block copolymer with PVK segment.
but the boss told me to leave it out. |
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w********h
发帖数: 12367 | 7
photocopying.
why?
When I worked on conjugated polymers, I once thought of systhesizing a
copolymer containing PVK and my original conjugated segments. Later I found
it is very conplicated and I was busy with other parts, so gave up leh. |
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w******r
发帖数: 43 | 8 Here is a review by Montaudo
"Mass Spectra of Copolymers"
Mass Spectrometry Reviews, 2002, 21, 108-144.
to
group |
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c****n
发帖数: 134 | 9 not PIP but PIB.
since the diblock copolymer is soluble in DMSO,
I have checked the structural integrity by NMR.
and----the homoPVA prepared in similar way was soluble in water.
is |
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c*******n
发帖数: 1648 | 10 It's very interesting result from cation. Argon's idea is pretty interesting
too, but his theory can not explain your homoPVA is soluble in hot water.
However, one point in Argon's post is very important. That's aggregation
effect. Again cation said homoPVA is soluble in hot water, but block is not.
Then there must have something to do with PIB block. Your system make a strong
segregated block copolymer system. Long range orderness can play very
important
role in your system. (Either BCC or FCC? |
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t*******n
发帖数: 66 | 11 Acording to my opinion, about one third of the paper in chemsitry is related
to the polymer to soem extent. The supermolecualr strcuture intitaed by block
or graft copolymer can be a great impact in teh future applciaiton in
optical, electronic and catalytis. The self -assembly with the polyemrs is
also a kind of promising research. |
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w********h
发帖数: 12367 | 12
block copolymer根据组成比不同会有miscrophase separation。
从sphere结构cylinderical结构到lamellae结构的变化，
再细致观察，在cylindrical与layer结构之间，
有两个复杂的结构，
一个叫做Bicontinuous,
一个叫做perforated layers (HPL)结构。
其中bicontinuous结构又叫double gyro phase,
也因结构复杂被称为“水管工的噩梦”。
大分子如何运动。
通常三种理论：Zimm, Rouse, and Reptation.
在polymer chain 高于一个临界分子量Mc的时候，
粘度的分子量依赖关系由M^1变化到M^3.4.
Mc通常和一个叫做entanglement molecular weight Me的量有关系，
Mc--2~3 Me.
对于不同种类的聚合物，Me不同。
在形容M>Me的聚合物，通常用Reptation理论，
由de Gennes首先提出tube model and snake-like motion,
Doi and Edwards |
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c***r
发帖数: 4631 | 13
Not really, I only do TEM for him, and he was focusing on block copolymer. And
I don't remember anything about that in his research. |
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c***r
发帖数: 4631 | 14 Do you ever think grow polymer-lithium battery from diblock or tri-block
copolymer directly on the IC? Or call it "Nano-battery"?
in
recently
with |
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m***n
发帖数: 266 | 15 Tg大於37C，还是小於37C，更容易降解？
为什么PGA-PLA的copolymer随PLA的量增大降解速度增快？ |
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w******z
发帖数: 29 | 16 The simplest one is Fox Equation: 1/Tg=w1/Tg1+w1/Tg2 |
|
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b***e
发帖数: 115 | 18 it seems there is the same formula in blends |
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w********h
发帖数: 12367 | 19
I
is
unperturbed
This one? Seems nobody cited.
What is the unperturbed state in polymer solutions?
Ganazzoli F
MACROMOLECULAR THEORY AND SIMULATIONS
9 (8): 682-686 NOV 14 2000
Document type: Article Language: English Cited References: 33
Times Cited: 0
Abstract:
Full Paper: We report theoretical results about amphiphilic random copolymers
in a quasi-ideal conformation with an overall size very close to that of the
analogue homopolymers. We found that a few states may coexist with |
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c*******n
发帖数: 1648 | 20 Just read the story in C&E but I don't have online resources of NATURE. It has
sth to do with pressure phase diagram. However, it's interesting to see that
the molded samples are transparent. What does the "core-shell" mean in the
paper? Something like micron size particles in HIPS, but smaller? Is it
poly(butyl acrylate) grafted with polystyrene? Microemulsion polymerization?
I have read her similar paper, but that's not something new, just
Todt for a block copolymer. It seems that this time, s |
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t*******s
发帖数: 9 | 21
化学基本是新科PHD，做的大多是nano和bio相关的。
催化剂只是一个小部分。物理方面，Block Copolymer的形态（加电磁场作用）
，和表征是一大块。聚电解质（DNA）的方面，表面吸附，自组装，理论和模拟，
也有好几个在做。工程，一个做传统的机械性能，一个刚招的PHD，做
表面adhesion 和combinatory screening。 |
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j****e
发帖数: 1 | 22 anybody can help me get this paper? Thanks a lot!
Acrylamide and polyarylamide 99
Published: Jun-76
This report deals with acrylamide and polyacrylamides. Acrylamide manufacture
by sulfuric acid hydrolysis and by catalytic hydration is evaluated.
Manufacturing processes for homopolymers and for copolymers having acrylamide
as the main component, as well as processes for derivatives of such
homopolymers .... |
|
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b***e
发帖数: 115 | 24 Okamoto, Shigeru; Yamamoto, Katsuhiro; Nomura, Kanako; Hara, Shigeo; Akiba, Isamu; Sakurai, Kazuo; Koyama, Atsushi; Nomura, Masaharu; Sakurai, Shinichi. Crystallization in Microdomains of a Block Copolymer Comprising Semicrystalline Block Observed by
Simultaneous Measurement of SAXS and WAXS with Hv-SALS or DSC. Journal of Macromolecular Science, Physics (2004), 43(1), 279-296. CODEN: JMAPBR ISSN:0022-2348. AN 2004:95230 CAPLUS
Thanks,
please send it to k*[email protected] |
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w********h
发帖数: 12367 | 25 Bates and Lodge already published something about this bah.... |
|
z**h
发帖数: 224 | 26 what determines the shape of the micelle?
Talmon, |
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c*****e
发帖数: 238 | 27 From scaling theory, this should be determined by the interaction between
polymer segments and solvent as well as on the concentration of the polymer. |
|
b**m
发帖数: 18 | 28 NYLON在300C的时候可以通过INJECTION MODING加工，有没有什么POLYMER在室温甚至0C的
时候就可以被这么加工？
一般来说Molecular Weight下降Tg减小。如果NYLON的MW减小Tg是否会降到室温？
多谢。 |
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w********h
发帖数: 12367 | 29
MODING加工，有没有什么POLYMER在室温甚至0C的
low Tg..
PIP, -60
PBD, -100
then that molecular weight is still useful? |
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b**m
发帖数: 18 | 30
Thanks a lot.
Are these polymers still solid at room temp? (For example, at the temperature
higher than Tg by 100C nylon is actually a liquid)
What will happen if we try to intrude nylon at room temp. using very high
pressure? Will it flow plastically? |
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w********h
发帖数: 12367 | 31
temperature
PIP and PBD surely are solid at room temperature..
I think the answer is yes. But I don't know this part in detail. |
|
b**m
发帖数: 18 | 32
Is PBD polybutadiene? Is it the official name of rubber? How come rubber (not
thermoplastics) can be extruded...? Thanks a lot. |
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w********h
发帖数: 12367 | 33
(not
yes. majorly 1,4-polybutadiene.
because they have low Tg and rubberlike at room temperature.
if the room temperature is 200C, plastics also becomes rubber, ;-) |
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b**m
发帖数: 18 | 34
Correct me if I am wrong. Rubber is rubber-like because of the low crosslink
density. If the crosslink density is 0, it becomes a thermoplastic, and if the
crosslink density is high, it is a thermoset. Based on this understanding, why
a thermoplastic turns to a rubber when Tg is reached? |
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w********h
发帖数: 12367 | 35 hehe, you must be in polymer engineering.
our languages are quite different.
my understanding is this:
your crosslink density is my entanglement molecular weight Me,
the lower Me, the higher crosslink density.
when Me=M0 (monomer molecular weight), it is crosslinked (also called
thermoset). is that right?
PS Tg=100C Me=18000g/mol
PBD Tg=-100C Me=1543g/mol
PS is normally glass-like (or thermoplastic) at room temperature because of
its high Tg.
When you increase your temperature to 130 to 150C,
yo |
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d****g
发帖数: 164 | 36 Good job! Wonderlich tongxue gave a clear explanation from the standpoint of
polymer dynamics. But I feel that you are still talking with different
languages. I have seen some rubber processing because my graduate lab in china
mainly worked on rubber, hope I can bridge your gap somehow.
Virgin PBD Rubber itself is thermoplastic before adding crosslinking agent
such as S. But PBD chains is crosslinked after the thermal processing with the
reaction of crosslink agent, thereafter it is thermoset. B |
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w********h
发帖数: 12367 | 37
china
the
yes. I am not talking about crosslinked (even slightly crosslinked) PBD.
yes, viscoelasticity.
of |
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b**m
发帖数: 18 | 38
of
Thank you so much, wonderlich and dafeng. You two debugged a long-time
misunderstanding in my mind. :-)
BTW, sometimes we classify polymers into three catagories: thermoplastics,
rubber, and thermosets. In this case, "rubber" is refered to the cross-linked
rubber. Is this correct? The difference between the three is mainly the
cross-link density.
polymer
this |
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d****g
发帖数: 164 | 39 Not exactly, I think this is the origin of your confusion. thermoplastic and
thermoset are talking about the repeating processability of plastics. I think
crosslink density is usually specific for rubbers.
It might be a convenient to manage the knowledge with familiar concepts, but
it is not necessary to be accurate. I encourage you to check a polymer physics
text for the accurate answer.
standpoint
agent
with
still
is
cross-linked
crosslinking). |
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c*******n
发帖数: 1648 | 40 comments, just because I was a polymer engineer before. Nylon can be
extruded just above its melting temp, not necessary at as high as 300C. Think
about their molecular weight and rheological curves. Not much relate to Tg.
Most of properties relate to crystallizations and h-bonds. Of course polymers
can be processed at room temp. Check rubber injection molding work or anybody
you know in Isayev's group. Even nylon solid can be processed at room
temperatures by pulverniztion using a specific extr |
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p******s
发帖数: 137 | 41 polymer ah...copolymers..
why they all like to get some porous materials? |
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y***e
发帖数: 6082 | 42 是高分子介孔材料吧
polymer ah...copolymers..
why they all like to get some porous materials? |
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c*******n
发帖数: 1648 | 43 Forgive my simple mind, I considered things from homopolymer point of view.
You already made excellent points. Proteins are way beyond the homo or block
copolymer level in terms of energetic combinations(of conformations). However,
based on your comments, manupulating surface of man-made materials still can
lead to success unless the signal mechanism proposed by boss is right. The
first thing caught in my mind is to understand how those proteins interact
with vesell surface. Why don't they aggre |
|
z**h
发帖数: 224 | 44 polymers.
any connection between spinodal decompostion and nanophase seperation of
diblock copolymers? |
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c*******n
发帖数: 1648 | 45 Or block copolymer system? to get well defined particle size and morphology?
After that, cleave one block off to get particles:) |
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c*w
发帖数: 50 | 46
Not exactly correct. PLA, PLGA and PLGA are hydrophibic, which makes the
implants or drug delivery devices opsonization in vivo. such shortcoming
results in a lot of work on the synthesis of Poly(ethylene glycol)-pLA
copolymers. |
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w********h
发帖数: 12367 | 47 刚才在整理我的硬盘（顺便问一下电脑通现在流行硬盘多少个G了？）时，
看到以前down的一个北卡的教学用powerpoint,
上面图示已经表明，五十年高分子材料的时代已经过去，
取而代之的是biomaterials, nanomaterials, and biomimic materials.
恍然想起这个我上个月提的话题以及cashine今天姗姗来迟的回应：
高分子科学，你是这个世纪的伴娘科学？
答案很遗憾，是的，它是。
但不意味着它丧失它的重要性。
高分子科学中高分子物理在1940年到1990年50年间已经构建成功，
剩下的人们在围绕reptation model进行对复杂体系的进攻；
高分子化学随着1995年ATRP的一声炮响沉寂多时，
小打小闹着为着所谓“分子设计”“分子裁剪”贡献着一批
又一批可能有用但更可能无用的block copolymer们。
高分子材料领域套着如今材料科学的东风和众多fancy的
名称如nano, 如photonic，如self-assembly，如supramolecular,
如biomimic继续在fancy的杂志上刊登着一些暂时影响因子硕高， |
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c*s
发帖数: 2145 | 48 this is a very broad area concerning the synthetic method,types of polymer,
application and so on.
for the purpose of synthesis of inorganic nanoparticles, diverse polymer
species have been employed as template. The template works as either structure
directing agents for the growth of nanostructure with special shape, or
protecting agents for nanoparticles with good size/size distribution.
Templates widely used so far include dendrimers, block copolymers and special
ones such as DNA.
for develop |
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c*s
发帖数: 2145 | 49 diagram of diblock copolymer? saw it tens of times, when I need this, I can
not find it, ft |
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