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zhangfangzhi

木虫 (职业作家)

[交流] 【讨论】RAFT 末端不带硫代羰基的死聚合物链有多少

RAFT后,末端不带硫代羰基的死聚合物链有多少,占总分子链多大比例?
Ezio Rizzardo说,
A key feature of RAFT polymerization is that the thiocarbonylthio
groups are retained in the polymeric product.

[ Last edited by zhangfangzhi on 2009-10-10 at 16:44 ]
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zhangfangzhi

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In the absence of chain transfer (to solvent, initiator,
or monomer), the total number of chains formed will be
equal to (or less than) the moles of dithio compound
employed plus the moles of initiator-derived radicals
generated during the course of the polymerization. In
block synthesis, these additional initiator-derived chains
are a source of homopolymer impurity. The level of
impurities can be controlled by appropriate selection of
the reaction conditions.14 For maximum purity, it is
desirable to use as low a concentration of initiator as
practicable and to choose solvents and initiators which
give minimal chain transfer. As with conventional
radical polymerization, the rate of RAFT polymerization
is determined by the initiator concentration. In practice,
it is usually not difficult to achieve block copolymers
with no detectable homopolymer impurity (<5%) while
still achieving an acceptable rate of polymerization.
9楼2009-10-11 13:46:23
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shinyman

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小木虫(金币+0.5):给个红包,谢谢回帖交流
15%的样子,这是我做过一个用CPDB为链转移剂通过核磁得来的,其它情况不是很了解
2楼2009-10-10 16:06:32
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zhangfangzhi

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谢谢
核磁是一种方法,可以证明链末端带硫代羰基,可以计算出末端不带硫代羰基的死聚合物链有多少。
3楼2009-10-10 16:31:35
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zhangfangzhi

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用RAFT合成嵌段共聚物A-B。先聚合A,后加B的话,会有不少A和B各自的均聚物了?
用RAFT合成嵌段共聚物,产物岂不很不纯?
4楼2009-10-10 16:34:34
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