Advisor： Professor Guey-Sheng LiouReporter： Huan-Shen Liu

2015 / 01 / 09 Special Topics on Polymers Synthesis Report

Hirao, A.; Uematsu, M.; Kurokawa, R.; Ishizone,T. Macromolecules 2011, 44,5638-5649

Outline

Introduction

Result and Discussion

Conclusions

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Introduction

Definitions-What is Graft Polymers?

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Graft polymers are segmented copolymers with a linear backbone of one composite and randomly distributed branches of another composite.

backbone (A)

graft chain (B)

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Three Parameters

The structure of a graft (co)polymer can be defined by the following three parameters:

Molecular weight of the backbone chain

Molecular weight of the graft chain

Distance (or molecular weight) between the graft chains3

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Paraskeva, S.; Hadjichristidis, N. J. Polym. Sci., Part A: Polym. Chem. 2000, 38,931

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Three General Methods

A variety of graft (co)polymers have been usually synthesized by three general methods:

(1)Grafting onto

(2)Grafting through

(3)Grafting from

J. H. Hu, X.Y. Huang, Chem. Soc. Rev., 2011,40, 1282-1295

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Synthesis of Exact Graft Copolymer

Paraskeva, S.; Hadjichristidis, N. J. Polym. Sci., Part A: Polym. Chem. 2000, 38,931

第一個 PILi接上去後所帶的 anionic會穩定整體結構，造成另一個雙鍵的反應性下降

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Synthesis of Exact Graft PSs Having Up to Five Graft Chains

Hirao, A.; Watanabe, T.; Kurokawa, R. Macromolecules 2009, 42, 3973

The addition reaction step ,which requires an exact 1:1 stoichiometry between the reagents, could be avoided in this methodology.

SN2

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Motivation

Although the developed methodology is thus effective for the synthesis of exact graft (co)polymers, the synthesis requires laborious multistep reactions.

Five PS graft chains 10 linking reaction steps

Process waste

Improve the synthesis of exact graft (co)polymers, with which a diverse range of exact (co)polymers including a double-tailed exact graft PS are synthesized by fewer numbers of reaction steps.

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Result and discussion① Preparation of In-Chain-(DPE)6-Functionalized

(PS)7 Used as a Backbone Polymer

② Synthesis of Exact Comb PS and Exact Graft Copolymers

③ Synthesis of Double-Tailed Exact Graft PS

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Preparation of In-Chain-(DPE)6-Functionalized (PS)7 Used as a Backbone Polymer

Figure 1. 1H NMR spectra of in-chain-DPE-functionalized PS α-terminal-functionalized with (a) 3-(tert-butyldimethylsilyloxy)propyl group, (b) 3-hydroxypropyl group, and (c) 3-bromopropyl group.

Method1

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Figure 2. Preparation of in-chain-(DPE)6-functionalized (PS)7 before (a) and after SEC fractionation (b).

Preparation of In-Chain-(DPE)6-Functionalized (PS)7 Used as a Backbone Polymer

Method2

Li–Br exchange reaction

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Preparation of In-Chain-(DPE)6-Functionalized (PS)7 Used as a Backbone Polymer

In this synthesis, the number of reaction steps has been greatly reduced by employing the coupling reaction at the final stage.

Method1 Method2

at least six coupling reactions three coupling reactions

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Synthesis of Exact Comb PS and Exact Graft Copolymers

Synthesis of Exact Graft Comb PS

Figure 3. SEC profiles of the reaction mixture (a) and exact graft comb PS having six PS graft chains obtained by fractional precipitation (b).

Deactivated PSLi

2.2-fold excess

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PILi was much less reactive than PSLi toward the DPE function in the PS chain.(same method as PSLi)

Synthesis of Exact Comb PS and Exact Graft Copolymers

Synthesis of Exact Graft Comb PI

Improve

PILi was end-capped with a few styrene units and then in situreacted with the backbone PS in order to complete the addition reaction.

在單體 isoprene和 styrene的活性是差不多的，所以就活性來說， PILi和 PSLi應該是差不多，可能原因就是對 DPE function的活性不同

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Synthesis of Exact Comb PS and Exact Graft Copolymers

Synthesis of Exact Graft Comb PMMA

The chain-end enolate anion of living PMMA cannot react with the DPE reaction site at all under normal conditions.

Improve

An α-phenyl acrylate (PA) function seems to be appropriate because of the quantitative linking reaction of the PA function with living PMMA.

 replace the DPE function by a more reactive reaction site

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Synthesis of Exact Comb PS and Exact Graft Copolymers

Synthesis of Exact Graft Comb PMMA

Figure 4. 1H NMR spectra of PS in-chain-multifunctionalized with (a) 3-tert-butyldimethylsilyloxy group, (b) hydroxyl group, and (c) α-phenyl acrylate group.

在 PMMA接上去後所產生的立體障礙以及拉電子的穩定性將造成其無法攻打另一個 PA產生交聯

MMA的單體活性較 styrene大，所以 PMMA的反應性較 PS的反應性小

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Synthesis of Exact Comb PS and Exact Graft Copolymers

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Synthesis of Double-Tailed Exact Graft PS

PS-D6

PS-(PS)6

PS-(PS2)6

Figure 5. SEC profiles of in-chain-(DPE)6-functionalized (PS)7 (a), exact graft comb PS (b), and double-tailed exact graft PS (c).

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Successfully synthesized a diverse range of new exact graft (co)polymers (PS backbone chain) having six PS, six PI, and six PMMA graft chains and double-tailed exact graft PS.

Conclusion

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The use of the coupling reaction enables the number of reaction steps to be significantly reduced.

Only the same chains in molecular weight and chemical structure can be introduced to the backbone polymer in the present methodology.

The relationship of possible distance between branching points along the main chain and length of graft chains

Next target

Conclusion

Thank you for your attention.

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Mitsunobu reaction