Successive Synthesis of Miktoarm Star Polymers Having up to Seven Arms by a New Iterative Methodology Based on Living Anionic Polymerization Using a Trifunctional Lithium Reagent Supervisor : Prof. Ru-Jong Jeng Student : Yu-Wei Cheng ( 鄭有為 ) Date : Shotaro Ito, Raita Goseki, Takashi Ishizone, Saeko Senda, and Akira Hirao*, Macromolecules 2013, 46, 819−827 TMS TBDMS THP α-phenyl acrylate

2 Outline Introduction Result & Discussion Conclusion

3 Introduction

4 (1)Hadjichristidis, N.; Iatrou, H.; Pispas, S.; Pitsikalis, M. J. Polym. Sci., Part A: Polym. Chem. 1999, 37, 857−871. (2)Hirao, A.; Higashihara, T.; Hayashi, M. Polym. J. 2008, 40, 923−941. Miktoarm star (m-star) polymers. Successive synthesis of asymmetric star-branched polymers by iterative methodology using 1. DPE

5 Scheme 1. “Second-Generation” Stepwise Iterative Methodology Based on Living Anionic Polymerization Using 1

6 Result & Discussion  General Synthesis of 4-Arm ABCD μ-Star Polymers by Using a Trifunctional Lithium Reagent.  Successive Synthesis of μ-Star Polymers by a New Stepwise Iterative Methodology.  Synthesis of a 6-Arm A2B2C2 μ-Star Polymer.

7 Scheme 2. Synthesis of 4-Arm ABCD μ-Star Polymer General Synthesis of 4-Arm ABCD μ-Star Polymers by Using a Trifunctional Lithium Reagent TBDMSPLi THF, -78 ℃, 15 min THF, -78 ℃, 2.5 hrTHF, -40 ℃, 20 hr THF, 25 ℃, 16 hrTHF, -40 ℃, 20 hr THF, 25 ℃, 16 hr THF, -40 ℃, 20 hr

8 Figure 1. SEC profiles of A, AB, 3-arm ABC, and 4-arm ABCD μ-star polymers. Table 1. Synthesis of 4-Arm ABCD μ-Star Polymers

9 Successive Synthesis of μ-Star Polymers by a New Stepwise Iterative Methodology

10 Scheme 3. Successive Synthesis of μ-Star Polymers by a New Iterative Methodology Based on Living Anionic Polymerization Using a Trifunctional Lithium Reagent, ℃, 12 hr THF, -78 ℃, 12 hr -78 ℃, 12 hr -40 ℃, 20 hr THF, -78 ℃, 12 hr -40 ℃, 24 hr

11 Table 2. Successive Synthesis of μ-Star Polymers by a New Iterative Methodology Figure 2. SEC profiles of 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, and 7-arm ABCDEFG μ-star polymers synthesized by a new iterative methodology.

12 Synthesis of a 6-Arm A2B2C2 μ-Star Polymer

13 Scheme 4. Synthesis of 6-Arm A2B2C2 μ-Star Polymer Figure 3. SEC profiles of the polymer mixture (a) and 6-arm A2B2C2 μ-star polymer isolated by SEC fractionation (b). Table 3. Synthesis of 6-Arm A2B2C2 μ-Star Polymer -78 ℃, 30 min Lithium naphthalenideDPE mmol mmol THF(4.87 mmol) at -78 ℃ 30 min Solution A ＋ Slow add solution A mmol for the PA functionality THF( l0 mL) at -78 ℃, 12 h

14 Conclusion

15 We have successfully developed a new stepwise iterative methodology based on living anionic polymerization using a trifunctional lithium reagent substituted with the TMS, TBS, and THP ethers of three protected hydroxyl functionalities convertible to three PA reaction sites. The key step is the reaction between the PA reaction site and the trifunctional lithium reagent to reintroduce these three ethers, with which the next reaction sequence is continued. One more important and advantageous point is that such three ethers are designed to be selectively and in turn deprotected under carefully selected conditions to convert them to three PA reaction sites step by step at different reaction stages. With these PA reaction sites, two arm segments, followed by the three ethereal functions, are introduced. A series of well-defined μ-star polymers with up to 7 arms and 7 components could be successively and efficiently synthesized. The success of the proposed new iterative methodology makes it possible to synthesize many-armed μ-star polymers by fewer processes. The trifunctional lithium reagent behaved as a tetrafunctional core compound was also recognized as a convenient and useful core agent access to the general synthesis of 4- arm ABCD and 6-arm A 2 B 2 C 2 μ-star polymers in a quite simple manner.

16 Thanks for your attention !