Star-shaped polymers heteroarm

Table 8.1 Overview CuAAC reactions for the synthesis of regular star-shaped (block co-) polymers and heteroarm star-shaped polymers... 

Further advances along that line include the development of anionic polymerization methods with the aim of attaining better control of the functionality in core-first methods and developing original strategies to access so-called heteroarm star-shaped polymers. 

B. Heteroarmed Amphiphilic Star-Shaped Polymers of Vinyl Ethers... 

The core functionalization in 21 may lead to the higher accumulation of polar hydroxyl groups in a core region that should be smaller in size than the arm moiety of the star-shaped polymers with functionalized arms. Another important feature of 21 is that an outer hydrophilic shell of 21 can effectively surround the hydrophilic microgel core with many hydroxyl groups. Therefore, the core-functionalized star polymers are amphiphilic but are expected to possess properties that differ from those of the star block and the heteroarm star amphiphiles. 

Xu, J. and Zubarev, E.R. (2004) Synthesis of heteroarm star-shaped amphiphiles with 12 alternating arms ofpolybntadieneandpoly(ethylene oxide). ACSPo/yw. Prepr. (Div. Polym. Chem.), 45(1), 762-763. 

Heteroarm or miktoarm star copolymers have attracted considerable attention in recent years due to the imique properties of these polymers, for example, they exhibit dramatic difference in morphology and solution properties. In comparison with the linear block and star-block copolymers, the s)mthesis of heteroarm or miktoarm star copolymers has been one of the more challenging projects available. A typical example is that the synthesis of the heteroarm H-shaped terpolymers, [(PLLA)(PS)]-PEO-[(PS)(PLLA)], in which PEO acts as a main chain and PS and PLLA as side arms (Fig. 4.11). The copolymers have been successfully prepared via combination of reversible addition-fragmentation transfer (RAFT) polymerization and ring-opening polymerization (ROP) by Han and Pan [166]. Another interesting example is that Pan et al. [167] successfully... 

Star polymers consist of several linear polymer chains connected at one point. Prior to the development of CRP, star molecules prepared by anionic polymerization had heen examined. However, due to the scope of ionic polymerization, the composition and functionality of the materials were limited. The compact structure and globular shape of stars provide them with low solution viscosity and the core-shell architecture facilitates entry into several applications spanning a range from thermoplastic elastomers (TPEs) to dmg carriers. Based on the chemical compositions of the arm species, star polymers can be classified into two categories homoarm star polymers and miktoarm (or heteroarm) star copolymers... 

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