Poly 2- stars

The anionic polymerization of methylmethacrylate at room temperature (originally called group transfer polymerization) [75-77] has provided a means for preparing star poly(methylmethacrylate) via the block polymerization with ethyleneglycoldimethacrylate ... 

In this section, it should be mentioned that star poly(tetrahydrofuran) has been prepared by coupling cationically polymerized THF with multifunctional diethylenetriamine [92] in the presence of 2,2 6,6 tetramethylpiperidine as a proton trap. When the MW of poly(THF) is 1600 seven chains are added to the triamine, when the MW is 8000 a five-arm star has been obtained. 

He also prepared a poly(styrene-g-styrene) polymer by this technique [114], The lack of crosslinking in these systems is indeed proof of the control achieved with this technique. An eight-arm star polystyrene has also been prepared starting from a calixarene derivative under ATRP conditions [115]. On the other hand, Sawamoto and his coworkers used multifunctional chloroacetate initiator sites and mediation with Ru2+ complexes for the living free-radical polymerization of star poly(methylmethacrylate) [116,117]. More recent work by Hedrick et al. [84] has demonstrated major progress in the use of dendritic initiators [98] in combination with ATRP and other methodologies to produce a variety of structure controlled, starlike poly(methylmethacrylate). 

Shen Z, Duan H, Frey H (2007) Water-soluble fluorescent ag nanoclusters obtained from multiarm star poly(acrylic acid) as molecular hydrogel templates. Adv Mater 19 349-352... 

Zeng F, Lee H, Chidiac M, Allen C (2005) Synthesis and characterization of six-arm star poly (5-valerolactone)-Woci -methoxy poly(ethylene glycol) copolymers. Biomacromolecules 6 2140-2149... 

AnBn-TypeStar Copolymers Polyfvinyl ether)n-Star-Poly(vinyl ether) ... 

Three arm amphiphilic star block copolymers of IBVE and 2-hydroxyethyl vinyl ether (HOVE) were prepared using the trifunctional initiator 8 with sequential cationic polymerization of two hydrophobic monomers, IBVE and AcOVE. Subsequent hydrolysis of the acetates led to the hydrophilic poly(HOVE) segments [38]. Two types of stars were prepared depending on which monomer was polymerized first three arm star poly(IBVE-h-HOVE), with the hydrophobic part inside and three arm star poly(HOVE-h-IBVE), with the hydrophobic part outside. When IBVE was polymerized first, the experimental conditions were the same as described in Sect. 2.2.1. After reaching quantitative monomer conversion, AcOVE was added and temperature was raised from 0 to 40 °C to accelerate the reaction since this monomer is less reactive than IBVE. When starting with AcOVE as a first block, both polymerizations were carried out at 40 °C. SEC analysis showed that MWDs were narrow for the two steps whatever the se-... 

Poly(isobutylene)2-Star-Poly(methyl vinyl ether)2... 

Poly (isobutylene)-Star-Poly (ethylene oxide) m... 

The exterior of carbosilane dendrimers can also serve as initiator sites for polymerization, in which case the dendrimers serve as cores for star polymers. Vasilenko and coworkers95 synthesized a multilithiated carbosilane dendrimer which they then used as an initiator for the ring-opening polymerization of hexamethylcyclotrisiloxane to yield star polymers of narrow weight distribution (Scheme 7). The researchers later extended this work to polymerize styrene, isoprene and ethylene oxide96,97. Star poly(ethylene oxides) were also prepared using hydroxy-terminated carbosilane dendrimers as the core98,99. 

Star poly(methylmethacrylates) were synthesized via atom transfer polymerization using a small carbosilane dendrimer functionalized with a tertiary bromide moiety as an initiator core (Figure 12)100,101. a convergent approach to star polymers with a carbosilane dendrimer core was described in a report by Allgaier and coworkers102, in which living poly(butadienyl-lithium) arms were coupled with various SiCl-terminated carbosilane den-drimers. Utilizing smaller dendrimers with lower functionality was found to yield nearly ideal results in terms of substitution and polydispersity. 

This method was extended to the synthesis of PBd stars having more than 200 arms.43 Low molecular weight linear and star poly(l,2-butadiene) with 18 arms was extensively hydrosilylated with methyldi-chlorosilane and used as linking agents to prepare multiarm PBd stars, as shown in Scheme 7. The... 

Figure 1. Anionic synthesis of star poly(dimethylsiloxanes) via blocked amine-functional initiators...

Figure 2. Anionic synthesis of four-arm star poly(dimethylsiloxanes) via coupling to titanium based cores...

HARA ET AL. Three-Arm Star Poly isobutylene-Based lonomers... 

Keywords Tissue engineering Cell culture Poly(A-isopropyl acrylamide) Biohybrid material Heparin Star-poly(ethylene glycol) Angiogenesis... 

Unlike previous researchers, Xue and Agarwal were more interested in the effect of core structure on the shear stability of star-shaped polymers. They synthesized six-arm star poly(methyl methacrylate) (PMMA) bearing either a linear core (A, M = 2,350 kDa) or a fused core (B, M = 2,100 kDa) (Fig. 31) [228,... 

KOW Kowalczuk,A., Kronek, J., Bosowska, K., Trzebicka, B., and Dworak, A., Star poly(2-ethyl-2-oxazohne)s Synthesis and thermosensitivity, Polym. Int., 60, 1001, 2011. 

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