Star-block copolymer methacrylate

Star block copolymers of IB and methyl methacrylate have been prepared very recently by the combination of living cationic and anionic polymerizations [44]. First, three arm star PIB (Mn=30,000 gmoL1) was prepared by living cationic... 

Block copolymers between alkyl or related methacrylates (B-1,132 198,357 B-2,198 and B-3115,146,148) were prepared via the ruthenium-, copper-, and nickel-catalyzed living radical polymerizations. These block copolymers can be synthesized both via sequential living radical polymerizations and via the living radical polymerization initiated from isolated polymers. For example, the ruthenium-catalyzed sequential living radical polymerization of MMA followed by nBMA affords AB block copolymers B-1 with narrow MWDs (Mw/Mn = 1.2), which can be extended further into ABA block copolymers B-2 with similarly narrow MWDs (Mw/Mn = 1.2).198 Star block copolymers with B-1 as arm chains were similarly synthesized but with multifunctional initiators.357... 

Haloester-type trifunctional initiators are obtained from triols by a method similar to those for bifunctional haloesters. 3-arm star polymers of MMA are obtained with dichloroacetates MI-28 and MI-29, for which Ru-1 and Al(acac)3 are employed.228 The polymers have controlled molecular weights and narrow MWDs. Similarly, MI-30 and MI-31 with copper catalysts gave 3-arm star polymers of styrene, acrylates, and methacrylates suitable copper catalysts vary with each monomer.199,326 358 368 The obtained star polymers can be further transformed into star block copolymers comprised of hydrophilic/hydropho-bic368 or organic/inorganic326 segments by block copolymerizations of other monomers. 

Self-assembled block copolymers are basically amphilic molecules which contain distinctively different polymers. This block copolymer contains two or more polymers quantitatively in the form of blocks. Some of the block copolymers are polyacrylic acid, polymethylacrylate, polystyrene polyethylene oxide, polybutadiene, polybutylene oxide, poly-2-methyloxazoline, polydimethyl sUoxane, poly-e-caprolactone, polypropylene sulfide, poly-A -isopropylacrylamide, poly-2-vinylpyridine, poly-2-diethylamino ethyl methacrylate, poly-2-(diisopropylamino) ethyl methacrylate, poly-2-(methacryloyloxy) ethyl phosphorylcholine, and polylactic acid. These copolymers contain more than polymers to form certain configurations like linear, branched, patterned. For example, if we take three polymers named A, B, and C, they can be combined to form arrangements AB, BA, AA, BAB, ABCAB, ABCABC, ABABAB, etc. in the form of branched configuration it forms (ABQa, (ABA)a, (AB)4, etc. Depending on the above-mentioned number of blocks, they are named as AB diblock copolymers, ABC triblock copolymers, ABC star block copolymers, etc. The covalent linkage between these different blocks of polymers makes macroscopic phase separation impossible, that is, in its place the phase separation... 

H) Atom transfer radical polymerization Numerous reports have been published regarding the synthesis of star polymers using multifunctional initiators capable of initiating the atom transfer radical polymerization (ATRP) of certain monomers, mainly styrene, methacrylates, and acrylates. The living character of the growing chain ends provides the possibility for the synthesis of star-block copolymers. 

Forman et compared a series of linear and star-block copolymers resist, prepared using the same scheme, for exposure at 193 nm (ArF resist). The star copolymers developed had as a core an oligoinitiator based on saccharose from which three standard ArF photoresist monomers, a-y butyrolactone methacrylate (GBLMA), methyladamantyl methacrylate (MAMA), and hydroxyl adamantyl methacrylate... 

Multifunctional initiators, produced by dendrimer techniques, have been used to synthesize dendrimer-like star-block copolymers by ATRP method (Hedrick et al., 1998). Starting from a hexafunctional initiator, e-caprolactone was polymerized and each hydroxyl group was then chemically transformed into two 2-bromo-isobutyrate moieties, which were used to initiate the ATRP of either MMA or a mixture of MMA and hydroxy ethyl methacrylate (HEMA) to produce, in the latter case, dendrimer-hke star-block copolymer composed of a poly(e-caprolactone) core... 

Hydrophilic aminoethyl methacrylate blocks can therefore be combined with various hydrophobic blocks as shown also by J6r6me and co-workers [195]. PDMAEMA-PMMA diblock and star-block copolymers, quaternized on the PDMAEMA block with different alkyl halides were synthesized by these authors who could demonstrate that with short alkyl halides the diblock copolymers behave like classical amphiphiles on micellization, whereas their behavior becomes similar to polysoaps in the case of long alkyl halides. 

Teyssie and coworkers found that the anionic polymerization ( Living Polymer-formation ) of methacrylate and acrylate esters in the presence of lithium chloride along with the anionic initiator results in polymers with particularly uniform molecular weight distributions. By this technique, di-and tri-block copolymers and star-block copolymers may readily be prepared. If rerr-butyl acrylate (or methacrylate) is one of the comonomers, hydrolysis of such copolymers with a small amount of / -toluenesulfonic acid leads to a copolymer containing acrylic (or methacrylic) acid [25-27]. 

Nasser-Eddine, M., Reutenauer, S., Delaite, C. et al. (2004) Synthesis of polystyrene-poly(tert-butyl methacrylate)-poly(ethylene oxide) triarm star block copolymers. Journal of Polymer Science Part A-Polymer Chemistry, 42,1745-1751. 

These sites were then employed for the polymerization of o-gluconamidoethyl methacrylate providing the corresponding star-block copolymers (Scheme 15.13). The reaction sequence was monitored by NMR and IR spectroscopy and SEC revealing that rather well-defined structures having relatively low polydispersities (1.18 [Pg.473]

With a similar method, star-block copolymer NLB-6 was prepared from St and DMDMA using the hexafunctional initiator NLI-5. After hydrolysis of the star-block copolymer NLB-6, an amphiphilic block copolymer NLB-7 was formed [160]. NLB-9, was prepared from trifunctional initiator NLI-8, n-butyl methacrylate and 2-(N,N-dimethylamino)ethyl methacrylate [161] NLB-11 from NLI-10, MMA, and n-butyl methacylate [162], NLB-14 and NLB-16 from multifunctional initiator NLI-12, t-butyl acrylate and MMA [163], and NLB-15 from 12-functional initiator NLB-13, tBuA and MMA. 

Star block copolymers in which each branch is an amphiphilic star block copol)nners can be obtained in a similar way. The polymerization of the second monomer can be initiated by the carbanions of the first one, that is, in the order of increasing electroaffinity. Typical examples include styrene/butyl methacrylate [75] and styrene/vinylpyridine [76]. 

Yijin X. and Caiyaun P., Block and star-hlock copolymers by mechanism transformation. 3. S-(PTHF-PSt)4 and S-(PTHF-PSt-PMMA)4 from living CROP to ATRP, Macromolecules, 33, 4750, 2000. Feldthusen J., Ivan B., and Mueller A.H.E., Synthesis of linear and star-shaped block copolymers of isobutylene and methacrylates hy combination of living cationic and anionic polymerizations. Macromolecules, 31, 578, 1998. 

N. Martinez-Castro, M.G. Lanzendorfer, A.H.E. Muller, J.C. Cho, M.H. Acar, and R. Faust, Polyisobutylene stars and polyisobutylene-block-poly(tert-butyl methacrylate) block copolymers by site transformation of thiophene end-capped polyisobutylene chain ends, Macromolecules, 36(19) 6985-6994, September 2003. 

Star or dendrimer block copolymers based on acrylate and methacrylate units. [N. Niessner, F. Seitz, Eur. Pat. 545,184,1993] [ 376]. 

Figure 9-19. A universal gel-permeation chromatography calibration curve obtained from measurements on linear poly(styrene) (O), comb-branched poly(styrene) (O ), star-branched poly(styrene) ( ), poly(methyl methacrylate) ( ), poly(vinyl chloride) (a) c -l,4-poly-(butadiene) (A), poly(styrene)-poly(methyl methacrylate) block copolymer (Qj ), random copolymer from styrene and methyl methacrylate O), and ladder polymers of poly(phenyl siloxanes) ( ) (according to Z. Grubisic, P. Rempp, and H. Benoit).

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