Diblock synthesis

The two reactor feeds were controlled to give copolymers with the desired ethylene-octene compositions, and a physical blend was produced for comparison prior to making a diblock OBC. For diblock synthesis, DEZ was added to the first reactor... 

Scheme 6.11 A-B diblock synthesis from end-functional polymers via the RAFT process.

Somewhat limited work has been reported over the last decade. There are several reports on the synthesis and physical and structural characterization of styrene-dimethylsiloxane 141 144) and methylmethacrylate-dimethylsiloxane145> diblock, triblock and multiblock copolymers. Several reports are also available on the thermal223), solution 224,2251 and surface196 2261 characterization of various styrene-dimethyl-siloxane block copolymers synthesized by anionic techniques. 

Synthesis of AB diblock followed by linking or coupling reaction... 

Kennedy J.P. and Shim J.S., Star-block polymers having multiple polyisobutylene containing diblock copolymers arm radiating from a siloxane core and a method of synthesis thereof. Disclosure 318, US Patent, Notice of Allowance, 2001. 

Based on the synthesis of polyphosphazenes and of diblock copolyphosp-hazenes by the living cationic polymerization of phosphoranimines [237,241], the triblock poly(phosphazene-ethylene oxide) copolymer XVIII was synthesized by Allcock [223]. 

Brzezinska KR, Deming TJ (2004) Synthesis of AB diblock copolymers by atom-transfer radical polymerization (ATRP) and living polymerization of alpha-amino acid-N-carboxyan-hydrides. Macromol Biosci 4 566—569... 

Abstract This review highlights recent (2000-2004) advances and developments regarding the synthesis of block copolymers with both linear [AB diblocks, ABA and ABC triblocks, ABCD tetrablocks, (AB)n multiblocks etc.] and non-linear structures (star-block, graft, miktoarm star, H-shaped, dendrimer-like and cyclic copolymers). Attention is given only to those synthetic methodologies which lead to well-defined and well-characterized macromolecules. 

Two methods have been developed for the synthesis of AB diblock copolymers (a) sequential addition of monomers and (b) couphng of two appropriately end-functionalized chains. The first method is the most widely used... 

Since the discovery of living anionic polymerization and the first synthesis of diblock copolymers, this technique has emerged as the most reliable... 

The living character of the ROMP promoted by the initiator Ru(CHPh)(Cl)2 (PCy3)2 (Cy = cyclohexane) was tested with the synthesis of diblock, triblock, and tetrablock copolymers of norbornene derivatives carrying acetyl-protected glucose, [2,3,4,6-tetra-O-acetyl-glucos-l-O-yl 5-norbornene-2-carboxylate], A or maltose groups, [2,3,6,2/,3/,4/,6/-hepta-0-acetyl-maltos-1-O-yl 5-norbornene-2-carboxylate], B, shown in Scheme 41 [102]. The AB, ABA, and ABAB structures were prepared by sequential addition of monomers with narrow molecular weight distributions to quantitative conversions. 

Diblock copolymers PEO-fo-PS have been prepared using PEO macroinitiator and ATRP techniques [125]. The macroinitiator was synthesized by the reaction of monohydroxy-functionalized PEO with 2-chloro-2-phenylacetyl-chloride. MALDI-TOF revealed the successful synthesis of the macroinitiators. The ATRP of styrene was conducted in bulk at 130 °C with CuCl as the catalyst and 2,2 bipyridine, bipy, as the ligand. Yields higher than 80% and rather narrow molecular weight distributions (Mw/Mn < 1.3) were obtained. The surface morphology of these samples was investigated by atomic force microscopy, AFM. 

The same heterobifunctional initiator, 2-phenyl-2-[(2,2,6,6-tetramethy-piperidino)oxy] ethyl 2-bromo-2-methyl propanoate, was employed for the synthesis of PMMA-fo-PfBuA-fo-PS triblock terpolymers via the combination of ATRP and NMP [136]. Styrene was initially polymerized through the alkoxyamine function in bulk at 125 °C, leading to PS chains with bromine end groups. Subsequent addition of fBuA in the presence of CuBr/PMDETA provided the PS-fr-PfBuA diblock. Further addition of CuCl, to achieve halogen exchange and MMA yielded the desired triblock copolymer with... 

Star-block copolymers are star polymers in which each arm is a block (diblock or triblock) copolymer. There are several methods used for the synthesis of star-block copolymers [142], and the most commonly used strategies are given in Scheme 67. 

Influence on the phase behaviour is observed if even small amounts (0.5 wt %) of hairy silica-like nanoparticles obtained by block-copolymer-directed sol-gel synthesis are added to a block copolymer [53,214]. On the example of a PS-fo-PI diblock copolymer a depression of the ODT of approx. 20 K was observed (Fig. 68), accompanied by a broadening of the transition. The largest depression was observed for rod-like nanoparticles, which is explained by the energy introduced by the defects [215]. 

The facility to introduce well-defined chain ends has been used to prepare star polymers557 and diblocks via reaction with macromolecular aldehydes.558 The synthesis of amphiphilic star block copolymers has also been described using a cross-linking agent.559 560 A similar strategy has recently... 

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