Block linear multiblock

The effects of architecture and block mass on the morphology and properties of linear multiblock copolymers was investigated by Spontak et al. [43]. They compared two matched series of compositionally symmetric (PS-fc-PI) block copolymers with 1 < n < 4, one possessing a constant chain mass and the other one having a nearly constant block mass. 

There have only been a very limited number of studies on multiblock copolymers with controlled block length (we exclude here the vast literature on random block copolymers such as polyurethanes). Microphase separation in (PS-PI) linear multiblocks with 1 < n < 4 with nearly equal block lengths was studied by Spontak and co-workers (Smith et al. 1993,1994). All (symmetric) samples were... 

There are many notations for representing block polymers. We have followed the most common in using A to represent a block of A mer units, with similar representation for B, C, etc., as shown in Table I. Here A-B represents a two block polymer, A-B-C a three block polymer, and A-B-A represents a three block polymer with A terminal blocks and B center blocks. (A-B)jj represents a linear multiblock polymer of alternating A and B blocks. 

Alginic acid is a linear multiblock copolymer from blocks of )3-(l 4)-d-... 

Linear multiblock copolymers comprising more than three sequential A and B blocks with the same degree of polymerization have been prepared following two routes sequential monomer addition, in which the monomers exhibit similar reactivity, and condensation polymerization of the a,co-functionalized A and B (or AB) building blocks, which however leads to polydisperse samples. 

Alginic acid is a linear multiblock copolymer from blocks of jS-(l->4)-D-mannuronic acid and a-(1 4)-L-guluronic acid, as well as alternating copolymers from these two monomer units. In natural products, the molecular weights reach about 150,000 and with regenerated products 30,000-60,000. Alginates are the salts of alginic acid. 

The polymerization is performed with sequential anionic polymerization. The polymers can be prepared as either a star block form or as a linear, multiblock polymer. The butadiene exists as a separate dispersed phase in a continuous matrix of polystyrene. The size of the butadiene phase is controlled to be less than the wavelength of light resulting in clear materials. 

Figure 1 Example block copolymer architectures available, (a) Linear diblock copolymer, (b) linear multiblock copolymer, (c) miktoarm copolymer, (d) star copolymer, (e) linear-graft copolymer, and (f) cyclic diblock copolymer. In all cases, the different colors represent different block chemistries.

A block copolymer is a macromolecule that is composed of distinct sections of different chemical species that are chemically bonded together to form a single molecule. The simplest kind is a diblock copolymer, with two blocks, such as poly(styrene>-fe-poly(isoprene), or PS- -PI. A general label for a diblock copolymer is A-fe-B, or simply AB. There are also triblock copolymers that can contain either two or three different species, for example, ABA or ABC, linear multiblocks, for example, ABAB..., and more complicated architectures, such as starblocks or graft copolymers. These are illustrated schematically in Figure 1. 

Compared to linear multiblock copolymers, the study on the phase behavior of hyperbranched multiblock copolymers has received less attention due to the lack of model samples. To the best of our knowledge, only a handful of work reported the related results [44, 77]. Namely, Hutchings et al. comparatively studied the phase behaviour of hyperbranched block copolymer hyper-(PS-PI)n and its linear precursor PS-PI-PS [44]. The TEM results indicated that the tendency of phase separation was strongly suppressed by the branching structure, as shown in Fig. 1.7 unfortunately, the structure of the studied hyperbranched samples were still not as perfect as we defined before [44]. 

Similar to the synthetic process of macromonomer polystyrene homopolymer, we have also synthesized Seesaw-type macromonomer triblock copolymer [1]. This is because we have been interested in the phase behaviors of long linear multiblock copolymer chains in selective solvents for many years [18, 19]. Therefore, we intentionally prepared Seesaw-type macromonomer triblock copolymers to construct hyperbranched block copolymers and study their solution properties. 

Although, there are many reviews on linear diblock chimeras, only a very few have addressed the synthesis of polypeptide-based materials with different macromolecular architectures (Hadjichristidis et al., 2009 Deming, 2006 Deming, 2000). In this chapter our discussion on the synthesis of well-defined complex chimeras, including linear multiblock co/ terpolymer, as well as nonlinear copolymer chimeras (e.g. star, graft, block-graft, dendritic), will hopefully enrich the current literature on macromolecular chimeras. This chapter will not address the self-assembly of these complex chimeras since this issue is discussed in another chapter of this volume. 

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. 

The actual knowledge of the basic molecular structure property relationships relies mainly on the availability of well defined linear architectures the di, tri- and multiblock copolymers. New and well controlled molecular structures could undoubtedly provide a deep understanding of the behavior of block copolymers and a more efficient mastering of their applications. ... 

Wu L, Cochan EW et al (2004) Consequences of block number on the order — disorder transition and viscoelastic properties of linear (AB)n multiblock copolymers. Macromolecules 37 3360-3368... 

During the last decade, more and more advanced techniques of living or controlled polymerization to prepare block copolymers have become available. It has become possible to prepare block copolymers of various architectures, solubility, and functionality [6]. Architectures comprise diblock, triblock, and multiblock copolymers arranged linearly, as stars or grafts. The solubilities vary from polar solvents such as water to media with very low cohesion energies such as silicon oil or fluorinated solvents. Control of functionality has become impor-... 

Block copolymers, BC, are macromolecular species in which long chains of one polymer are joined to long chains of another polymer. Thus, BC s are made of at least two chemically different chains arranged linearly, in form of multi-branch stars, combs, etc. Linear block copolymers are the most common — diblock, AB, triblock, ABA, or multiblock, A(BA). ... 

FIGURE 2.3.4 Chemical structures of linear-type biodegraciable block polymers exhibiting temperature-responsive sol-to-gel transition in aqueous solutions, (a) PLGA-b-PEG-b-PLGA triblock copolymer, (b) PEG/PLLA multiblock copolymer,... 

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