Alternating copolymer grafting

Polymer Blends, Statistical and Alternating Copolymers, Graft and Block Copolymers. 147... 

The present chapter is primarily concerned with the simultaneous polymerization of two monomers to produce random, statistical, and alternating copolymers. Graft copolymers and block copolymers are not synthesized by the simultaneous polymerization of two monomers. These are generally... 

XXXI. Alternating Copolymer Graft Copolymers VI. Synthesis in the Absence and Presence of Complexing Agents... 

The radical-catalyzed copolymerization of isoprene and maleic anhydride in the presence of polystyrene gives the corresponding alternating copolymer graft copolymer (Table IX). Similar results are obtained with other dienes and appropriate substrate polymers. 

Alternating copolymer graft copolymers are also produced when comonomers that yield alternating copolymers with but not without a complexing agent are copolymerized in the presence of a complexing agent and a suitable polymer, either with or without a free-radical precursor (14). 

The results in Table XIV were obtained by adding an aqueous zinc chloride solution to a poly (butyl acrylate) latex. After precomplexation at 30°C, the monomer mixture and the redox catalyst were added, and the polymerization was carried out at 30°C. Because of the heterogeneity of the reaction mitxure, a large amount of alternating copolymer accompanied the alternating copolymer graft copolymer. 

Similarly, an alternating copolymer containing complexed complexing agent may be prepared from a comonomer mixture and then mixed with different comonomers to form an alternating copolymer graft copolymer. 

Random Copolymers Alternating Copolymers Graft Polymers Block Copolymers... 

A polymer resulting from polymerisation of two or more different monomers i.e., ter-polymer, tetra-polymer for two- and three monomers, respectively. (see also RANDON COPOLYMER, ALTERNATING COPOLYMER, GRAFT COPOLYMER, BLOCK COPOLYMER.)... 

Theoretical models for other systems, such as star, branched, and ring polymers, random and alternating copolymers, graft and block copolymers are discussed in the book by Mattice and Suter [1]. Block copolymers are discussed in Chap. 32 of this Handbook [2]. Theories of branched and ring polymers are presented in the book by Yamakawa [3]. Liquid-crystalline polymers are discussed in the book by Grosberg and Khokhlov [4], and liquid crystalline elastomers in the recent book of Warner and Terentjev [5]. Bimodal networks are discussed by Mark and Erman [6,7]. Molecular theories of filled polymer networks are presented by Kloczkowski, Sharaf and Mark [8] and recently by Sharaf and Mark [9]. 

A homopolymer consists of only one type of constitutional repeating unit (A). A copolymer, on the other hand, consists of two or more constitutional repeating units (A, B, etc). Several classes of copolymer are possible block copolymers, alternating copolymers, graft copolymers and statistical copolymers (Fig. 1.10). 

Gaylord, N. G. and Anand, L.C. (1971). Alternating Copolymer Graft Copolymers. III. Cellulose Graft Copolymers. I. Grafting of Alternating Styrene-Acrylonitrile Copolymers onto Cellulose in Presence of Zink Chloride. J. Polym. Scl Part B Polym. Phys., 9,617—621. 

Other copolymer forms are alternating copolymers, block copolymers and graft polymers. 

Figure 2.16. (a) Random copolymer, (b) alternating copolymer, (c) block copolymer, (d) graft... 

Draw representative structures for (a) homopolymers, (b) alternation copolymers, (c) random copolymers, (d) AB block copolymers, and (e) graft copolymers of styrene and acrylonitrile. 

While the percentage composition of copolymers (i.e., the ratio of comonomers) is not given, copolymers with architecture other than random or statistical are identified as alternating, block, graft, etc. Random or statistical copolymers are not so identified in the CA index. Oligomers with definite structure are noted as dimer, trimer, tetramer, etc. 

The copolymer described by Eq. 6-1, referred to as a statistical copolymer, has a distribution of the two monomer units along the copolymer chain that follows some statistical law, for example, Bemoullian (zero-order Markov) or first- or second-order Markov. Copolymers formed via Bemoullian processes have the two monomer units distributed randomly and are referred to as random copolymers. The reader is cautioned that the distinction between the terms statistical and random, recommended by IUPAC [IUPAC, 1991, in press], has often not been followed in the literature. Most references use the term random copolymer independent of the type of statistical process involved in synthesizing the copolymer. There are three other types of copolymer structures—alternating, block, and graft. The alternating copolymer contains the two monomer units in equimolar amounts in a regular alternating distribution ... 

This chapter is concerned primarily with the simultaneous polymerization of two monomers to produce statistical and alternating copolymers. The different monomers compete with each other to add to propagating centers, which can be radical or ionic. Graft and block copolymers are not synthesized by the simultaneous and competititive polymerization of two monomers. Each monomer undergoes polymerization alone. A sequence of separate, noncompetitive polymerizations is used to incorporate the different monomers into one polymer chain. The synthesis of block and graft copolymers and variations thereof (e.g., star, comb) are described in Secs. 3-15b-4, 3-15b-5, 5-4, and 9-9. 

A polymer is considered to be a copolymer when more than one type of repeat unit is present within the chain. There are a variety of copolymers, depending on the relative placement of the different types of repeat units. These are broadly classified as random, block, graft, and alternating copolymers (see Fig. 2.1 for structural details Cheremisinoff 1997 Ravve 2000 Odian 2004). Among these stmctures, block copolymers have attracted particular attention, because of their versatility to form well-defined supramolecular assemblies. When a block copolymer contains two blocks (hydrophobic and hydrophilic), it is called an amphiphilic diblock copolymer. The immiscibility of the hydrophilic and lipophilic blocks in the polymers provides the ability to form a variety of assemblies, the stmctures and morphologies of which can be controlled by tuning the overall molecular weight and molar ratios of the different blocks (Alexandridis et al. 2000). 

Random copolymers are characterized by the statistical placement of comonomer repeating units along the backbone chain. Alternating copolymers, as the name suggests, are characterized by the alternate placement of monomers. Graft copolymers are made of chemically linked pairs of homopolymers and resemble a comb. Block copolymers are composed of terminally connected structures. 

Similarly, poly(butadiene-g-styrene) represents the graft copolymer in Equation 2, where it is understood that the symbol -g- means graft copolymer, the first indicated species forms the backbone, and the second the side chain. Similarly, the symbol -co- stands for a random copolymer, -a- for an alternating copolymer, and occasionally the symbol -cl- is used for crosslinked systems. 

Copolymers can be distinguished into alternating-, random-, graft-, and block copolymers. 

Alternating copolymers may be considered as homopolymers with a structural unit composed of the two different monomers. Random copolymers are obtained from two or more monomers, which are present simultaneously in one polymerisation reactor. In graft polymerisation a homopolymer is prepared first and in a second step one or two monomers are grafted onto this polymer the final product consists of a polymeric backbone with side branches. In block copolymerisation one monomer is polymerised, after which another monomer is polymerised on to the living ends of the polymeric chains the final block copolymer is a linear chain with a sequence of different segments. 

Polymers that contain more than one type of monomeric repeat unit are called copolymers. By copolymerizing two or more monomers in varying ratios and arrangements, polymeric products with an almost limitless variety of properties can be obtained. As shown in Eq. (20), there are four basic types of copolymers as defined by the distribution of comonomers A and B, for example. Although the properties of a random copolymer are intermediate between those of the two homopolymers, block and graft copolymers exhibit the properties of both homopolymers. The properties of an alternating copolymer are usually unique. 

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