Branched Copolymers

Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

Figure 9. Relative scission efficiencies of short-chain branches in the 7 radiolysis of ethylene-a-olefin copolymers. Branch types are indicated.

Important products are based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, and foams... 

Pluronic-g- polyethyleneimine (Pluronic-g-PEI) Graft-copolymer, branched PEI segment grafted with nonionic triblock copolymer In vitro and in vivo transfections and oligonucleotide delivery (Nguyen etal., 2000)... 

AB)n-type star corresponds to a star with n similar AB block copolymer branches... 

Graft copolymers can be obtained in one or two steps applying the preirradiation or direct method. Random copolymer branches are obtained when the grafting is carried out in one step using two monomers (Figure 10.12a). For the two-step method, branches containing only one kind of monomer are formed (Figure 10.12b). 

Dimethyl-tetrachlorophenyl siloxane, copolymer, branched, trimethylsiloxy 1.428 [11]... 

When a dispersant is employed, the dispersant is a random or structured polymer. Preferred random pol5miers include acrylic polymers and styrene-acryhc polymers. Most preferred are structured dispersants, which include AB, BAB and ABC block copolymers, branched polymers and graft polymers. 

Figure 3 shows the right-hand side of Eq. 1 versus (Q Rg) for branched polymer 1 as compared with the triblock copolymer and branched polymer 2. Branched polymer 1 is the only one of the calculated polymers that is not composed strictly of triblock copolymers. Branched polymer 1 may be considered as an infinite polymer made up of tetrablock copolymers or of triblock copolymers in the backbone with diblock copolymers as branches. The maximum in the scattering curve for branched polymer 1 is at larger values of (Q Rgn than that of the other polymers, partly because the Rg of this polymer pertains to the tetrablock copolymer subunit. Branched polymer 1 was included in the calculation because synthetic methods for this polymer are easier to find than for the other branched polymers. 

There are several methods to deliberately introduce branching to polymers prepared by ATRP. This includes various graft-and comb-shaped copolymers, branched and hyperbranched structures, stars, and networks. 

Since 2005, click chemistry has attracted inaeasing attention in polymer science [134] to synthesize different polymeric architectures [135] (linear polymers, linear copolymers, branched polymers, polymeric assemblies, and cross-linked polymers). Another application of click chemistry is the surface functionalization of latex particles. 

Activation energy, apparent (kJ/mol) Copolymer 0-80°C Copolymer, branched, 50°C Diffilsion coelficient, average, 25°C (cm /s) Copolymer Copolymer, branched Copolymer, linear and branched Carbon dioxide Activation energy (kJ/mol)... 

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