Polymers grafting functional molecules

The A-B type iniferters are more useful than the B-B type for the more efficient synthesis of polymers with controlled structure The functionality of the iniferters can be controlled by changing the number of the A-B bond introduced into an iniferter molecule, for example, B-A-B as the bifunctional iniferter. Detailed classification and application of the iniferters having DC groups are summarized in Table 1. In Eqs. (9)—(11), 6 and 7 serve as the monofunctional iniferters, 9 and 10 as the monofunctional polymeric iniferters, and 8 and 11 as the bifunctional iniferters. Tetrafunctional and polyfunctional iniferters and gel-iniferters are used for the synthesis of star polymers, graft copolymers, and multiblock copolymers, respectively (see Sect. 5). When a polymer implying DC moieties in the main chain is used, a multifunctional polymeric iniferter can be prepared (Eqs. 15 and 16), which is further applied to the synthesis of multiblock copolymers. 

The use of reactive antioxidants containing two polymerisable polymer-reactive functions in the same antioxidant molecule is outlined here. Careful choice of the processing parameters, the type, and the amount of free radical initiator can lead to very high levels of antioxidant grafting [53, 57]. For example, melt grafting of concentrates (e.g. 5-20 wt%) of the di-acrylate hin-... 

Fig. 3. Ratio of number-average DP of the mother polymer and number-average DP of the whole backbone having grafted branches, PB,g/PjB,0 5 a function of the average number of branches in one graft copolymer molecule, Ng o PB.g/PB.O at Nt- (),/. ., Ng- 1...

Imparting new functional properties or an esthetic look to complex polymers is a fast growing area where peroxidases are actively being pursued. Basically the polymer is either oxidized by the enzyme alone or in the presence of mediators followed by grafting as shown in the general scheme in Fig. 7.3. This results in increased binding either between polymers or with introduced functional molecules. 

Polymer Grafting of Carbon Nanotubes by Con-trolled/Living Radical Polymerization Polymer grafting techniques that use direct covalent functionalization methods, such as radical reactions, have been developed in order to avoid the problems associated with the functionalization of CNTs using acids. These grafting techniques eliminate the need for nanotube pretreatment before the functionalization and allow attachment of polymer molecules to pristine tubes without altering their original structure. 

The presence of appropriate active functional groups such as carboxylic acids or amines on the CNT surface allows for further covalent functionalisation with polymer molecules (polymer grafting). Two main approaches for the covalent functionalisation of CNTs with polymers have been reported grafting from and grafting The main differences, advantages... 

As mentioned above, controlled degradation of polypropylene was one of the earliest reactive extrusion technologies developed. A fairly substantial literature on the subject has appeared in the past 15 years. The mechanism of free radical attack of the polymer backbone is now thought to be well known (3-6). The following sequence of free radical reactions in the extruder provide a summary of key process steps involved in grafting functional groups onto chains of the polypropylene molecules. 

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