Chain ends, polymers within backbone

CHEMICAL MODIFICATION OF POLYMERS WITHIN BACKBONE AND CHAIN ENDS... 

II. Chemical Modification of Polymers Within Backbone and Chain Ends... 

Thermal degradation of an acrylic polymer, polymerised using a free-radical method, proceeds in three steps of mass loss the first and easiest (Scheme 19(1)) is initiated by scissions of head-to-head linkages at about 160 C (representing one type of defect at the polymer backbone) the second (Scheme 19(2)) by scissions at the chain-end initiation from vinylidene ends at around 270 °C and the last (Scheme 19(3)) by random scission within the polymer chain (at the weakest bonds) 894653 (805908) 784305 737106 711105 630026 600788 a.442j. 

Cyclic polymers represent a special class of macromolecules among the various possible polymeric architectures. Because of the absence of chain ends in cyclic polymers, different chain dynamics can strongly influence physical properties compared with linear analogs of the same mass [95]. Recently, therefore, large cyclic polymers have emerged from the realm of scientific curiosities to that of potentially useful macromolecular architectures for a variety of functional applications [96-99]. By virtue of the lUPAC definition [1], cyclic polymers can be considered as macrocycles. Polymers with (small or large) cyclic repeating units within the macromolecular backbone, cyclopolymers, have been known for some time [100-104], and they must not be assimilated to cyclic polymers. 

The self-assembly of the various polymer systems described in the above sections is only a brief summary of the attempts by chemists to create multifunctional materials based on noncovalent interactions. The unique regions present within a polymer including the (1) main-chain/backbone, (2) end groups, (3) side-chains and (4) dendritic periphery, along with the ability to functionalize any of these regions with recognition units, provide chemists with a wide array of self-assembly possibilities with which to build and create multifunctional materials. 

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