Polymers with reactive functional groups

Oligomers and polymers with reactive functional groups have been used extensively to prepare a great variety of polymeric materials. In many cases the behavior of these functional homopolymers is largely dependent on the nature and number of functional groups. In a number of important applications the functional groups are located at the end of the polymer chain macromolecules with terminal functional groups are usually termed telechelics or macromonomers . To characterize them it is necessary to have information not only about their molar mass but also on their functionality. 

The synthesis of end functional polymers by NMP, ATRP and RAFT has already been discussed in Section 9.7. The "grafting to approach involves the covalent attachment of an end-funetionalized polymer with reactive surface groups on the substrate. The approach is inherently limited by the crowding of chains at the surface and the limit this places on the final graft density. 

The theories of Miller and Macosko are used to derive expressions for pre-gel and post-gel properties of a crosslinking mixture when two crosslinking reactions occur. The mixture consists of a polymer and a crosslinker, each with reactive functional groups. Both the polymer and crosslinker can be either collections of oligomeric species or random copolymers with arbitrary ratios of M /Mj. The two independent crosslinking reactions are the condensation of a functional group on the polymer with one on the crosslinker, and the self-condensation of functional groups on the crosslinker. 

As mentioned above, Pcs can be incorporated as side groups of a main polymeric chain. Two routes can be followed to achieve this goal. One of them involves the polymerization (or copolymerization) of unsymmetrically substituted Pcs, i.e., holding reactive sites at one of the isoindole subunits. The second one requires the preparation of a polymer with side functional groups that can react in a further step with an appropriately functionalized Pc. 

Yoshida K et al. (2003) Synthesis of novel Double-decker-shaped phenylsilsesquioxane with reactive functional group of tetrasilanol. Polym Prep Jpn (Soc Polym Sci Jpn) 52 131... 

Table I shows the fracture energies for epoxy resin which have been toughened by liquid polymers with different functional groups. Clearly the selectivity of the functional groups is more important than the reactivity. MTBN, with the most reactive mercaptan end groups, had the least improvement in fracture energy the cured material is trans-...

Reactive Polymers with Multiple Functional Groups. 124... 

In reactive compatibilization the copolymers are produced at the interface. From the economic and the performance points of view, this method is more attractive than that by addition of a compatibilizer. Owing to the cost of TSE, these machines are operated with short residence time of 1-4 min. For this reason, to complete the reactive compatibilization one must use either high concentration of reactive groups (e.g., for chain-end groups, low MW reacting polymers), highly reactive functional groups, or efficient catalyst. Thus, the basic requirements for efficient reactive compatibilization are ... 

Bioactive molecules can be immobilized on polymeric surfaces by covalent chemical attachment or physical adsorption [251]. Solid polymer surfaces with reactive functional groups (OH, NH, COOH, SH, and CHCH ) present an opportunity for covEdent conjugation with biomolecules either directly or via a spacer linker [251]. Relatively inert polymers can also be treated with surface modification techniques to introduce reactive functional groups and allow chemical functionalization with desired biochemical moieties [251], Alternatively, biomolecules can also be physically immobilized on polymeric surfaces via van der Waal forces, affinity binding, or electrostatic interaction [251]. Notably, these biomolecules must be presented on the material surfaces with stabilized conformations and correct orientations to preserve their bioactivity [252-255]. 

The grafting to method was used for the preparation of composites with the polymers containing reactive functional groups. One of the first examples of the grafting to approach was published by Fu et al in 2001. In this work, carboxylic acid groups on the nanotube surface were converted into acyl chlorides by refluxing the samples in thionyl chloride. Then the acyl chloride functionalised CNTs have been reacted with hydroxyl groups of dendritic PEG polymers via esterification reactions. 

Telechelic polymers are macromolecules with reactive functional groups at the terminal ends of the chains. An example of telechelic polymers is polybutadiene with carboxylic acid end groups ... 

Polyaddition and polycondensation reactions usually lead to functional polymers, since the polymers produced are terminated with reactive functional groups. A higher degree of functionality is easily affordable if monomers with additional reactive groups are used that do not participate in the step-growth polymerization. In emulsion polymerizations, neither polyaddition nor polycondensation reactions can be carried out consequently, the miniemulsion technique is of special interest as no diffusion of the monomers takes place. The first polyaddition in miniemulsion were performed in 2000, with the reaction of polyepoxides and hydrophobic diamines, bisphenols, and dimercaptanes [105]. Stable latexes of epoxy resins could be obtained, and apparent molecular weights of up to 20 000 g mol were measured. 

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