Polymers amine terminated

Antioxidants markedly retard the rate of autoxidation throughout the useful life of the polymer. Chain-terminating antioxidants have a reactive —NH or —OH functional group and include compounds such as secondary aryl amines or hindered phenols. They function by transfer of hydrogen to free radicals, principally to peroxy radicals. Butylated hydroxytoluene is a widely used example. 

St. Clair et. al. investigated a series of maleimide and nadimide terminated polyimides and developed LARC-13 [8,9]. Changing the terminal group from maleimide to nadimide, the value of the lap shear strength of a titanium lap shear joint increased from 7 to 19 MPa [9]. They also added an elastomeric component to the adhesive formulation. The introduction of 15 wt% of a rubbery component, ATBN (amine terminated butadiene nitrile polymer) and ADMS (aniline terminated polydimethyl siloxane) enhanced the adhesive properties as follows 19 MPa to 25 MPa (ATBN) titanium T-peel strength 0.2 kN/m to 1.4... 

Combinatorial approach to unsymmetrically tiered macromolecules [214] is a brand new area of research which would allow dendrimerization of materials (e. g., glass, classical polymers, fibers) and thus enable fine tuning of macromole-cular properties. For example, treatment of an amine terminated dendrimer with a mixture of complementary, isocyanate-based monomers [215, 216] affords a heterogeneous surfaced dendrimer. Selective transformation of the surface nitrile moieties via metal-catalyzed reduction to obtain a new polyamine dendrimer allows further combinatorial-based elaboration as illustrated in Fig. 42. 

Another approach uses reactive alkyl halogen compounds containing a terminal carboxylate group on the other end to form spacer arms off the dextran polymer from each available hydroxyl. In this manner, Brunswick et al. (1988) used chloroacetic acid to modify the hydroxyl groups to form the carboxymethyl derivative. The carboxylates then were aminated with ethylene diamine to create an amine-terminal derivative (Inman, 1985). Finally, the amines were modified with iodoacetate to form a sulfhydryl-reactive polymer (Figure 25.14). 

In a somewhat similar scheme, Noguchi et al. (1992) prepared a carboxylate spacer arm by reacting 6-bromohexanoic acid with a dextran polymer. The carboxylate then was aminated with ethylene diamine to form an amine-terminal spacer (Figure 25.15). This dextran derivative finally was reacted with N-Succinimidyl 3-(2-pyridyldithio)propionate (SPDP) (Chapter 5, Section 1.1) to create the desired sulfhydryl-reactive polymer (Section 2.4, this chapter). The SPDP-activated polymer then could be used to prepare an immunoconjugate composed of an antibody against human colon cancer conjugated with the drug mitomycin-C. 

Amination. The synthesis of polymers with primary amine end-group functionality has been a challenge because the primary amine group can undergo rapid chain transfer and termination reactions with car-banionic chain ends (14). Schulz and Halasa (15) used a phenyllith-ium initiator with a bis(trimethylsilyl)-protected amine group to prepare amine-terminated polydienes. Nakahama and coworkers (16,17)... 

A variety of these physisorbed molecules were used as anchor points for covalent immobilization in a so-called hybrid approach [16]. That is the case of bifunctional pyrenes (i.e. 1 -pyrenebutanoic acid sucdnimidyl ester, pyrene maleimide) or polymers with terminal amine/carboxylic groups that have been used to covalently immobilize proteins, functionalized oligonucleotides, and so on, (Figure 3.9) [43,44]. 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

Reactions analogous to that outlined with tertiary amines may be carried out with other amines. The reaction of secondary amines with polyTHF should result in tertiary amines terminated polymers (equation 7), and experimentation Involving gpc and H nmr analysis has broadly confirmed this expectation. The reaction with dlethylamlne, dicyclohexylamlne and piperidine... 

Of course the tertiary amine terminated polymer thus produced Is capable of being quaternlzed by alkyl halides and this has been confirmed experimentally. Moreover, It can be reacted with further living polyTHF to yield a polymer possessing a quaternary ammonium salt moiety at a point along the chain controlled by the relative molecular weights of the two living THF polymers reacted In the system, and again experiments have shown this to occur. 

It Is evident that reactions similar to those carried out on secondary amines should be capable of application to primary amines to yield polymers with terminal secondary amine groups. 

Other telechelics of interest are amine-ended polymers. tert-Amine terminated polymers have been prepared by use of the tert-amine functional initiator,... 

Another interesting example belonging to the same general principle was described by Graham (56). On one hand he prepared an amine terminated polystyrene (sodium amide initiation in liquid ammonia) and showed that it contained only one terminal primary amine group per polymer chain. On the other hand copolymers were prepared by free-radical initiated solution copolymerization of small amounts of /S-iso-cyanatoethyl methacrylate with several other monomers as methyl, butyl and lauryl methacrylates, acrylonitrile and styrene. 

Graham, R. K. Preparation of graft copolymers by the reaction of primary amine-terminated polystyrene with copolymers containing /3-isocyanatoethyl methacrylate. J. Polymer Sci. 24, 367 (1957). 

Hirao, et al., 3411 have described a very useful method for the animation of living anionic polymers. Polymeric anions were reacted with a trimethylsilyl derivative of an aldimine ( >) which generated the primary amine-terminated polymers after quenching with dilute acid (Eq. (83)). 

Figure 388 An amine terminal derivative of dextran may be prepared through a two-step process involving the reaction of chloroacetic acid with the hydroxyl groups of the polymer to create carboxylates. Next, ethylene diamine is coupled using a carbodiimide-mediated reaction to give the primary amine functional groups.

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