Telechelic precursor

A precise characterization of the telechelic precursor is necessary, prior to the crosslinking reaction, since precise stoichiometry must be achieved if the number of defects in the network is to be kept as small as possible. 

In order to selectively construct such polymer topologies, an electrostatic self-assembly and covalent fixation (ESA-CF) process has been developed which employs a linear or star telechelic precursor having cyclic ammonium salt end groups, accompanied by a plurifunctional carboxylate counterion [6-8]. This combination... 

A three-armed star telechelic precursor having cyclic ammonium salt groups was self-assembled with a tricarboxylate counteranion under dilution to form a one-to-one complex upon balancing the charges. The subsequent covalent fixation by heating produced a -shaped polymer very effectively (Scheme 18.3a) [14]. 

The combination of a linear bifunctional telechelic precursor with a tricarboxylate counteranion produced a self-assembly that consisted of three polymer units and two counteranions under dilution. Subsequent heat treatment produced a pair of covalently fixed constitutional isomers, namely manacle-shaped and 0-shaped polymers (Scheme 18.3b) [6, 15]. These relevant pairs of polymeric isomers were formed from a self-assembly of two units of a three-armed star telechelic precursor and three units of a dicarboxylate counteranion [16], as well as from the double-metathesis condensation of an H-shaped telechehc polymer precursor having four alkene end groups (Scheme 18.3c) [17]. 

An electrostatic self-assembly of two units of a linear telechelic precursor and a unit of a tetracarboxylate counteranion and subsequent covalent conversion produced a spiro-dicydic 8-shaped polymer effectively (Scheme 18.5a) [6, 9-11]. Alternatively, a four-armed star telechelic precursor having alkene end groups was subjected to a intramolecular metathesis condensation to form an 8-shaped... 

Scheme 18.5 Synthesis of 8-shaped poly- (d) Intramolecular metathesis conden-mers. (a) ESA-CF process (b) Intramolecular sation of a tv/in-tail tadpole prepolymer metathesis condensation of a four-armed (e) Intramolecular metathesis condensa-star telechelic precursor (c) Bimolecular tion of a monocyclic prepolymer having two...

Scheme 1S.6 Click chemistry between a monocyclic prepolymer having an alkyne group and linear telechelic precursor with azide end groups, resulting in the selective formation of a fcndged-dicyclic manacle-shaped polymer.

For the synthesis of cyclic PSs, telechelic precursors having quinudidinium salt groups carrying a difunctional terephtha-late counterion were used. This ionically linked precydized polymer precursor was then subjected to heat treatment in diluted conditions to convert the ionic ends into a stable covalent linkage. 

As shown in the section above, a self-assembly composed of the two units of a linear telechelic precursor having cyclic ammonium salt groups and one unit of a tetracarboxylate counteranion... 

Adachi, K., Irie, H., Sato, T. et al. (2005) Electrostatic self-assembly and covalent fixation with cationic and anionic telechelic precursors for new loop and branch polymer topologies. Macmmolecules, 38,10210-10219. 

Tezuka, Y., Mori, K., and Oike, H. (2002) Efficient synthesis of cyclic poly (oxyethy lene) by electrostatic self-assembly and covalent fixation with telechelic precursor having cyclic ammonium salt groups. Macromolecules, 35,5707-5711. 

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