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Towards highly functionalized and semi‐rigid polyzwitterions, 2. Poly(zwitterionic isocyanides): synthesis and specific properties
Author(s) -
Bieglé Alain,
Mathis André,
Galin JeanClaude
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(20000101)201:1<113::aid-macp113>3.0.co;2-7
Subject(s) - chemistry , polymer chemistry , ethylene glycol , upper critical solution temperature , aqueous solution , dimethylformamide , lower critical solution temperature , polymerization , polymer , salt (chemistry) , organic chemistry , solvent , copolymer
Selective quaternization of the tertiary amino site of N,N ‐dimethyl‐ N ‐(3‐isocyanopropyl)amine by 1,3‐propanesultone or 2,2‐dicyanoketene‐ethylene acetal quantitatively yields the zwitterionic isocyanides of the ammoniopropanesulfonate ( SI , —N + (CH 3 ) 2 —(CH 2 ) 3 —SO 3 – ) or ammonioethoxydicyanoethenolate ( EI , —N + (CH 3 ) 2 —(CH 2 ) 2 —O—CO—C – (CN) 2 ) type, respectively. Their polymerization initiated with NiCl 2 ·6 H 2 O in methanol ( SI ) or in N,N ‐dimethylformamide ( EI ) solution leads with high yields (>70%) to the corresponding poly(isocyanides) in a rather low molecular weight range ( DP w ˜ 80–600). PSI is soluble in a few organic protic solvents such as glycol or m ‐cresol and displays typical UCST behavior in pure water ( T c ≈ 35°C) with “salting in” effects in the presence of LiClO 4 . PEI is soluble in a few dipolar aprotic solvents such as DMF, NMP or DMSO with typical LCST behavior and “salting in” effects in the presence of LiCl; secondly, in fairly concentrated KSCN aqueous solutions (>1 M) with a typical UCST behavior strongly dependent on salt concentration (d T /d[KSCN] ≈ 252°C·L·mol –1 ). Analysis of the [ η ] – M w data for PSI (0.05 M LiClO 4 in H 2 O) and PEI (0.05 M LiCl in DMF) according to the Bohdanecky's approximation of the Yamakawa‐Fujii theory for wormlike chains allows to estimate their persistence length to be about 60 Å for a hydrodynamic diameter of about 15 Å. For polymer volume fractions Φ p > 0.30, the PSI /glycol gels display local nematic order as revealed by polarizing optical microscopy and small angle X‐ray scattering (Bragg spacing d ∝ Φ p –0.45 ). The two poly(isocyanides) are non‐crystalline but slightly birefringent polymers showing only local order (one SAXS peak). PSI dissolves stoichiometric amounts of NaB(C 6 H 5 ) 4 , LiClO 4 , NaI and NaSCN to yield amorphous and birefringent blends which display optimized long range order in the latter case: a hexagonal bidimentional lattice of zwitterionic cylinders spreading over a coherence length of about 300 Å.