André Mathis

Poly(sulphopropylbetaines): 3. Bulk properties

The bulk properties of a series of five atactic aliphatic and aromatic poly(sulphopropylbetaines) have been studied by u.v. and broad line n.m.r. spectroscopy, differential scanning calorimetry (d.s.c.), X-ray scattering (WAXS, SAXS) and thermally stimulated depolarization currents (t.s.d.c.). The high density in dipolar units N+(CH2)3SO−3 affords a number of specific properties to these poly(zwitterions): very high glass transition temperatures (d.s.c., n.m.r.); (ii) a strong polarity typified by an apparent local dipole moment of about 5.5 D (u.v.) and a dielectric increment at Tg > 1 × 102 (t.s.d.c.); (iii) the ability to dissolve LiClO4 in stoichiometric amounts to yield amorphous microphase separated blends (WAXS, SAXS) without much change in chain dynamics (slight increase in Tg and in n.m.r. linewidth); (iv) a very high affinity for water which behaves as a very efficient plasticizer with 6.5 moles of ‘unfreezable bound water’ per monomeric unit.

A water soluble methanofullerene derivative: synthesis, micellar aggregation in aqueous solutions, and incorporation in sol–gel glasses for optical limiting applications

Amphiphilic methanofullerene derivative 1 is water soluble and micellar aggregation has been evidenced by small-angle X-ray scattering measurements and UV/Vis spectroscopy. Thanks to the high solubility of 1 in polar solvents widely used in sol–gel processing, successful inclusion of 1 in the sol–gel could be easily achieved. The optical limiting properties of the doped sol–gel samples have been evaluated and a fast S1–S0 relaxation has been observed for these samples. This observation appears to be consistent with the presence of micellar aggregates of 1 in the sol–gel. Indeed, the interactions between the fullerene spheres of neighbouring molecules in the clusters may be at the origin of this fast S1–S0 relaxation as already shown in solid C60-films.

Towards highly functionalized and semi-rigid polyzwitterions, 1 poly(dizwitterionic methacrylates) : synthesis and specific properties

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+(CH3)2—(CH2)3—SO3–) or ammonioethoxydicyanoethenolate (EI, —N+(CH3)2—(CH2)2—O—CO—C–(CN)2) type, respectively. Their polymerization initiated with NiCl2·6 H2O 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 (DPw ˜ 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 (Tc ≈ 35°C) with “salting in” effects in the presence of LiClO4. 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 (dT/d[KSCN] ≈ 252°C·L·mol–1). Analysis of the [η] – Mw data for PSI (0.05 M LiClO4 in H2O) and PEI (0.05 M LiCl in DMF) according to the Bohdaneckys approximation of the Yamakawa-Fujii theory for wormlike chains allows to estimate their persistence length to be about 60 A for a hydrodynamic diameter of about 15 A. For polymer volume fractions Φp > 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 ∝ Φp–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(C6H5)4, LiClO4, 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 A.

Poly(ammonioalkanesulfonate) Blends with Polar Organic Species and Alkali Metal Salts: Structure, Glass Transition and Ionic Conductivity

Because the dipole moment of its zwitterionic side group is very high (μ∼23 D), poly[3-(N,N-diethyl-N-(5-methacryloyoxy-3-oxopentyl)-ammonio) propanesulfonate] affords a unique polar host matrix possessing a strong solvation power towards a variety of polar or ionic guest species. Water, glycerol, liquid ethylammonium nitrate, triethylammoniopropanesulfonate are all good plasticizers with a fairly similar efficiency of ΔTg∼−2°C/mol% of additive, while a dizwitterion behaves as a weak antiplasticizer. The stoichiometric blends of the polyzwitterion with alkali metal salts of low enough lattice energy such as thiocyanates, trifuoromethanesulfonates, iodides, perchlorates, tetrafluoro or tetraphenylborates, are amorphous systems showing a single glass transition, with plasticization or antiplasticization effects depending on the salt nature. Microphase separation systematically occurs in these binary systems but long-range order is observed only in some cases, with development of lamellar (I−) or hexagonal (SCN−) structures. Conductivity increases and the dielectric constant of the material decreases as salt is added. The activation energies of the conductivity are not strongly affected either by the state of the material, glassy or viscoelastic, or by the salt nature.

Random ethylacrylate zwitterionic copolymers: 3. Microphase separation as a function of the zwitterion structure

Abstract The structural characteristics of a series of statistical ethylacrylate (A) copolymers bearing a wide variety of zwitterionic units (B) (i.e. quaternary ammonium carboxy or sulphonato betaine, dicyanomethylid and dicyanoethenolate), were analysed by differential scanning calorimetry and small angle X-ray scattering (SAXS, 20–100°C). For low to moderate B content (0.07 [ LiClO 4 ] [ B ]=1 ) show a single glass transition temperature (Tg) and a very characteristic SAXS peak, still present in the liquid state (Tg + 50°C) which corresponds to correlation distances in the range 30–50 A. Microphase separation of the zwitterionic units B, in dipolar domains dispersed in the weakly polar A matrix, occurs systematically whatever the structure of the zwitterion (dipole moment in the range 3–10 × 10−29 C m) and its relative position with respect to the chain backbone.

Morphology development during the polymerization of styrene within a polyurethane network: Investigations by small‐angle X‐ray and light scattering

Phase separation that takes place during the formation of semi-interpenetrating polymer networks based on crosslinked polyurethane and linear polystyrene was studied by small-angle X-ray scattering and light scattering. The kinetics of the chemical reactions was followed by Fourier transform infrared spectroscopy. The occurrence of broad peaks in the X-ray scattering curves was interpreted in terms of distances between the urethane crosslinks. Small modulations on these curves were assigned to sphere-like structures with a diameter of around 5 nm which might be related to the urethane crosslink regions. Small modulations on the light-scattering curves at the beginning of styrene polymerization were assigned to spheres with diameters of around 4.5 μm, which can be related to the polystyrene-rich phase. These modulations disappear with time, which might indicate an increasing polydispersity of the domain sizes. The final morphology was found to depend on the time at which polymerization of styrene is initiated with respect to the time of gelation of polyurethane.

Matrix polarity effects on microphase separation in zwitterionomers, 2. Structural analysis of the model random zwitterionomers

Matrix polarity effects on the potential microphase separation in zwitterionomers were analyzed on four homologous series of model zwitterionic A i B copolymers. They combine in their chain various A i units -CH 2 -CH(CH 2 R i )-O- of finely tuned polarity such as epichlorohydrin (PEC, R i =Cl), glycidol (PGOH, R=OH), glycidyl acetate (PGAC, R i =O-CO-CH 3 ) or glycidyl p-nitrobenzoate (PONB, R i -O-CO-C 6 H 4 -NO 2 ) and highly dipolar and constant B units -CH 2 -CH[-CH 2 -O-(CH 2 ) 2 -N + (C 2 H 5 ) 2 -(CH 2 ) 2 -O-CO-C - (CN) 2 ]-O- of the ammonioethoxydicyanoethenolate type (μ = 25.9 D, molar transtion F n < 0.3). The bulk structure of the varions zwiterionomers was analyzed by differential scanning calcrimetry (glass transitions) and solid state NMR CH dipolar line shape analysis, chain dynamics) and correlated with the solubility properties of a model zwitterion in a series of solvent models of the various polymetic matrices (A i ) n . a) PGOH zwitterionomers are monophasic (one T g between 3 and 31°C) as a result of specific A-B hydrogen bonding, b) PGNB zwitterionomers are likely monophasic (one T g around 58°C) as a result of strong dipolar and dispersion A-B interactions but this feature cannot be definitely ascertained because of the too close glass transitions of the parent homopolymers c) The PEC zwitterionomer of F B = 0.11 is a biphasic material characterized by a quasi-quantitative segregation of the dipolar units in the hard phase (high T g ≃ 22°C) and a segregation case of PFC units in the soft phase (low T g ≃ -18°C) of about 84%. d) PGAC zwitterionomers are monphasic (one T g between -12 and 15°C), despite larly close and weak Van der Waals A-B interactions and study simular matrix mobility when compared to the previous PEC case. Thus, microphase separation in model A.B random zwitterionomers appears very sensitive towards small variations of the matrix polarity and of the A-B interactions.

Sulfonatopropylbetaine random copolymers: Zwitterionic analogues of ionomers

Random and atactic ethylacrylate (A) -sulfonatopropylbetain (B) copolymers, bearing the zwitterionic structure \(3\overset{+}{{\text{N}}}-({\text{CH}}_{2})_3-{\text{SO}}_{3}^{-}\) were studied by WAXS and SAXS in bulk within the whole range of composition and in absence or presence of stoichiometric amounts of LiClO4 ([LiClO4]/[B]=1). Microphase separation is actually observed in both cases, as a result of agregation of tie dipolar zwitterionic units in separate domains within the apolar ethylacrylate matrix. For low B content, random zwitterionic copolymers thus appear as pseudoionomers.