Claudio A. Terraza

Synthesis and characterization of new bi-functional monomers based on germarylene or silarylene units: 4,4′-(R1R2-silylene)bis(phenyl chloroformates) and 4,4′-(R1R2-germylene)bis(phenyl chloroformates)

Following the reaction route between a diphenol and phosgene/toluene solution in basic medium, six new bis(chloroformates) containing germarylene or silarylene units were synthesized with good yield. The variation on the structure is due to the nature of the groups bonded to the heteroatom. Therefore, combinations of Me, Et and Ph groups were used. 4,4′-(Diethylsilylene)bis(phenyl chloroformate), 4,4′-(ethylmethylsilylene)bis(phenyl chloroformate) and 4,4′-(diethylgermylene)bis(phenyl chloroformate) were obtained as a slightly yellow oil, while 4,4′-(diphenylsilylene)bis(phenyl chloroformate), 4,4′-(methylphenylsilylene)bis(phenyl chloroformate) and 4,4′-(diphenylgermylene)bis(phenyl chloroformate) were obtained as a white solid. The new bi-functional monomers were characterized by FT-IR, 29Si-, 13C- and 1H-NMR spectroscopy and elemental analysis. The T m of the products in general was higher in samples containing germanium as the central atom, compared to those containing silicon.

Inclusion effect of gold and copper particles in a poly(amide) matrix that contains a thiophene moiety and Si or Ge atoms in the main chain

Soluble pure silicon or germanium-containing poly(amide)s and their metallic composites (Cu or Au) were synthesized and characterized. Optical band gaps of pure polymer were comparable to an insulator behavior; however, the conductivity of some composites at several concentrations shows a diode-like behavior. Samples exhibit a monoclinic lattice mixed with amorphous structures. Specifically, polymer–Au composites showed distortion of this unit cell, associated with an increase in the conductance. This effect would be related to the coordination of the central atom (Si or Ge) to the incorporated metal, producing a homogeneous distribution of metallic particles within the system.

Synthesis of Oligomeric Silicon-containing Poly(imide-amide)s Derived from Trimellitic Anhydride and Amino-Acids. Vibration Spectral, Optical, Thermal and Morphological Characterization

Poly(imide-amide)s (PIAs) were synthesized from diacids, which were obtained by trimellitic anhydride and glycine, L-alanine, L-phenylalanine, L-valine, L-leucine, L-isoleucine and p-aminobenzoic acid, and bis(4-aminophenyl)diphenylsilane. Compounds were characterized by elemental analysis, optical activity, IR and NMR spectroscopies. Yields were good, but ηinh values were low, showing materials of oligomeric nature, confirmed by MALDI-TOF spectrometry. PIAs were soluble in polar aprotic solvents, while those derived from amino acids with bulky side groups were soluble in CHCl3 and acetone. The wavenumber of vibrational bands were compared by Infrared and Raman spectroscopy. However, the high fluorescence emitted for PIAs, difficult to predict the vibrations of certain functional groups by Raman spectroscopy. The incorporation of chiral, amide and imide moieties interrupt the conjugation and increase the flexibility of the system. In addition, the adjacent phenyl units from the silicon-containing diamine, disfavors the planar conformation, which affects the optical properties showing an insulator behavior. DSC analyses showed that PIA-VII of aromatic nature had the higher glass transition temperature (Tg) value. For the other PIAs the Tg values decreased when volume of the side groups was increased, with the exception of PIA-VI derived from L-isoleucine. The thermal decomposition temperatures showed that only PIA-VII derived from p-aminobenzoic acid was thermostable. For the other PIAs it was possible to see a decrease of the TDT values when the size of the side chain is increased. The size and shape of the polymeric particles were studied by Scanning Electronic Microscopy (SEM), showing a relation between structure, incorporation of rigid aromatic rings and voluminous group into the system.

Silicon-containing oligomeric poly(imido-amides) with amino moieties. Synthesis, characterization and thermal studies

Silicon-containing oligomeric poly(imido-amides) (PIAs) were synthesized from dicarboxylic imido-acids containing a Si atom, which were obtained from dianhydrides and the amino acids glycine, L-alanine, L-phenylalanine, L-valine, L-leucine, L-isoleucine and p-aminobenzoic acid (I–III-(a–g)), were polymerized with the diamine bis(4-aminophenyl)diphenylsilane. Monomeric dicarboxylic imido-acids and PIAs were characterized by IR and 1H, 13C and 29Si NMR spectroscopy and, when necessary, optical rotation, and the results were in agreement with the proposed structures. The yields were very good, greater than 90%, but the ηinh values were low, indicating that PIAs were of oligomeric nature, especially those derived from dicarboxylic imido-acids with aromatic groups bonded to the Si central atom. PIAs were soluble in polar aprotic solvents, and also in other organic solvents like m-cresol, tetrahydrofuran, and several in CHCl3 and acetone, due to the inclusion of Si atoms and amino acidic residues in the main chain. The glass transition temperature (Tg) values were obtained by DSC, and showed a tendency in the sense that when the side chain of the amino acidic residue is increased, the Tg values decrease, as the higher volume of the side chain implies a higher chain separation and consequently a higher free rotation of them. PIAs including glycine or p-aminobenzoic acid residues, without side groups, showed higher Tg values due to an increase of the molecular rigidity. The thermal stability was determined by dynamic thermogravimetry showing that almost all PIAs were thermally stable, with TDT10% values greater than 400 °C. The most stable PIAs were those including the p-aminobenzoic residue in the main chain. The groups, methyl or phenyl, bonded to the Si atom of the carboxylic imide-acids residue did not show an important influence. The UV-vis transparency was studied showing that the increase of the aromatic content decreases the UV-vis transparency. PIAs derived from carboxylic imide-acids containing only phenyl groups bonded to the Si atom, were non-transparent.

Silarylene-containing poly(ether-amide)s obtained by Yamazaki–Higashi phosphorylation technique: use of bis(4-(4-aminophenoxy)phenyl)ethylmethyl silane

Abstract Aromatic poly(ether-amide)s (PEAs) based on -(R1,R2)diphenylsilane- and oxyether units were synthesized by direct polycondensation of a diamine and two dicarboxylic acids. For this, the diamine bis(4-(4-aminophenoxy)phenyl)ethylmethylsilane was obtained by reduction of the respective dinitro compound, which was synthesized by nucleophilic aromatic halogen displacement from 1-fluoro-4-nitrobenzene with bis(4-hydroxyphenyl)ethylmethylsilane in basic medium. New silicon-containing aromatic diamine and the PEAs were characterized by elemental analysis, FT-IR, 1H, 13C and 29Si NMR spectroscopy and the results were in agreement with the proposed structures. The incorporation of aliphatic units such as methyl and/or ethyl groups on the silicon atoms affected positively the solubility of the PEAs in organic polar solvents. When their thermal and optical properties were compared with two PEAs of similar structure, containing phenyl groups bonded to the silicon atoms, it was observed a decrease of the glass transition temperature and transmittance values, maintaining a high thermal resistance.

SYNTHESIS OF CONDENSATION POLYMERS DERIVED FROM SILYLATED MONOMERS UNDER PHASE TRANSFER CATALYSIS

The synthesis of the poly(carbonate) and poly(thiocarbonate) derived from the diphenol bis(4-hydroxyphenyl)-phenylmethylsilane and the poly(ester) derived from the same diphenol and the acid dichloride bis(4-chloroformylphenyl)-phenylmethylsilane are described. Polymers were synthesized under phase transfer conditions and the results were evaluated by the yields and inherent viscosity values. The phase transfer process was effective, but the results were affected by the increase of the NaOH concentration in the aqueous phase, in the sense that it was possible to see hydrolytic processes that decrease the yields and the inherent viscosity values. Also there was an influence of the nature of the catalysts, with BTEAC being efficient due to it hydrophilic nature

Silicon-containing oligomeric poly(amides) with phthalimidyl-amide side groups: synthesis, characterization and thermal studies

Oligomeric poly(amide)s (PAs) were synthesized from monomeric diacids, which were obtained from phthalic anhydride and the amino acid glycine, l-alanine, l-phenylalanine, l-valine, l-leucine, l-isoleucine and p-aminobenzoic acid. The phthalimidyl acids (IA-1 to IA-7) reacted with 5-amino-isophthalic acid in order to obtain the monomeric diacids (1-7). Furthermore, the monomeric diacid 8 was obtained by direct reaction between phthalic anhydride and 5-amino-isophthalic acid. The isophthalic acid derivatives were reacted with bis(4-aminophenyl)diphenylsilane in order to obtain the PAs. Monomers and polymers were characterized by infrared and 1H-, 13C- and 29Si-NMR spectroscopy, elemental analysis and, when necessary, optical rotation. The results were in agreement with the proposed structures. The yields were generally good, but the η inh values were low, indicating that the polymers were of oligomeric nature, namely, a chain of moderate molecular weight. The polymers were soluble in polar aprotic solvents and some of them were soluble in m-cresol and tetrahydrofuran. The glass transition temperatures (T g) values were obtained by differential scanning calorimetry, showing, in general, a decrease in value when the volume of the side chain of the amino acid moiety was increased. The thermal stability of the polymers was determined by dynamic thermogravimetry, showing good values of thermal decomposition temperatures (TDT), especially for those with aromatic residue in the amino acid, and for PA without amino acid. For PAs in which the side chain of the amino acid was larger, the TDT values were lower, probably due to the lack of symmetry and the length of the side chain, both of which have influence on the thermal stability.

Synthesis and characterization of poly(carbonates) and poly(thiocarbonates) derived from diphenols containing silicon as central atom

Poly(carbonates) and poly(thiocarbonates) containing silicon in the main chain and derived from the diphenols bis(4-hydroxyphenyl)-dimethylsilane, bis(4-hydroxyphenyl)-ethylmethylsilane, and bis(4-hydroxyphenyl)-diethylsilane with phosgene or thiophosgene, respectively, were synthesized under phase transfer conditions, using several phase transfer catalysts. Polymers were characterized by spectroscopic methods (IR and 1 H, 13 C, 29 Si NMR) and the results were evaluated by the yields and the η inh values. In general the effectiveness of the phase transfer process was low, the best results being obtained when the NaOH concentration was increased from the stoichiometric due to a salting-out effect. However, at higher concentrations hydrolytic process were observed. Poly(carbonates) and poly(thiocarbonates) showed, in general, the same trend with the catalysts.

Silarylene-containing oligo(ether-amide)s based on bis(4-(4-amino phenoxy)phenyl)dimethylsilane. Effect of the dicarboxylic acid structure on some properties

Oligo(ether-amide)s (PEAs) based on diphenylsilane and oxyphenyl units were synthesized through a Yamazaki–Higashi phosphorylation polyamidation technique. Thus, three new aromatic monomers were synthesized and characterized: a di(ether-amine), bis(4-(4-aminophenoxy)phenyl)dimethylsilane, and two dicarboxylic acids, bis(4-(4-carboxyphenoxy)phenyl)dimethylsilane and bis(4-(4-carboxyphenoxy)phenyl)diphenylsilane. MALDI-TOF mass spectrometry analyses show that the average molecular masses of the PEAs ranged from 1334 to 2097 m/z. The UV-vis technique was used to determine the optical band gap (Eg) of the oligomers. These values were between 3.91 and 4.57 eV. On the other hand, the conductivity of the samples was measured in the solid state (film) through the “four point method” showing a slight conductor behavior (13.3 and 5.0 S cm−1). Determination of fluorescence emission peaks showed two absorption bands. The first peak is related to a lesser electron-donating nature from an amide group, while the second peak was attributed to the polar solvent. Raman spectroscopy was used to determine the functional group in order to corroborate the structure and the crystallinity degree of the PEAs. Microstructural analyses of the samples were developed by using grazing incidence X-ray diffraction, showing amorphousness in the system studied. AFM micrographs showed that all the samples present certain porosity. On the other hand, the incorporation of flexibility inducing oxyether linkages affected positively the solubility of the PEAs in common organic solvents, and also decreased significantly the values of the glass transition temperature (Tg) and increased the transparency in the UV-vis region. In all cases, the thermal decomposition temperature values (TDT10%) were above 400 °C.

Synthesis and Characterization of Poly(carbonates) and Poly(thiocarbonates) Derived from Diphenols Containing Germanium as a Central Atom

Poly(carbonates) and poly(thiocarbonates), containing germanium in the main chain and derived from the diphenols bis(4‐hydroxyphenyl)‐dimethyl‐germane, bis(4‐hydroxyphenyl)‐diethyl‐germane, and bis(4‐hydroxyphenyl)‐dibutyl‐germane reaction with phosgene and thiophosgene, respectively. The products were synthesized under phase transfer conditions, using two phase transfer catalysts. The products were characterized by spectroscopic methods. The results were evaluated by the yields and ηinh values which showed different behaviors for poly(carbonates) and poly(thiocarbonates). The yields and the ηinh values for the poly(carbonates) were low due to a hydrolytic process when the NaOH concentration was increased. For the poly(thiocarbonates) the phase transfer was effective and also there was an increase of both parameters when the NaOH concentration was increased, due to a salting out effect.