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The polycondensation of [3-(methacryloxy)propyl]trimethoxysilane was performed in bulk, using 98 wt % formic acid (molar ratio HCOOH/Si = 3 or 6), at 50 or 70 °C, for periods of time of up to 1 month. The resulting silsesquioxanes (SSOs) were characterized by ¹H NMR, FTIR, SEC, UV−MALDI−TOF MS (linear, reflector, and post-source decay modes), and ESI−TOF MS. The residual concentrations of Si−OCH3 groups, and generated CH3OH and HCOOCH3, were quantitatively monitored by ¹H NMR during the initial stage of the synthesis. After 2 days of reaction at 50 °C, or about 6 h at 70 °C, the resulting SSO mainly contained residual Si−OH groups with only traces of Si−OCH3 groups, as was also confirmed by FTIR and UV−MALDI−TOF MS in the reflector mode. After this time, the polycondensation continued slowly during storage at room temperature, basically through Si−OH + Si−OH reactions. The average fraction of intramolecular cycles increased continuously during the polycondensation. An average value, fav = 0.81, was found for species containing 6−24 Si atoms in a typical reaction product. This evidenced the presence of species with relatively closed structures. In MS/MS spectra, fragmentation of one or more ester groups attached to Si atoms was observed, following a McLafferty rearrangement. The addition of water to the initial formulation (about 3:1 H2O/Si molar ratio) led to a slower polycondensation rate and to a decrease of the average fraction of intramolecular cycles (formation of more open structures). Therefore, the use of 98 wt % formic acid was useful to synthesize SSOs containing a higher fraction of intramolecular cycles than those resulting from conventional formulations.

The NaOH-catalyzed hydrolytic condensation of the reaction product between N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and phenyl glycidyl ether (PGE) was followed by matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS). After 24 h at 50 °C, main condensation products were a mixture of perfect and imperfect polyhedra:  T8, T9(OH), and T10, with traces of T7(OH) and T11(OH). Every one of these products was composed of a series of peaks in the mass spectra, accounting for the incomplete reaction of PGE with the aminosilane (e.g., T8 showed the presence of the species containing 24 PGE units arising from the complete reaction of the initial silane, as well as species containing 23, 22, and 21 PGE units). A thermal treatment to 150 °C led to the appearance of extra peaks corresponding to intramolecular dehydration products. Peaks corresponding to the loss of one water molecule from T9(OH) and T7(OH) were present and could be ascribed to the reaction between SiOH and a secondary OH group. Dehydration products from T8 and T10 were observed, as well as species arising from the loss of two water molecules from T9(OH) and T7(OH). A plausible explanation for the presence of these peaks is the rupture of a Si−O−Si bond in the presence of NaOH, followed by condensation of the resulting fragments with secondary OH groups.

1,6-Diaminohexane and a 2-(S)-hydroxypentanedioic acid 5,2-lactone derivative (3) were polycondensed to afford an aregic polyamide 4. A chiral monomer (5) having a 2-fold axis of symmetry was chemoselectively constructed from 3, and upon polymerization with the diamine led to an AABB-type polyamide having a syndioregic orientation of the hydroxyl substituents. The analogous isoregic polyamide 11 was also prepared. The three polymers had the same basic structure, but they differ in their regio and stereoregularity. These polyamides, which displayed optical activity, were characterized by IR and ¹H and ¹³C NMR, and their molecular weights were estimated by GPC, viscosimetry, and matrix-assited ultraviolet laser desorption/ionization time-of-flight mass spectrometry (UV−MALDI−TOF MS). This technique was particularly convenient to confirm the repeat units and to detect the functional groups at both ends of the chains. In accordance with their growth processes polyamides 11 and 12 showed the typical UV−MALDI−TOF spectrum for homopolymerization, and polyamides 4 and 6 showed those corresponding to growing by copolymerization. Besides, in agreement with their stereoregularity, polyamides 6 and 11 showed better crystalline properties than those of 4.

High-molar-mass silsesquioxanes (SSQO) based on (3-glycidoxypropyl)trimethoxysilane (GPMS) and (3-methacryloxypropyl)trimethoxysilane (MPMS) were synthesized. The hydrolytic condensation of GPMS was performed using HCOOH (0.1 N) as catalyst, keeping the molar ratio H2O/Si = 3. A first step was performed in tetrahydrofuran (THF) at 50 °C, followed by a second step in diglycidyl ether of bisphenol A (DGEBA), where temperature was increased in steps up to 140 °C. The hydrolytic condensation of MPMS was performed in bulk with HCOOH 98%, at T = 50 or 70 °C, using molar ratios of HCOOH/Si = 3 or 6. Homogeneous solutions were obtained for both silanes. The reaction was followed by size exclusion chromatography (SEC), and final products were characterized by matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS), FTIR, and ¹H and ²⁹Si NMR. Molar-mass distributions showed the presence of clusters corresponding to products formed in different generations. With the aid of UV-MALDI-TOF MS, the different species present in every cluster could be identified for one of the silsesquioxanes derived from MPMS. During the initial stage of the hydrolytic condensation, species with 7−12 Si atoms were produced. They mainly consisted of incompletely condensed polyhedra (species with 1−3 OH per molecule) and ladder-type structures (species with 4 OH per molecule). Species with more OH groups were condensed with a higher probability, giving place to a second generation of products. This process accounts for the presence of a cluster of species with 14−24 Si atoms and the enrichment of the first cluster in the more condensed structures (T7(OH), T8(OH)2, and T9(OH)). Third and fourth generations of condensation products were also present. Structures of different species may be depicted as combinations of incompletely condensed polyhedra with ladder fragments.