Analysis of poly(bisphenol A carbonate) by size exclusion chromatography/matrix-assisted laser desorption/ionization. 2. self-association due to phenol end groups

Biodegradation of Polystyrene by Plastic-Eating Tenebrionidae Larvae

Polystyrene (PS) is an extremely stable polymer with a relatively high molecular weight and a strong hydrophobic character that makes it highly resistant to biodegradation. In this study, PS was subjected to biodegradation tests by Tenebrio Molitor (T. Molitor) and Zophobas Morio (Z. Morio) larvae. Specifically, six different experimental diets were compared: (i) T. Molitor fed with bran; (ii) T. Molitor fed only PS; (iii) T. Molitor fed only PS treated with H2O2; (iv) Z. Morio fed with bran; (v) Z. Morio fed only PS; and (vi) Z. Morio fed only PS treated with H2O2. Therefore, the mass change of the larvae and the survival rate were measured periodically, while the frass collected after 15 and 30 days was analyzed by different analyses, such as spectroscopy (FTIR), spectrometry (molecular weight and polydispersity), thermal analysis (TGA) and microscopy (scanning electron microscopy observations). The obtained results suggest that in the case of T. Molitor larvae, larvae feeding on bran showed the highest survival rate of ~94% at 30 days, while in the case of the Z. Morio larvae, the highest survival rate was exhibited by larvae eating PS-H2O2. Although not strongly pronounced, the Mw and Mn of PS in the frass of both T. Molitor and Z. Morio larvae decreased over 30 days, suggesting PS biodegradation. Finally, the morphological analysis shows that PS samples isolated from the frass of T. Molitor and Z. Morio larvae showed completely different, rough and irregularly carved surface structures, in comparison to PS before biodegradation.

Synthesis, characterization and optical properties of distyrylanthracene-based polymers

Distyryl- and nitrodistyrylanthracene-based polymers (P1 and P2, respectively) have been synthesized and characterized. The polymers are fully soluble in common organic solvents and have number-average molecular weights of 18 570 and 23 480 g mol−1 for P1 and P2, respectively. The optical properties of the polymers were investigated by UV-visible absorption and photoluminescence spectroscopies. The optical gaps were estimated from the absorption-onsets of the polymer films; their values were 2.79, 2.75 eV for P1 and P2, respectively. A blue photoluminescence was observed in dilute solution. In solid thin film, Π–Π interactions influence the optical properties, and red-shifted photoluminescence spectra were obtained; a green emission (573 nm) for P1 and an orange one (605 nm) for P2 were observed. The HOMO and LUMO levels were estimated using cyclic voltammetry analysis. Single-layer devices of the indium-tin oxide/polymer/aluminum configuration were fabricated and showed relatively low turn-on voltages (5.14 V for P1 and 5.00 V for P2).

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with size-exclusion chromatographic fractionation for structural characterization of synthetic aliphatic copolyesters

We report matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and off-line coupling of size-exclusion chromatography with MALDI-TOFMS analysis (SEC/MALDI-TOFMS) methods for the detailed characterization of poly[(R,S)-3-hydroxybutyrate-co-L-lactic acid], P[(R,S)-3HB-co-LA], and poly[(R,S)-3-hydroxybutyrate-co-epsilon-caprolactone], P[(R,S)-3HB-co-CL], copolymer samples which are expected to be used in special medical application as scaffolds for cartilage and soft tissue engineering. The novel copolyesters contained randomly distributed (R,S)-3-hydroxybutyrate structural units, were synthesized by transesterification of the corresponding homopolymers, i.e. atactic poly[(R,S)-3-hydroxybutyrate], a-PHB, and poly(L-Lactide) (PLLA) or poly(epsilon-caprolactone) (PCL), respectively. The MS methods used for the characterization of the resulting polydisperse copolyester samples were supported by classical methods (NMR, SEC). The structures of individual copolyester macromolecules, including end-group chemical structures, were established using initially MALDI-TOFMS and then SEC/MALDI-TOFMS. The compositions of the copolyesters were determined by two methods, namely based on 1H NMR and MALDI-TOF spectra. The two sets of values showed good agreement. The sequence distribution was determined using the signal intensities of individual copolyester macromolecules, which appeared in MALDI-TOF mass spectra. Furthermore, sequence analysis gave information about the degree of transesterification. The copolyesters synthesized, with only one exception, were demonstrated to be almost random, which implies that the ester-ester exchange was close to completion.

Data Processing Method for the Determination of Accurate Molecular Weight Distribution of Polymers by SEC/MALDI-MS

A novel data processing method for a hyphenated technique, size exclusion chromatography/matrix-assisted laser desorption/ionization-mass spectrometry (SEC/MALDI-MS), has been proposed to determine accurate molecular weight distributions on the basis of the individual oligomer species of a polymer. This method is based on the concept that the individual peak intensities of MALDI mass spectrum observed for every SEC fraction with narrow molecular weight distribution could be adjusted to the quantified values to reveal the accurate molecular weight distribution using the signal intensity of the corresponding fraction on the SEC chromatogram observed with a refractive index detector. At first, the theory of the proposed date processing is described in detail. Then, experimental verification of the method is described. This was performed through the characterization of mixtures of three kinds of monodispersed polystyrene reference materials (weight average molecular weight = ca. 6000, 10000, and 18000) as model samples. An accurate trimodal molecular weight distribution for the individual oligomer species of the sample was obtained without any influence of the chromatographic band broadening observed in the original SEC chromatogram. Moreover, the method for depicting the elution profiles of individual oligomer species during SEC separation was also obtained as a "mass chromatogram" using the data processing procedure.

Matrix-assisted laser desorption/ionization mass spectrometry of discrete mass poly(butylene glutarate) oligomers

The mass dependency of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) response has been studied using equimolar mixtures of synthetic discrete mass poly(butylene glutarate) (PBG) oligomers of known structure having degrees of polymerization of 8, 16, 32, and 64. Mass discrimination observed was attributed to choice of matrix and detector saturation caused by higher laser intensity and inclusion of matrix ions in the MALDI spectra. Optimization of sample preparation and instrumental parameters provided uniform response over the mass ranged spanned by these four oligomers. The oligomer mixture was shown to serve as a model of more complex polymer distributions in the mass range 780-6000 Da, and application of the discrete mass oligomers as internal and calibration standards was demonstrated. Inclusion of PBG discrete mass oligomers as an internal standard in a quasi-equimolar mixture with polydispersed poly(butylene adipate) (PBA) indicated that some diminution of response occurred during the analysis of this mixture of materials. Reasons for differences in the corrected molecular weight averages of the polydispersed PBA obtained from measurements using MALDI and GPC were studied using individual discrete mass oligomers as calibration standards for GPC. The data indicated that differences in hydrodynamic volumes of PBG oligomers and PEG standards at similar masses resulted in an overestimation by GPC of the molecular weight averages of the PBA distribution.