We report quantitative MALDI-TOF measurements for polydimethylsiloxane (PDMS) of two different molecular weights using the relative ratio of the signal intensities of integrated oligomer distributions for these two molecular weight distributions. By reporting the ratio of intensities of the integrals of two oligomer distributions, we assume that the ionization and desorption efficiencies, crystallization conditions and other factors affecting intensity are similar. Poly(methyl methacrylate) (PMMA-33,000) was mixed with PDMS samples to show whether the presence of another material might affect the desorption efficiency. Quantitative values for the number-average molecular weight (M n ), weight-average molecular weight (M w ) and polydispersities (D) were calculated using the oligomer distributions. The results show a linear relationship between the analyte concentrations and the signal intensities in the range from 1,000 Da to 10,000 Da, and the desorption efficiency of these two PDMS materials was the same even in the presence of PMMA. (J Am Soc Mass Spectrom 2002, 13, 914 -920)

The development of soft ionization methods such as matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI) and secondary ion mass spectrometry (SIMS) has led to an increased use of mass spectrometry in characterizing technical (synthetic) polymers. In this paper, we compare the relative performance of these three ionization methods for characterizing the molecular weights, polydispersities and quantification of relative amounts of polymer components in mixtures. Two polymers used in biomaterials, poly(dimethylsiloxane) and poly(ethylene glycol), are employed as the model polymer systems for our survey because of their well-defined molecular weights and importance as surfactants in biomaterials and because many of their surface and solutionphase properties are well understood. Matrix-assisted laser desorption/ionization can be used to examine the surface and bulk composition of biomaterials, whereas secondary ion mass spectrometry is used for examining monolayer and submonolayer coverage of polymers on surfaces and electrospray ionization is suited for examination of extractables from biomaterials. Secondary ion mass spectrometry and electrospray show discriminate behavior against ionization of higher molecular weight oligomers, especially of poly(dimethylsiloxane). Matrix-assisted laser desorption/ionization appears to exhibit the best performance for reliable molecular weight determination at higher masses and polydispersity characterization as well as for quantification of components in polymer mixtures. The results are discussed within the context of the ionization mechanisms by which each soft ionization technique operates and by the attributes of the mass analyzers (time-of-flight and Fourier transform mass spectrometers) employed.

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Innovation is the first driving force for development, and green innovation efficiency (GIE) plays a very important role in regional sustainable development. Data from 31 provinces and cities in China from 2011 to 2020 were used to select the proportion of energy saving and environmental protection costs in GDP as the green financial value, and the proportion of industrial pollution control input in GDP as the environmental regulation index. Green innovation efficiency is measured from two aspects of input and output by DEA method, and carried out for 31 provinces and cities in three regions. Using the DEA-Malmquist index to measure regional green innovation efficiency, the results show that the green innovation efficiency in three regions basically presents an upward trend, but the upward trend of green innovation efficiency is different between the three regions. A Tobit regression model is constructed to explore the impact of green finance and environmental regulations on the green innovation efficiency in these three regions. Research indicates that environmental regulations, the proportion of output value of tertiary industry in GDP, industrial structure, and foreign direct investment have significant impacts on the green innovation efficiency in all regions. Green finance, industrial structure, and power consumption have a significant impact on the green innovation efficiency in eastern China. Industrial structure has a significant impact on green innovation efficiency in central China, while power consumption and industrial structure have a significant impact on green innovation efficiency in western China. Therefore, each region needs to improve the standard of environmental regulation innovation, and introduce and use foreign investment in a scientific and reasonable way so as to promote the improvement of industrial infrastructure.