High-Throughput Screening of Selectivity of Melt Polymerization Catalysts Using Fluorescence Spectroscopy and Two-Wavelength Fluorescence Imaging

Abstract

A new general approach for rapid assessment of polymerization catalysts is introduced. Native fluorescence emission of solid polymers is measured directly in combinatorial 96-microreactor arrays and polymers produced in a laboratory-scale validation reactor. Fluorescence features collected with a CCD-based spectrofluorometer are correlated with chemical properties of interest such as polymer molecular weight, amount of branching, and catalyst selectivity. The approach is illustrated by screening of selectivity of melt polymerization catalysts used in synthesis of an aromatic bisphenol A polycarbonate. Selectivity of catalysts correlated with the ratio of fluorescence intensities at 400 and 500 nm at 340-nm excitation. The relative standard deviation (RSD) in spectroscopic serial measurements was 1-12.5%. This spread included instrument variability (< or = 1% RSD) and sample inhomogeneity. Parallel quantitative screening of catalyst selectivity in combinatorial 96-microreactor arrays was performed as a two-wavelength ratiometric fluorescence imaging through 400- and 500-nm interference filters and showed a good correlation (R2 = 0.994) with serial screening. Our approach is an attractive alternative to traditional separation-based techniques if speed and nondestructive nature of analysis are critical and when the high cross-linking or solvent resistance of polymers complicates traditional analysis.

Combinatorial Methods, Automated Synthesis and High‐Throughput Screening in Polymer Research: The Evolution Continues

“…Therefore, a CCD-based spectrofluorometer and/ or a fluorescence scanning system were utilized. [82] Both fluorescence screening tools revealed good correlation to each other and to conventional characterization techniques. It was, for instance, possible to correlate the fluorescence (excitation 280 nm, emission 305 nm) of the solid polymer samples with their number-average molecular weight obtained by GPC.…”

“…[33,82] Utilizing a 96-microreactor array for the preparation of bisphenol A polycarbonates, properties of interest such as molecular weight, the amount of branching, or catalyst selectivity could be correlated to fluorescence features. Therefore, a CCD-based spectrofluorometer and/ or a fluorescence scanning system were utilized.…”

Evaluation of Process Degradation of Polymer Formulations Utilizing High‐Throughput Preparation and Analysis Methods

“…[5][6][7][8] Fluorescence spectra were not corrected for the spectral response of the optical system. [9] For in-line determinations, the common end of the bifurcated fiber-optic probe was positioned near the die exit of the extruder.…”

Sensors in Combinatorial Polymer Research

“…As a demonstration of this powerful monitoring concept, we performed determinations of volatiles during melt polymerization of polycarbonate in thin-film polymerization reactors. [37,39,129,130] Melt polymerization reactions of polycarbonate were performed by reaction of an aromatic diphenol such as 2,2 0 -bis(4-hydroxyphenyl)propane with a derivative of carbonic acid, such as diphenyl carbonate in the presence of a catalyst candidate. These reactions were performed in small quartz vials that served as polymerization microreactors (Figure 13a) in a sequence of steps of increasing temperature [131] with a maximum temperature of 280 8C.…”