Fluorescence probes for monitoring polymerization processes

Interfacial and Fluorescence Studies on Stereoblock Poly(N-isopropylacryl amide)s

“…The emission intensities of 4HP dispersed in aqueous solution of PNIPAM begin to increase at the onset of the phase transition temperatures; see Figure and the Supporting Information. The fluorescence intensity of 4HP has been shown to reflect the microviscosity around the probe, a higher intensity corresponding to higher viscosity. − ,, All of the samples with isotactic-rich blocks show much higher emission intensity than the atactic reference at temperatures below the phase transition temperature, indicating their localization in the isotactic regions with limited mobility. The limited mobility results from the probe residing inside the aggregates and, possibly, due to the increased rigidity of the isotactic chains due to junction formation .…”

“…4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H -pyran (4HP) is a probe that can be used to study the mobility and rigidity (microviscosity) of its immediate surroundings. 4HP emits very weakly in water but is known to emit strongly in micellar systems, − and it has been used in fluorescence studies of PNIPAM–PEO systems. , Both probes can be used to evaluate the polarity of the mesoglobules or aggregates of stereoblock PNIPAMs.…”

“…The surface activity of amphiphilic polymers shows an abrupt change at the critical micellization concentration (cmc). At room temperature, atactic PNIPAM above the cmc lowers the surface tension of water (71.8 mN/m) to ∼40 mN/m. ,, Thus, atactic PNIPAM can be seen as a very surface active polymer as compared to polyethylene oxide, PEO. Aqueous PEO solutions show surface tensions of around 60 mN/m above the cmc.…”

A Self‐Reporting Photocatalyst for Online Fluorescence Monitoring of High Throughput RAFT Polymerization

“…In recent years, the use of such plate reading technology has become widespread both at the laboratory scale in the biological sciences (such as in cell viability assays) as well as in the pharmaceutical industry for quality control purposes or for the discovery of novel drug targets. Although fluorescence‐based monitoring has previously been applied for the monitoring of conventional FRP, these techniques generally require the addition of exogenous fluorophores to the polymerization mixture. For instance, Zhao's group demonstrated that the addition of a pro‐fluorescent monomer could be used to study the polymerization kinetics of dilute microemulsions .…”

Push−Pull Aminobithiophenes — Highly Fluorescent Stable Fluorophores

“…While nonrigid conjugated systems such as bithiophene can be readily modified for addressing the shortcomings of their rigid counterparts, they are weakly fluorescent (Φ fl = 0.015) . The fluorescence yield of nonrigid conjugated biaryls can dramatically be increased by incorporating complementary electron-donating and -withdrawing groups . The electronic push−pull effect is typically achieved with an electron-donating amine .…”