Polymer Labelling with a Conjugated Polymer-Based Luminescence Probe for Recycling in the Circular Economy

Abstract

In this paper, we present the use of a disubstituted polyacetylene with high thermal stability and quantum yield as a fluorescence label for the identification, tracing, recycling, and eventually anti-counterfeiting applications of thermoplastics. A new method was developed for the dispersion of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) into polymer blends. For such purposes, four representative commodity plastics were selected, i.e., polypropylene, low-density polyethylene, poly(methyl methacrylate), and polylactide. Polymer recycling was mimicked by two reprocessing cycles of the material, which imparted intensive luminescence to the labelled polymer blends when excited by proper illumination. The concentration of the labelling polymer in the matrices was approximately a few tens ppm by weight. Luminescence was visible to the naked eye and survived the simulated recycling successfully. In addition, luminescence emission maxima were correlated with polymer polarity and glass transition temperature, showing a marked blueshift in luminescence emission maxima with the increase in processing temperature and time. This blueshift results from the dispersion of the labelling polymer into the labelled polymer matrix. During processing, the polyacetylene chains disentangled, thereby suppressing their intermolecular interactions. Moreover, shear forces imposed during viscous polymer melt mixing enforced conformational changes, which shortened the average conjugation length of PTMSDPA chain segments. Combined, these two mechanisms shift the luminescence of the probe from a solid- to a more solution-like state. Thus, PTMSDPA can be used as a luminescent probe for dispersion quality, polymer blend homogeneity, and processing history, in addition to the identification, tracing, and recycling of thermoplastics.

Incorporation of the New anti-Octadecaborane Laser Dyes into Thin Polymer Films: A Temperature-Dependent Photoluminescence and Infrared Spectroscopy Study

“…Since a decrease in PL intensity of borane cluster in PL spectra is connected with the α-transition of MEH-PPV matrix, other polymers PTMSDPA and PDMSi-MPSi were tested in the same experiment. PTMSDPA has a very high molecular weight (10 6 PTMSDPA vs. 10 3 PDMSi-MPSi) and glass transition temperature, which is considered higher than 200 °C [ 35 , 36 ]. PTMSDPA is therefore very rigid and temperature-resistant with limited solubility.…”

“…Polystyrene with molecular weight 350 000 g/mol (PS350; M w ~ 350,000, M n ~ 170,000) and 35,000 g/mol (PS35; M w ~ 35,000), poly(N-ethyl-2-vinylcarbazole) (PVK; M w ~ 990,000), and poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV; M n 40,000–70,000) were purchased from Sigma Aldrich. A high-molecular-weight polymer poly [1-phenyl-2-[p-(trimethylsilyl)diphenyl]acetylene] (PTMSDPA, M w ~ 10 6 ) was prepared at the Faculty of Science of the Charles University in Prague according to the procedure described in [ 35 ]. Poly(dimethylsilane-methylphenylsilane) (PDMSi-MPSi; M w ~ 82,000, M n ~ 18,000) was obtained from Fluorochem Ltd., and polycarbonate Makrolon (PC, M w ~ 58,000, M n ~ 25,000) was obtained from Bayer.…”

The temperature dependence of the Photoluminescence stability of octadecaborane in polystyrene matrix thin films

“…Under such operation conditions, no luminescence from borane could be expected. On the other hand, such behaviour is suitable for polymer labeling when the thermal history of the material needs to be indicated [7]. If the boranes should be still considered as active materials for blue-emitting diodes, a stabilization strategy must be developed.…”

Barbier single-atom polymerization induced emission as a one-pot approach towards stimuli-responsive luminescent polymers

“…1–11 Luminescent polymers have gained considerable research attention on account of their outstanding properties and applications in the areas of labelling, imaging, display, etc . 12–20 Stimuli-responsive luminescent polymers, possessing both stimuli-responsive and luminescence properties simultaneously in one polymer chain, represent multi-functional polymers that can exhibit stimuli-responsive behaviour accompanied by reversible disappearance or appearance of luminescence upon external stimuli, and are therefore highly desirable. 21–27…”