Design of Thermochromic Polynorbornene Bearing Spiropyran Chromophore Moieties: Synthesis, Thermal Behavior and Dielectric Barrier Discharge Plasma Treatment

Abstract

Abstract:A new class of thermochromic polynorbornene with pendent spiropyran moieties has been synthesized. Functionalization of norbornene monomers with spirobenzopyran moieties has been achieved using Steglich esterification. These new monomeric materials were polymerized via Ring Opening Metathesis Polymerization (ROMP). In spite of their poor solubility, polynorbornenes with spirobenzopyran exhibited thermochromic behavior due to the conversion of their closed spiropyran moieties to the open merocyanine form. Moreover, these polymers displayed bathochromic shifts in their optical response, which was attributed to the J-aggregation of the attached merocyanine moieties that were associated with their high concentration in the polymeric chain. The surface of the obtained polymers was exposed to atmospheric pressure air Dielectric Barrier Discharge (DBD) plasma system, which resulted in the reduction of the surface porosity and converted some surface area into completely non-porous regions. Moreover, the plasma system created some areas with highly ordered J-aggregates of the merocyanine form in thread-like structures. This modification of the polymers' morphology may alter their applications and allow for these materials to be potential candidates for new applications, such as non-porous membranes for reverse osmosis, nanofiltration, or molecular separation in the gas phase.

Removal of anionic dye Congo red from aqueous environment using polyvinyl alcohol/sodium alginate/ZSM-5 zeolite membrane

“…2 a. The crystalline peak centered at 2θ = 20°, is attributed to the reflection from (100) and (200) plane of PVA and SA 60 , 61 . Comparison of XRD pattern of pristine PVA/SA membrane with PVA/SA/ZSM-5 zeolite membranes shows that both the membrane possesses similar diffraction pattern.…”

Cast, Dip, Spray, and Print─Covalently Embedded Photochromic Materials from a Versatile Spiropyran Conjugate

“…In general, the relative ease of photoisomerization depends on the position of the photochromic unit in the polymer chain, with photoisomerization being the fastest in free dyes, followed by chain ends, as the pendant group and the slowest when present in the middle of the polymer chain. − Recently, fast photochromic switching was reported in polymers tethered with one photochromic unit per chain. ,,− However, initiation was slow, the molecular weight of the polymers obtained was low, and by using these photochromic unit tethered initiators it was challenging to polymerize functional monomers. − In order to make the process of forming photochromic materials environmentally friendly, various photochromic polymers and glasses have been prepared by dispersing the dye in solid matrixes. , …”