New results on the influence of the nature of the nucleophile in the stereospecific modification of poly(vinyl chloride)

Abstract

The nucleophilic substitution reactions on poly(vinyl chloride) (PVC) with potassium 4-acetamidothiophenolate, potassium 2-naphthalenethiolate, and sodium 2-mercaptobenzothiazolate have been undertaken in a cyclohexanone solution. The aim was to study, from a comparative point of view, the influence of nucleophile characteristics, in particular bulkiness, reactivity, and nucleophile polarity, on the reaction mechanisms by following the microstructural evolution with the degree of substitution of the same PVC sample with three types of nucleophile under the same experimental conditions. The quantitative microstructural analysis as a function of conversion has been followed by 13 C NMR spectroscopy. Because of the steric hindrance and moderate reactivity of 2-mercaptobenzothiazolate, the stereoselective nature of the reaction is enhanced, occurring via the meso-racemic (mr) triad of mmr tetrad, inoperative in practice, unlike the other nucleophiles. This circumstance and the fact that the bulkiness of the nucleophile and interacting effects provide an enhancement of the molecular microstructure-based mechanisms, such that glass-transition temperature (T g ) varies with the degree of substitution, in all cases, along with the ratio between the extent to which mmr and rrmr structure intervene in the substitution reaction, thereby providing new and valuable information regarding the T g -microstructure relationship.

Importance of Covalent Linkages in the Preparation of Effective Reduced Graphene Oxide−Poly(vinyl chloride) Nanocomposites

“…This decrease has been assigned to a change in the global process of degradation. Since it has been reported that the nucleophilic substitution of PVC proceeds through a stereoselective mechanism, ,, it was proposed that a selective substitution brings about a strong progressive stabilization until a degree of substitution of ∼1% is attained. Afterward, the stability decreases with increasing degree of substitution.…”

Recent Advances in the Covalent Modification of Graphene With Polymers

“…A similar strategy has been approached to modify r‐GO with poly(vinyl chloride) (PVC) 57. Due to the absence of susceptible groups for esterification in PVC, these were provided by a previous nucleophilic substitution reaction 77, 78. As the premodification reaction is stereospecific, GO is also located at specific sites in the polymer, once again the preferred being the isotactic configurations.…”

Functionalization of Multi-Walled Carbon Nanotubes by Stereoselective Nucleophilic Substitution on PVC

“…[26][27][28] Besides, the prominent role of the tacticity-governed microstructure on the chemical reactivity has been recently reported. 29,30 Finally, the preparation of nanocomposites of PVC with carbon nanotubes has been reported. [31][32][33] However, to the best of our knowledge, covalent functionalization of CNTs with PVC has never been approached.…”