Grafting of POSS Hybrid Nanoparticles onto Poly(Vinyl Chloride) via Diels-Alder Click Reaction

Abstract

In this study, commercially available PVC was successfully modified with POSS hybrid nanoparticles at various molar ratios via catalyst-free Diels-Alder (DA) click chemistry, achieved by simple heating at approximately 80 degrees C. Furan and maleimide clickable groups were independently attached to PVC and aminopropyl isobutyl POSS through nucleophilic substitution reactions. However, furan functionalization of Poly(vinyl chloride) (PVC) led to partial chain scission and HCl elimination, confirmed by gel permeation chromatography (GPC) analysis, resulting in reduced molecular weight and mechanical properties. The furan functionalization degree was 3.67% (H-1-NMR) and 3.98% (elemental analysis). Among the modified samples, only PVC-g-POSS-1:0.25 (PVC:POSS molar ratio) was soluble in DMSO-d(6), with a grafting degree of 3.78% and DA reaction efficiency of 97.08%. Chemical grafting improved thermal and mechanical properties significantly. The glass transition temperature increased from 60.4 degrees C (neat PVC) to 84.1 degrees C, and the 50% degradation onset rose from 254.02 degrees C to 362.11 degrees C. Mechanical testing showed enhanced performance (yield stress: 14.2 MPa; elongation: 69.4%; elastic modulus: 300.6 MPa), outperforming physically mixed controls. SEM and TEM analyses showed that the best polyhedral oligomeric silsesquioxanes (POSS) dispersion occurred in PVC-g-POSS-1:0.25, with a relatively uniform distribution. As the POSS content increased in PVC-g-POSS-1:0.5, larger aggregates (>200 nm) formed, indicating stronger nanoparticle interactions and reduced dispersion.