Minimizing the Strong Screening Effect of Polyhedral Oligomeric Silsesquioxane Nanoparticles in Hydrogen-Bonded Random Copolymers.

Wei-Cheng Chen,Shiao-Wei Kuo,Ruey-Chorng Lin,Shih-Min Tseng

doi:10.3390/polym10030303

Wei-Cheng Chen, Shiao-Wei Kuo + Show 2 more

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https://doi.org/10.3390/polym10030303

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Abstract

A series of poly(vinylphenol-co-methacryisobutyl polyhedral oligomeric silsesquioxane) (PVPh-co-PMAPOSS) random copolymers have been synthesized through free radical copolymerizations of acetoxystyrene with methacryisobutyl POSS monomer and subsequent hydrazine monohydrate-mediated hydrolysis of the acetoxyl units. These random copolymers were characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC), which revealed that the POSS content in the random copolymers could be varied by changing the POSS monomer feed ratio by 1H NMR analyses. This molecular design approach allowed us to investigate the thermal properties and hydrogen bonding interactions of these PVPh-co-PMAPOSS random copolymers in comparison with those of PVPh/PMAPOSS blend systems. Hydrogen bonding interactions were absent in the PVPh/PMAPOSS blend system, because of a strong screening effect; in contrast, the PVPh-co-PMAPOSS random copolymers experienced enhanced intramolecular hydrogen bonding that minimized the strong screening effect of the POSS nanoparticles.

Highlights

Hydrogen bonding interactions in polymeric materials has garnered much interest over the past three decades for their ability to enhance thermal properties, improve miscibility behavior, induce self-assembly structures, and form nanocomposites [1,2,3,4,5,6,7]
Coleman et al determined the miscibility behavior and inter-association equilibrium constant (KA = 37.4) of such PVPh/PMMA blends [13]. They proposed the concepts of functional group accessibility and intramolecular screening effects (γ) based on comparisons with the interactions of PVPh and ethyl isobutyrate (EIB) in solution and of analogous PVPh-co-PMMA random copolymers [15,16,17,18]
Because of the limited content of polyhedral oligomeric silsesquioxane (POSS) nanoparticles possible at the chain end of a PMMA homopolymer, we examined the effects of grafting them onto the side chains of PMMA

Summary

Introduction

Hydrogen bonding interactions in polymeric materials has garnered much interest over the past three decades for their ability to enhance thermal properties, improve miscibility behavior, induce self-assembly structures, and form nanocomposites [1,2,3,4,5,6,7]. Coleman et al determined the miscibility behavior and inter-association equilibrium constant (KA = 37.4) of such PVPh/PMMA blends [13] They proposed the concepts of functional group accessibility and intramolecular screening effects (γ) based on comparisons with the interactions of PVPh and ethyl isobutyrate (EIB) in solution and of analogous PVPh-co-PMMA random copolymers [15,16,17,18]. The intramolecular screening effect has been defined as the self-bending of a polymer chain as a result of same-chain contact, through long-range, and local, connectivity effects This group observed a high screening effect when PVPh was blended with a dendrimer-like polyester (γ = 0.8) [19], but a low effect with a linear PVPh/PMMA blend (γ = 0.3) [15,16,17,18,19]

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Conclusion