Effect of Shell Growth on the Morphology of Polyvinyl Acetate/Polystyrene Inverted Core-Shell Latex Fabricated by Acrylonitrile Grafting.

Jiaxing Sun,Long Bai,Zhiguo Li,Zhao Jia,Xiao Zhang,Jiyou Gu

doi:10.3390/ma11122482

Jiaxing Sun, Long Bai + Show 4 more

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https://doi.org/10.3390/ma11122482

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Abstract

A novel strategy for fabricating inverted core-shell structured latex particles was implemented to investigate the morphology and properties of polyvinyl acetate (PVAc)-based latex. In this study, active grafting points were synthesized onto the surface of PVAc latex cores via grafting acrylonitrile (AN) to obtain a controllable coating growth of the shell monomer, styrene (St). The effect of shell growth on the morphological evolvement was explored by tuning the time of shell monomer polymerization. Unique particle morphologies, transferring from “hawthorn” type, over “peeled pomegranate” type, to final “strawberry-like” type, were observed and verified by electron microscopy. The morphological structure of latex particles exerted a significant effect on the particle size, phase structure, and mechanical properties of the obtained emulsions. The water-resistance of PVAc-based latex was also evaluated by the water absorption of latex films. More importantly, the experimental results provided a reasonable support for the controlled growth of St monomer, that is, the self-nucleation of dispersive St monomer can be transformed to in-situ coating growth on the PVAc core surface depending on the AN-active grafting points. This fabricating approach provides a reference for dynamical design and control of the latex particle morphology.

Highlights

Core-shell structure was commonly used to design and prepare structured emulsion-based polymers owing to its special heterogeneous structure and stratification effect [1,2,3,4,5,6]
A functional monomer, acrylonitrile (AN), was employed to form the grafting structure on the surface of the monitored polyvinyl acetate (PVAc) cores, providing active grafting sites to initiate the polymerization of St monomer
Thermodynamic non-equilibrium PVAc-AN/PS inverted core-shell structured latex particles with controllable morphologies and surface topographies were successfully synthesized via semi-continuous seeded emulsion polymerization

Summary

Introduction

Core-shell structure was commonly used to design and prepare structured emulsion-based polymers owing to its special heterogeneous structure and stratification effect [1,2,3,4,5,6]. How to design and synthesize well-defined core-shell latex particles with a unique morphology, structure, and function attracts considerable attention in the field of colloid research [8]. The fabricating procedures for core-shell structured latex, such as multiple-stage emulsion polymerization [11,12], interfacial process [13], and heterocoagulated reaction [2], have been well reported. Among these approaches, emulsion polymerization was a facile, efficient, and cost-effective method. For emulsion-based core-shell, Materials 2018, 11, 2482; doi:10.3390/ma11122482 www.mdpi.com/journal/materials

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