Microencapsulation by in situ Polymerization of Amino Resins

ABSTRACT

By surrounding small droplets with a coating, one can obtain micrometer-size capsules (microcapsules), and combine multiple properties into a single system. This technology has allowed the design of advanced and functional materials. Amino resins are composed principally of urea and/or melamine and formaldehyde, and exhibit advantages as wall-forming materials, such as high mechanical strength and chemical resistance. In this review, a general description of the encapsulation process by in situ polymerization of amino resins is given. Characterization methods, and the influence of the physical and design parameters are discussed. A mechanistic description and some of the promising avenues of research are also presented.

KEYWORDS:

• Microcapsule
• encapsulation
• in situ polymerization
• urea-formaldehyde
• amino resin
• mechanism

Notes

* Also referred to as fill, payload, encapsulate, nucleus, internal phase, active ingredient, or active agent.

^φ Also known as shell, shell wall, coating, external phase or membrane.

^ϕ Microencapsulation techniques are sometimes divided among three categories, viz. chemical, physico-chemical, and physico-mechanical methods.^239,240

^σ In situ polymerization in some instances is regarded as a type of interfacial polymerization.