Polymerization within Nanoporous Anodized Alumina Oxide Templates (AAO): A Critical Survey

In the last few years, the polymerization of monomers within the nanocavities of porous materials has been thoroughly studied and developed, allowing for the synthesis of polymers with tailored morphologies, chemical architectures and functionalities. This is thus a subject of paramount scientific and technological relevance, which, however, has not previously been analyzed from a general perspective. The present overview reports the state of the art on polymerization reactions in spatial confinement within porous materials, focusing on the use of anodized aluminum oxide (AAO) templates. It includes the description of the AAO templates used as nanoreactors. The polymerization reactions are categorized based on the polymerization mechanism. Amongst others, this includes electrochemical polymerization, free radical polymerization, step polymerization and atom transfer radical polymerization (ATRP). For each polymerization mechanism, a further subdivision is made based on the nature of the monomer used. Other aspects of "in situ" polymerization reactions in restricted AAO geometries include: conversion monitoring, kinetic studies, modeling and polymer characterization. In addition to the description of the polymerization process itself, the use of polymer materials derived from polymerization in AAO templates in nanotechnology applications, is also highlighted. Finally, the review is concluded with a general discussion outlining the challenges that remain in the field.