## 3 Polymerization Reactions within AAO Templates
### Radical Polymerization
The proposed model accurately predicted that as the diameter pore decreases the probability of termination is increased, as a consequence of the higher local radical concentration and thus resulting in a decrease of the polymerization rate. See Reference [104] for further details of polymerization model. SEM morphological studies were conducted in order to establish the final nanostructure of the obtained polymer and to demonstrate the ability to replicate the well-defined surface structure of anodic aluminum oxide (AAO) templates by in situ polymerization. Interestingly, the hydrophobic character of Polyperfluorodecyl acrylate (PFA) surfaces as observed by contact angle measurements increased considerably as a function of pore diameter after nanostructuring a fluorinated acrylic polymer using AAO templates. In fact, the contact angle switched from 114\({}^{\circ}\) to 159\({}^{\circ}\) when increasing the roughness of the polymer surface from planar (bulk) to rough (extracted nanopillars from 250 nm diameter and 1.5 \(\upmu\)m length AAO templates). When a slight angle of 8\({}^{\circ}\) was applied to the substrate, the water droplet easily rolled off, thus demonstrating a lotus leaf mimetic surface [125]. Polymerization of methyl methacrylate was studied by [PERSON] et al. [126] in AAO templates as model monomer that shows a gel effect during polymerization. The evolution of the conversion versus time showed the onset of a rapid polymerization and a strong gel effect for all the polymerization temperatures studied leading to a limiting conversion, similar to polymerization in bulk, Figure 7. In addition, it was also observed that the conversion at which the gel effect appears was higher as the reaction temperature increased and that the maximum conversion obtained increased with increasing reaction temperature. Moreover, the initial rate of polymerization was much faster as the degree of confinement  
Figure 6: (**a**). The Raman spectra of in situ polymerized PFA in AAO templates as a function of time. (**b**) Graph of conversion versus time for polymerization of PFA in AAO template. Symbols represent experimental points while the dotted and solid lines represent the model prediction for bulk and nanoconfined polymerization, respectively [125]. Copyright 2015. Reproduced with permission from the publisher: RSC. increased. Finally, the molecular weight of polymers obtained in the AAO nanoreactors was significantly lower than those obtained in bulk across all the temperatures studied. In order to explain the differences between reactions conducted under nanoconfinement and in bulk, the authors proposed a mathematical model based on the free volume approach and three different confinement effects. In the initial phase of polymerization, within the AAO template, a faster decomposition of the initiator molecule was assumed, leading to a faster rate of polymerization. That was confirmed by DSC experiments in which the decomposition of AIBN was observed to occur significantly faster than reported values in bulk. Later, the onset of diffusional limitations was observed to occur earlier which was attributed to the higher glass temperature of polymers under nanoconfinement, which was also experimentally confirmed. Finally, due to the lower effective volume experienced by each radical when placed under nanoconfinement in the AAO templates, the pairwise combination of radicals in the diffusion limiting region would occur faster in the nanoconfined system. These confinement effects combined to give a polymer of lower molecular weight and of lower dispersity. Polymerization of vinyl pyrrolone. The kinetic study of thermal and photoinduced radical polymerization of vinyl pyrrolone (VP) in the restricted geometry of AAO templates was reported as an example of the polymerization of a less activated monomer [127]. The thermal polymerization of VP with AIBN as initiator at 60 \({}^{\circ}\)C was monitored using NMR.