## 4 Conclusions  
We conducted a systematic study to analyse the impact of the concentration and chain length of oligoglycidol-based surfrmers on the emulsion polymerisation of styrene. We studied the influence of surfrmer concentration on the particle size, both for polymerisations carried out at concentrations below and above the critical micelle concentration (CMC). Additionally, we analysed the influence of oligoglycidol chain length on the average particle size whilst keeping the surfrmer concentration constant. Our study unveiled that below the CMC the average particle size decreased with increasing surfrmer concentration. Here, an increase in surfrmer molecules led to a higher homogeneous nucleation rate. When the CMC passed, a more steep decrease in particle size occurred due to a change in nucleation mechanism. Being above the CMC heterogeneous nucleation inside the formed micelles--according to the mechanism proposed by [PERSON] and [PERSON]--led to a large increase in the nucleation rate, and therefore a large decrease in particle size. Furthermore, an increase in particle size with increasing oligoglycidol chain length was observed whilst keeping the concentration of the surfrmer constant. This can be explained by increased hydrophobicity of oligoglycidol with increased chain length, and therefore an increased tendency to be buried inside the polystyrene nanoparticle instead of being positioned at the particle-water interface. Furthermore, an influence of the oligoglycidol chain length on the reactivity of the surfrmer can play a role in the rate of nucleation. Additionally, we analysed the colloidal stability of polystyrene nanoparticles in aqueous NaCl solutions as function of particle size and oligoglycidol chain length. Our study showed that an increase in particle size led to an increase in colloidal stability. At average particle sizes around 350 nm no large agglomerates were formed even at NaCl concentrations of 5 mol\(\cdot\)L\({}^{-1}\). An effect of the oligoglycidol chain length on colloidal stability could not be observed. In general it can be concluded that colloidal stability of all oligoglycidol functionalised polystyrene nanoparticles is based on a combination of surface charge due to sulphate groups originating from the initiator, and the oligoglycidol surfrmer. The charge stabilisation did not contribute to the colloidal stability in NaCl, whereas the addition of oligoglycidol led to increased colloidal stability. Contrary to our expectation, an increase in oligoglycidol chain length led to increased hydrophobicity of the surfrmer and to larger particles. For the same oligoglycidol chain length an increase in surfrmer concentration led to decreasing particle size, and the largest particles, synthesized with the least amount of surfactant, show the highest colloidal stability. **Supplementary Materials:** The following are available online at [[http://www.mdpi.com/2073-4360/12/7/1557/s1](http://www.mdpi.com/2073-4360/12/7/1557/s1)]([http://www.mdpi.com/2073-4360/12/7/1557/s1](http://www.mdpi.com/2073-4360/12/7/1557/s1)), Figure S1-S3: 1H-NMR spectra of VBA, 1a and 2a. Figure S4-S6: LC-MS spectra of 2a-c. Figure S7: GC-MS chromatogram of latex 3a. Figure S8-S15: SEM images of particles **3b-d, 4a-c, 5** and 6**. **Author Contributions:** Conceptualization, K.S., D.M. and P.B. ; methodology, K.W., S.C. and R.v.Z. ; validation, J.W., E.B. and H.K. ; formal analysis, K.W., R.v.Z., K.S. and D.M. ; investigation, K.W., S.C. and R.v.Z. ; writing--original draft preparation, D.M. ; writing--review and editing, K.S., D.M. and P.B. ; visualization, K.W. and D.M. ; supervision, P.B. ; All authors have read and agreed to the published version of the manuscript. **Funding:** The research work in this paper was carried out within Brightlands Materials Center, a joint research initiative between TNO and the province of Limburg. The work is funded by the Dutch government as well as the province of Limburg.