Question
What factors can influence polymerisation?
Answer
Polymerisation is influenced by a variety of factors that can affect the rate, efficiency, and properties of the resulting polymers. These factors include chemical, physical, and environmental conditions.
Key Factors Influencing Polymerisation
Initiator and Polymerisation Conditions: The type and concentration of initiators, as well as polymerisation time and temperature, significantly impact polymer performance. For instance, using a low concentration of initiator and low temperature over a long period can enhance selectivity and performance in molecularly imprinted polymers (Mijangos et al., 2006).
Temperature and Monomer Concentration: These are critical in determining the polymerisation rate. Higher temperatures and monomer concentrations generally increase the rate of polymerisation, as observed in the polymerisation of ethylene using metallocene catalysts (Tisse et al., 2010).
Catalyst Activity and Stability: The chemical nature of catalysts, such as transition metals, and their immobilization on supports like silica or magnesium chloride, affect both the activity and stability of the polymerisation process. The balance between these factors can influence the polymer yield and structure (Severn and Chadwick, 2013).
Physical Properties of Supports: The porosity and fragmentation ability of supports during polymerisation facilitate monomer diffusion, impacting the polymer’s physical properties and the catalyst’s effectiveness (Severn and Chadwick, 2013; McKenna et al., 2010).
Non-isothermal Conditions: The heat transfer conditions, such as adiabatic or non-isothermal environments, can influence the kinetics of polymerisation and the resulting polymer’s properties (Davtyan, Zhirkov and Vol’fson, 1984).
Polymer Architecture: The structure of the polymer, including cyclic, dendritic, or star architectures, can modulate mechanochemical reactions, affecting the location and rate of bond scission events (Peterson and Choi, 2021).
Photo-polymerisation Variables: The type of photo-initiator and the irradiance level during photo-polymerisation can influence the thermal response and structural order of polymers, affecting their thermal expansion and glass transition temperature (Sirovica et al., 2020).
Conclusion
Polymerisation is a complex process influenced by a multitude of factors including initiator type, temperature, catalyst properties, and polymer architecture. Understanding and optimizing these factors can lead to improved polymer performance and desired material properties.
References
Mijangos, I., Navarro-Villoslada, F., Guerreiro, A., Piletska, E., Chianella, I., Karim, K., Turner, A., & Piletsky, S., 2006. Influence of initiator and different polymerisation conditions on performance of molecularly imprinted polymers.. Biosensors & bioelectronics, 22 3, pp. 381-7. https://doi.org/10.1016/J.BIOS.2006.05.012
Davtyan, S., Zhirkov, P., & Vol’fson, S., 1984. Problems of Non-isothermal Character in Polymerisation Processes. Russian Chemical Reviews, 53, pp. 150-163. https://doi.org/10.1070/RC1984V053N02ABEH003035
Severn, J., & Chadwick, J., 2013. Immobilisation of homogeneous olefin polymerisation catalysts. Factors influencing activity and stability.. Dalton transactions, 42 25, pp. 8979-87. https://doi.org/10.1039/c3dt33098b
McKenna, T., Martino, A., Weickert, G., & Soares, J., 2010. Particle Growth During the Polymerisation of Olefins on Supported Catalysts, 1 – Nascent Polymer Structures. Macromolecular Reaction Engineering, 4, pp. 40-64. https://doi.org/10.1002/MREN.200900025
Tisse, V., Boisson, C., Prades, F., & McKenna, T., 2010. A systematic study of the kinetics of polymerisation of ethylene using supported metallocene catalysts. Chemical Engineering Journal, 157, pp. 194-203. https://doi.org/10.1016/J.CEJ.2009.12.006
Peterson, G., & Choi, T., 2021. The influence of polymer architecture in polymer mechanochemistry.. Chemical communications. https://doi.org/10.1039/d1cc02501e
Sirovica, S., Guo, Y., Guan, R., Skoda, M., Palin, W., Morrell, A., Romanyk, D., Martin, R., & Addison, O., 2020. Photo-polymerisation variables influence the structure and subsequent thermal response of dental resin matrices.. Dental materials : official publication of the Academy of Dental Materials. https://doi.org/10.1016/j.dental.2019.12.004
