Lärmipolümeeriseerimine

Lärmipolümeeriseerimine, also known as acoustic polymerization or sonopolymerization, is a process that utilizes high-frequency sound waves, typically ultrasound, to initiate and/or accelerate polymerization reactions. The sound waves generate cavitation bubbles within the reaction mixture. The collapse of these bubbles produces localized high temperatures and pressures, creating transient radical or ionic species that can initiate the polymerization process. This can lead to a faster reaction rate, a narrower molecular weight distribution, or the polymerization of monomers that are difficult to polymerize by conventional methods.

The mechanism involves the formation and violent collapse of cavitation bubbles. This generates extreme conditions within the bubble, including temperatures up to thousands of Kelvin and pressures up to hundreds of atmospheres, albeit for very short durations. These conditions can lead to the homolytic cleavage of monomer molecules or initiator molecules, generating reactive species that start the polymer chain growth. Alternatively, the high pressures can influence reaction equilibria and kinetics.

Lärmipolümeeriseerimine has been explored for various types of polymerization, including free radical polymerization, anionic polymerization, and cationic polymerization. It can be applied to monomers in liquid or solid phases, and can be used in bulk, solution, or emulsion systems. Potential applications include the synthesis of polymers with tailored properties, the development of novel materials, and in processes where traditional methods are inefficient or lead to undesirable side reactions. The control over reaction parameters, such as frequency, intensity, and irradiation time, allows for manipulation of the polymerization process and the resulting polymer characteristics.