Fabrication of Polydiacetylene Fibrous Microcrystals by the Reprecipitation Method

Abstract

The size and morphology control of polydiacetylcne microcrystals has heen investigated by changing preparation conditions such as temperature and added surfiictant in the reprccipitiition mcthod. As a result, fibrous microcrystals (diameter: 50 nm, length: 5-10 pm) of conjugated polyiners were interestingly fabricated under an optimum condition. The formation mechanism of polydiacetylene fibrous microcrystals and their optical properties were also investigated.

Effects of DNA on the Growth and Optical Properties of Luminescent Organic Microcrystals

“…The two parameters of highest importance are the concentration and the temperature of the organic solution. ,− In some cases, additives can also be introduced into the medium to control the reprecipitation process. They are often small molecules, such as surfactants, that are thought to act mainly as crystal growth inhibitors. ,, The use of macromolecules is infrequent and poorly documented, although synthetic polymers are empirically used as stabilizers in the crystallization of drugs. , …”

Microcrystals of an organic fluorescent dye grown in the presence of various PAMAM dendrimers: Control of the morphology and optical properties

“…Another one was to introduce additives into the medium. These often are surfactants, which act as inhibitors, preventing one or many crystal faces from growing [2,[11][12][13]. To our knowledge, macromolecules have not been used as additives in the reprecipitation method.…”

“…These tiny particles display original solid-state properties, which markedly differ from those of bulk crystals. For instance, their characteristics in UV/visible absorption [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and emission [15][16][17][18][19][20][21] are closely related to their size. This behaviour must be distinguished from the conventional quantum confinement effect, widely studied for inorganic semiconductors with a size below 10 nm [22], and which is expected to be weak for organic compounds.…”

Free‐standing microcrystals of a fluorescent organic dye: Preparation and spectroscopic study

“…In this basic framework, several parameters can be tuned with the aim to gain control on the microcrystal size. These parameters are, for example, the concentration of the injected solution and the temperature [12], the use of microwaves [13] or ultrasounds [14], the time left to the suspension for aging [15], and the addition of various substances in the reprecipitation medium [12,[16][17][18]. Very often, the substances used as additives are small molecules, such as surfactants, that get inserted into the crystal network and interfere with crystal growth.…”