Department of Mechanical Engineering, Yale University, New Haven, CT 06520-8286, USA.
J Colloid Interface Sci. 2010 Mar 1;343(1):125-33. doi: 10.1016/j.jcis.2009.10.002. Epub 2009 Oct 24.
We developed a well-controlled method to generate PLGA microparticles of different morphologies using the electrospray drying route. By judiciously selecting polymer molecular weight, concentration, and solution flow rate, we can control the order in which polymer entanglements and Coulomb fission occur in the droplets and their relative importance, and subsequently govern the morphology of the resulting polymer particles. We show that spherical, monodisperse particles are generated when sufficiently strong polymer entanglements set in the evaporating droplets before they undergo any Coulomb fission. On the other hand, tailed and elongated particles are obtained if the Coulomb fission occurs first and if the droplets/particles are sufficiently evaporated to freeze in their irregular shape. Strictly spherical particles are unachievable for polymer solutions below a critical concentration, because the onset of Coulomb fission always sets in prior to the development of a sufficiently entangled polymer network. An extension of a simple model, originally used to determine the onset of electrospinning of polymer solutions, adequately predicts when non-spherical particles are produced. We conclude by demonstrating the scale-up of this approach to the synthesis of polymer particles using a compact, microfabricated, multiplexed electrospray system, which would make it suitable for practical applications.
我们开发了一种可控的方法，通过电喷雾干燥途径生成具有不同形态的 PLGA 微球。通过巧妙地选择聚合物分子量、浓度和溶液流速，可以控制聚合物缠结和库仑分裂在液滴中发生的顺序及其相对重要性，从而控制所得聚合物颗粒的形态。我们表明，当在发生任何库仑分裂之前，蒸发液滴中形成足够强的聚合物缠结时，会生成球形、单分散的颗粒。另一方面，如果首先发生库仑分裂，并且液滴/颗粒蒸发到足以冻结其不规则形状的程度，则会得到具有尾部和细长形状的颗粒。对于低于临界浓度的聚合物溶液，无法获得严格的球形颗粒，因为库仑分裂的开始总是先于形成足够缠结的聚合物网络。对最初用于确定聚合物溶液电纺起始的简单模型的扩展，充分预测了何时会产生非球形颗粒。我们最后通过使用紧凑、微加工、多路复用的电喷雾系统来展示这种方法在聚合物颗粒合成中的放大，这将使其适用于实际应用。
