Collaborative Research: Optical Gradient Polymeric Materials via Isothermal Frontal Polymerization

该项目的目标是了解如何有效地使用等温正面聚合(IFP)来生产梯度光学材料。IFP是一种制备聚合物的方法，在该方法中，自由基聚合的局部反应区通过单体和引发剂的未搅拌溶液以每天约1厘米的速度传播。将聚合物的“种子”放在试管的底部，然后将带有自由基引发剂的聚合物单体的溶液放在上面。系统保持恒温。聚合反应在本体溶液中进行得很慢，但在聚合物区域，由于凝胶效应，单体使其膨胀，聚合速度要快得多。总体效果是聚合物和单体/引发剂溶液之间过渡区的缓慢传播。利用激光线偏转，我们将测量在甲基丙烯酸甲酯聚合过程中产生的梯度，并将其与解析和数值模型进行比较。梯度光学材料是具有光学性质的空间梯度的材料。通过IFP可以制备两种类型的材料。一种是梯度折射率(GRIN)透镜和纤维。另一类是有机光学限幅器。通过在单体/引发剂溶液中加入折射率不同于聚合物折射率的掺杂剂，可以产生RI梯度。掺杂剂由传播前沿重新分布，以产生掺杂剂浓度梯度和所产生的折射率梯度。使用非线性光学染料作为掺杂剂，可以在聚合物基质中产生这种染料的浓度变化。影响：该项目将使我们更好地理解如何利用等温正面聚合来制备具有有用应用的特殊材料。梯度折射率光纤在商业上用于必须在短距离的设备之间传输大量数字信号的应用。塑料纤维的生产成本更低，因此这项研究可以帮助生产消费产品和用于计算机网络的纤维。光学限幅器用于保护人眼免受强激光脉冲的伤害。用聚合物制备这种器件可以使它们的重量和成本更低，从而使它们的实用性更大。这项研究将有利于两名研究生的教育。数学家和化学家之间的合作将为他们在合作研究中提供重要的学习经验。由于USM有大量的非裔美国人和女性，这些群体将从这个项目中受益。

The goal of the project is to learn how isothermal frontal polymerization (IFP) can be efficiently used to produce gradient optical materials. IFP is a method of producing polymers in which a localized reaction zone of free-radical polymerization propagates at the rate of about one cm per day through an unstirred solution of monomer and initiator. A "seed" of polymer is placed at the bottom of a cuvette, and a solution of the polymer's monomer with a free-radical initiator is placed over it. The system is maintained at a constant temperature. Polymerization occurs slowly in the bulk solution but much faster in the region of polymer as the monomer swells it because of the gel effect. The overall effect is the slow propagation of a transition zone between polymer and the monomer/initiator solution. Using Laser Line Deflection, we will measure the gradients created during the polymerization of methyl methacrylate and compare these to analytical and numerical models.A gradient optical material is a material that possesses a spatial gradient of an optical property. Two types can be prepared via IFP. One type is Gradient Refractive Index (GRIN) lenses and fibers. The other type is organic optical limiters. The RI gradient can be produced by adding a dopant, with a refractive index different from that of the polymer, to the monomer/initiator solution. The dopant is redistributed by the propagating front to create a dopant concentration gradient and resulting refractive index gradient. Using a nonlinear optical dye as the dopant allows the creation of a concentration variation of this dye in a polymer matrix.Impact:This project will result in a superior understanding of how isothermal frontal polymerization can be used to prepare special materials with useful applications. Gradient refractive index fibers are used commercially for applications in which large amounts of digital signals must be transferred between devices over a short distance. Plastic fiber is cheaper to produce and so this research can help the production of consumer products and fibers for computer networks. Optical limiters are used for protecting human eyes from intense laser pulses. Preparing such devices with polymers can make their weight and cost lower and thus their utility greater.The research will benefit the education of two graduate students. The collaboration between mathematicians and chemists will provide them an important learning experience in collaborative research. Because of the significant number of African-Americans and women at USM, these groups will benefit from this project.