Department of Chemistry, ‡Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, and §Department of Engineering, Aarhus University , Aarhus, Denmark.
ACS Appl Mater Interfaces. 2014 Dec 10;6(23):21308-15. doi: 10.1021/am5062823. Epub 2014 Nov 7.
In this work, various lengths and densities of poly(methyl methacrylate) (PMMA) brushes were synthesized on stainless steel (SS) surfaces via surface initiated atom transfer radical polymerization. Subsequently, the joints between the bulk PMMA and the PMMA brushed stainless steel were obtained by injection molding, and for these the degree of adhesion was assessed by tensile testing. Several conditions are required to facilitate the mixing between the brushes and the bulk polymer and to reduce the residual stress at the interface: preheating of the SS samples before the injection molding; a long packing time; and a mold temperature above the glass transition temperature (Tg) of PMMA during the injection molding. This treatment leads to a cohesive failure in the bulk PMMA. It was observed that the stress concentrated at the rim, due to contraction of bulk PMMA during cooling, results in a weak adhesion at the rim of the joint. A combination of high density and long brush length of PMMA film provides better adhesion. The large number of PMMA brush chains apparently promotes good penetration into the bulk PMMA chains and ultimately results in high adhesion strength.
在这项工作中，通过表面引发原子转移自由基聚合，在不锈钢（SS）表面合成了不同长度和密度的聚甲基丙烯酸甲酯（PMMA）刷。随后，通过注塑成型获得了 PMMA 本体与 PMMA 刷涂不锈钢之间的接头，通过拉伸试验评估了接头的附着程度。需要满足以下几个条件，以促进刷与本体聚合物之间的混合，并降低界面处的残余应力：在注塑成型前对 SS 样品进行预热；较长的填充时间；以及在注塑成型过程中模具温度高于 PMMA 的玻璃化转变温度（Tg）。这种处理会导致 PMMA 本体发生内聚失效。观察到由于 PMMA 在冷却过程中的收缩，在接头的边缘处会产生应力集中，导致边缘处的附着力较弱。PMMA 薄膜的高密度和长刷长组合提供了更好的附着力。大量的 PMMA 刷链显然促进了对 PMMA 本体链的良好渗透，最终导致了高的附着强度。
