Adsorption and Adhesion on Semi-Crystalline Polymers

几乎不可能在任何一种材料中找到体积性能（强度、透明度等）和表面性能（防水性、粘性等）的完美结合。达到目标表面特性的方法通常被称为表面修饰。尽管表面改性的概念并不新鲜——古埃及人使用天然产品通过胶水和清漆实现了这一点——优化这些新材料的方法和有效利用有限的现有材料资源的需求变得更加重要。许多日常使用的聚合物，如聚乙烯（PE）、聚丙烯（PP）和PET，都需要进行表面改性以实现新的功能。某些应用，特别是在印刷、电子和包装方面，需要修改这些聚合物的天然表面特性。许多涂层技术已经开发克服这一限制，但大多数需要额外的处理步骤。此外，人们总是担心涂层要么浪费材料（太厚），要么太薄或易碎，无法正常发挥其功能。我们提出了一种实现表面改性的替代途径，即将宿主聚合物与少量添加剂聚合物混合，其不同之处在于每个添加剂聚合物分子的一端已被化学修饰。如果化学修饰基团能被吸引到共混物表面，则添加剂聚合物在共混物表面的吸附将修饰其外表面性质。在某些情况下，这种吸引是自发的，很容易实现，在其他情况下，它可能是由仔细控制的加工条件引起的。以前我们已经证明这种技术可以很好地用于几种非晶体聚合物，但是从未尝试过用于半晶体聚合物，如聚乙烯。PE、PP和PET的半结晶性质对其优异的体性能至关重要，但也使这些材料更难分析。然而，由于这些材料的表面性质也很难通过其他方法进行修改，因此确实需要进一步探索这种可能性。最近，我们已经证明，在达勒姆使用的离子束分析技术非常适合于检查半结晶聚合物混合物，因此我们有很好的条件来开展这个项目。我们对共混物中表面改性聚合物在其表面的吸附与矿物在共混物外表面的沉积或吸附之间的关系特别感兴趣。显然，这些过程应该是相关的，因为聚合物共混物内部的吸附将为外部介质的吸附提供模板。这对聚合物的生物物理特性非常重要，比如骨生物相容性，我们计划对这种关系进行第一次系统的研究。

Rarely can the perfect combination of bulk properties (strength, transparancy etc) and surface properties (water repellency, stickyness, etc) be found in any single material. Methods to achieve the desired surface properties of an object are commonly referred to as surface modification. Although the surface modification concept is not new - the ancient Egyptians achieved this with glue and varnish using natural products - the need to optimise these methods for new materials and to make efficient use of limited existing material resources is ever more important.Many everyday polymers such as polyethylene (PE), polypropylene (PP) and PET require surface modification to fulfil new functions. Certain applications, notably in printing, electronics and packaging, require modification of the native surface properties of these polymers. Many coating techniques have been developed to overcome this limitation, but most require additional processing steps. Furthermore, there is always some concern that the coating is either wasteful of material (too thick), or may be too thin or fragile to perform its function properly.We propose an alternative route to achieve surface modification, whereby the host polymer is blended with a small amount of a additive polymer, that differs only in that one end of each additive polymer molecule has been chemically modified. Provided the chemically modified groups can be attracted to the blend surface, the adsorption of the additive polymer to the surface of the blend will modify its external surface properties. In some cases this attraction is spontaneous and very easily achieved, in others, it may be induced by careful control of the processing conditions. Previously we have shown that this technique can work extremely well for several non-crystalline polymers, however it has never been attempted for a semi-crystalline polymer such as polyethylene. The semi-crystalline nature of PE, PP, and PET is vital to their excellent bulk properties, but also makes these materials more difficult to analyse. However, since the surface properties of these materials are also notoriously difficult to modify by other methods, there is a real need to explore this possibility further. Recently we have shown that the ion beam analysis techniques used at Durham are perfectly well suited to examine semi-crystalline polymer blends, therefore we are well placed to carry out this project.We are especially interested in the relationship between the adsorption of surface modifying polymers within the blend to its surface, and mineral deposition or adsorption to the external surface of the blend. Clearly these processes should be related since adsorption within the polymer blend will provide a template for adsorption from external media. This is potentially extremely very important for biophysical properties of the polymer, such as bone biocompatibility, and we plan to carry out the first sytematic study of this relationship.