Synthesis And Characterization Of Polyacrylates Based Pressure-sensitive Adhesives For Medical Applications

Pressure-sensitive adhesives (PSAs) are important and indispensable ones of polymer materials for medical applications. Since PSAs offer the advantages of convenience of use, good stability, simplicity of manufacture and good appearance, PSAs have been utilized in a wide range of medical applications. Recently, typical medical applications of PSAs include wound coverings and closures, surgical drapes, ostomy mounts, electrocardiogragh electrode mounts, electrosurgical grounding pads, transdermal drug delivery systems, various medical PSAs labels and tapes, and et al. With the development of the enterprises related to public health, PSAs will play a more and more important role in medical applications.In medical applications, compared to other PSAs, polyacrylates have many advantages. Acrylic PSAs, the single-component adhesives, do not require various additives, therefore, can avoid a separate blending process that has the potential problem of migration of small molecular components to the adhesive surface. Furthermore, the organic solvent-based, or emulsion acrylic PSAs are the final, ready-to-use adhesives. Therefore, acrylic PSAs have great advantages in preparation and processing. By copolymerization of acrylic esters, acrylic acid and other functional monomers in various feed ratio and controlling of chain structure, molecular weight and distribution of copolymers, acrylic PSAs with the desired adhesive properties can be produced according to the requirements in applications. Therefore, acrylic PSAs have great advantages in tailoring the polymer properties. In addition, acrylic PSAs offer favorable biocompatibility, good skin-adhesion property and good compatibility with a range of drugs and excipients. All these advantages indicate that acrylic PSAs are a good candidate adhesive with great potential for use in medical devices.In this thesis, various PSAs for use in medical devices and their recentdevelopments were comprehensively reviewed, and the properties and synthetic technologies of PSAs were also reviewed. Based on the current development and research in this field, the organic solvent-based and emulsion acrylic PSAs were prepared and characterized by the measurement of pressure-sensitive properties, DMA, DSC and analysis of particle size. The two following relations were discussed: the relation between component and technics parameters, molecular weight and distribution of acrylic copolymers, and pressure-sensitive properties of acrylic PSAs; and the relation between particle size and distribution, and pressure- sensitive properties of acrylic PSAs. In addition, two kinds of the modification of emulsion acrylic PSAs, that is, emulsion multicopolymerization and emulsion blend were studied. The results are as follows.For organic solvent-based or emulsion acrylic PSAs, the composition, types of comonomers and the molecular weight and molecular weight distribution of copolymers have critic effects on adhesion properties of acrylic PSAs. Functional monomers can significantly improve adhesion properties. As for emulsion acrylic PSAs, the dosage of functional monomers is confined in order to maintain the stability of emulsion polymerization, leading to the restriction of adhesion properties of emulsion PSAs. In contrast, adhesion properties of organic solvent-based PSAs can be adjusted in a wide range, without the restriction of the dosage of functional monomers. The suitable molecular weight and molecular weight distribution of copolymers is important to obtain the balanced adhesion properties. In the preparation of emulsion PSAs, the utilization of chain-transfer agent is the critic technique for controlling the molecular weight and molecular weight distribution, whereas, in the synthesis of solvent-based PSAs, chain-transfer agent is used to maintain the stability of solution polymerization, as a result, the adjustment of molecular weight and its distribution is realized by different feeding steps of initiator. In addition, the viscosity of adhesive and the process of the preparation of PSAs tapes, have dire...