Proposed abstract for the PSCT 2013 Technical Seminar TECH 36

Title of the abstract: Interplay Between Viscoelastic and Chemical Tunings in Fatty Acid-Based Polyester Adhesives: Engineering Biomass towards Functionalized Step-Growth Polymers and Soft Networks

Richard Vendamme*,†

† Nitto Denko Europe N.V., 22 Eikelaarstraat, 3600 Genk, Belgium.

* , Tel: +32-(0)89-36 04 95, Fax +32-(0)89-36 22 42

Abstract: Today, the world is faced with major environmental challenges such as global warming, the increasing emissions of green house gases and the recognized depletion of the earth limited petroleum reserves. The growing awareness of society towards environmental issues combined with the recent governments regulations and incentives towards the reduction of carbon dioxide emissions is pushing the adhesive industry to develop greener products and to find alternative growth strategies based on sustainable economical models. In this context, the use of raw materials derived from renewable feedstock seems a particularly relevant option. Biomass, which is created when solar energy and atmospheric carbon dioxide are stored as organic molecules through photosynthesis, emerges as one of the carbon sources of the future, because it is abundant, renewable and versatile. However, finding sustainable and efficient ways to transform biofeedstocks into highly functional adhesive materials and coatings is still very challenging. The design of functional biobased materials able to compete with their highly optimised petrochemical counterparts can be seen as the foundation for the successful development of the biorefinery concept.

Based on the above statements, it is no surprise that the design of PSAs derived from renewable resources is currently attracting a lot of attention in several academic and industrial laboratories throughout the world. Fatty acids derivatives are an attractive resource for the development of biobased adhesives because of their intrinsically low glass transition temperature and the ever-increasing range of chemical and bio-refining operations available for plant oils.

This contribution describes the synthesis and characterisation of renewable self-adhesive coatings with tunable viscoelastic properties and equipped with well-defined amounts of carboxylic acid “sticker” groups with adhesion promoting characteristics. Hydroxyl-ended polyesters with various architectures (linear, branched) were synthesised by melt polycondensation of dimerized fatty acids and fatty diols, and then cured with maleic anhydride-modified triglycerides (such as maleinized soybean oil) in the presence of the amidine catalyst 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU). The curing reaction of alcoholysis has the dual effect of chain extending/cross-linking the base polymers via creation of polymeric half-esters linkages, while introducing carboxylic acid functions within the gel structure. We demonstrated how the adhesion properties can be finely tuned from molecular design and formulation of the network precursors and how the rheology and functionality of the coatings influence the adhesive bond formation and development. These renewable polyester adhesives proved to be suitable materials for pressure-sensitive adhesives applications with respect to adhesion strength, viscoelasticity and functionality. In addition, the environmental benefits of such materials are briefly discussed.

For more information on this work, please see:

Vendamme et al. Biomacromolecules, 13, 1933-1944 (2012)

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