title: Physical tuning of cellulose-polymer interactions utilizing cationic block copolymers based on PCL and quaternized PDMAEMA.
abstract: In this work, the objective was to synthesize and evaluate the properties of a compatibilizer based on poly(ε-caprolactone) aimed at tuning the surface properties of cellulose fibers used in fiber-reinforced biocomposites. The compatibilizer is an amphiphilic block copolymer consisting of two different blocks which have different functions. One block is cationic, quaternized poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and can therefore electrostatically attach to anionic reinforcing materials such as cellulose-based fibers/fibrils under mild conditions in water. The other block consists of poly(ε-caprolactone) (PCL) which can decrease the surface energy of a cellulose surface and also has the ability to form physical entanglements with a PCL surface thereby improving the interfacial adhesion. Atom Transfer Radical Polymerization (ATRP) and Ring-Opening Polymerization (ROP) were used to synthesize three block copolymers with the same length of the cationic PDMAEMA block but with different lengths of the PCL blocks. The block copolymers form cationic micelles in water which can adsorb to anionic surfaces such as silicon oxide and cellulose-model surfaces. After heat treatment, the contact angles of water on the treated surfaces increased significantly, and contact angles close to those of pure PCL were obtained for the block copolymers with longer PCL blocks. AFM force measurements showed a clear entangling behavior between the block copolymers and a PCL surface at about 60 °C, which is important for the formation of an adhesive interface in the final biocomposites. This demonstrates that this type of amphiphilic block copolymer can be used to improve interactions in biocomposites between anionic reinforcing materials such as cellulose-based fibers/fibrils and less polar matrices such as PCL.
authors.affiliation: Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, SE-100 44 Stockholm, Sweden. utsel@kth.se
authors.forename: Simon
authors.initials: S
authors.lastname: Utsel
authors.forename: Carl
authors.initials: C
authors.lastname: Bruce
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Pettersson
authors.forename: Linda
authors.initials: L
authors.lastname: Fogelström
authors.forename: Anna
authors.initials: A
authors.lastname: Carlmark
authors.forename: Eva
authors.initials: E
authors.lastname: Malmström
authors.forename: Lars
authors.initials: L
authors.lastname: Wågberg