ATRP copolymerization of BMA/HEA in AAO nanoreactor and bulk to obtain hydrophobic/hydrophilic materials

LAIA LEÓN; CATALINA VON BILDERLING; JUAN M GIUSSI; CARMEN MIJANGOS

Burgos

Congreso; X CONGRESO DE JÓVENES INVESTIGADORES EN POLÍMEROS; 2019

Polymer properties, such a glass transition temperature, thermal degradation or kinetics behavior can be important features to learn about copolymer system and control it by the feeding from the synthesis is the most interesting challenge. Moreover, topographical aspects, nano and micro aspects of polymer surface, have a noticeable impact on material surface properties and therefore on the applicability. For instance, in polymer scaffolds, cell growing only can occur under correct mechanical features of the polymer [1]. Well-known techniques for topographical patterning are nanoimprint, nano/microlithography or nanomolding strategies using hard cylindrical porous anodic aluminum oxide (AAO) nanomolds where a polymer melt is infiltrated. Moreover, surface wettability, hydrophobic/hydrophilic behavior and mechanical properties, are not easily obtained from the single and bulk monomer. For this reason, copolymerization and nanostructuration of copolymer is used to modify, control and improve the properties of polymers to meet specific needs. The in-situ polymerization method complements the more traditional polymer infiltration method and expanded the capability of anodic aluminum oxide (AAO) templates to pattern polymer nanostructures [2-6]. These advantages make the polymer nanostructures to be adaptable to a wide range of devices. Recently, we have reported the preparation of polymer nanostructures by in-situ free radical copolymerization of different monomers using AAO nanocavities as reactors [7].This work presents the process to study chemical, thermal properties and kinetics reaction of the system copolymerized by ATRP based on butyl methacrylate (BMA) and 2-hidroxyethyl acrylate (HEA) monomers and wettability, topography and mechanical properties of copolymer nanostructures obtained from AAO as reactors.The fabrication of porous AAO templates was carried out by a two-step electrochemical anodization process following a procedure already reported in the literature [8-9]. Diameter and length of AAO nanocavities were controlled by specific parameters of anodization process. Chemical composition of copolymer and copolymerization kinetics was determined by H1-RMN, glass transition by DSC and thermal degradation by TGA. The morphology of AAO templates was characterized by Scanning Electron Microscopy (SEM) and topographical study of free nanopillars was carried out by atomic force microscopy (AFM) and wettability of copolymer by contact angle.BMAx-HEAy copolymers in all range of compositions, where x and y are the BMA and HEA molar fraction in the feed respectively, were synthesized by Atom Transfer Radical Polymerization (ATRP) using EBIB as initiator and Copper/Bipy as catalyst with monomer/Initiator ratio of 100, at 90ºC during 30 minutes previously purged monomer mixture with N2.In case of in-situ copolymerization the substrates were initially modified with 25 mM of α- bromoisobutyryl bromide (containing triethylamine, also in a concentration of 25 mM) in dry THF under N2 at room temperature overnight.Preliminary results showed relevant differences in copolymers compositions and microstructures between copolymers obtained in bulk and confined conditions. The surface properties of free nanopillars showed good properties and potential applications in surface science.