Polyurethanes based on polyacrylate-soft segments and PU-hard segments for cosmetic application (2016)

Since the ‘50s, hairstyling products have always been in evolution and many polymers were developed to satisfy customers. Nowadays, hairstyling products have to maintain the hairstyle by natural holding. For the chemist, getting polymers which combine hold and flexibility of hair are new challenges. Moreover the VOC (Volatile Organic Compounds) regulation applied in US tends to be introduced in Europe, which makes some restrictions for formulators. Polyurethanes generally based on polyester-diol or polyether-diol are interesting with regard to good flexibility of the hairstyle and to be used in low VOC formulations. Polyacrylates are also remarkable due to their good interactions with the hair and to provide the hold. The goal of this thesis was to synthesize a new polymer which combines the properties of polyacrylates and polyurethanes. The thesis is composed of three main parts: the synthesis of hydroxyl-telechelic polyacrylates, the preparation of polyurethanes based on the synthesized polyacrylates and the performance of these polyurethanes on hair. For the synthesis of hydroxyl-telechelic polyacrylates, two different controlled radical polymerizations were chosen: (i) Atom Transfer Radical Polymerization (ATRP) and (ii) Single Electron Transfer-Living Radical Polymerization (SET-LRP); and two different post-polymerization modifications were studied: (i) nucleophilic substitution and (ii) click reaction. Methyl acrylate (MA) and methyl methacrylate (MMA) were used as monomers; and methyl dichloroacetate (MDCA), ethyl dibromoacetate (EDBA) and in some cases 2-hydroxyethyl 2-bromoisobutyrate (HEBIB) were used as bifunctional initiators. Nucleophilic substitutions were performed with n-butylamine, 2-methylamino ethanol and 3-amino-1-propanol; and propargyl alcohol was tested for click reaction. Regarding the end-group fidelity determined by MALDI-TOF analyses, the best route to obtain hydroxyl-telechelic polyacrylates was the SET-LRP of MA with HEBIB as initiator followed by nucleophilic substitution of the bromine end-groups by azide and click reaction with propargyl alcohol performed in an one-pot reaction. Hydroxyl-telechelic PMAs with a molecular weight of 2000g/mol were obtained with a share of 83 mol% functionality of 2. Polyurethanes (PUs) based on these hydroxyl-telechelic PMAs were obtained by successive addition of diisocyanates and diamines. Isophorone diisocyanate (IPDI), 4,4’-methylenebis(cyclohexyl isocyanate) (HMDI) and 4,4’-methylenediphenyl diisocyanate (MDI) were used as diisocyanates; while isophorone diamine (IPDA), 4,4’-methylenebis(cyclohexyl amine) (HMDA) and 4,4’-methylenediphenyl diamine (MDA) as diamines. High molecular weights of PUs were obtained which prove the high degree of bifunctionality of the hydroxyl-telechelic PMAs used as starting materials – for example PU based on PMA, IPDI and IPDA had a molecular weight of 44500 g/mol with a dispersity of 3.5. After this synthetic part, PUs based on PMA, IPDI and IPDA were applied on hair in order to determine theperformance of these new products and compare them to the traditional PUs based on polyether-diol (with poly(THF)) or polyester-diol (with poly(ε-caprolactone)), IPDI and IPDA. The interaction of PU based on PMA and the hair fibers seems to be more adhesive and stiffer than the other PUs. Moreover, by increasing the molecular weight of PU, the wash-ability of the final product was worse, but the styling retention was improved.