Telechelic Poly(methyl acrylate)s as Constituents for Multiblock Poly(urethane urea)s

Abstract

New poly(urethane urea)s based on telechelic poly(methyl acrylate)s (PMAs) and different diisocyanates and diamines are prepared by a two‐step polyaddition process—formation of an isocyanate telechelic prepolymer followed by chain extension with a diamine to form the final poly(urethane urea)s. Hydroxyl‐telechelic or mixed amino‐hydroxyl‐telechelic PMAs are obtained by two different concepts: (i) according to the first concept methyl acrylate (MA) was polymerized by single electron transfer‐living radical polymerization (SET‐LRP) using 2‐hydroxyethyl 2‐bromoisobutyrate as initiator followed by nucleophilic substitution of the halogen end group with n‐butylamine, 2‐methylamino ethanol, or 3‐amino‐1‐propanol and (ii) according to the second concept after SET‐LRP under the same conditions the halogen end group is converted to an azide followed by a click reaction using sodium azide and propargyl alcohol in a one‐pot reaction. Applying the second concept, a hydroxyl‐functional PMA with a share of 83 mol% bifunctionality is obtained. This PMA‐diol is used in polyaddition reaction with different diisocyanates (isophorone diisocyanate (IPDI), 4,4′‐methylenebis(cyclohexyl isocyanate) (HMDI), and 4,4′‐methylenediphenyl diisocyanate (MDI)) resulting in an isocyanate‐telechelic prepolymer followed by chain extension with the corresponding diamines (isophorone diamine (IPDA), 4,4′‐methylenebis(cyclohexyl amine) (HMDA), and 4,4′‐methylenediphenyl diamine (MDA)). The polyurethane based on hydroxyl‐telechelic PMAs and IPDI/IPDA has a molecular weight of Mn = 44 500 g mol−1 and a dispersity Đ = 3.5, respectively; those based on HMDI/HMDA and MDI/MDA have Mn = 24 600 g mol−1 and Đ = 2.2 and Mn = 16 100 g mol−1 and Đ = 2.0, respectively. image