Free‐Radical Initiated Polymerization of N‐methacryl‐N,N′‐diisopropylurea with Styrene

Abstract

Free‐radical initiated copolymerization of N‐methacryl‐N,N′‐diisopropylurea (MA‐DiPrU) with styrene (St) was performed to low conversion by using dibenzoyl peroxide (Bz₂O₂) in butanone at 70°C. The copolymer composition was calculated on the basis of nitrogen content in copolymers. The reactivity ratios determined by the Kelen‐Tüdös method are: r₁(MA‐DiPrU)=0.39 and r₂(St)=1.03. In all cases, regardless of the monomer‐to‐monomer ratios in the feed, an excess of St was present in copolymers. Copolymers decompose under TGA conditions in nitrogen by a two‐step mechanism. In the first step between 180°C and 250°C, isopropylisocyanate (iPrNCO) separates by degradation of diisopropylurea in the side chain. The thermally stable residue represents the copolymer of methacryl‐isopropylamide (MA‐iPrU) with St, which decomposes by a one‐step mechanism between 280°C and 450°C.

Keywords:

• methacryl‐N,N′‐diisopropylurea
• styrene
• poly(methacryl‐isopropylurea‐co‐styrene)
• poly(methacryl‐isopropylamide‐co‐styrene)
• thermal properties
• thermal degradation
• isopropylisocyanate

Acknowledgment

The Ministry of Science, Education and Sport of Croatia supported this work.