Iterative synthesis of monodisperse pendants for making comb-like polyurethanes

作者：Wu Chien Hsin; Chen Yu Ching; Dai Shenghong A; Chen Su Chen; Tung Shih Huang^*; Lee Rong Ho^*; Su Wen Chiung; Jeng Ru Jong^*

来源：Polymer, 2017, 119: 1-12.

DOI：10.1016/j.polymer.2017.05.014

• Iterative synthesis
• Dendrons
• Polyurethanes
• Shape memory materials

Polyurethanes grafted with well-defined polar pendants were synthesized and investigated. A series of linear and dendritic poly(urea/malonamide)s with uniform chain length were first prepared from an iterative synthesis route, which is based on a dual-functional building block, 4-isocyanate-4 '-(3,3-dimethy1-2,4-dioxo-azetidine)diphenyl methane (IDD). Moreover, side chain polyurethanes (SPUs) bearing azetidine-2,4-dione functional groups were prepared from one pot reaction for following post-functionalization of poly(urea/malonamide)s when IDD-diols were added to polyurethane prepolymers as chain extenders. Subsequently, the azetidine-2,4-dione functional groups on the SPUs underwent addition reactions with amino functional group containing dendritic or linear poly(urea/malonamide)s under mild condition, without the need of catalyst and protection/deprotection procedure to achieve polyurethanes grafted with well-defined pendants. Mechanical properties of these comb-like polyurethanes strongly depend on the architecture and the molecular length of poly(urea/malonamide) pendants, which could be adjusted by the grafting fractions of the dendritic or linear poly(urea/malonamide)s with various generations. These poly(urea/malonamide) pendants provided strong hydrogen bonding interactions to achieve physical crosslinking effects in the polyurethanes. Consequently, the polyurethanes with improved mechanical properties and sustained phase transition exhibit shape memory properties.

• 出版日期2017-6-16