UPMC Université Paris 06, UMR 7610, Chimie des Polymères, F-75005 Paris, France.
Beilstein J Org Chem. 2010 Sep 21;6:869-75. doi: 10.3762/bjoc.6.102.
Supramolecular polymers are linear chains of low molar mass monomers held together by reversible and directional non-covalent interactions, which can form gels or highly viscous solutions if the self-assembled chains are sufficiently long and rigid. The viscosity of these solutions can be controlled by adding monofunctional compounds, which interact with the chain extremities: chain stoppers. We have synthesized new substituted ureas and thioureas and tested them as chain stoppers for a bis-urea based supramolecular polymer. In particular, the bis-thiourea analogue of the bis-urea monomer is shown not to form a supramolecular polymer, but a good chain stopper, because it is a strong hydrogen bond donor and a weak acceptor. Moreover, all substituted ureas tested reduce the viscosity of the supramolecular polymer solutions, but the best chain stopper is obtained when two hydrogen bond acceptors are placed in the same relative position as for the monomer and when no hydrogen bond donor is present.
超分子聚合物是由低摩尔质量单体组成的线性链，通过可逆和定向的非共价相互作用结合在一起，如果自组装链足够长且刚性，则可以形成凝胶或高粘性溶液。这些溶液的粘度可以通过添加与链末端相互作用的单官能化合物来控制：链封端剂。我们已经合成了新型取代脲和硫脲，并将其用作基于双脲的超分子聚合物的链封端剂进行了测试。特别是，双脲单体的双硫脲类似物不形成超分子聚合物，而是一种良好的链封端剂，因为它是强氢键供体和弱氢键受体。此外，所有测试的取代脲都降低了超分子聚合物溶液的粘度，但当两个氢键受体以与单体相同的相对位置放置且不存在氢键供体时，可获得最佳的链封端剂。
