Synthesis and Characterization of Segmented Block Copolymers Based on Hydroxyl-Terminated Liquid Natural Rubber and a,o-Diisocyanato Telechelics Gerhard Maier,* 1,2 Vendula Knopfova, 1 Brigitte Voit, 3 Pham Huu Ly, 4 Bui Tien Dung, 4 Do Bich Thanh 4 1 Lehrstuhl fu ¨r Makromolekulare Chemie, Technische Universita ¨t Mu ¨nchen, Lichtenbergstrasse 4, D-85747 Garching, Germany E-mail: gerhard.maier@ch.tum.de 2 polyMaterials AG, Innovapark 20, D-87600 Kaufbeuren, Germany 3 Institute of Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany E-mail: voit@ipfdd.de 4 Institute of Chemistry, National Center for Natural Sciences and Technology of Vietnam, 18-Hoang Quoc Viet Rd., Cau Giay District, Hanoi, Vietnam E-mail: phly@ich.ncst.ac.vn Received: February 9, 2004; Revised: July 21, 2004; Accepted: July 22, 2004; DOI: 10.1002/mame.200400039 Keywords: block copolymers; ‘‘criss-cross’’-cycloaddition; synthesis; thermoplastic elastomers Introduction Block copolymers allow to combine properties of two or more polymers in a new polymeric product, resulting in materials with tailor-made property profiles. Depending on the ratio, relative position, miscibility, morphology, and glass transition temperature of the different polymeric seg- ments, a wide variety of macroscopic properties can be achieved. Thus, a large number of conventional segmented multiblock copolymers with different structure such as poly(urethane) and poly(ether-esters) were created, result- ing in the formation of thermoplastic elastomers in which the phase separation between the block copolymer seg- ments was shown to be one of the key factors determining the property profile and synergism. [1–3] Segmented block copolymers have been well character- ized by the incompatibility of the segments present and the subsequent phase segregation of the hard and soft segments into separate microdomains. [4,5] Materials based on poly- butadiene, [6–8] polyisobutylene, [9] and polymyrcene [10] soft segments are reported examples for segmented block copolymers with hydrocarbon soft segments. Block co- polymers consisting of non-polar soft segments and polar hard segments which possess high degree of phase separa- tion can be considered as ideal systems for studies of the structure-property relations. [11] This article concerns the synthesis, characterization and study of some physical properties of new segmented block copolymers in which the non-polar soft segments are derived from hydroxyl-terminated liquid natural rubbers Summary: Segmented block copolymers, consisting of non- polar soft segments from hydroxyl-terminated liquid natural rubber (HTNR) and polar hard segments from a,o-diisocya- nato telechelics obtained by ‘‘criss-cross’’-cycloaddition, have been synthesized. The block copolymer formation took place under relatively mild reaction conditions at 80 8C in dichloroethane in the presence of dibutyltin dilaurate as a catalyst. The resulting block copolymers were characterized by spectroscopic techniques ( 1 H NMR, FTIR, UV-vis spec- troscopy) as well as GPC for molar mass determination. The block copolymers were compression molded in a hot stage press, and the resulting samples were characterized by DSC and stress-strain measurement. The solubility and phase morphology of the materials have also been studied. Segmented block copolymer from HTNR and a,o-diisocya- nato telechelics Macromol. Mater. Eng. 2004, 289, 927–932 DOI: 10.1002/mame.200400039 ß 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Full Paper 927