Poly(ε-caprolactone)-poly(isobutylene): A crystallizing, hydrogen-bonded pseudo-block copolymer

The crystallization of block copolymers (BCPs) under homogeneous and heterogeneous nucleation is currently well understood revealing the strong interplay of crystallization in competition to microphase separation. This article reports investigations on synthesis and crystallization processes in weakly interacting supramolecular pseudo‐BCPs, composed of poly(ε‐caprolactone) (PCL) and poly(isobutylene) (PIB) blocks, connected by a specifically interacting hydrogen bond (thymine/2,6‐diaminotriazine). Starting from ring opening polymerization of ε‐caprolactone, the use of “click”‐chemistry enabled the introduction of thymine endgroups onto PCL polymer, thus generating the fully thymine‐substituted pure PCLs (1a, 1b) as judged via NMR and MALDI analysis. Physical mixing of 1a, 1b with a bivalent, bis(2,6‐diaminotriazine)‐containing molecule (2) generated the bivalent polymers BC1 and BC2, whereas mixing of 1a or 1b with the 2,6‐diaminotriazine‐substituted PIB (3) generated the supramolecular pseudo‐BCPs BC3 and BC4. Thermal investigations (DSC, Avrami analysis) revealed only minor changes in the crystallization behavior of BC1–BC4 with Avrami exponents close to three, indicative of a confluence of the growing crystals during the crystallization process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 We present investigations on crystallization processes in supramolecular pseudo‐block copolymers composed of crystallizable poly(ε‐caprolactone) and amorphous poly(isobutylene) (PCL‐b‐PIB) blocks. The blocks are connected via specifically interacting hydrogen‐bonding moieties (thymine/2,6‐diaminotriazine). Because of the presence of hydrogen bonds acting as a partially reversible attractive force between the polymer blocks, the presented systems display a dynamic character during crystallization. Melt rheology and temperature‐dependent IR analyses prove the existence and influence of the supramolecular bonds between blocks. Isothermal crystallization studies reveal Avrami exponents close to three, indicative of a confluence of the growing crystals during the crystallization.