@article{IzraylitGouldKratzetal.2020,
  author    = {Izraylit, Victor and Gould, Oliver E. C. and Kratz, Karl and Lendlein, Andreas},
  title     = {Investigating the phase-morphology of PLLA-PCL multiblock copolymer/PDLA blends cross-linked using stereocomplexation},
  series = {MRS advances},
  volume    = {5},
  journal   = {MRS advances},
  number    = {14-15},
  publisher = {Cambridge Univ. Press},
  address   = {New York},
  issn      = {2059-8521},
  doi       = {10.1557/adv.2019.465},
  pages     = {699 -- 707},
  year      = {2020},
  abstract  = {The macroscale function of multicomponent polymeric materials is dependent on their phase-morphology. Here, we investigate the morphological structure of a multiblock copolymer consisting of poly(L-lactide) and poly(epsilon-caprolactone) segments (PLLA-PCL), physically cross-linked by stereocomplexation with a low molecular weight poly(D-lactide) oligomer (PDLA). The effects of blend composition and PLLA-PCL molecular structure on the morphology are elucidated by AFM, TEM and SAXS. We identify the formation of a lattice pattern, composed of PLA domains within a PCL matrix, with an average domain spacing d0 = 12 - 19 nm. The size of the PLA domains were found to be proportional to the block length of the PCL segment of the copolymer and inversely proportional to the PDLA content of the blend. Changing the PLLA-PCL / PDLA ratio caused a shift in the melt transition Tm attributed to the PLA stereocomplex crystallites, indicating partial amorphous phase dilution of the PLA and PCL components within the semicrystalline material. By elucidating the phase structure and thermal character of multifunctional PLLA-PCL / PDLA blends, we illustrate how composition affects the internal structure and thermal properties of multicomponent polymeric materials. This study should facilitate the more effective incorporation of a variety of polymeric structural units capable of stimuli responsive phase transitions, where an understanding the phase-morphology of each component will enable the production of multifunctional soft-actuators with enhanced performance.},
  language  = {en}
}
@article{SchoeneSchulzRichauetal.2014,
  author    = {Sch{\"o}ne, Anne-Christin and Schulz, Burkhard and Richau, Klaus and Kratz, Karl and Lendlein, Andreas},
  title     = {Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments},
  series = {Macromolecular chemistry and physics},
  volume    = {215},
  journal   = {Macromolecular chemistry and physics},
  number    = {24},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201400377},
  pages     = {2437 -- 2445},
  year      = {2014},
  abstract  = {A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt\% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments.},
  language  = {en}
}
@article{SauterKratzLendlein2013,
  author    = {Sauter, Tilman and Kratz, Karl and Lendlein, Andreas},
  title     = {Pore-size distribution controls shape-memory properties on the macro- and microscale of polymeric foams},
  series = {Macromolecular chemistry and physics},
  volume    = {214},
  journal   = {Macromolecular chemistry and physics},
  number    = {11},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201300062},
  pages     = {1184 -- 1188},
  year      = {2013},
  abstract  = {Open porous foams with identical foam density but different pore-size distributions (bimodal or monomodal) are prepared from a shape-memory polyetherurethane (PEU) by thermally induced phase separation. The shape-memory effect of the two PEU foams is explored by cyclic thermomechanical compression tests and microstructural analysis. The obtained results reveal that the PEU foam with a bimodal pore-size distribution exhibits an increased shape-recovery under stress-free conditions, both on the macro- (foam level) as well as the microscale (pore level). While bimodal pore-size distributions induce microscale bending during compression, buckling occurs in foams with monomodal pore-size distributions, leading to both a reduced and delayed shape recovery.},
  language  = {en}
}