@article{JiangMansfeldFangetal.2018, author = {Jiang, Yi and Mansfeld, Ulrich and Fang, Liang and Kratz, Karl and Lendlein, Andreas}, title = {Temperature-induced evolution of microstructures on poly[ethylene-co-(vinyl acetate)] substrates switches their underwater wettability}, series = {Materials \& design}, volume = {163}, journal = {Materials \& design}, publisher = {Elsevier}, address = {Oxford}, issn = {0264-1275}, doi = {10.1016/j.matdes.2018.12.002}, pages = {10}, year = {2018}, abstract = {Material surfaces with tailored aerophobicity are crucial for applications where gas bubble wettability has to be controlled, e.g., gas storage and transport, electrodes, bioreactors or medical devices. Here, we present switchable underwater aerophobicity of hydrophobic polymeric substrates, which respond to heat with multilevel micro-and nanotopographical changes. The cross-linked poly[ethylene-co-(vinyl acetate)] substrates possess arrays of microcylinders with a nanorough top surface. It is hypothesized that the specific micro-/nanotopography of the surface allows trapping of a water film at the micro interspace and in this way generates the aerophobic behavior. The structured substrates were programmed to a temporarily stable, nanoscale flat substrate showing aerophilic behavior. Upon heating, the topographical changes caused a switch in contact angle from aerophilic to aerophobic for approaching air bubbles. In this way, the initial adhesion of air bubbles to the programmed flat substrate could be turned into repellence for the recovered substrate surface. The temperature at which the repellence of air bubbles starts can be adjusted from 58 +/- 3 degrees C to 73 +/- 3 degrees C by varying the deformation temperature applied during the temperature-memory programming procedure. The presented actively switching polymeric substrates are attractive candidates for applications, where an on-demand gas bubble repellence is advantageous. (c) 2018 Helmholtz-Zentrum Geesthacht, Zentrum fur Material- und Kustenforschung. Published by Elsevier Ltd.}, language = {en} } @article{ZhangRudolphBenitezetal.2019, author = {Zhang, Quanchao and Rudolph, Tobias and Benitez, Alejandro J. and Gould, Oliver E. C. and Behl, Marc and Kratz, Karl and Lendlein, Andreas}, title = {Temperature-controlled reversible pore size change of electrospun fibrous shape-memory polymer actuator based meshes}, series = {Smart materials and structures}, volume = {28}, journal = {Smart materials and structures}, number = {5}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0964-1726}, doi = {10.1088/1361-665X/ab10a1}, pages = {10}, year = {2019}, abstract = {Fibrous membranes capable of dynamically responding to external stimuli are highly desirable in textiles and biomedical materials, where adaptive behavior is required to accommodate complex environmental changes. For example, the creation of fabrics with temperature-dependent moisture permeability or self-regulating membranes for air filtration is dependent on the development of materials that exhibit a reversible stimuli-responsive pore size change. Here, by imbuing covalently crosslinked poly(ε-caprolactone) (cPCL) fibrous meshes with a reversible bidirectional shape-memory polymer actuation (rbSMPA) we create a material capable of temperature-controlled changes in porosity. Cyclic thermomechanical testing was used to characterize the mechanical properties of the meshes, which were composed of randomly arranged microfibers with diameters of 2.3 ± 0.6 μm giving an average pore size of approx. 10 μm. When subjected to programming strains of εm = 300\% and 100\% reversible strain changes of εʹrev = 22\% ± 1\% and 6\% ± 1\% were measured, with switching temperature ranges of 10 °C-30 °C and 45 °C-60 °C for heating and cooling, respectively. The rbSMPA of cPCL fibrous meshes generated a microscale reversible pore size change of 11\% ± 3\% (an average of 1.5 ± 0.6 μm), as measured by scanning electron microscopy. The incorporation of a two-way shape-memory actuation capability into fibrous meshes is anticipated to advance the development and application of smart membrane materials, creating commercially viable textiles and devices with enhanced performance and novel functionality.}, language = {en} } @article{PengBehlZhangetal.2018, author = {Peng, Xingzhou and Behl, Marc and Zhang, Pengfei and Mazurek-Budzynska, Magdalena and Feng, Yakai and Lendlein, Andreas}, title = {Synthesis of Well-Defined Dihydroxy Telechelics by (Co)polymerization of Morpholine-2,5-Diones Catalyzed by Sn(IV) Alkoxide}, series = {Macromolecular bioscience}, volume = {18}, journal = {Macromolecular bioscience}, number = {12}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-5187}, doi = {10.1002/mabi.201800257}, pages = {11}, year = {2018}, abstract = {Well-defined dihydroxy telechelic oligodepsipeptides (oDPs), which have a high application potential as building blocks for scaffold materials for tissue engineering applications or particulate carrier systems for drug delivery applications are synthesized by ring-opening polymerization (ROP) of morpholine-2,5-diones (MDs) catalyzed by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane (Sn(IV) alkoxide). In contrast to ROP catalyzed by Sn(Oct)(2), the usage of Sn(IV) alkoxide leads to oDPs, with less side products and well-defined end groups, which is crucial for potential pharmaceutical applications. A slightly faster reaction of the ROP catalyzed by Sn(IV) alkoxide compared to the ROP initiated by Sn(Oct)(2)/EG is found. Copolymerization of different MDs resulted in amorphous copolymers with T(g)s between 44 and 54 degrees C depending on the molar comonomer ratios in the range from 25\% to 75\%. Based on the well-defined telechelic character of the Sn(IV) alkoxide synthesized oDPs as determined by matrix-assisted laser desorption/ionization time of flight measurements, they resemble interesting building blocks for subsequent postfunctionalization or multifunctional materials based on multiblock copolymer systems whereas the amorphous oDP-based copolymers are interesting building blocks for matrices of drug delivery systems.}, language = {en} } @article{SchmidtBehlLendleinetal.2014, author = {Schmidt, Christian and Behl, Marc and Lendlein, Andreas and Beuermann, Sabine}, title = {Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {66}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra06815g}, pages = {35099 -- 35105}, year = {2014}, abstract = {Polyglycolide (PGA) is a biodegradable polymer with multiple applications in the medical sector. Here the synthesis of high molecular weight polyglycolide by ring-opening polymerization of diglycolide is reported. For the first time stabilizer free supercritical carbon dioxide (scCO(2)) was used as a reaction medium. scCO(2) allowed for a reduction in reaction temperature compared to conventional processes. Together with the lowering of monomer concentration and consequently reduced heat generation compared to bulk reactions thermal decomposition of the product occurring already during polymerization is strongly reduced. The reaction temperatures and pressures were varied between 120 and 150 degrees C and 145 to 1400 bar. Tin(II) ethyl hexanoate and 1-dodecanol were used as catalyst and initiator, respectively. The highest number average molecular weight of 31 200 g mol(-1) was obtained in 5 hours from polymerization at 120 degrees C and 530 bar. In all cases the products were obtained as a dry white powder. Remarkably, independent of molecular weight the melting temperatures were always at (219 +/- 2)degrees C.}, language = {en} } @article{MelchertYongvongsoontornBehletal.2012, author = {Melchert, Christian and Yongvongsoontorn, Nunnarpas and Behl, Marc and Lendlein, Andreas}, title = {Synthesis and characterization of telechelic oligoethers with terminal cinnamylidene acetic acid moieties}, series = {Journal of applied biomaterials \& functional materials}, volume = {10}, journal = {Journal of applied biomaterials \& functional materials}, number = {3}, publisher = {Wichtig}, address = {Milano}, issn = {2280-8000}, doi = {10.5301/JABFM.2012.10364}, pages = {185 -- 190}, year = {2012}, abstract = {Purpose: The formation of photoresponsive hydrogels were reported by irradiation of star-shaped poly(ethylene glycol)s with terminal cinnamylidene acetic acid (CAA) groups, which are capable of a photoinduced [2+2] cycloaddition. In this study we explored whether oligo(ethylene glycol) s and oligo(propylene glycol)s of varying molecular architecture (linear or star-shaped) or molecular weights could be functionalized with CAA as terminal groups by esterification or by amide formation. Methods: Oligo(ethylene glycol) (OEG) and oligo(propylene glycol) (OPG) with varying molecular architecture (linear, star-shaped) and weight average molecular weights between 1000 and 5000 g.mol(-1) were functionalized by means of esterification of hydroxyl or amine endgroups with cinnamylidene acetic acid (CAA) or cinnamylidene acetyl chloride (CAC) as telechelic endgroups. The chemical structure, thermal properties, and molecular weights of the oligoethers obtained were determined by NMR spectroscopy, UV spectroscopy, DSC, and MALDI-TOF. Results: CAA-functionalized linear and star-shaped OEGs or OPGs could be obtained with a degree of functionalization higher than 90\%. In MALDI-TOF measurements an increase in Mw of about 150 g.mol(-1) (for each terminal end) after the functionalization reaction was observed. OEGCAA and OPGCAA showed an increase in glass transition temperature (T-g) from about -70 degrees C to -50 degrees C, compared to the unfunctionalized oligoethers. In addition, the melting temperature (T-m) of OEGCAA decreased from about 55 C to 30 degrees C, which can be accounted for by the hampered crystallization of the precursors because of the bulky CAA end groups as well as by the loss of the hydroxyl telechelic end groups. Conclusion: The synthesis of photoresponsive oligoethers containing cinnamylidene acetic acid as telechelic endgroup was reported and high degrees of functionalization could be achieved. Such photosensitive oligomers are promising candidates as reactive precursors, for the preparation of biocompatible high molecular weight polymers and polymer networks.}, language = {en} } @article{PengBehlZhangetal.2017, author = {Peng, Xingzhou and Behl, Marc and Zhang, Pengfei and Mazurek-Budzyńska, Magdalena and Feng, Yakai and Lendlein, Andreas}, title = {Synthesis and characterization of multiblock poly(ester-amide-urethane)s}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {2}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, publisher = {Cambridge University Press}, address = {Cambridge}, issn = {2059-8521}, doi = {10.1557/adv.2017.486}, pages = {2551 -- 2559}, year = {2017}, abstract = {In this study, a multiblock copolymer containing oligo(3-methyl-morpholine-2, 5-dione) (oMMD) and oligo(3-sec-butyl-morpholine-2, 5-dione) (oBMD) building blocks obtained by ring-opening polymerization (ROP) of the corresponding monomers, was synthesized in a polyaddition reaction using an aliphatic diisocyanate. The multiblock copolymer (pBMD-MMD) provided a molecular weight of 40, 000 g·mol-1, determined by gel permeation chromatography (GPC). Incorporation of both oligodepsipeptide segments in multiblock copolymers was confirmed by 1H NMR and Matrix Assisted Laser Desorption/Ionization Time Of Flight Mass Spectroscopy (MALDI-TOF MS) analysis. pBMD-MMD showed two separated glass transition temperatures (61 °C and 74 °C) indicating a microphase separation. Furthermore, a broad glass transition was observed by DMTA, which can be attributed to strong physical interaction i.e. by H-bonds formed between amide, ester, and urethane groups of the investigated copolymers. The obtained multiblock copolymer is supposed to own the capability to exhibit strong physical interactions.}, language = {en} } @article{FriessLendleinWischke2021, author = {Frieß, Fabian and Lendlein, Andreas and Wischke, Christian}, title = {Switching microobjects from low to high aspect ratios using a shape-memory effect}, series = {Soft matter}, volume = {17}, journal = {Soft matter}, number = {41}, publisher = {Royal Society of Chemistry}, address = {London}, issn = {1744-6848}, doi = {10.1039/d1sm00947h}, pages = {9326 -- 9331}, year = {2021}, abstract = {Spherical particles from shape-memory polymers (SMP) can be stretched to ellipsoids with high aspect ratio (AR) and temporarily stabilized. They can switch back to low AR upon thermal stimulation. Here, the creation of an alternative shape-switching capability of particles from low to high AR is introduced, where a SMP matrix from polyvinyl alcohol (PVA) is used to create crosslinked high AR particles and to program the embedded micrometer-sized particles from a second SMP (oligo(epsilon-caprolactone) micronetworks, MN) with a low switching temperature T-sw. This programming proceeds through shape-recovery of the PVA matrix, from which the MN are harvested by PVA matrix dissolution. The use of a dissolvable SMP matrix may be a general strategy to efficiently create systems with complex moving capabilities.}, language = {en} } @article{WischkeBaehrRachevaetal.2018, author = {Wischke, Christian and Baehr, Elen and Racheva, Miroslava and Heuchel, Matthias and Weigel, Thomas and Lendlein, Andreas}, title = {Surface immobilization strategies for tyrosinase as biocatalyst applicable to polymer network synthesis}, series = {MRS Advances}, volume = {3}, journal = {MRS Advances}, number = {63}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {2059-8521}, doi = {10.1557/adv.2018.630}, pages = {3875 -- 3881}, year = {2018}, abstract = {Enzymes have recently attracted increasing attention in material research based on their capacity to catalyze the conversion of polymer-bound moieties for synthesizing polymer networks, particularly bulk hydrogels. hi this study. the surface immobilization of a relevant enzyme. mushroom tyrosinase, should be explored using glass as model surface. In a first step. the glass support was functionalized with silanes to introduce either amine or carboxyl groups, as confirmed e.g. by X-ray photoelectron spectroscopy. By applying glutaraldehyde and EDC/NHS chemistry, respectively, surfaces have been activated for subsequent successful coupling of tyrosinase. Via protein hydrolysis and amino acid characterization by HPLC, the quantity of bound tyrosinase was shown to correspond to a full surface coverage. Based on the visualized enzymatic conversion of a test substrate at the glass support. the functionalized surfaces may be explored for surface-associated material synthesis in the future.}, language = {en} } @article{LangeBrauneLuetzowetal.2012, author = {Lange, Maik and Braune, Steffen and Luetzow, Karola and Richau, Klaus and Scharnagl, Nico and Weinhart, Marie and Neffe, Axel T. and Jung, Friedrich and Haag, Rainer and Lendlein, Andreas}, title = {Surface functionalization of poly(ether imide) membranes with linear, methylated oligoglycerols for reducing thrombogenicity}, series = {Macromolecular rapid communications}, volume = {33}, journal = {Macromolecular rapid communications}, number = {17}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201200426}, pages = {1487 -- 1492}, year = {2012}, abstract = {Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as thrombocyte adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers.}, language = {en} } @article{FedericoNoechelLoewenbergetal.2016, author = {Federico, Stefania and N{\"o}chel, Ulrich and L{\"o}wenberg, Candy and Lendlein, Andreas and Neffe, Axel T.}, title = {Supramolecular hydrogel networks formed by molecular recognition of collagen and a peptide grafted to hyaluronic acid}, series = {Acta biomaterialia}, volume = {38}, journal = {Acta biomaterialia}, publisher = {Elsevier}, address = {Oxford}, issn = {1742-7061}, doi = {10.1016/j.actbio.2016.04.018}, pages = {1 -- 10}, year = {2016}, abstract = {The extracellular matrix (ECM) is a nano-structured, highly complex hydrogel, in which the macromolecules are organized primarily by non-covalent interactions. Here, in a biomimetic approach, the decorin-derived collagen-binding peptide LSELRLHNN was grafted to hyaluronic acid (HA) in order to enable the formation of a supramolecular hydrogel network together with collagen. The storage modulus of a mixture of collagen and HA was increased by more than one order of magnitude (G\&\#8242; = 157 Pa) in the presence of the HA-grafted peptide compared to a mixture of collagen and HA (G\&\#8242; = 6 Pa). The collagen fibril diameter was decreased, as quantified using electron microscopy, in the presence of the HA-grafted peptide. Here, the peptide mimicked the function of decorin by spatially organizing collagen. The advantage of this approach is that the non-covalent crosslinks between collagen molecules and the HA chains created by the peptide form a reversible and dynamic hydrogel, which could be employed for a diverse range of applications in regenerative medicine. Statement of Significance Biopolymers of the extracellular matrix (ECM) like collagen or hyaluronan are attractive starting materials for biomaterials. While in biomaterial science covalent crosslinking is often employed, in the native ECM, stabilization and macromolecular organization is primarily based on non-covalent interactions, which allows dynamic changes of the materials. Here, we show that collagen-binding peptides, derived from the small proteoglycan decorin, grafted to hyaluronic acid enable supramolecular stabilization of collagen hydrogels. These hydrogels have storage moduli more than one order of magnitude higher than mixtures of collagen and hyaluronic acid. Furthermore, the peptide supported the structural organization of collagen. Such hydrogels could be employed for a diverse range of applications in regenerative medicine. Furthermore, the rational design helps in the understanding ECM structuring.}, language = {en} }