TY  - JOUR
A1  - Behrendt, Felix Nicolas
A1  - Schlaad, Helmut
T1  - Metathesis polymerization of cystine-based macrocycles
JF  - Polymer Chemistry
N2  - Macrocycles based on L-cystine were synthesized by ring-closing metathesis (RCM) and subsequently polymerized by entropy-driven ring-opening metathesis polymerization (ED-ROMP). Monomer conversion reached similar to 80% in equilibrium and the produced poly (ester-amine-disulfide-alkene)s exhibited apparent molar masses (M-w(app)) of up to 80 kDa and dispersities (D) of similar to 2. The polymers can be further functionalized with acid anhydrides and degraded by reductive cleavage of the main-chain disulfide.
Y1  - 2016
U6  - https://doi.org/10.1039/c6py01864e
SN  - 1759-9954
SN  - 1759-9962
VL  - 8
IS  - 2
SP  - 366
EP  - 369
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Behrendt, Felix Nicolas
A1  - Schlaad, Helmut
T1  - Entropy-Driven Ring-Opening Disulfide Metathesis Polymerization for the Synthesis of Functional Poly(disulfide)s
JF  - Macromolecular rapid communications
N2  - Metal-free entropy-driven disulfide metathesis polymerization of unsaturated L-cystine based macrocycles produces high-molar-mass heterofunctional poly(disulfide)s, i.e., poly(ester-disulfide-alkene) and poly(amide-disulfide-alkene); M-w(app) = 44-60 kDa, (sic) > 1.7. The polymerization is fast and reaches equilibrium within 1-5 minutes (monomer conversion 70-90%) in polar aprotic solvents such as N,N-dimethylacetamide, dimethylsulfoxide, or y-valerolactone. Thiol-terminated polymers are stable in bulk or when dissolved in weakly polar solvents, but rapidly depolymerize in dilute polar solution.
KW  - disulfide
KW  - macrocycles
KW  - metathesis
KW  - ring-opening polymerization
Y1  - 2018
U6  - https://doi.org/10.1002/marc.201700735
SN  - 1022-1336
SN  - 1521-3927
VL  - 39
IS  - 6
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Behrendt, Felix Nicolas
A1  - Hess, Andreas
A1  - Lehmann, Max
A1  - Schmidt, Bernd
A1  - Schlaad, Helmut
T1  - Polymerization of cystine-derived monomers
JF  - Polymer Chemistry
N2  - Cystine was used as a platform chemical to prepare cyclic and acyclic monomers for entropy-driven ringopening polymerization (ED-ROMP) via olefin or disulfide metathesis and for step-growth polymerization. The olefin ED-ROMP of an olefin/disulfide containing 16-atom macrocycle using the 3rd generation Grubbs catalyst was examined in greater detail. Kinetic studies revealed that the catalyst turned inactive during the polymerization, which limited the achievable (apparent) polymer molar mass to similar to 70 kg mol(-1). Such limitation could be overcome with the disulfide ED-ROMP of the same macrocycle to yield polymers with molar masses of up to 180 kg mol(-1). The step-growth polymerizations of acyclic diene and dithiol monomers via olefin metathesis or oxidation were far less effective and yielded just low molar mass polymers or oligomers; photopolymerization of a thiol-ene monomer produced a polyester with a molar mass of 35 kg mol(-1).
Y1  - 2019
U6  - https://doi.org/10.1039/c9py00118b
SN  - 1759-9954
SN  - 1759-9962
VL  - 10
IS  - 13
SP  - 1636
EP  - 1641
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Debsharma, Tapas
A1  - Behrendt, Felix Nicolas
A1  - Laschewsky, Andre
A1  - Schlaad, Helmut
T1  - Ring-opening metathesis polymerization of biomass-derived levoglucosenol
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker
N2  - The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.
KW  - degradable polymers
KW  - metathesis
KW  - ring-opening polymerization
KW  - sustainable chemistry
KW  - thermoplastics
Y1  - 2019
U6  - https://doi.org/10.1002/anie.201814501
SN  - 1433-7851
SN  - 1521-3773
VL  - 58
IS  - 20
SP  - 6718
EP  - 6721
PB  - Wiley-VCH
CY  - Weinheim
ER  -