Search Results - "Kricheldorf, Hans"

Polypeptides and 100 Years of Chemistry of α-Amino Acid N-Carboxyanhydrides by Kricheldorf, Hans R.

“…Syntheses and polymerizations of α‐amino acid N‐carboxyanhydrides (NCAs) were reported for the first time by Hermann Leuchs in 1906. Since that time, these…”
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Syntheses of Biodegradable and Biocompatible Polymers by Means of Bismuth Catalysts by Kricheldorf, Hans R

“…Eco-friendly polymers synthesized using bismuth catalysts are explored. Such biodegradable and biocompatible compounds are catalyzed from cyclic esters…”
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The Ring‐Opening Polymerization–Polycondensation (ROPPOC) Approach to Cyclic Polymers by Kricheldorf, Hans R., Weidner, Steffen M.

“…A new concept called ring‐opening polymerization–polycondensation (ROPPOC) is presented and discussed. This synthetic strategy is based on the intermediate…”
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About Polycondensation, Disproportionation, and Cyclization of Acetylated Poly(L‐Lactide) Esters by Kricheldorf, Hans R., Weidner, Steffen M., Meyer, Andreas

“…L‐lactide (LA) is polymerized with ethyl L‐lactate or trifluoroethanol as initiators (LA/In = 30/1), and the resulting poly(L‐lactide) esters are acetylated…”
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Ring-expansion polymerization (REP) of l-lactide with cyclic tin(II) bisphenoxides by Kricheldorf, Hans R., Weidner, Steffen M., Scheliga, Felix

“…[Display omitted] •A new synthetic method for a convenient preparation of novel tin(II) catalysts.•Two of the new catalysts are extraordinarily efficient for…”
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SnOct2‐Catalyzed and Alcohol‐Initiated ROPS of l‐Lactide—Control of the Molecular Weight and the Role of Cyclization by Kricheldorf, Hans R., Weidner, Steffen M., Scheliga, Felix

“…Ring‐opening polymerizations (ROP) of l‐lactide (LA) are conducted in bulk at 130, 160, or 180 °C and are initiated with two different alcohols at 160 °C. The…”
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Syntheses of Polyglycolide via Polycondensation: A Reinvestigation by Kricheldorf, Hans R., Weidner, Steffen M., Meyer, Andreas

“…The Na salt of chloroacetic acid is condensed in suspension. Furthermore, glycolic acid is condensed in bulk or in concentrated solution by means of SnCl2 or…”
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SnOct2-catalyzed and alcohol-initiated ROPs of L-lactide – About the influence of initiators on chemical reactions in the melt and the solid state by Weidner, Steffen M., Meyer, Andreas, Falkenhagen, Jana, Kricheldorf, Hans R.

“…[Display omitted] •The established mechanism of SnOct2-catalyzed and alcohol-initiated ROPs of L-lactide needs modification.•The structure of the initiator has…”
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High molar mass cyclic poly(l-lactide) via ring-expansion polymerization with cyclic dibutyltin bisphenoxides by Kricheldorf, Hans R., Weidner, Steffen M.

“…The purpose of this work is to demonstrate the suitability of a new class of cyclic tin catalysts for a potential racemization-free, technical production of…”
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About the Influence of (Non‐)Solvents on the Ring Expansion Polymerization of l‐Lactide and the Formation of Extended Ring Crystals by Kricheldorf, Hans R., Weidner, Steffen M., Meyer, Andreas

“…Ring‐expansion polymerizations (REPs) catalyzed by two cyclic tin catalysts (2‐stanna‐1.3‐dioxa‐4,5,6,7‐dibenzazepine [SnBiph] and…”
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ROPs of l-lactide catalyzed by neat Tin(II)2-ethylhexanoate - Influence of the reaction conditions on Tm and ΔHm by Meyer, Andreas, Weidner, Steffen M., Kricheldorf, Hans R.

“…l-Lactide was polymerized by means of neat SnOct2 with variation of LA/Cat ratio, temperature and time. The resulting cyclic polylactides crystallized…”
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High molecular weight poly(l‐lactide) via ring‐opening polymerization with bismuth subsalicylate–The role of cocatalysts by Kricheldorf, Hans R., Weidner, Steffen M.

“…The catalytic potential of bismuth subsalicylate (BiSub), a commercial drug, for ring‐opening polymerization of l‐lactide was explored by variation of…”
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Syntheses of high molecular mass polyglycolides via ring‐opening polymerization with simultaneous polycondensation (ROPPOC) by means of tin and zinc catalysts by Kricheldorf, Hans R., Weidner, Steffen M., Meyer, Andreas

“…Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2‐ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro‐phenoxide)…”
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Syntheses of Cyclic Poly(l‐lactide)s by Means of Zinc‐Based Ring‐Opening Polymerization with Simultaneous Polycondensation (ROPPOC) Catalysts by Kricheldorf, Hans R., Scheliga, Felix, Weidner, Steffen M.

“…Ring‐opening polymerizations of l‐lactide are studied in bulk at 140 or 160 °C with zinc n‐hexanoate, zinc 4‐chlorothiophenolate, and zinc pentafluoro…”
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About the transformation of low T m into high T m poly(l-lactide)s by annealing under the influence of transesterification catalysts by Weidner, Steffen M, Meyer, Andreas, Chatti, Saber, Kricheldorf, Hans R

“…Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of…”
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Cyclic poly(l-lactide)s via simultaneous ROP and polycondensation (ROPPOC) catalyzed by dibutyltin phenoxides by Kricheldorf, Hans R., Weidner, Steffen M.

“…[Display omitted] •Better mechanistic understanding of ROPPOC approach.•Synthesis of optically pure cyclic poly(l-lactide)s.•Results in contradiction to…”
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About the influence of salicylic acid on tin(II)octanoate-catalyzed ring-opening polymerization of l-lactide by Kricheldorf, Hans R., Weidner, Steffen M.

“…[Display omitted] •A new catalyst system yielding cyclic poly(l-lactide)s is presented.•The polylactides are optically pure, colorless and have high molar…”
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Matrix‐assisted laser desorption/ionization behavior of neat linear and cyclic poly(L‐lactide)s and their blends by Weidner, Steffen M., Kricheldorf, Hans R.

“…Rationale Numerous new tin catalysts that enable the synthesis of cyclic polylactides with broad variation in their molecular mass were recently developed. The…”
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Ring‐Expansion Polymerization of ε‐Caprolactone, Glycolide, and l‐lactide with a Spirocyclic Tin(IV) Catalyst Derived from or 2,2′‐Dihydroxy‐1,1′‐Binaphthyl – New Results and a Revision by Kricheldorf, Hans R., Weidner, Steffen M., Scheliga, Felix

“…In contrast to other cyclic tin bisphenoxides, polymerizations of glycolide and l‐lactide with the spirocyclic tin(IV) bis‐1,1′‐bisnapthoxide yield linear…”
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Polymerization of l-lactide with SnCl2: A Low Toxic and Eco-friendly Catalyst by Kricheldorf, Hans R., Weidner, Steffen M.

“…Polymerizations of l -lactide catalyzed either by neat SnCl 2 or by SnCl 2  + difunctional cocatalysts were conducted in bulk at 180, 160 and 140 °C with…”
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