70022-27-4

Upstream product

• 95-96-5 D,L-lactide 
• 100-51-6 benzyl alcohol 
• 2051-96-9 benzyl lactate 
• 18162-48-6 tert-butyldimethylsilyl chloride 

Relevant academic research and scientific papers

Janus Graft Block Copolymers: Design of a Polymer Architecture for Independently Tuned Nanostructures and Polymer Properties

The graft-through synthesis of Janus graft block copolymers (GBCPs) from branched macromonomers composed of various combinations of homopolymers is presented. Self-assembly of GBCPs resulted in ordered nanostructures with ultra-small domain sizes down to 2.8 nm (half-pitch). The grafted architecture introduces an additional parameter, the backbone length, which enables control over the thermomechanical properties and processability of the GBCPs independently of their self-assembled nanostructures. The simple synthetic route to GBCPs and the possibility of using a variety of polymer combinations contribute to the universality of this technique.

Selective alcoholysis of lactide catalyzed by bulky Lewis pairs of tris(pentafluorophenyl)borane and phosphines

This study investigated the selective alcoholysis of lactide catalyzed by Lewis pairs, B(C6F5)3-phosphines. Among the phosphines examined in this study, tricyclohexylphosphine (Cy3P) exhibited both high activity

Crystallization Induced Self-Assembly: A Strategy to Achieve Ultra-Small Domain Sizes

Achieving self-assembled nanostructures with ultra-small feature sizes (e. g., below 5 nm) is an important prerequisite for the development of block copolymer lithography. In this work, the preparation and self-assembly of a series of giant molecules composed of vinyl polyhedral oligomeric silsesquioxane (VPOSS) tethered with monodispersed oligo(L-lactide) chains are presented. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) results demonstrate that ultra-small domain sizes (down to 3 nm) of phase separated lamellar morphology are achieved in bulk, driven by the strong tendency and fast kinetics for crystallization of VPOSS moieties. Moreover, upon gamma ray radiation, VPOSS cages in the lamellar structure can be crosslinked via polymerization of the vinyl groups. After pyrolysis at high temperature, ultra-thin two-dimensional nano-silica sheets can be obtained.

Iterative Convergent Synthesis of Large Cyclic Polymers and Block Copolymers with Discrete Molecular Weights

We report here the synthesis of cyclic polymers and block copolymers consisting of discrete numbers of repeating units without linear contaminants. The synthesis utilizes the intramolecular cyclization of end-functionalized poly(rac-lactide) (PLA) and its block copolymers with as many as 512 lactic acid units (37 kDa), synthesized by the iterative linear convergence of orthogonally protected building blocks. By exploiting the change in hydrodynamic volume upon cyclization of the linear polymers, macrocyclic polymers were isolated without linear precursors by preparative size-exclusion chromatography as a purification method. Our procedure also allowed the synthesis of a monodisperse cyclic block copolymer in a desired block ratio as a single compound (14 kDa).

Synthesis and Self-Assembly of Discrete Dimethylsiloxane-Lactic Acid Diblock Co-oligomers: The Dononacontamer and Its Shorter Homologues

Most of the theoretical and computational descriptions of the phase behavior of block copolymers describe the chain ensembles of perfect and uniform polymers. In contrast, experimental studies on block copolymers always employ materials with disperse molecular makeup. Although most polymers are so-called monodisperse, they still have a molecular weight dispersity. Here, we describe the synthesis and properties of a series of discrete length diblock co-oligomers, based on oligo-dimethylsiloxane (oDMS) and oligo-lactic acid (oLA), diblock co-oligomers with highly noncompatible blocks. By utilizing an iterative synthetic protocol, co-oligomers with molar masses up to 6901 Da, ultralow molar mass dispersities (D ≤ 1.00002), and unique control over the co-oligomer composition are synthesized and characterized. This specific block co-oligomer required the development of a new divergent strategy for the oDMS structures by which both bis- and monosubstituted oDMS derivatives up to 59 Si-atoms became available. The incompatibility of the two blocks makes the final coupling more demanding the longer the blocks become. These optimized synthetic procedures granted access to multigram quantities of most of the block co-oligomers, useful to study the lower limits of block copolymer phase segregation in detail. Cylindrical, gyroid, and lamellar nanostructures, as revealed by DSC, SAXS, and AFM, were generated. The small oligomeric size of the block co-oligomers resulted in exceptionally small feature sizes (down to 3.4 nm) and long-range organization.

Acyclic guanidines as organic catalysts for living polymerization of lactide

We describe a facile route to structurally diverse guanidinium organic catalysts by reaction of carbodiimides with secondary amines. The efficacy of these catalysts for the living ring-opening polymerization (ROP) of lactide was demonstrated including predictable molecular weights and end-group fidelity. Theoretical studies indicate that the acyclic guanidines are less basic than 1, 5, 7-triazabicyclo[4.4.0]dec-5-ene (TBD), but as for the more active TBD, they catalyze ring opening by activation of the alcohol and by stabilizing the resultant tetrahedral intermediates through hydrogen bonding. These results demonstrate that weak secondary interactions are an important concept for controlled polymerization.