When convergent syntheses of graft block copolymers diverge: The treachery of chemical images

Abstract

A synthetic strategy to produce graft block copolymers (BCPs) with controlled grafting densities using both graftingthrough and grafting-from methods is reported. For graftingthrough, poly(4-methylcaprolactone-block-D,L-lactide) macromonomers were synthesized with a polymerizable maleimide end group. These macromonomers were copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization with styrene and various amounts of N-ethylmaleimide to control grafting density. A kinetic study showed that the macromonomers (>10 kDa) polymerized at the same rate as N-ethylmaleimide under RAFT conditions, suggesting that uniform grafting density could be achieved. However, incorporating more than 5-10 grafts per chain was found to be challenging and potentially limited by kinetics. A higher number of grafts per chain with controlled densities was achieved using a grafting-from technique. Macroinitiators of styrene, N-ethylmaleimide, and N-(2-hydroxyethyl)maleimide were copolymerized with a fixed density of grafting sites. Subsequently, BCPs were grown off of the macroinitiator using ring-opening transesterification polymerization (ROTEP).

Physical Aging of Polylactide-Based Graft Block Polymers

“…Scheme shows the grafting-from synthesis of model graft BCPs with the chemical structure of poly­[(styrene- alt - N -hydroxyethylmaleimide)- stat -(styrene- alt - N -ethylmaleimide)]- graft -(P4MCL block -PLA). This synthetic strategy affords control over the grafting density, number of grafts, graft molar mass, and PLA volume fraction …”

“…This synthetic strategy affords control over the grafting density, number of grafts, graft molar mass, and PLA volume fraction. 51 Four model graft polymers were prepared with PLA volume fractions ranging from 0.8 to 1.0. Details on the synthesis and characterization data are provided in the Supporting Information; Table 1 lists the molecular characterization for all of the model polymers.…”

“…Poly­[(styrene- alt - N -hydroxyethylmaleimide)-random-(styrene- alt - N -ethylmaleimide)]- graft -[poly­(4-methyl caprolactone)- block -PLA] graft BCPs were prepared as reported by Maher et al Linear triblock PLA- block -poly­(4-methyl caprolactone)- block -PLA BCPs were prepared by ring-opening transesterification polymerization as described by Watts et al Linear 100% PLA (NatureWorks 4060D, M n = 45.3 kg/mol) was purchased from NatureWorks. In all cases, the polymers were prepared using a racemic (±) lactide monomer, resulting in an amorphous PLA.…”

Scalable synthesis of an architectural library of well‐defined poly(acrylic acid) derivatives: Role of structure on dispersant performance

“…As an illustrative example, polyethylene, one of the simplest and most widely used commodity polymers, can be either a high strength or ductile material, depending on the degree of backbone branching . Significantly, solubility, crystallinity, and morphology are also dictated by polymer architecture . While a systematic understanding of the influence of these structural features on polymer properties would be highly beneficial, studies that tune and compare architectural isomers are synthetically challenging.…”

“…4 Significantly, solubility, crystallinity, and morphology are also dictated by polymer architecture. [5][6][7][8][9][10][11][12] While a systematic understanding of the influence of these structural features on polymer properties would be highly beneficial, studies that tune and compare architectural isomers are synthetically challenging. and filler particles (e.g., calcium carbonate, CaCO 3 ), with the specific aim of achieving uniform dispersions, improving particle stability, and increasing the dispersant efficiency.…”