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ABSTRACT Cellulose‐based polymer brushes with variable grafting densities and low dispersity were synthesized by grafting poly(n‐butyl acrylate) (PBA) side chains from cellulose‐derived backbones via ATRP. Esterification of commercially available cellulose acetate with 2‐bromoisobutyryl bromide (2‐BiBB) in NMP provided cellulose‐based macroinitiators averaging one initiation site per double glucose unit. ATRP macroinitiators averaging up to 6 initiation sites per repeating double glucose unit were prepared by acylation of microcrystalline cellulose (MCC) in LiCl/DMAc solvent system with 2‐BiBB. A series of linear macroinitiators with narrow MWD were obtained by fractional precipitation process. The content of initiating sites was determined by elemental analysis. (Meth)acrylate side chains were then grafted from the cellulose‐based macroinitiators. The prepared cellulose‐based polymer brushes showed tunable degradation rates dependent on grafting density of the brush, following two different degradation pathways, either cleavage of the main chain or detachment of the side chains. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019,57, 2426–2435 

Model poly(n-butyl acrylate) (PBA) networks were prepared by photoinduced atom transfer radical polymerization (photoATRP), followed by curing of polymer stars via atom transfer radical coupling (ATRC) with a nitrosobenzene radical trap. The resulting nitroxyl radical installed thermally labile alkoxyamine functional groups at the junctions of the network. The alkoxyamine crosslinks of the network were degraded back to star-like products upon exposure to temperatures above 135 °C. Characterization of the degraded products via gel permeation chromatography (GPC) confirmed the inversion of polymer topology after thermal treatment. 

Minimally invasive injection yields robust hydrogels that mimic the mechanics and water fraction of surrounding tissue.