Microphase segregation and selective chain scission of poly(2‐methyl‐2‐oxazoline)‐block‐polystyrene

Abstract

Herein, we report the design and synthesis of a block copolymer (BCP) with a high Flory-Huggins interaction parameter to access 10 nm feature sizes for potential lithographic applications. The investigated BCP is poly[(2-methyl-2-oxazoline)-blockstyrene] (PMeOx-b-PS), where the PMeOx segment functions as a hydrophilic segment. Two BCPs with different molecular weights were prepared using PMeOx as macroinitiator for copper(0) mediated controlled radical polymerization. The thin film self-assembly of the obtained PMeOx-b-PS was performed by solvent annealing and investigated by atomic force microscopy. Both polymers formed PMeOx cylinders in a PS matrix with an average cylinder diameter of 10.5 nm. Additionally, the ability of the PMeOx domains to selectively degrade under ultraviolet irradiation was explored. It was shown that scission of the PMeOx block does occur selectively, and furthermore that the degraded domains can be removed while leaving the PS matrix intact. By combining synthetic accessibility, small feature sizes, and a selectively cleavable domain, this new BCP system holds significant promise as a lithographic mask for patterning surfaces with high precision.

Hybrid Multiblock Copolymers of 2-Oxazoline and Acrylates via Cu-Catalyzed Azide–Alkyne Cycloaddition Step-Growth Mechanism

“…Therefore, this further indicates that the majority of the chains have the end-group desired. It should be noted that this end-capping reaction with BMPA and subsequent chain extension have been previously reported with styrene monomers. , The chain extension was also carried out successfully with methyl acrylate (MA) and with other PEtOx-I macroinitiators with different degrees of polymerization (25,40) (Figure S4, ESI ). The kinetic plots for the chain extension with both MA and EHA can be seen in Figure S5, ESI.…”

“…It should be noted that this end-capping reaction with BMPA and subsequent chain extension have been previously reported with styrene monomers. 11,12 The chain extension was also carried out successfully with methyl acrylate (MA) and with other PEtOx-I macroinitiators with different degrees of polymerization (25,40) (Figure S4, ESI).…”

“…8 Previous examples of this include a heterofunctional initiator that was used to combine poly(2oxazoline) with styrene 9 and poly(2-oxazoline)s end-capped with an appropriate initiator for another polymerization technique such as reversible addition−fragmentation chaintransfer polymerization (RAFT) 10 and Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-RDRP). 11,12 Furthermore, different chemistries of each polymer block can lead to interesting physical behavior such as amphiphilicity. 13 Frequently, post-polymerization click reactions such as the thiol−ene reaction 14 and copper(I)-catalyzed azide−alkyne cycloaddition (CuAAC) 15,16 are used as simple techniques to access higher orders of polymeric architecture such as stars, 17 brushes, 18 cyclic polymers, 19 and multiblock polymers.…”

“…Additionally, the side group of 2-oxazoline can be utilized to introduce functional groups, which allow for tuning the physical properties of the polymer. , Poly­(2-oxazoline)­s can further be functionalized by combination with other types of polymerization technique . Previous examples of this include a heterofunctional initiator that was used to combine poly­(2-oxazoline) with styrene and poly­(2-oxazoline)­s end-capped with an appropriate initiator for another polymerization technique such as reversible addition–fragmentation chain-transfer polymerization (RAFT) and Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-RDRP). , Furthermore, different chemistries of each polymer block can lead to interesting physical behavior such as amphiphilicity …”

PLGA's Plight and the Role of Stealth Surface Modification Strategies in Its Use for Intravenous Particulate Drug Delivery

“…The US FDA has approved using one member of the POx family, poly(2-ethyl-2-oxazoline), in food additives, attesting to its low toxicity and general biocompatibility. Extensive literature points to POxylation of biomacromolecules such as polystyrene, [163][164][165] albumin, [166] uricase, [166] liposomes, [167][168][169] and polycaprolactone. [170][171][172] In several reports, the antifouling properties of POx were useful in limiting protein adsorption, [173][174][175] extending particle circulation time, and reducing accumulation in organs of the RES system.…”