Swelling Behavior of Multiresponsive Poly(methacrylic acid)‐block‐‐poly(N‐isopropylacrylamide) Brushes Synthesized Using Surface‐Initiated Photoiniferter‐Mediated Photopolymerization

Abstract

Surface‐initiated photoiniferter‐mediated photopolymerization (SI‐PMP) in presence of tetraethylthiuram disulfide is used to directly synthesize surface‐grafted poly(methacrylic acid)‐block‐poly(N‐isopropylacrylamide) (PMAA‐b‐PNIPAM) layers. The response of these PMAA‐b‐PNIPAM bi‐level brushes to changes in pH, temperature and ionic strength is investigated by using in‐situ multi‐angle ellipsometry to measure changes in solvated layer thickness. As expected for a block copolymer architecture, PMAA blocks swell as pH is increased, with the maximum change in the thickness occurring near pH = 5, and PNIPAM blocks exhibit lower critical solution temperature (LCST) behavior, marked by a broad transition between swollen and collapsed states. The response of the bi‐level brushes to changes in added salt at constant pH is complex, as the swelling behaviors of both the weak polyelectrolyte, PMAA, and thermoresponsive PNIPAM are affected by changes in ionic strength. This work demonstrates not only the robustness of SI‐PMP for making novel, bi‐level stimuli‐responsive brushes, but also the complex links between synthesis, structure, and response of these materials.

Drug encapsulated aerosolized microspheres as a biodegradable, intelligent glioma therapy

“…PNIPAM is an extensively studied polymer due to its sharp, reversible liquid-gel phase transition, demonstrating a lower critical solution temperature (LCST) of about 32 °C in deionized water [76]. Below the LCST, PNIPAM is a liquid, but above the LCST, PNIPAM phase transitions to a gel.…”

“…PNIPAM, a biostable polymer, has been synthesized by numerous polymerizations techniques ranging from atom transfer radial polymerization (ATRP) to surface-initiated, photoiniferter-mediated photopolymerization to reversible addition fragmentation transfer (RAFT) [76,96,97]. However, for the synthesis of a biodegradable PNIPAM, there are only limited reports [98,99].…”

Effect of silver nanoparticle on the properties of poly(methyl methacrylate) nanocomposite network made by in situ photoiniferter-mediated photopolymerization

“…19,20 There are several attempts to synthesis linear and brush PMMA by means of different photoiniferter, e.g., N,N-(diethylamino)dithiocarbamoylbenzyl (trimethoxy)silane (SBDC) 21 and tetraethylthiuram disulphide (TED). [22][23][24][25][26] Moreover, in another work brush and crosslinked hydrogel brushes were from polyacrylamide using SBDC as photoiniferter. 27 Although PMMA/Ag nanocomposites have been synthesized and investigated by several researchers via free radical thermal polymerization 28 and photopolymerization, 5 to the best of our knowledge, no empirical research exists addressing the investigation of AgNP effect on PMMA network properties prepared via living radical photopolymerization, i.e., PMP.…”

Regulation of Stem Cell Fate by Nanomaterial Substrates

“…91 pH responsive biointerfaces are mainly based on poly(acrylic acid) (PAA) and poly(methacrylic acid) PMAA. 118,119 They undergo changes in surface charge and water content similar to thermoresponsive surfaces. Integration of these materials with high aspect ratio topographical features allows the use of pH responsive gels to reversibly modulate the orientation of surface topographical features.…”

“…Dual stimuli responsive surfaces have been prepared as copolymers of NIPAM (temperature responsive) and acrylic acid or methacrylic acid (pH responsive) via surface initiated polymerisations. 118,119 The materials were characterised in terms of wettability 118 and swelling characteristics 119 , displaying changes in these properties in response to either temperature or pH. Biological applications of such materials remain to be demonstrated.…”