scholarly journals Grafting with RAFT—gRAFT Strategies to Prepare Hybrid Nanocarriers with Core-shell Architecture

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2175
Author(s):  
José L. M. Gonçalves ◽  
Edgar J. Castanheira ◽  
Sérgio P. C. Alves ◽  
Carlos Baleizão ◽  
José Paulo Farinha
Keyword(s):  
Polymer Chains ◽  
Polymer Materials ◽  
Stimuli Responsive ◽  
Grafted Polymer ◽  
Stimuli Responsive Polymers ◽  
Surface Areas ◽  
Cargo Delivery ◽  
Responsive Polymer ◽  
Grafting From ◽  
The Impact

Stimuli-responsive polymer materials are used in smart nanocarriers to provide the stimuli-actuated mechanical and chemical changes that modulate cargo delivery. To take full advantage of the potential of stimuli-responsive polymers for controlled delivery applications, these have been grafted to the surface of mesoporous silica particles (MSNs), which are mechanically robust, have very large surface areas and available pore volumes, uniform and tunable pore sizes and a large diversity of surface functionalization options. Here, we explore the impact of different RAFT-based grafting strategies on the amount of a pH-responsive polymer incorporated in the shell of MSNs. Using a “grafting to” (gRAFT-to) approach we studied the effect of polymer chain size on the amount of polymer in the shell. This was compared with the results obtained with a “grafting from” (gRAFT-from) approach, which yield slightly better polymer incorporation values. These two traditional grafting methods yield relatively limited amounts of polymer incorporation, due to steric hindrance between free chains in “grafting to” and to termination reactions between growing chains in “grafting from.” To increase the amount of polymer in the nanocarrier shell, we developed two strategies to improve the “grafting from” process. In the first, we added a cross-linking agent (gRAFT-cross) to limit the mobility of the growing polymer and thus decrease termination reactions at the MSN surface. On the second, we tested a hybrid grafting process (gRAFT-hybrid) where we added MSNs functionalized with chain transfer agent to the reaction media containing monomer and growing free polymer chains. Our results show that both modifications yield a significative increase in the amount of grafted polymer.

scholarly journals Effect of Structure of Polymers Grafted from Graphene Oxide on the Compatibility of Particles with a Silicone-Based Environment and the Stimuli-Responsive Capabilities of Their Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 591 ◽  
Author(s):  
Monika Zygo ◽  
Miroslav Mrlik ◽  
Marketa Ilcikova ◽  
Martina Hrabalikova ◽  
Josef Osicka ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Graphene Oxide ◽  
Radical Polymerization ◽  
Polymer Brushes ◽  
Silicone Oil ◽  
Polymer Chains ◽  
Butyl Methacrylate ◽  
Raman Shift ◽  
Stimuli Responsive ◽  
Grafted Polymer

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.

scholarly journals Stimuli-responsive polymers and their applications

2017 ◽  
Vol 8 (1) ◽  
pp. 127-143 ◽  
Author(s):  
Menglian Wei ◽  
Yongfeng Gao ◽  
Xue Li ◽  
Michael J. Serpe
Keyword(s):  
Drug Delivery ◽  
Physical Properties ◽  
Artificial Muscles ◽  
Stimuli Responsive ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Responsive Polymer ◽  
External Stimuli

Responsive polymer-based materials are capable of altering their chemical and/or physical properties upon exposure to external stimuli. This review highlights their use for sensing and biosensing, drug delivery, and artificial muscles/actuators.

Emerging applications of stimuli-responsive polymer materials

2010 ◽  
Vol 9 (2) ◽  
pp. 101-113 ◽  
Author(s):  
Martien A. Cohen Stuart ◽  
Wilhelm T. S. Huck ◽  
Jan Genzer ◽  
Marcus Müller ◽  
Christopher Ober ◽  
...  
Keyword(s):  
Polymer Materials ◽  
Stimuli Responsive ◽  
Responsive Polymer ◽  
Stimuli Responsive Polymer

Stimuli-responsive polymer-based systems for diagnostic applications

2020 ◽  
Vol 8 (32) ◽  
pp. 7042-7061 ◽  
Author(s):  
Tong Shu ◽  
Liang Hu ◽  
Qiming Shen ◽  
Li Jiang ◽  
Qiang Zhang ◽  
...  
Keyword(s):  
Molecular Diagnostics ◽  
Stimuli Responsive ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Responsive Polymer ◽  
Diagnostic Applications ◽  
Stimuli Responsive Polymer

The unique properties of stimuli-responsive polymers make them valuable for myriad applications, their use for biosensing and molecular diagnostics is reviewed here.

Self-Storage: A Novel Family of Stimuli-Responsive Polymer Materials for Optical and Electrochemical Switching

2014 ◽  
Vol 35 (22) ◽  
pp. 1943-1948 ◽  
Author(s):  
Yixiao Dong ◽  
Chaocan Zhang ◽  
Lili Wu ◽  
Yanjun Chen ◽  
Yuanyuan Hu
Keyword(s):  
Polymer Materials ◽  
Stimuli Responsive ◽  
Responsive Polymer ◽  
Stimuli Responsive Polymer

Coaxial nanotubes of stimuli responsive polymers with tunable release kinetics

Soft Matter ◽  
2015 ◽  
Vol 11 (41) ◽  
pp. 8069-8075 ◽  
Author(s):  
Efe Armagan ◽  
Gozde Ozaydin Ince
Keyword(s):  
Release Kinetics ◽  
Polymer Chemistry ◽  
Stimuli Responsive ◽  
Release Rates ◽  
Polymer Layers ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Responsive Polymer ◽  
Tunable Release ◽  
Stimuli Responsive Polymer

Coaxial nanotubes with different stimuli responsive polymer layers demonstrate triggered response with release rates that can be controlled by tuning the polymer chemistry.

scholarly journals Adamantane Functionalized Poly(2-oxazoline)s with Broadly Tunable LCST-Behavior by Molecular Recognition

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 374
Author(s):  
Joachim F. R. Van Guyse ◽  
Debaditya Bera ◽  
Richard Hoogenboom
Keyword(s):  
Phase Transition ◽  
Molecular Recognition ◽  
High Specificity ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Side Chains ◽  
Stimuli Responsive ◽  
Thermal Transitions ◽  
Stimuli Responsive Polymers ◽  
Interactive Behavior

Smart or adaptive materials often utilize stimuli-responsive polymers, which undergo a phase transition in response to a given stimulus. So far, various stimuli have been used to enable the modulation of drug release profiles, cell-interactive behavior, and optical and mechanical properties. In this respect, molecular recognition is a powerful tool to fine-tune the stimuli-responsive behavior due to its high specificity. Within this contribution, a poly(2-oxazoline) copolymer bearing adamantane side chains was synthesized via triazabicyclodecene-catalyzed amidation of the ester side chains of a poly(2-ethyl-2-oxazoline-stat-2-methoxycarbonylpropyl-2-oxazoline) statistical copolymer. Subsequent complexation of the pendant adamantane groups with sub-stoichiometric amounts (0–1 equivalents) of hydroxypropyl β-cyclodextrin or β-cyclodextrin enabled accurate tuning of its lower critical solution temperature (LCST) over an exceptionally wide temperature range, spanning from 30 °C to 56 °C. Furthermore, the sharp thermal transitions display minimal hysteresis, suggesting a reversible phase transition of the complexed polymer chains (i.e., the β-cyclodextrin host collapses together with the polymers) and a minimal influence by the temperature on the supramolecular association. Analysis of the association constant of the polymer with hydroxypropyl β-cyclodextrin via 1H NMR spectroscopy suggests that the selection of the macrocyclic host and rational polymer design can have a profound influence on the observed thermal transitions.

scholarly journals Tailoring and Remotely Switching Performance of Ultrafiltration Membranes by Magnetically Responsive Polymer Chains

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 219
Author(s):  
Anh Vu ◽  
Arijit Sengupta ◽  
Emily Freeman ◽  
Xianghong Qian ◽  
Mathias Ulbricht ◽  
...  
Keyword(s):  
Polymer Chains ◽  
Superparamagnetic Nanoparticles ◽  
Regenerated Cellulose ◽  
Pore Surface ◽  
Permeate Flux ◽  
Ultrafiltration Membranes ◽  
Surface Polymerization ◽  
Grafted Polymer ◽  
Rejection Coefficient ◽  
Grafting From

Magnetically responsive ultrafiltration membranes were prepared by grafting poly(2-hydroxyethyl methacrylate) chains from the outer surface of 100-kDa regenerated cellulose ultrafiltration membranes. Surface-initiated atom transfer radical polymerization was used to graft the polymer chains. Grafting from the internal pore surface was suppressed by using glycerol as a pore-filling solvent during initiator immobilization at varied densities. Glycerol suppresses the initiator attachment to the pore surface. Polymerization times of up to four hours were investigated. Superparamagnetic nanoparticles were covalently attached to the chain end. Membrane performance was determined using bovine serum albumin and dextran as model solutes. Increasing the grafted polymer chain density and length led to a decrease in the permeate flux and an increase in the apparent rejection coefficient. In an oscillating magnetic field, movement of the grafted polymer chains led to a decrease in the permeate flux, as well as an increase in the apparent rejection coefficient of the model solutes.

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