Development of dual-sensitive smart polymers by grafting chitosan with poly (<italic>N</italic>-isopropylacrylamide): an overview

Abstract

A great deal of research on polymers over the past two decades has been focused on the development of stimuli-responsive polymers to obtain materials able to respond to specific surroundings. In this paper, an overview is presented of the concepts, behavior and applicability of these "smart polymers". Polymers that are temperature-or pH-sensitive are discussed in detail, including the response mechanisms and types of macromolecules, because they are easy to handle and have a wide range of applications. Finally, the combination of pH and temperature responsive properties by means of graft copolymerization of chitosan with poly (N-isopropylacrylamide) (PNIPAM) was chosen to represent some synthetic routes and properties of dual-sensitive polymeric systems developed currently.

Ultrasound-assisted synthesis of polyacrylamide-grafted sodium alginate and its application in dye removal

“…Polysaccharides derivatives have many potential applications such as hydrogel, tissue engineering, cell immobilization, food applications and have also been used extensively as adsorbents for contaminants removal from polluted water [1,2] . The solubility, hydrophobicity, physicochemical properties, and biological characteristics of the polysaccharides can be modified by reacting the hydroxyl and carboxyl groups with suitable compounds through derivatization of the functional groups [3][4][5] , grafting [6,7] , oxidative reactions [8] , and/or hydrolytic degradation [9] .…”

“…A convenient method to produce polysaccharide derivatives is the grafting of synthetic polymers onto the polysaccharide backbone [6,7,10,11] . Alginate grafted with acrylamide obtained by conventional, gamma rays and microwaves methods has frequently been used as polyelectrolyte in drug delivery [1,12,13] , flocculant [14][15][16] and adsorbent in dyes removal [17] .…”

Membranas termossensíveis baseadas em redes poliméricas semi-interpenetrantes de Quitosana e Poli(N-isopropilacrilamida)

“…Membranas termossensíveis a base de quitosana também são obtidas a partir da síntese de copolímeros graftizados de QUI-g-PNIPAm (HONGQIAN, et al, 2010;MARQUES, et al, 2015).…”

Preparação de micropartículas de quitosana incorporadas de nanogéis de poli-(N-vinilcaprolactama-<i>co</i>-ácido itacônico-<i>co</i>-dimetacrilato de etilenoglicol) via secagem por pulverização para liberação controlada de cetoprofeno

“…O aumento da temperatura fornece ao sistema a entalpia necessária para o rompimento de ligações hidrogênio, favorecendo o predomínio de interações hidrofóbicas entre cadeias poliméricas (polímero-polímero). Ao atingir a LCST, as cadeias poliméricas antes solvatadas, perdem solubilidade, assumindo uma estrutura de glóbulo compacto (SCHATTLING et al, 2014;MARQUES et al, 2015). (SUDHAKAR et al, 2015;LIU et al, 2014).…”

“…Quando o pH do meio é superior ao pk a dos grupos aniônicos ou inferior ao pk a dos grupos catiônicos, os grupos ácido ou bases ionizados, respectivamente, repelem entre si e as cadeias poliméricas se afastam, proporcionando um aumento do volume hidrodinâmico ocupado por essas cadeias. Em contrapartida, quando o pH do meio é inferior ao pk a dos grupos aniônicos ou superior ao pk a dos grupos catiônicos, o grau de ionização desses grupos diminui e as cadeias se aproximam causando a diminuição do volume hidrodinâmico do sistema (Figura 2.6) (MARQUES et al, 2015). Alguns exemplos de polieletrólitos estudados para aplicações biomédicas estão apresentados na Tabela 2.2.…”