Preparation and swelling properties of homopolymeric alginic acid fractions/poly(N‐isopropyl acrylamide) graft copolymers

Abstract

Graft copolymers of crosslinked poly(N‐isopropyl acrylamide) (PNIPAAm) and homopolyguluronic acid (GG) and homopolymannuronic acid (MM) fractions of alginic acid were synthesized. MM and GG block fractions were obtained by partial acid hydrolysis of the alkaline extract from the brown seaweed Macrocystis pyrifera. The conjugation of these block fractions with the synthetic polymer was achieved by amidation with crosslinked PNIPAAm functionalized with an amino group at the end of the polymer chain. The structure of conjugates was determined by Fourier transform infrared and NMR spectroscopy. Atomic force microscopy of the graft copolymer GG‐g‐PNIPAAm showed a regular porous pattern, whereas the MM‐g‐PNIPAAm graft copolymer showed a regular netlike structure. Aqueous solutions of the synthesized graft copolymers afforded hydrogels by stirring with 0.1M CaCl2. The hydrogels showed a well‐defined stimulus–response to temperature and pH. The swelling, thermal, and pH characterizations demonstrated the superior properties of the GG‐g‐PNIPAAm hydrogel over the MM‐g‐PNIPAAm hydrogel. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42398.

Optimization and characterization of Alginic acid synthesized from a novel strain of Pseudomonas stutzeri

“…6 ); it showed a large doublet centered peak at 4.85 ppm, which was assigned to the anomeric proton resonances of guluronic (G) and manuronic (M) acid residue, which are the two building blocks of alginate and these monomers arrangement can be in GG, MM or GM blocks distributed in a non-regular order along the alginate chain [ 46 ]. These results were similar to those published for fraction of sodium alginate from an algae Macrocystis pyrifera and bacterial alginate from P. aeruginosa respectively [ 47 , 48 ]. The intent signal observed between 4.2 and 5.1 ppm is assigned to alginate G5-H2 moieties of l -glucuronic acid in homopolymeric blocks [ 49 ].…”

“… Fraction M-5 M-3 M-2(M) M-2(G) G-5 G-2 Fig. 6 1 H NMR Spectra of alginate in D 2 O 4.85 4.0 3.99 3.76 3.81 5.1 According to previous Literature Martínez‐Gómez et al [ 47 ] & Gonzalez-Gil et al [ 45 ] 1 H NMR Spectra of alginate in D 2 O 4.65-5.6 4.04-3.90 4.03-3.74 4.14-3.89 4.46-3.76 5.1-4.9 …”

Injectable Thermoresponsive Hydrogel Formed by Alginate-g-Poly(N-isopropylacrylamide) That Releases Doxorubicin-Encapsulated Micelles as a Smart Drug Delivery System

“…The linear PNIPAAm samples had an M n ranging from 3500 to 5200, with a polydispersity index from 1.08 to 1.21, as measured by GPC. The ATRP method allowed for better control of the molecular weight as well as the molecular weight distribution of the linear PNIPAAm, as compared to the previously reported free radical polymerization method . The 1 H NMR spectrum of one PNIPAAm sample (PN 48 ) is shown in Figure .…”

“…Two G-block aligned regions could form a diamond-shaped hole whose dimensions are ideal for the cooperative binding of divalent cations such as calcium ions to form physically cross-linked hydrogels. In previous studies, hydrogels based on alginate and PNIPAAm are formed by a semi-interpenetration network, , addition of calcium ions as physical cross-linker, − addition of glutaraldehyde as chemical cross-linker, or grafting PNIPAAm to alginate. − In addition, alginate- g -PNIPAAm could form self-assembled micelles due to temperature change and doxorubicin (DOX)-encapsulated micelles showed passive accumulation at the tumor site due to the enhanced permeability and retention (EPR) effect …”

Alginate-g-PNIPAM-Based Thermo/Shear-Responsive Injectable Hydrogels: Tailoring the Rheological Properties by Adjusting the LCST of the Grafting Chains

“…Among others, alginate-based graft copolymers [ 7 ] have been designed to form 3D networks through the association of the pendant grafting chains, responding to a trigger like a temperature. In this case, poly( N -isopropylacrylamide), PNIPAM, was mainly used as the type of grafting chain due to its appropriate lower critical solution temperature (LCST), appearing at about 32 °C, below the physiological temperature [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Above a percolation concentration of alginate-g-PNIPAM (gelator) in water, the graft copolymer forms a 3D network upon heating, above a critical temperature, T gel , exhibiting a sol-to-gel transition.…”