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Abstract  

The miscibility of poly(N-isopropylacrylamide) (PNIPA) with poly(vinyl pyrrolidone) (PVP) and a cross-linked poly(acrylic acid) (Carbopol 971P) was evaluated from the rheological data of aqueous dispersions and the temperature of glass transitions of films made of binary mixtures. PNIPA has a low critical solubility temperature (LCST) of about 33C, below which 1% dispersion behaves as a viscous system. At temperatures above LCST, the hydrophobic interactions among the isopropyl groups initially provide transient networks of greater elasticity. The LCST of PNIPA as well as its T g (144C, estimated by DSC and MTDSC of films) were not modified by the presence of PVP. The immiscibility of PNIPA and PVP was confirmed by the absence of interaction between both polymers as shown by FTIR analysis of the films. In contrast, PNIPA and carbopol were miscible and the behaviour of their mixtures differed significantly from that of the parent polymers; i.e. a strong synergistic effect on the viscoelasticity of the dispersions was observed below the LCST. As temperature increased, the blends showed a decrease in the loss and storage moduli, especially those with greater PNIPA proportions. The fall was smoother as the PNIPA proportion decreased. This behaviour may be explained as the result of the balance between PNIPA/carbopol hydrogen bonding interactions (as shown in the shift of C=O stretch in FTIR spectra) and PNIPA/PNIPA hydrophobic interactions. The T g values of the films of the blends showed a positive deviation from the additivity rule; the mixtures containing more than 1:1 amide:carboxylic acid groups have a notably high Tg (up to 181C). This increase is related to the stiffness induced in the films by the PNIPA/carbopol interactions.

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methods Materials Aceclofenac was used as received from Tecoland (New Jersey, USA). The examined additives in the retard tablets were Carbopol 940 (Noveon Consumer Specialties, Ohio, USA), hydroxypropyl-methyl-cellulose (HPMC

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Interventional Medicine and Applied Science
Authors: Kamal Dua, Venkata Ramana Malipeddi, Jyotsna Madan, Gaurav Gupta, Srikumar Chakravarthi, Rajendra Awasthi, Irene Satiko Kikuchi, and Terezinha De Jesus Andreoli Pinto

evaluate their antimicrobial activity and burn wound-healing efficacy and compare with Silver Sulfadiazine 1% cream, USP. Materials and Methods NF and MTZ (Pfiscar India Ltd., Murthal, Haryana, India) and Carbopol (Noveon, Mumbai

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Journal of Thermal Analysis and Calorimetry
Authors: Carmen Rodríguez-Tenreiro, Carmen Alvarez-Lorenzo, Ángel Concheiro, and J. Torres-Labandeira

Abstract  

The interactions between Carbopol and β-cyclodextrin (BCD) or hydroxypropyl-β-cyclodextrin (HPBCD) were studied by differential scanning calorimetry (DSC) and FTIR spectroscopy. Aqueous solutions of both components were desiccated by freeze-drying or heating in an oven (films) at various temperatures. The use of different drying procedures allowed their influence on the interactions to be studied. The evolution of the Carbopol glass-transition was also evaluated by DSC using first heating runs up to different temperatures. Disappearance of the Carbopol glass-transition was observed in the freeze-dried systems prepared with either of the cyclodextrins and in the films that contained HPBCD. The changes in the FTIR band of Carbopol at 1700 cm-1 confirmed the existence of interactions with both cyclodextrins, especially with HPBCD. This information may be useful for optimising the solubilizing capacity and controlled release performance of aqueous Carbopol-cyclodextrin systems.

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.L.: Safety and efficacy of an inactivated Carbopol-adjuvanted goose haemorrhagic polyomavirus vaccine for domestic geese. Avian Pathol 39 (2), 111–116 (2010). Guerin J.L. Safety and

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737 743 López-Cacho, J.M., González- R, P.L., Talero, B., Rabasco, A.M. & González-Rodríguez, M.L. (2012): Robust optimization of alginate-carbopol 940 bead

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Journal of Thermal Analysis and Calorimetry
Authors: José Lamartine Soares-Sobrinho, Monica Felts de La Roca Soares, Pedro José Rolim-Neto, and Juan J. Torres-Labandeira

– 539 10.1016/j.ejpb.2007.03.005 . 9. Rodriguez-Tenreiro , C , Alvarez-Lorenzo , C , Concheiro , A , Torres-Labandeira , JJ 2004 Characterization of cyclodextrin–carbopol

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8 . 2. Mayo-Pedrosa , M , Alvarez-Lorenzo , C , Concheiro , A . Thermorheological and glass transition properties of PNIPA/PVP and PNIPA/Carbopol blends . J Therm Anal Calorim

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. , Martins-Green , M. : Improved burn wound healing by the antimicrobial peptide LLKKK18 released from conjugates with dextrin embedded in a carbopol gel . Acta Biomater 26 , 249 – 262 ( 2015 ). 10.1016/j.actbio.2015

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