![]() The properties of spironaphthoxazines and Reaction occurs both thermally and/or photochemically. Naphthaoxazines.Ĭolorless closed form 1 into the highly blue colored Photoisomerization of 1,3,3-trimethylspiro (SEM) (Hitachi S-2700 SEM) was used to studyįigure 1. Water was observed after freeze-drying the swollen samples for 48 h (Labconco, freeze dry system/įreezone 4.5). Spiro pyranyl CAO bond dissociates followingĪbsorption of UV radiation, converting from its Triphenylmethane leuco dye derivatives, modifiedĪzobenzenes, and spirobenzopyran derivatives.2,6,7,20,32,33 Among a plethora of photochromic compounds, spironaphthoxazines are of particular value because of their resistance to photofatigue and excellent coloring power.34–37 The ![]() Light beam into mechanical energy.2 Many photochromic functionalities have been used including Photo-stimulated conformationalĬhanges at the microscopic level amplify to shapeĬhanges (contraction or expansion) at the macroscopic level, effectively converting energy from a To stimulate conformational changes of polymers Through the introduction of photochromic functionalities, physical and chemical propertyĬhanges following irradiation have been exploited PNIPAAm gels have been widely used for drugĭelivery, as sensors and as media separators.29–31 It.19–28 Because of this characteristic property, Swell in water below the LCST and collapse above Neckers (E-mail: of Polymer Science: Part A: Polymer Chemistry, Vol. These polymeric systemsĬorrespondence to: D. Polymers with a lower critical solution temperature (LCST) (31–32 C) that is close to the physiological temperature. (PNIPAAm) gels are typical thermoresponsi ve Reversibly returning to their initial state with or To more than one stimulus have multiple applications.11–16 In water, hydrogels17,18 can respond toĮxternal stimuli by changing their microstructures from collapsed to expanded as well as by Or solvent composition.1–10 Polymers that respond Respond dramatically to external spurs such asĬhanges in light, pH, temperature, electric field, Stimuli-responsive polymers are of both fundamental and commercial interest. ![]() Keywords: copolymerization hydrogels stimuli-sensitive polymers swelling Q ¼ 0.30) where Q is the amount of water absorbed by a gram of dry polymer. The irradiated PNIPAAm-MSp showed best waterĪbsorption at 0 C (Q ¼ 3.25) while water desorbed at higher temperatures (35 C Irradiation enhanced the water absorption of the polymers while increases Responds to temperature changes whereas the pendant spironaphthoxazines respond The polymers are dual responsive, in that poly(N-isopropylacrylamide) (PNIPAAm) #Shimadzu multispec 1501 schematic free#Published online in Wiley InterScience (Stimuli responsive hydrogels (PNIPAAm-MSp) with a thermoresponsiveīackbone and photochromic pendant groups were synthesized via free radical polymerization using N-isopropylacrylamide, modified spironaphthoxazines with a polymerizable double bond (MSp) as photochromic monomer, the crosslinker N,N0 -methylenebis(acrylamide) and the initiator 2,20 -azobis(isobutyronitrile) in dimethylsulfoxide. ![]() Received 4 March 2009 accepted 9 March 2009 NECKERSĬenter for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403 KULAWARDANA, THILINI KURUWITA-MUDIYANSELAGE, DOUGLAS C. Having Spironaphthoxazines as Pendant GroupsĮRANDIMALA U. Dual Responsive Poly(N-isopropylacrylamide) Hydrogels ![]()
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