Phase Behavior of Poly(N-isopropylmethacrylamide) in Aqueous Solution and Changes in Hydration Observed Yin pohsun 20151215

Outline Review of the Literature Introduction Experimental Results and discussion Conclusion References Future work

Review of the Literature Recently, we have reported FTIR spectroscopic investigation on the coil-globule transition of PiPA, PnPA,and poly(N-cyclopropylacrylamide) in water. IR spectroscopy is a quite suitable method for observing changes in hydration states of individual chemical groups on the polymer chain. In particular, analysis of the amide I band, which is mainly due to the C=O stretching vibration, provides important information concerning hydrogen bonding of the C=O group. In short, the amide I band of PnPA and PiPA observed below Tp contains a single component that can be assigned to C=O----H-O (polymer-water hydrogen bond),whereas, the second component due to C=O----H-N (polymer-polymer hydrogen bond) exists above Tp.

Review of the Literature Poly(N-isopropylacrylamide) (PNIPAM) is a thermoresponsive polymer which is often used as a simple model for proteins. PNIPAM undergoes a lower critical solution temperature (LCST) transition in which collapsed and aggregated structures form upon increasing temperature. Such hydrophobic collapse typically involves both intra- and intermolecular hydrogen bonding. This fact has made PNIPAM particularly useful as a mimic for the cold denaturation of proteins.Also, the influence of salts on the LCST of this polymer has been shown to follow the Hofmeister series, just as is the case for the physical properties of most proteins.

Introduction Thermoresponsive polymer ? Applications of the thermoresponsive polymer： Drug delivery system Bio-conjugate Tissue engineering Biosensor

Poly(N-isopropyl-methacrylamide) Introduction LCST Poly(N-isopropyl-methacrylamide) PNIPMAM The presence or absence of the α-methyl group has a strong effect on the physical structure of water solutions.

Introduction Poly(N-isopropylmethacrylamide) are known to exhibit phase transitions in water at critical temperatures. The phase separations of these polymer solutions are accompanied by large conformational changes in the polymer chains. Have hydtogen bonding ? polymer-H2O hydrogen bonding polymer-polymer hydrogen bonding

Experimental Material Methacryloyl chloride Isopropylamine MAIB Acetonitrile Methanol

Experimental Synthesis of monomer N2 Methylene chloride 100 ml Monomer and inpurity 1mol at 5oC Methylene　chloride 400ml for 3h 1mol recrystallization  purity 99%

Experimental radical polymerization UV light 375nm MAIB 0.02 mol 24h monomer 2mol additive1mol In Diethyl ether to Reprecipitation in CH3CN or MeOH for 0oC, -20 oC,-40oC, respectively

Results and discussion NMR spectra Fig .1 1H NMR spectra of NIPMAm measured in CDCl3 at r.t..

Results and discussion NMR spectra Fig .2 1H NMR spectra of PNIPMAm measured in DMSO at r.t.. Fig .3 13C NMR spectra of PNIPMAm measured in DMSO at 100 oC.

Results and discussion Fig .4 13C NMR spectra of PNIPMAm measured in DMSO at 100 oC.

Results and discussion Table 1. Radical polymerization of NIPMAm with LiNTf2. sample solvent [NIPMAm]0 [LiNTf2]0 [MAIB]0 Temperture Time Yield(%) Tacticitya(%) r dyadb(%) Mnc PDIc NO. (mol/L) (oC) (h) mm mr rr 104 IN1-1 CH3CN 2 1 0.02 24 30.1 0.524 67 33 66.5 1.366 2.362 IN2-2 0.01 16 5.3 n.d. 5.572 2.141 IN2-3 14 3.64 4.101 IN2-4 7.8 5.376 4.474 IN2-8 30.93 55 45 73.5 7.38 6.604 IN2-11 MeOH 15 25 75 87.5 IN2-16 24.9 76 88 IN2-20 -40 6 86 93 IN2-23 -20 16.2 aDetermined by 13C NMR signals of the quaternary carbons.bCalculated with r = rr + 1/2 mr. cDetermined by SEC.

Results and discussion When polymerization use MeOH Syndiotactic mm：0% mr ：55% rr ：45% mm：0% mr ：25% rr ：75% mm：0% mr ：24% rr ：76% Fig . 5 1H NMR spectra of PNIPMAAm measured in DMSO-d6 at -40oC.

Results and discussion Polymerization temperature Syndiotactic Fig . 6 13C NMR spectra of PNIPMAAm measured in DMSO-d6 at 40oC.

Results and discussion Fig .7. Temperature dependence of the light transmittance (500nm) of the aqueous of PNIPMAAm(0.1W/V%,heating and cooling rates = 0.5 oC/min).  

Results and discussion amide I amide II Fig. 8. ATR FTIR spectra of PNIPAM: 10 wt % solution in D2O at (a) 40, (b) 45, (c) 50, (d) 55 ⁰C,(e) 60 ⁰C.

Conclusion With temperature decreases, r dyad increased too. r dyad incerase, Hysteresis increased too. Further by IR analysis the presence or absence of hydration

References Department of Applied Chemistry and Biotechnology, Fukui University, Fukui 910-8507, Japan Received February 6, 2001; Revised Manuscript Received August 10, 2001 Vibrational Spectroscopy 51 (2009) 44–51 dx.doi.org/10.1021/la5026334 | Langmuir 2014, 30, 11433−11441