CaltechAUTHORS
  A Caltech Library Service

Microheterogeneous solutions of amphiphilic copolymers of N-isopropylacrylamide. An investigation via fluorescence methods

Schild, Howard G. and Tirrell, David A. (1991) Microheterogeneous solutions of amphiphilic copolymers of N-isopropylacrylamide. An investigation via fluorescence methods. Langmuir, 7 (7). pp. 1319-1324. ISSN 0743-7463. https://resolver.caltech.edu/CaltechAUTHORS:SCHIl1991c

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:SCHIl1991c

Abstract

Four copolymers of N-isopropylacrylamide (NIPAAM) with N-hexadecylacrylamide (HDAM) were prepared by radical copolymerization. Incorporation of more than 1.5 mol 5% of HDAM renders the copolymers insoluble in water at room temperature. The solution properties of NIPAAM copolymers containing 0.4-1.1 mol 5% HDAM were compared with those of the NIPAAM homopolymer (PNIPAAM). Cloud point and microcalorimetric measurements report lower critical solution temperatures (LCST) for the copolymers that are slightly depressed in comparison with the LCST of PNIPAAM. Fluorescence emission spectra were recorded for four probes (pyrene (11, 1-pyrenecarboxaldehyde (PyCHO, 2), 8-anilino-1-naphthalenesulfonic acid (ANS, 3), and 2-(N-dodecylamino)naphthalene-6-sulfonic acid (C_(12)NS, 4)) dissolved in aqueous solutions of PNIPAAM and of the NIPAAMIHDAM copolymers. Pyrene reports a decrease in polarity (inferred from an abrupt decrease in I_1/I_3) at the LCST of PNIPAAM but reports either no change or a modest increase in polarity in the copolymer solutions. Similar inferences may be drawn from the behavior of C_(12)NS. In contrast, PyCHO reports large polarity losses at the LCST in each of the polymer solutions. The behavior of ANS is intermediate, in that small decreases in polarity are reported at the LCST of each of the copolymers. These results are interpreted in terms of a micellar model for the amphiphilic copolymers in which a relatively nonpolar HDAM core is segregated at room temperature from a hydrated NIPAAM corona. Collapse of the corona at the LCST is accompanied by increased mixing of NIPAAM and HDAM units. The consequences of such mixing in terms of fluorescence emission spectra are strikingly dependent upon the micellar site of probe solubilization.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/la00055a005DOIArticle
http://pubs.acs.org/doi/abs/10.1021/la00055a005PublisherArticle
ORCID:
AuthorORCID
Tirrell, David A.0000-0003-3175-4596
Additional Information:© 1991 American Chemical Society. Received July 19,1990. In Final Form: November 27, 1990. Registry NO. 1,129-00-0; 2,3029-19-4; 3,82-76-8; 4,129985-62-2; (HDAM)(NIPAAM) (copolymer), 125300-01-8; acryloyl chloride, 814-68-6; hexadecylamine, 143-27-1; N-hexadecylacrylamide, 21216-80-8
Issue or Number:7
Record Number:CaltechAUTHORS:SCHIl1991c
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:SCHIl1991c
Official Citation:Microheterogeneous solutions of amphiphilic copolymers of N-isopropylacrylamide. An investigation via fluorescence methods Howard G. Schild and David A. Tirrell Langmuir 1991 7 (7), 1319-1324
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53512
Collection:CaltechAUTHORS
Deposited By: Anne Hormann
Deposited On:23 Jan 2015 23:26
Last Modified:03 Oct 2019 07:50

Repository Staff Only: item control page