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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2005-11-18
pubmed:abstractText
N-isopropylacrylamide (NIPA) homopolymers having carboxylic acid-end groups were synthesized by using mercaptoacetic acid (MAA) as the chain transfer agent. Polymerization was achieved in ethanol using azobisisobutyronitrile (AIBN) as the initiator. Average molecular weight of the homopolymer estimated by titration was 1958. This carboxylic acid-ended poly(NIPA) was then copolymerized with polyethylenimine (PEI, M(W)-2000) using a water soluble carbodiimide (EDAC). With respect to carboxyl-ended poly(NIPA), the block copolymers exhibited a pH dependent-temperature sensitivity and higher LCST values in acidic pH. Scanning tunneling microscopy (STM) images of both the homopolymer and the copolymer were obtained at 25 and 45 degrees C with tip-sample bias voltages of up to 800 mV and tunneling currents approximately 1 nA. These images showed that STM can be used to visualize both the formation of copolymer chains and their structure, and also their stimuli-responsive behavior.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9797
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
251
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
424-8
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Observation of phase transition of thermo-responsive poly(NIPA)-PEI block copolymers by STM.
pubmed:affiliation
Department of Chemistry, University of Washington, Seattle, Washington, USA.
pubmed:publicationType
Journal Article