Supported Aqueous-Phase Catalysis for Atom Transfer Radical Polymerization

277 Pages·2016·4.34 MB·English

by  Ravi Aggarwal

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Doctoral Dissertations Graduate School
8-2010
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Ravi Aggarwal
University of Tennessee - Knoxville, [email protected]
Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss
Part of the Polymer Chemistry Commons
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Aggarwal, Ravi, "Supported Aqueous-Phase Catalysis for Atom Transfer Radical Polymerization. " PhD
diss., University of Tennessee, 2010.
https://trace.tennessee.edu/utk_graddiss/771
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[email protected].
To the Graduate Council:
I am submitting herewith a dissertation written by Ravi Aggarwal entitled "Supported Aqueous-
Phase Catalysis for Atom Transfer Radical Polymerization." I have examined the final electronic
copy of this dissertation for form and content and recommend that it be accepted in partial
fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry.
Jimmy. W. Mays, Major Professor
We have read this dissertation and recommend its acceptance:
Durairaj Baskaran, Mark Dadmun, Mike Kilbey, Bin Hu
Accepted for the Council:
Carolyn R. Hodges
Vice Provost and Dean of the Graduate School
(Original signatures are on file with official student records.)
To the Graduate Council:

I am submitting herewith a dissertation written by Ravi Aggarwal entitled “Supported
Aqueous-Phase Catalysis for Atom Transfer Radical Polymerization”. I have examined the
final electronic copy of this dissertation for form and content and recommend that it be
accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy,
with a major in Chemistry.

Jimmy Mays, Major Professor

We have read this dissertation
and recommend its acceptance:

Durairaj Baskaran

Mark Dadmun

Michael Kilbey

Bin Hu

Accepted for the Council:

Carolyn R. Hodges
Vice Provost and Dean of the Graduate School

(Original Signatures are on file with official student records.)
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Supported Aqueous-Phase Catalysis
for
Atom Transfer Radical Polymerization

A Dissertation
Presented for the
Doctor of Philosophy Degree
The University of Tennessee, Knoxville

Ravi Aggarwal
August 2010
Translation
Guru is the washer man, disciple is the cloth,
the name of God liken to the soap,
wash the mind on foundation firm,
to realize the glow of truth.
Sant Kabir

Translation

Some food for the stomach is brought,
when the ear gets no food for thought.

Thirukural, Verse 412
Dedication

This work is dedicated to my loving Grandparents and Parents.
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Acknowledgements
Research is never a solitary endeavor and mine has been no different. The work
presented here is the culmination of the questions, the faith and the experiences of a lot many
people who have granted me this opportunity. At the very onset, I would like to acknowledge
the role of my advisor Prof. Durairaj Baskaran, who fulfilled the roles of a friend, philosopher
and guide. This research pursuit has been the most exhilarating at times, to find a mind that so
challenges your boundaries and motivates you to strive for answers. I hope in this work, I was
able to „compartmentalize‟ the ideals and lessons he imparts and stands for. I would also like
to extend my gratitude to my co-advisor Prof. Jimmy Mays for his constant support,
encouragement and guidance through challenging times. I shall forever be indebted to both of
them for this opportunity to grow.
The „catalysts‟ that my parents are, have always supported and encouraged me to
sought knowledge. I still remember the times, when I used to seek the answers to my father‟s
(Sh. Virender. K. Aggarwal) questions about varied topics and here is an attempt to find
answers to some of those. Hope I have been able to „quench‟ some of those queries with this
fledgling venture. My mother (Smt. Kamlesh Aggarwal) has been all that a mother can be and
so much more, to express my gratitude to her is beyond the scope of my lexicon. It has always
been her unconditional love and support that has provided an „interface‟ of hope in the most
difficult times and made life exciting. My sisters (Nidhi and Nisha) have never just been my
younger siblings, but always the rudder that gets one back on course, a fountain of strength
and hope. I would like to thank my brother-in-law (Vishal) who has been supportive of me in
and out. Recently, Nidhi and Vishal have been blessed with a son and I wish them all the
happiness in the world. Also, I couldn‟t be more appreciative of all my uncles, aunts and
cousins for all the love and support they have blessed me with. I would also like to extend
special thanks to my cousin (Dr. Vibha Gupta) and brother-in-law (Dr. Rakesh Gupta) who
were instrumental in helping me to adjust to new surroundings and place when I first came to
USA.
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I have been blessed with „solid supports‟, who have long assisted me at every step of
my developmental trajectory. I would like to sincerely thank my friends (Ashish, Naveen,
Mugdha, Sandeep, Angie, James and David) and all those who responded and gave their time,
honest opinion and encouragement. I hope I have been able to justify their beliefs which were
shared with such honesty.
I would like to acknowledge the contribution of my past and present group members
who have contributed towards my scientific growth. Of the many that have helped me towards
completion of this journey, I would especially like to thank Rahman, George, Haining, Wade,
Brandon, Ildoo, Nick, Trish, Tom and Sachin. Teachers come in all garb and I would like to
take this opportunity to thank them all for all the pains they took.
I know many take delight in this act, my parents, teachers, family and friends, and yet
there are a few like my grandparents (Sh. Laxmi Narayan Aggarwal and Smt. Mahadevi
Aggarwal) whose elation at this culmination would be incomparable to mine. Nonetheless, the
joy to work at this has been mine, the act of seeking answers and getting notions challenged is
a heady and yet humbling experience. It has been an opportunity for which I shall forever be
grateful. And nevertheless I understand that this remains a first step, which questions more
than it answers, and I am thankful to all of the above who have kept me grounded, motivated
and made me aware of the endless future possibilities towards new horizons.

Ravi Aggarwal

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Abstract
Atom transfer radical polymerization (ATRP) which utilizes transition metal based
catalysts is a versatile methodology for the synthesis of a wide spectrum of polymers with
controlled architectures. However, high concentrations of soluble catalyst required in an
ATRP process makes the final polymer colored and toxic. Thus, the catalyst
removal/reduction/recycling remains a challenge in the field of ATRP.
Supported catalysts on insoluble solids such as silica gel, polystyrene beads, etc. have
been used in ATRP to facilitate the catalyst recovery and recycling. However, the ability of
the supported catalysts to mediate a polymerization is substantially reduced due to their
reduced mobility and leaching problems.
In this thesis, we report a series of novel and recyclable physisorbed CuBr /N, N, N’,
2
N’’-pentamethyldiethylene-triamine supported catalytic systems operating in conjunction with
hydration. Supported aqueous-phase catalysis (SAPC) for ATRP was evaluated for different
inorganic (Na-clay, silica and zeolite) and organic (polysaccharides) supports. The hydrated
physisorbed supported catalysts were used for the polymerization of benzyl methacrylate and
methyl methacrylate using an activator generated electron transfer ATRP process.
The catalyst was effectively retained on the surface of supports through hydration as
was verified by UV-Vis measurements. The supported catalyst was easily removed from the
polymerization by simple filtration process affording a colorless polymer solution. The
polymerizations produced high conversion and colorless polymers with moderately narrow
polydispersity indices (PDI). The catalyst maintained high activity during the recycling
experiments.
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We also investigated the kinetic and mechanistic behavior of these solid supported
polymerization systems. Based on split kinetics experiments and UV-Vis studies it was
believed that the activation and deactivation processes took place at the diffused hydrated
interface between the solid support and organic phase.
The branched (stars and graft) polymers were also synthesized using Na-clay
supported catalyst. The produced polymers had narrow PDI and good initiator efficiencies.
The functionality of the star polymers was confirmed using 1H NMR and dilute solution
properties. The synthesis of graft-copolymer was confirmed by 1H NMR and atomic force
microscopy.
This thesis demonstrates the successful use of SAPC for ATRP to produce
contamination free linear and branched polymers with moderately narrow PDI and high
recycling efficiency.
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