new dual initiators for polyisobutylene-based block and star polymers

169 Pages·2016·7.57 MB·English

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Dissertations
Spring 5-2012
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Yaling Zhu
University of Southern Mississippi
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Zhu, Yaling, "New Dual Initiators for Polyisobutylene-Based Block and Star Polymers" (2012).
Dissertations. 759.
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The University of Southern Mississippi

NEW DUAL INITIATORS FOR POLYISOBUTYLENE-BASED

BLOCK AND STAR POLYMERS

by

Yaling Zhu

Abstract of a Dissertation
Submitted to the Graduate School
of The University of Southern Mississippi
in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy

May 2012
ABSTRACT

NEW DUAL INITIATORS FOR POLYISOBUTYLENE-BASED

BLOCK AND STAR POLYMERS

by Yaling Zhu

May 2012

Polyisobutylene (PIB), available solely by living carbocationic polymerization
(LCP), is a commercially important polymer with excellent thermal stability, good
flexibility and extraordinary impermeability to gases. Due to these attractive properties,
coupling PIB to other polymer blocks is expected to result in new and useful products.
Two types of new dual initiators possessing initiating sites for both LCP and atom
transfer radical polymerization (ATRP), have been designed for the preparation of AB
linear and A B miktoarm star copolymers, where A is PIB-based block copolymer that
2
grows cationically and B is polyacrylate or other radically-derived polymer block,
without intermediate modification.
Mono-cationic mono-radical dual initiators, 3,3,5-trimethyl-5-chlorohexyl 2-
bromopropionate (IB BP) and 3,3,5-trimethyl-5-chlorohexyl 2-bromo-2-
2
methylpropionate (IB BMP) were synthesized and used to prepare AB linear polymers.
2
PIBs obtained from both initiators showed high efficiency in ATRP initiations of methyl
acrylate (MA), yielding polymers with targeted block length and narrow polydispersity
index (PDI). However, IB BMP and IB BP displayed slow cationic initiation of
2 2
isobutylene (IB) leading to moderate initiation efficiencies (0.50 < I < 0.80) at low
eff
temperature (-70 °C) and low monomer/initiator ratio (82). 3,3,5,5,7-Pentamethyl-7-
chlorooctyl 2-bromo-2-methylpropionate (IB BMP), which differs from IB BMP by the
3 2
ii
inclusion of one additional isobutylene (IB) repeating unit, was then synthesized. It
showed quantitative initiation efficiency (I ~1) in TiCl -co-initiated LCP of IB under
eff 4
various reaction conditions. I and PDI of the resulting PIBs were identical to those
eff
obtained with the standard mono-cationic initiators. The superiority of IB BMP
3
compared to IB BMP in carbocationic initiation was attributed to elimination of
2
through-space interactions between the tert-chloride initiating site and the
TiCl :carbonyl complex at the ATRP initiating site.
4
Di-cationic mono-radical dual initiator 3-[3,5-bis(1-chloro-1-
methylethyl)phenyl]-3-methylbutyl 2-bromo-2-methylpropionate (DCCBMP) was
syntheized for the preparation of miktoarm star copolymers. Initiation efficiency of
DCCBMP was high (0.89 < I < 0.98) for LCP of IB and it was comparable to the
eff
standard di-cationic initiator. Using sequential monomer addition under LCP
conditions, narrow-polydispersity poly(styrene-b-isobutylene-b-styrene) (PS-PIB-PS)
triblock copolymers were prepared, yielding poly(acrylic acid-b-styrene-b-isobutylene) -
2
s-poly(acrylic acid) [(PAA-PS-PIB) -s-PAA] amphiphilic miktoarm star polymer after
2
ATRP of tert-butyl acrylate (tBA) and thermolysis of poly(tert-butyl acrylate) (PtBA)
block. Upon thermolyzing PS-PIB-PS macroinitiator, poly(styrene-b-isobutylene) -s-
2
poly(acrylic acid) [(PS-PIB) -s-PAA] stars were obtained in the same manner.
2
iii
COPYRIGHT BY

YALING ZHU

2012
The University of Southern Mississippi

NEW DUAL INITIATORS FOR POLYISOBUTYLENE-BASED

BLOCK AND STAR POLYMERS

by

Yaling Zhu

A Dissertation
Submitted to the Graduate School
of The University of Southern Mississippi
in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy

Approved:

Robson F. Storey ______________________
Director

Sarah E. Morgan______________________

Sergei I. Nazarenko____________________

William L. Jarrett _____________________

Jeffrey S. Wiggins ____________________

Susan A. Siltanen_____________________
Dean of the Graduate School

May 2012
DEDICATION

To my father, Bingqiu Zhu,
for your endless love and support.

iv
ACKNOWLEDGMENTS

I would like to gratefully and sincerely thank Dr. Robson F. Storey for his
guidance, understanding, and most importantly, his friendship during my graduate studies
at Southern Miss. He taught me how to question thoughts and express ideas, encouraged
me to attend academic conference meetings, and helped me overcome many problems
and finally finished this dissertation. I am also thankful to him for spending so much
time on reading and commenting my manuscripts and helping me to improve my writing
skills with tremendous patience. Thank you, Doc, for everything you have done for me.
I would like to thank polymer science department, especially those members of
my doctoral committee, Dr. Jarrett, Dr. Morgan, Dr. Nazarenko and Dr. Wiggins, for
their input, valuable discussions and accessibility. In particular, I would like to thank Dr.
Morgan, Dr. Jarrett and Dr. Savin, for their insightful advices and support.
Additionally, I am very grateful for the friendship of all of the members of Storey
research group. I would like to thank Lisa Kemp, David Morgan and Irene Gorman, for
their technical guidance and help, and their humor and entertainment outside lab. I would
also like to thank Qi Wu, Ashley Johnson, Jacob Ray, Jianwei Tu, and Yingji Wu, with
whom I worked closely at the end of my graduate study and puzzled over many analysis
problems.
Most importantly, I would like to thank my parents Bingqiu Zhu and Wangjiu
Tian, and my husband Peng Li, for their support, encouragement, patience and love. I
couldn’t have done it without you. I am also grateful to all my friends for their various
forms of support during my graduate study.
v
TABLE OF CONTENTS

ABSTRACT .......................................................................................................................ii
DEDICATION...................................................................................................................iv
ACKNOWLEDGMENTS...................................................................................................v
LIST OF TABLES...........................................................................................................viii
LIST OF ILLUSTRATIONS.............................................................................................ix
LIST OF ABBREVIATIONS..........................................................................................xiii
CHAPTER
I. INTRODUCTION.......................................................................................1
II. DESIGN AND SYNTHESIS OF MONO-CATIONIC MONO-
RADICAL DUAL INITIATORS TO COMBINE LIVING
CARBOCATIONIC POLYMERIZATION AND ATOM TRANSFER
RADICAL POLYMERIZATION.............................................................27

Objective
Experimental
Results and Discussion
Conclusions

III. MODIFICATION OF MONO-CATIONIC MONO-RADICAL DUAL
INITIATORS TO TARGET QUANTITATIVE INITIATION
EFFICIENCY............................................................................................59

Objective
Experimental
Results and Discussion
Conclusions

IV. DESIGN AND SYNTHESIS OF DI-CATIONIC MONO-RADICAL
DUAL INITIATOR FOR POLYISOBUTYLENE-BASED
MIKTOARM STAR POLYMERS............................................................93

Objective
Experimental

vi
Results and Discussion
Conclusions

REFERENCES................................................................................................................135

vii