TY - JOUR
T1 - Preparation of ultrahigh molecular weight syndiotactic poly(vinyl alcohol) microfibrillar fibers by low-temperature solution polymerization of vinyl pivalate in tertiary butyl alcohol and saponification
AU - Lyoo, Won Seok
AU - Kim, Sam Soo
AU - Ghim, Han Do
AU - Kim, Jae Pil
AU - Lee, Sang Seob
PY - 2002/8/29
Y1 - 2002/8/29
N2 - Vinyl pivalate (VPi) was solution polymerized in tertiary butyl alcohol (TBA) and in dimethyl sulfoxide (DMSO) with a low chain transfer constant using a low temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN). The effects of polymerization temperature and initiator concentration were investigated in terms of polymerization behavior and molecular structures of poly(vinyl pivalate) (PVPi) and its Saponification product poly(vinyl alcohol) (PVA). TBA was absolutely superior to DMSO in increasing the syndiotacticity and molecular weight of PVA. In contrast, TBA was inferior to DMSO in causing conversion to polymer, indicating that the initiation rate of VPi production in TBA was lower than that in DMSO. These effects could be explained by a kinetic order of ADMVN concentration, calculated by the initial rate method. Low-temperature solution polymerization of VPi in TBA or DMSO by adopting ADMVN proved to be successful in obtaining PVA of ultrahigh molecular weight [maximum number-average degree of polymerization (Pn): 13,500-17,000] and of high yield (ultimate conversion of VPi into PVPi: 55-83%). In the case of bulk polymerization of VPi at the same conditions, maximum Pn and conversion were 14,500-17,500 and 22-36%, respectively. The Pn and syndiotactic diad content were much higher and the degree of branching was lower with PVA prepared from PVPi polymerized at lower temperatures in TBA. Moreover, PVA from the TBA system was fibrous, with a high degree of orientation of the crystallites, indicating the syndiotactic nature of TBA polymerization.
AB - Vinyl pivalate (VPi) was solution polymerized in tertiary butyl alcohol (TBA) and in dimethyl sulfoxide (DMSO) with a low chain transfer constant using a low temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN). The effects of polymerization temperature and initiator concentration were investigated in terms of polymerization behavior and molecular structures of poly(vinyl pivalate) (PVPi) and its Saponification product poly(vinyl alcohol) (PVA). TBA was absolutely superior to DMSO in increasing the syndiotacticity and molecular weight of PVA. In contrast, TBA was inferior to DMSO in causing conversion to polymer, indicating that the initiation rate of VPi production in TBA was lower than that in DMSO. These effects could be explained by a kinetic order of ADMVN concentration, calculated by the initial rate method. Low-temperature solution polymerization of VPi in TBA or DMSO by adopting ADMVN proved to be successful in obtaining PVA of ultrahigh molecular weight [maximum number-average degree of polymerization (Pn): 13,500-17,000] and of high yield (ultimate conversion of VPi into PVPi: 55-83%). In the case of bulk polymerization of VPi at the same conditions, maximum Pn and conversion were 14,500-17,500 and 22-36%, respectively. The Pn and syndiotactic diad content were much higher and the degree of branching was lower with PVA prepared from PVPi polymerized at lower temperatures in TBA. Moreover, PVA from the TBA system was fibrous, with a high degree of orientation of the crystallites, indicating the syndiotactic nature of TBA polymerization.
KW - Fibrous
KW - High yield
KW - Poly(vinyl alcohol) (PVA)
KW - Syndiotacticity
KW - Tertiary butyl alcohol (TBA)
KW - Ultrahigh molecular weight
KW - Vinyl pivalate (VPi)
UR - http://www.scopus.com/inward/record.url?scp=0037194692&partnerID=8YFLogxK
U2 - 10.1002/app.10800
DO - 10.1002/app.10800
M3 - Article
AN - SCOPUS:0037194692
SN - 0021-8995
VL - 85
SP - 1992
EP - 2003
JO - Journal of Applied Polymer Science
JF - Journal of Applied Polymer Science
IS - 9
ER -