Crystal Structure and Morphology of Linear Aliphatic n-Polyurethanes

被引:32
作者
Fernandez, C. E. [1 ]
Bermudez, M. [1 ]
Munoz-Guerra, S. [1 ]
Leon, S. [2 ]
Versteegen, R. M. [3 ]
Meijer, E. W. [3 ]
机构
[1] Univ Politecn Cataluna, Dept Engn Quim, ETSEIB, E-08028 Barcelona, Spain
[2] Univ Politecn Madrid, Dept Ingn Quim, ETSII, E-28006 Madrid, Spain
[3] Eindhoven Univ Technol, Lab Macromol & Organ Chem, NL-5600 MB Eindhoven, Netherlands
关键词
INFRARED TEMPERATURE; MOLECULAR-STRUCTURES; NYLON; 46; POLYMERS; CRYSTALLIZATION; DIISOCYANATE; POLYAMIDES; BEHAVIOR;
D O I
10.1021/ma100299p
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
The crystal structure and morphology of a series of linear aliphatic polyurethanes with generic formula -(CH2)(n)OCONH- and containing from 5 to 12 methylene units have been investigated by using TEM combined with X-ray and electron diffraction analysis. Lamellar crystals with a thickness ranging between 5 and 10 nm displaying a variety of crystal habits were obtained by isothermal crystallization from diluted solution in different solvents. A crystal structure similar to that described for the layered alpha-form of nylons seems to be commonly adopted by these polyurethanes. It essentially consists of a triclinic lattice made of hydrogen-bonded sheets with chains in fully extended conformation. Chains within the sheets are arranged in the antiparallel mode giving a normal scheme of hydrogen bonds. Sheets are stacked along the b-axis and progressively shifted along both a and c axes. The interchain and intersheet distances in this lattice are of values similar to those found in nylons. Energy calculations were in agreement with the arrangement proposed for chain packing. X-ray diffraction recorded from heated samples at real times showed that none of these polyurethanes undergoes Brill transition although odd members displayed structural changes concomitant with the occurrence of an unfinished ongoing process. The IR analysis at variable temperature revealed that approximately 50% of hydrogen bonds were retained upon heating at temperatures fairly above melting.
引用
收藏
页码:4161 / 4171
页数:11
相关论文
共 32 条
  • [11] THE CRYSTAL STRUCTURE OF POLYCAPROAMIDE - NYLON-6
    HOLMES, DR
    BUNN, CW
    SMITH, DJ
    [J]. JOURNAL OF POLYMER SCIENCE, 1955, 17 (83): : 159 - 177
  • [12] KINOSHITA Y, 1959, MAKROMOLEKUL CHEM, V33, P1
  • [13] Synthesis methods, chemical structures and phase structures of linear polyurethanes.: Properties and applications of linear polyurethanes in polyurethane elastomers, copolymers and ionomers
    Krol, Plotr
    [J]. PROGRESS IN MATERIALS SCIENCE, 2007, 52 (06) : 915 - 1015
  • [14] Kusan J, 2001, MACROMOL SYMP, V165, P63, DOI 10.1002/1521-3900(200103)165:1<63::AID-MASY63>3.0.CO
  • [15] 2-X
  • [16] Thermodynamics of linear poly(pentamethylene urethane and poly(hexamethylene urethane) in the range from 0 to 450 K
    Lebedev, B
    Kulagina, T
    Smirnova, N
    Markin, A
    Meijer, B
    Versteegen, R
    [J]. MACROMOLECULAR CHEMISTRY AND PHYSICS, 2004, 205 (02) : 230 - 240
  • [17] Synthesis and characterization of polyethylene-like polyurethanes derived from long-chain, aliphatic α,ω-diols
    McKiernan, RL
    Gido, SP
    Penelle, J
    [J]. POLYMER, 2002, 43 (10) : 3007 - 3017
  • [18] Structure of 22,12-polyurethane in chain-folded lamellar crystals
    McKiernan, RL
    Sikorski, P
    Atkins, EDT
    Gido, SP
    Penelle, J
    [J]. MACROMOLECULES, 2002, 35 (22) : 8433 - 8439
  • [19] Influence of hydrogen bonding on the crystallization behavior of semicrystalline polyurethanes
    McKiernan, RL
    Heintz, AM
    Hsu, SL
    Atkins, EDT
    Penelle, J
    Gido, SP
    [J]. MACROMOLECULES, 2002, 35 (18) : 6970 - 6974
  • [20] MUNOZGUERRA S, 1992, J MATER SCI, V27, P89, DOI 10.1007/BF02403648